+

WO1996005347A1 - Materiaux composites a base de fibres de jute et de kenaf et procedes de production - Google Patents

Materiaux composites a base de fibres de jute et de kenaf et procedes de production Download PDF

Info

Publication number
WO1996005347A1
WO1996005347A1 PCT/US1995/010098 US9510098W WO9605347A1 WO 1996005347 A1 WO1996005347 A1 WO 1996005347A1 US 9510098 W US9510098 W US 9510098W WO 9605347 A1 WO9605347 A1 WO 9605347A1
Authority
WO
WIPO (PCT)
Prior art keywords
fiber
thermoplastic
fibers
polypropylene
method recited
Prior art date
Application number
PCT/US1995/010098
Other languages
English (en)
Inventor
Paul W. Skillicorn
Garry E. Balthes
Original Assignee
Skillicorn Paul W
Balthes Garry E
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Skillicorn Paul W, Balthes Garry E filed Critical Skillicorn Paul W
Publication of WO1996005347A1 publication Critical patent/WO1996005347A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N1/00—Pretreatment of moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
    • B27N3/04—Manufacture of substantially flat articles, e.g. boards, from particles or fibres from fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B9/00—Making granules
    • B29B9/12—Making granules characterised by structure or composition
    • B29B9/14—Making granules characterised by structure or composition fibre-reinforced

Definitions

  • the present invention relates to the field of fiber reinforced structures and more particularly to the use of jute and kenaf fibers to reinforce thermoplastic compositions including polypropylene.
  • Manufacturing materials of many types are employed in various services for the production of structures and packaging.
  • containers are often made of wood for its strength and weight characteristics, but it has low tolerance to its environment where water, through absorption, and other agents may cause rotting and denigration of its integrity and strength.
  • the structure's life cycle is shortened requiring further wood resources to make new containers and creating a disposal problem for the wood from previously used containers.
  • most wood product containers are hammered shut and pried open repeatedly, which tends to wear out the product and increase its susceptibility to rotting and breakdown.
  • Agro-wastes and wood flour have played an important role in the plastics industry.
  • the earliest phenolics were mixed with wood flour to reduce cost and improve the processing of the resin.
  • the use of lignocellulosic material as fillers in thermoplastics such as polyethylene and polypropylene has, however, been limited, because of difficulties associated with surface instructions.
  • the inherent polar and hydrophilic nature of the fibers and the nonpolar characteristics of the polyolefins result in difficulties in compounding of these materials and poor-stress-transfer efficiencies.
  • Commonly used coupling agents in fiber-composite production do not function efficiently in lignocellulosic-polyolefin systems and may be too expensive
  • Plastics are increasingly employed in place of wood in many structures. Plastics offer the advantages of enhanced resistance to the ambient environment. Some plastics, however, can harden, crack, and suffer loss in performance and damage to structural characteristics. Certain plastics, known as high-end plastics, have higher resistance to aging and environmental effects as well as improved structural characteristics. Their extremely high cost, however, make them impractical for use in most applications. Application of high-end plastics is further limited by their high material density which can often result in unacceptably high product weight
  • Creep is a major issue with structural material manufactured of thermoplastics. Under load conditions, the popular low-end structural thermoplastics, primarily polypropylene and high density polyethylene, experience
  • plastics With plastics, the structural shapes which enhance the strength to weight ratio of products and material are obtained by molding. Molded materials have significant advantages over carved, cut, hewn or otherwise reduction-formed material in that there are no dead loss of material, such as shavings, sawdust, and odd pieces. This is a significant disadvantage of wood. This moldability advantage of plastics, however, is still unsufficient to overcome the cost and/or inherent structural limitations of plastics in many applications. High-end plastics are still too expensive, and low end plastics do not, themselves, have adequate structural properties.
  • plastics are non-polar, fillers such as wood and paper are difficult to bond to the plastic material. In such cases, the filler may actually cause the resulting composite to have inferior characteristics with respect to the use of the plastic alone.
  • the principal advantage in the use of such materials becomes that of extending the
  • the finished product will typically have lower tensile strength characteristics than the underlying thermoplastic matrix.
  • Materials of high strength such as carbon fibers, glass fiber, mica, Wollastanite (calcium metasilicate [CaSiO 3 ]) and other material, bond more readily with thermoplastics to produce a high strength composite, but they add prohibitively to the cost.
  • Such composites are fine for, high-valued specialty applications where material costs represent only a minor element in the total item cost (or value), or such applications, as in airplane and rocket parts, where item cost is relatively unimportant, and strength-for- weight is an overriding consideration. Use of these materials in large, high volume applications is typically prohibitive.
  • Some of the more popular fillers reinforcers are also highly abrasive materials. Significant damage can be caused to compounding and molding equipment. The dramatically high price of metal molds and dies can make this type of damage extremely costly. Abrasiveness is also an inherent quality problem in the finished product. Once the smooth finish on the abraisive-reinforced plastic material is scratched, it will interact with other abrasive surfaces to wear down the scratched surface itself, as well as any adjacent surface with which it may come into contact.
  • Plastic products reinforced with abraisive materials can be harmful to humans who handle and work near or with those products. Dermal and respiratory irritation, including possibility of the presence of carcinogenic agents as fillers, are limiting factors for glass fiber and other substances, including wollastanite, and asbestos. While packaging has been cited as an example, a vast array of other applications could benefit from use of a low cost reinforcing material in a low-end plastic.
  • Typical consumer products that would benefit include boxes, large item housings and other packaging; children's play sets, toys and play houses; luggage shells and reinforcing; bulk packaging including containers and crates used with containerized shipping, home appliances, tools, refrigerators, home furnishings, and furniture; industrial sector packaging of fasteners, parts, pharmaceuticals, food stuffs, manufactured goods, supplies, construction materials, and automotive products; drums for dry goods packaging and storage; boxes; harvesting bins; dry waste bins; household and kitchen products, including storage devices, racks, hangers, liners, and furniture framing and base material; construction/building materials, including wall, ceiling and floor paneling, temporary, interlocking flooring and walkways for
  • buildings and construction sites permanent, interlocking flooring and roofing for buildings (replacing plywood), shaped, reusable interlocking forms for concrete work, molded joints, connectors, pieces for housing and construction, "work pieces” for building and construction, reusable, movable work benches, saw horses; highway devices including signposts, barriers and molded crash containers; automotive parts including under-the-hood housings and molded interior trim material.
  • a single component should not exceed the shot capacity of the injection molding machine being utilized to produce the structurally enhanced article.
  • Parts manufactured using continuous extrusion processes, multiple shot/batch press, vacuum or rotational forming, and preformed mat material can, however, be very large structures.
  • Natural fibers have been considered as strengthening agents for plastics
  • jute-like fibers such as jute, kenaf, roselle, aramina and sunnhemp Crotalaria junce ⁇
  • the long cellulosic fibers of jute-like plants are the world's most abundant natural fiber source, after cotton. Fibers from jute, kenaf, roselle, aramina and sunnhemp share similar characteristics.
  • Table 1 presents a typical fiber profile:
  • Diameter 10 to 20 ⁇ m range, length: 2 to 10 mm
  • Fiber bundles are used in the manufacture of threads and
  • METHODS FOR PRODUCING SUCH COMPOSITIONS discloses the problem of pulling long fibers through viscous molten resin while achieving adequate wetting. This process is known generally as pultrusion.
  • Cogswell et al The methods disclosed by Cogswell et al were specifically for continuous fibers where the fibers were sufficiently long to give a roving or tow of sufficient strength under the processing conditions used, to be hauled through the molten polymer without the frequency of breakage which would result in an unworkable process or resulting product.
  • Fiber alignment is an important feature of the pultrusion process.
  • This method of Cogswell et al is so narrowly defined, that the reference teaches that fibrous products such as mats made up of randomly disposed continuous fibers are not suitable for use in the invention unless they form part of a fiber structure in which at least 50% by volume of the fibers are aligned in the direction of the draw.
  • This pultrusion process has its own specialized drawbacks, including the necessity to apply an electrical charge to the bundles of fibers to spread them as they are being wetted by the molten resin.
  • Other methods were contemplated in Cogswell et al to maximize contact between the fibers and the plastic material, including the extrusion of both through a die, and the pressing of both through rollers. All of the above methods make clear that the central idea is such that the longitudinal continuity of the fiber orientation cannot be broken. Further, Cogswell et al required the tensioning of the fiber bundles, which combined with the above considerations makes for a difficult and onerous process.
  • Jute-like fibers are hygroscopic and inherently polar. This renders them incompatible with thermoplastics that are non-polar and hydrophobic. Inter facial sheer properties between fiber and matrix are inherently weak. Results have been disappointing.
  • Ichiharasi describe the composition as having high rigidity and demonstrating significantly less warpage than moldings of neat polypropylene or propylene-ethylene co-polymers.
  • Ichiharsi et al. state a preference for polyamide type fibers, polyester type fibers and cotton fibers in some mixture and in any configuration - ". . woven, knitted or non- woven . . " Fiber content is preferred at between 30% and 50%, by weight, of the final composite.
  • Ichiharasi et al. describe a related composition which also contains an amount of inorganic filler which at its maximum amount should be less than 20%, by weight, of the final composition.
  • Ichiharasi et al. describe production of the "composition” as involving heating, stirring and kneading in a Heschell mixer or super mixer at 190°C or by melting and kneading in "a banbury mixer, a roll, a single screw or twin screw extruder or co-kneader.” This should be followed by production of pellets.
  • the inventors state that care should be taken to prevent fiber decomposition and recommends practices wherein the "original shape as fibers are maintained.” They conclude by recommending that the final composition can be molded using any conventional plastics forming apparatus.
  • Ichiharasi et al. suggest that the composition may prove to be a superior replacement for glass-fiber reinforced material in automotive interior trim, because it has demonstrably less deformation under heat stress than do products manufactured from that material.
  • Ichiharasi et al. pay little attention to manufacturing processes, stating only that a virtual grab bag of fiber types and one of a variety of unsaturated carboxylic acid acids may be mixed with an ethylene-propylene copolymer in a variety of commercially available equipment (banbury, single screw, twin-screw among others) for an indeterminate amount of time.
  • the specific advantage of the composite material formed by the claimed process is that it enables manufacture of a wide range of recyclable structural and packaging materials that have superior strength-for-weight and lower cost than comparable wood-based and polymer-based products.
  • the thermoplasticity of the composite material enables manufacture of structural forms that have superior strength, utility and safety.
  • a pulp-paper based drum cannot be formed in a tapered shape, and the plywood box cannot be molded to include integral fasteners and strength-optimizing ribbing.
  • the composite box will not chip - as do plywood or wood boxes and crates.
  • comparable plastic materials the products of the present invention have lower cost, as well as superior strength and creep attributes.
  • the composite-manufactured materials have similar strength and creep attributes, but enjoy significant strength for weight and cost advantages.
  • the solution involves the grafting of a pendant chain of plastic to the fiber which is compatible with the encapsulating thermoplastic matrix.
  • Maleic anhydride is used to react with the lignin and the cellulose of the fiber, producing a stable, high strength bond.
  • Another general objective is to maximize the
  • fiber aspect ratio This translates into seeking to minimize agitation during blending to achieve a maximum strength bond.
  • the long fiber length (up to 500 aspect ratio), results in high strength.
  • Additional stif ⁇ hess can be imparted with the addition of microsphere and powdered organic filler material (such as powdered kenaf and jute core material) without sacrificing strength.
  • acrylic acid and its derivative anhydride have also been successfully used in the textile industry.
  • the OH groups on the "jute, kenaf, roselle, crotelaria or aramina backbone" - react with carboxyl groups in acrylic (one) or maleic anhydride (two) - called graft copolymerization.
  • Another beneficial substance is the use of recently available maleic-anhydride-grafted polyolefins as compatibilizers. This has resulted in considerable enhancements in the properties of the composite of the present invention.
  • thermoset polymer particularly, phenolic or epoxy resins (and their catalysts)
  • inclusion of a small amount ( ⁇ 5%) of unreacted thermoset polymer, particularly, phenolic or epoxy resins (and their catalysts) in the final molding process produces additional property enhancements through dynamic cross-linking, than are achieved by maleic anhydride grafting alone.
  • the present invention also enhances the convenience to the molding industry, thereby also reducing their costs, by incorporating all compound ingredients, including the thermoset resins, in a single cold-pressed pellet.
  • the present invention utilizes maleated polypropylene to form strong anhydride-hyroxyl bonds through the reaction of the two carboxylic groups of maleic anhydride with the hydroxyl groups on the fiber surface.
  • the resulting inter facial sheer is superior to that of other known graft copolymers.
  • Maleic anhydride reacts with the lignin and the cellulose, producing a stable, high strength bond.
  • the strength of the maleated polypropylene-fiber bond is principally a function
  • connection with the surrounding polymer matrix is through molecular entanglement.
  • the strength of the connection is a function of the length of the maleated polypropylene molecular chain and the crystallinity of the surrounding matrix.
  • the present invention also allows discretionary use of dynamic cross-linking with phenolic and epoxy resins to achieve enhanced composite material strength. Resin and catalyst application must coincide with the bonding of maleated polypropylene with fibers.
  • preparation of the composite material can be accomplished by the steps of preparation of the bast fiber by either retting or mechanical separation of fiber bundles, and preparation of the transported bast fiber for processing - involving combing to "open up" baled material and discretionary chopping to reduce fiber bundle lengths to between 1 and 20 centimeters.
  • the maleated polypropylene is prepared. If commercially marketed maleated polypropylene appropriate to the specific application is not available, then maleated polypropylene should be manufactured by mixing maleic anhydride (3% to 6%) with powdered polypropylene or finely ground polypropylene pellets or particles. The size of the particles or pellets may vary, but the finer or smaller the size of the granules or pellets, the better the result.
  • the mean diameter of the pellets will be below 10 microns.
  • the reaction is catalyzed with 3% by weight t-butyl peroxyster and conducted for 2 hours in an inert atmosphere at a temperature of from about 120° to about 130° C.
  • the fibers and up to 20% by weight maleated polypropylene (and possibly phenolic resin and hexamethylene tetramine at up to 5% and 0.5% by weight of the final composite respectively, or partially reacted phenolic resin inclusive of hexamethylene tetramine at up to 5.5%) are blended in such a manner as to achieve
  • the material is particularly suitable for injection molding, it may also be press molded, extruded, rotation molded, blow molded or vacuum formed on various conventional molding apparatus.
  • the resulting molded composite natural jute-like reinforcing fibers are matrix sensitive - as opposed to surface sensitive - and therefore, unlike glass, will not shear as easily during molding during injection or extrusion.
  • Strain from load is transferred through the resin mix from fiber to fiber.
  • the fiber is stronger and has a higher modulus than the matrix. Much higher stress is induced in the fiber than is carried in the matrix surrounding it.
  • Figure 1 is a process flow diagram which illustrates the overall process steps possible regarding the composite and method of making of the present invention
  • Figure 2 A illustrates the shape of the wall sections into which the composite of the present invention was made, in order to perform further testing
  • FIG. 2B illustrates the test setup with which the wall sections of Figure 2 A
  • Figure 3 is a graphical comparison of tensile stress-strain curves for the blends of Example 1;
  • Figure 4 is a bar graph which compares notched impact energy for each of the composite blends of Example 1;
  • Figure 5 is a bar graph which compares the un-notched impact energy for each the composite blends of Example 1;
  • Figure 6 is a bar graph which compares the cantilever modulus of elasticity for each of the composite blends of Example 1;
  • Figure 7 is a bar graph which compares the maximum cantilever strength for each of the composite blends of Example 1;
  • Figure 8 is a bar graph which compares the flexural modulus of elasticity for each of the composite blends of Example 1;
  • Figure 9 is a bar graph which compares the maximum flexural strength for the composite blends of Example 1;
  • Figure 10 is a bar graph which compares the tensile modulus of elasticity for the composite blends of Example 1;
  • Figure 11 is a bar graph which compares the maximum tensile strength for the composite blends of Example 1;
  • Figure 12 is a bar graph indicating the change in mass after water soak of each of the composite blends of Example 1;
  • Figure 13 is a bar graph indicating the percent change in length after ambient water soak of the composite blends of Example 1;
  • Figure 14 is a bar graph indicating the percent change in width after ambient water soak of the composite blends of Example 1;
  • Figure 15 is a bar graph indicating the percent change in thickness after ambient water soak of the composite blends of example 1;
  • Figure 16 is a bar graph indicating the percent change in cantilever secant modulus after ambient water soak of the composite blends of Example 1
  • Figure 17 is a bar graph indicating the percent change in maximum cantilever strength after ambient water soak of the composite blends of Example 1;
  • Figure 18 is a graph of the generalized relationship between jute and kenaf fiber loading and composite strength for fiber lengths of one millimeter and one centimeter.
  • the present invention allows use of low-cost, low-end thermoplastics such as polypropylene and high density polyethylene (HDPE), in combination with discrete binders and compatibalizers, to compete favorably against high-end polymers and more expensive synthetic fiber (glass, nylon, kevlar, boron, carbon etc..) reinforced polymers.
  • low-cost, low-end thermoplastics such as polypropylene and high density polyethylene (HDPE)
  • HDPE high density polyethylene
  • jute-like fibers include jute, kenaf, roselle, aramina, and sunnhemp (crotelaria).
  • Thermopolymer material that can be utilized as the base matrix material in the present invention may have a material density ranging between about 0.908 and 1.08 g/cm3 and have a melt flow index (MFI) of between 8 and 50 g/10 min at (230 * 72160 g). Elongation at break of the resulting composite material is less than about 8% with respect to the decrease in impact strength. At a density of approximately .9 g/ml, the melt flow index will range between 8 and about 50 g/10 min (230 * 72160 g).
  • the composite material of the present invention is more ductile than brittle.
  • the present invention utilizes maleic anhydride in combination with polypropylene and natural jute-like fibers to form a reinforced, maleated thermoplastic.
  • maleated polypropylene is employed to form strong anhydride-hyroxyl bonds through the reaction of the two carboxylic groups of maleic anhydride with the hydroxyl groups on the fiber surface. The resulting inter facial sheer is superior to that of other known graft copolymers.
  • the strength of the maleated polypropylene-fiber bond is principally a function of the percentage of maleic anhydride in the maleated polypropylene.
  • Connection with the surrounding polymer matrix may be predominantly through molecular entanglement.
  • the strength of the connection is a function of the length of the maleated polypropylene molecular chain and the crystallinity of the surrounding matrix and the fiber aspect ratio.
  • the present invention also allows discretionary use of dynamic cross-linking with phenolic resins to achieve enhanced composite material strength. Resin and catalyst application should coincide with the blending of maleated polypropylene with fibers. Although the contemplated variations are many, preparation of the composite material is centrally related to the following discrete steps.
  • the fiber is obtained.
  • jute-like fibers are obtained from harvesting on an annual crop basis.
  • the plant material of interest is the external bast which are bark based fibers of the jute-like plant.
  • the fiber characteristics include strong polarity and a relatively lower percentage of lignin and hemicellulose than other natural lignocellulosic fibers, therefore making it a potentially a better binder.
  • Table 2 Approximate Composition of Jute-Like Fibers
  • the jute-like fibers are lignocellulosic fibers which are the most abundant renewable agricultural fiber resource, after cotton.
  • the fibers are typically obtained in filaments comprising bundles of individual fibers. Bundles can be up to 3.5 meters long, but have a tensile strength and modulus approximately half that of the individual fibers.
  • Individual fibers, themselves, can have aspect ratio's between 100 and 500 (ratio of length to width) and are very efficient reinforcing agents. A 10 fold increase in aspect ratio will result in an approximate doubling of tensile strength - which, nevertheless, derives its primary power from the tensile strength of the underlying fiber.
  • Other differences with respect to glass fibers, aside from cost, include energy processing requirements. Jute-like fiber processing consumes only 2% of the energy used to produce and process glass fiber.
  • jute-like fibers permits the use of high fiber loadings without the extensive damage to compounding and molding equipment that can occur with much harder mineral-based fibers/platelets such as glass and mica.
  • Jute, kenaf, sunnhemp (crotelaria), roselle, and aramina fibers, among the category of jute-like fibers, may all be utilized with the present invention.
  • fibers are extracted from the bast of the plant Hibiscus cannabinus, and filament lengths of about 1 m are common.
  • the filaments consist of discrete individual fibers
  • fibers are fibers. It is preferred that individual fibers remain chemically bound as filaments (fiber
  • jute-like fibers kenaf holds particular importance because it is now a crop grown commercially in the United States.
  • the use of more expensive, higher strength, or longer aspect ratio agro-based fibers, such as cotton, flax, ramie, and hemp may result in some better properties than those obtainable with jute-like fibers. None, however, can compete with with jute-like fibers with respect to the cost-efficiency of those properties.
  • Processed jute and kenaf fibers for instance, can be obtained for less than one third the price of flax and one seventh the price of cotton, yet they produce comparable strength properties when employed as reinforcers in composite materials.
  • Jute is a strong coarse fiber used for making burlap, gunny sacks, cordage and ca ⁇ et material. It is obtained from two east India plants, Corchorus capsularis is and Corchorus olitohus of the linden family. These fibers are important with respect to the present invention because of their relative abundance and low cost.
  • the jute-like bast fiber is prepared by either retting or mechanical separation of fiber bundles. Cleaned, separated fibers are then either baled for transporting, or directed to a shredder/chopper, where fiber bundles or filaments are reduced to lengths to between 1 and 20 centimeters.
  • maleated polypropylene is prepared. If a commercially marketed maleated polypropylene appropriate to the specific application is not available, then maleated polypropylene should be manufactured by mixing maleic anhydride (3% to 6%) with powdered polypropylene. The reaction is catalyzed with 3% by weight t-butyl peroxyster and conducted using slow mixing for 2 hours in an inert atmosphere at 120° - 130° C The result is the maleated polypropylene compound used as a binder in the present invention. Specific properties of the maleated polypropylene are a function of maleic anhydride strength and amount, catalyst
  • the jute-like fiber material and up to 20% maleated polypropylene is blended in such a manner as to achieve even coating of the fibers with an intended amount of maleated polypropylene.
  • a preferred amount of phenolic resin or epoxy resin in the final compound will range between 0.5 and 1.5% by total weight.
  • Phenolic resin is preferably applied in a semi-reacted state as a fine powder, but appropriate amounts (by supplier recommendation) of hexamethylenetetramine (hexa) curing agent can also be blended directly during the final molding process.
  • the blending step can be accomplished by mixing, charged particle, free falling contact application, or dipping.
  • blending is a vigorous mixing step
  • the mixing of fiber and blended, powdered maleated polypropylene and semi-cured phenolic resin and/or phenolic resins and hexamethylenetetramines and/or epoxy resins and catalysts is accomplished in an airlay or pneumatic process.
  • a continuous bat or mat of coated fiber can then be passed through an infrared oven or hot rollers to fix the powders. This step is preferably performed at a temperature ranging between 160° C to 180° C, and preferably at about 170° C.
  • the, powdered maleated polypropylene, and semi-reacted phenolic resins and/or phenolic resins and catalysts and or epoxy resins and catalysts may be electrostatically charged and spray-attached to the chopped, separated fibers in a free-fall reaction chamber.
  • the coated fibers are then passed by belt through an infrared oven as described in the mixing step to the same temperature
  • the maleated polypropylene is applied to the fiber by dipping a continuous bat or mat of fiber through an emulsion bath.
  • the emulsion preferably consists of maleated polypropylene at between 20% and 40% by weight, water content of from about 50% to about 70% by weight, potassium hydroxide of from about 2% to about 4% by weight, sodium metabisulfite in an amount of about 0.3% by weight and an appropriate surfactant in an amount of from about 5% to about 8% by weight.
  • the surfactant is preferably one such as Igepal CO-630, which is commercially obtainable from the Rhone-Poulenc, Prospect Plains Road, Cranebury, NJ. 06512.
  • Igepal CO 630 is a nine mole ethoxylate of nonylphenol, which will be referred to simply as nonylphenol. It is made by reacting ethylene oxide (oxirane) with nonylphenol. The dipping method is not suitable for inclusion of phenolic or epoxy resin components.
  • the airlay or pneumatic process is acceptable, and the dip method is suitable for lower molecular weight maleated polypropylene.
  • the maleated polypropylene modifies the degree of adhesion - or interfacial sheer properties between the matrix and the fiber.
  • the bat or mat is, as was the case with mixing and free-fall, air dried in an infrared or other type oven at the temperatures recited above for the mixing step, before being passed through hot rollers for fixing.
  • the combined fiber and maleated polypropylene (and possibly phenolic or epoxy resin) mixture, having been heat-fixed is then further blended with the primary polymer, preferably filamented polypropylene of between 8 and 50 g/10 min. MFI, and comprising between 40% and 80%, by weight, of the final composition.
  • the primary polymer preferably filamented polypropylene of between 8 and 50 g/10 min. MFI, and comprising between 40% and 80%, by weight, of the final composition.
  • the primary polymer preferably filamented polypropylene of between 8 and 50 g/10 min. MFI, and comprising between 40% and 80%, by weight, of the final composition.
  • the primary polymer preferably filamented polypropylene of between 8 and 50 g/10 min. MFI, and comprising between 40% and 80%, by weight, of the final composition.
  • the primary polymer preferably filamented polypropylene of between 8 and 50 g/10 min. MFI, and comprising between 40% and 80%, by weight, of the final
  • the ingredients are introduced simultaneously and batch mixed in a vessel such as a Banbury Mixer or a Farrel Continuous Mixer (FCM). Mixing occurs when the base polypropylene melts due to shear induced temperature elevation. Once the mixture is completely fluxed, mixing should continue for an additional 30 seconds to 1 minute to enable adequate blending. The fluxed mixture can then be fed through standard extrusion pelleting apparatus to form pellets.
  • a vessel such as a Banbury Mixer or a Farrel Continuous Mixer (FCM).
  • FCM Farrel Continuous Mixer
  • measured, balanced, continuous streams of ingredients including the maleated polypropylene/fiber mixture and polypropylene, as either filaments, powder, pellets, flakes or ground material, are fed directly through a twin or single mixing screw, wherein the material is shear-melted and mixed, and from whence the material is directed to pelleting apparatus to form pellets.
  • the mixture may not include either phenolic or epoxy resins and their associated catalysts.
  • thermoset polymers would react during fluxing and pellet
  • a third and less preferred category of mixing methods precludes the stage of first blending maleated polypropylene (and possibly phenolic and epoxy resins) with the jute-like fibers.
  • This method includes simply adding all ingredients simultaneously in either: (a) a mixing airstream and cold press pelleting operation; a batch banbury or FCM process followed by extrusion-pelletizer; or (c) a twin or single screw mixing extruder and pelletizer.
  • the results (compound quality) produced by these methods differ from preferred methods (see above) in that the statistical probability that maleated polypropylene will (be able to) react with jute-like fiber surfaces are significantly lower. This is presumed to result in marginally inferior mechanical properties for parts, and equipment manufactured from these compounds.
  • maleic anhydride is the "inte ⁇ hase properties" of the substance.
  • One key aspect is high molecular weight for the polypropylene and high percentage of maleic anhydride.
  • the method of connection with the fiber is due to maleic anhydride (covalent acid-based interaction - formation of anhydride-hyroxyl covalent bonds) and the connection with the polymer is through molecular entanglement with the surrounding polymer matrix. Note that the more amo ⁇ hous the polypropylene - i.e., the less crystalline - the longer the molecular chain should be - or, the greater the molecular weight.
  • Maleated polypropylene contains succinic anhydride moieties which are
  • the polar maleic anhydride is strongly attracted to the polar fiber surfaces. In one-step mixing, despite being less than .02% of the composition, a significant percentage of the maleic anhydride interacts with the fiber surface. Two carboxylic groups of maleic anhydride react with the hydroxyl groups on the fiber surface.
  • the fibers have been initially introduced to the maleated polypropylene, as described above, to form the maleated polypropylene/resin-coated fiber preform, it is added to polypropylene for final mixing to form the composite of the present invention.
  • the fiber preform is added to the polypropylene in a ratio of from about 20% to about 60% preform to about 80% to about 40% polypropylene.
  • pelletizing will aid in handling and later use for injection molding, press molding, rotation molding, blow molding, vacuum molding and/or extrusion.
  • the final material composition may be directly injection molded, press molded, rotation molded, extruded, press-formed, vacuum molded or otherwise used immediately upon its formation.
  • the final mixing of the maleated polypropylene/resin-coated fiber preform with the polypropylene (or polyethylene) to form the final composite composition may, as has been described above, be accomplished by several methods.
  • the preferred method of mixing and pelletizing can be accomplished with the use of a specially adapted cold-press pelleting mill, sometimes also known as the California Pellet Mill - after the American company of the same name (A number of other manufactures do, however, make similarly configured pelleting machines).
  • This system uses a drum die rotated in a vertical plane (using a horizontal drive). Stationary, opposing compacting compression wheels ride inside the die.
  • Kahl process Another variation on this method is sometimes known as the Kahl process - after the German company of the same name (a number of other manufacturers do, however, make similarly configured pelleting machines).
  • This device pushes material through a die, which is usually horizontally disposed, by using grooved metal wheels travelling about a vertical axis.
  • the material to be treated is usually gravity fed from above the Kahl system.
  • the outer edge of the Kahl die maintains a higher rotational velocity than the inner, active portion of the die, and thus introduces significant grinding to the material being treated. While grinding is useful in the treatment of some substrates, it is detrimental to the jute-like fibers processed in this fashion.
  • Both of these systems form pellets by pushing material through holes drilled through the dies.
  • Pellet integrity is maintained as a function of compaction and strength of the outer "skins" formed by the process.
  • the strength of the skin is a function of the materials employed, die configuration and the maximum temperature achieved during the process.
  • the maximum temperature is a function of the material density, toughness and abrasiveness, hole diameter and taper, hole distribution and die thickness.
  • measured quantities of maleated polypropylene/resin- coated fiber preform are added to a melted batch of polypropylene and mixed at medium speed for between 5 and 10 minutes.
  • the favored method of batch mixing is with a mixer such as a Banbury and Farrel Continuous Mixer. These mixers use the shear process to create heat, melting the polypropylene (or polyethylene) and thus assisting in physical mixing.
  • the final material composition is passed to an extruder and pelletizer or directly to an injection (or other) molding machine.
  • the cold press pelleting method for mixing and pelleting the compound ingredients enjoys significant advantages over other, less preferred methods. Specifically, these advantages include: (a) the ability to include phenolic and expoxy resin constituents in an un-fluxed (unmelted) pellet; and (b) significant cost advantages amounting to a final pellet production cost of between one eighth and one third that of other methods.
  • the final acceptable, though less preferred mixing method involves feeding a measured, balanced, continuous streams of ingredients, including the maleated polypropylene/fiber mixture and polypropylene, as either filaments, powder, pellets, flakes or ground material, directly through a twin or single mixing screw, wherein the material is shear-melted and mixed, and from whence the material is directed to pelleting apparatus to form pellets.
  • the next step is then to mold products using prepared pellets or hot-blended compounds under conditions in which material temperatures are maintained below about 230°C and injection pressure, should that method be used, is held below about 28,000 psi.
  • Rheological properties can be improved by selecting a polypropylene having a high melt flow index. A resulting reduction in flexural modulus can be
  • Fiber orientation which provides significantly higher directional strength, is achieved by varying flow convergence and expansion. Injection flow under convergent conditions leads to axial unidirectional orientation, and under expanding conditions leads to orthogonal orientation.
  • the resulting composite material of the present invention is characterized by high stif ⁇ hess, low creep, high tensile and flexural strength; low weight (relative to other reinforced plastic material) and low abrasiveness (relative to other reinforced plastic material).
  • Products manufactured from the composite material and having between 30% and 60% fiber content (by weight) have tensile and flexural strength of between 2 and 6 times that of similar material having approximately the same overall weight and volume that is manufactured from the underlying neat thermopolymer material (polypropylene and polyethylene).
  • Jute and kenaf fibers were reduced to a size enabling introduction, along with other composition ingredients (maleated polypropylene and base polypropylene), into a small laboratory-scale high-intensity thermokinetic mixer ("K-Mixer").
  • K-Mixer high-intensity thermokinetic mixer
  • Blends of 50/50 by weight kenaf/polypropylene (12 melt flow index) and jute/polypropylene (12 melt flow index) were prepared, with and without coupling agents (maleated polypropylene).
  • blends of 40/60 by weight kenaf/polypropylene with the maleated polypropylene mixture coupling agent were prepared using two different types of polypropylene.
  • the polypropylenes were Polypropylene-L (12 melt flow index) and Polypropylene-H (50 melt flow index-nucleated, high stiffriess). Typical mechanical tests including stiffriess, strength, and Izod impact, along with water abso ⁇ tion, were performed, in addition to a modified compression test.
  • the resulting composite material was compared to existing samples cut from standard wound fiber drum material.
  • An alternative, generalized method of producing the composite of the present invention includes the formation of a molded article.
  • a molded article is formed from a natural jute-like fibre reinforced thermoplastic composition in a process that includes several steps. The steps include: (a) the step of evenly blending a composition containing between 80% and 99% by weight natural jute-like fibers and between 1% and 20% maleated polypropylene as powder, emulsion or melted polymer, (b) the step of heat-fixing a bond between the jute-like fibers and maleated polypropylene; (c) the step of chopping the coated fibers to lengths between 1 and 40 mm; (d) the step of melting and homogenizing a composition containing between 10% and 80% maleated polypropylene-coated fiber and 90% and 20% crystalline or semi-crystalline polypropylene; and (e) a step of injection molding, press molding, blow molding, rotation molding, or vacuum molding under conditions in which material temperatures are maintained below 230 °C and injection or press
  • the Jute or Kenaf 51, polymer 53 and coupling agent 55 are mixed together by dry mixing 57.
  • a melt blending step 59 occurs, and then a granulating step 61.
  • a colorant 63 step may be included.
  • either of two steps may occur, including an injection molding 65 step, or a panel pressing 67 step.
  • thermokinetic mixer K- mixer
  • This apparatus consists of a cylindrical chamber in which several blades rotate at high speed and impart kinetic energy to solids that are present.
  • fluxing and mixing begin and the temperature begins to rise very rapidly.
  • the molten mixture is discarded through a bottom door which is temperature activated.
  • total blending time may be from 20 seconds up to perhaps 2 minutes.
  • the effectiveness of blending the K-mixer can be a function of several parameters, including plastic and filler properties, batch size, starting temperature, blade speed, time, and discharge temperature.
  • the K-mixer is excellent for producing well dispersed systems, but may cause fiber attrition. If the composite material of the present invention is performed at or near the quality level required of
  • each batch of a particular blend may be granulated and mixed with the other batches of that blend.
  • the resultant blends may be injection molded into standard ASTM test specimens using a Cincinnati-Milacron 33 -ton reciprocating screw injection molder. It may be preferable to injection mold with a flat temperature profile of about 188°C (370°F), and to utilize injection pressures between about 1000 to about 1300 psi maximum. The mold is typically neither heated nor cooled. Once molded, specimens and remaining blend materials are preferably stored over desiccant in sealed bags at 90 °F and 20% relative humidity for 3 days before testing.
  • FIG. 2 A A graphical view of the test set up used for the panels is shown in Figures 2 A and 2B.
  • Panels 71 may be shaped to an eleven inch radius as is shown in Figure 2A.
  • Figure 2B illustrates the use of a pressure ball 73 bearing down upon an upper pressure plate 75 which in turn bears down upon the panel 71 specimen under test 71, which bears down upon a lower pressure plate 77, which is supported by a base 79.
  • one method preferably entails the use of 360 grams of the granulated material to be placed in a mold in a hot press and pressed at 193 °C (380°F) at a pressure of about 500 psi for 5 min., then at 1000 psi for 1 min.
  • the final dimensions of the pressed panel are preferably 12" x 12" x 0.138".
  • These panels 71 can be mechanically sawed down to 10" x 10" square pieces for further forming.
  • the panels 71 may then be sawed down to 10" x 10" square pieces for further forming.
  • the panels 71 can then be formed to
  • a 27.5 cm radius of curvature This can be accomplished by placing a single panel on a stainless steel form of equal curvature, placing a mated form on the top of the panel, and loading approximately 8 kg of mass on the top form to assist its correct forming.
  • the entire apparatus can then placed in a forced air oven at 150° C for 10 minutes, after which time the curved panel can be removed, then cooled and stored under the same conditions as injection molded test specimens.
  • the objective of the present example is to assess the potential of kenaf and jute bast fibers as reinforcing fibers in a polypropylene matrix.
  • the end-use of such a composite would be a stackable, 55 gallon drum, used for the food shipping industries.
  • the ongoing goal is to create an inexpensive, yet strong and durable material, that can subsequently be recycled into the same or similar types of products.
  • composite drum should withstand axial forces up to 6,000 lbs when stacked in a
  • the jute used for this Example 1 was a 50/50 blend of Indian and Bangladeshi virgin Tossa Grade A Cuttings. Cuttings were taken from the lower stalk section of the jute plant, and ranged from 7 to 12 cm in length. The jute was obtained from Dixie Manufacturing Company of Norfolk, Virginia, as separate bales of the Indian and Bangladeshi fiber. Dixie Manufacturing is a producer of non- woven jute
  • the kenaf was obtained from Kenaf International of Mc Allen, Texas, and was approximately 90 percent by weight bast fiber and 10 percent core, as received.
  • the kenaf fibers were about the same length as the jute fibers and both were washed before processing to remove dirt and core material.
  • the fibers were then dried at 105°C, and then sent through a small granulator to chop the fibers to approximately 1/2" lengths to allow further processing during the melt-blending stage.
  • Example 1 Two types of polypropylene were used in this Example 1. The first was a virgin homopolymer in pelleted form obtained from Solvay Polymers (Houston, Texas) - Fortilene 1602. Fortilene 1602 (Polypropylene-L) is a typical injection molding grade polypropylene with a Melt Flow Index (MFI) of 12 g/10 min. FORTILENE 1602 is a polypropylene homopolymer produced by SOLVAY Polymers utilizing unique catalyst technology. It is designed for injection molding and general pu ⁇ ose extrusion. This material is advertised as meeting the Food and Drug Administration requirements of 21CFR 177.1520.
  • MFI Melt Flow Index
  • Fortilene 1986 Polypropylene-H
  • Fortilene 1986 has a higher melt flow index of 50 g/10 min. It is specifically designed for high speed injection molding.
  • FORTILENE 1986 is produced by SOLVAY Polymers utilizing unique catalyst technology. It is both antistated and nucleated and
  • the coupling agent was EPOLENE G-3002, a maleated polypropylene wax which was obtained in pellet and powder form from Eastman Chemical Co. of Kingsport, Tennessee. Previous work on coupling agents at the FPL has found the greatest improvement in properties from using G-3002 as compared to other maleated polypropylenes.
  • EPOLENE G-3002 has a higher acid number (reactivity) and higher molecular weight than the other agents studied. The higher molecular weight translates into longer polymer chain lengths, which facilitate greater miscibility and hence better interaction with the polypropylene matrix polymer.
  • a white titanium dioxide master batch colorant was added to two kenaCpolypropylene blends. The colorant is commercially available from General Color & Chemical Co. of Minerva, Ohio.
  • the reference drum material was a standard, industrial 55 -gallon wound fiber drum commercially available from Sonoco, Inc.
  • Example 1 a total of 8 blends were produced to determine the effects of the following variables on the final composite material of the present invention. These variable are (1) fiber type: (kenaf (K) or jute (J)), (2) coupling agent (0% or 3% by mass of fiber), (3) polypropylene type (Polypropylene-H or Polypropylene-L), and (4) fiber content (40% or 50% by total mass).
  • fiber type (kenaf (K) or jute (J)
  • coupling agent 0% or 3% by mass of fiber
  • polypropylene type Polypropylene-H or Polypropylene-L
  • fiber content 50% by total mass
  • Blends 9 and 10 were 100 g portions of blend 4, where the colorant was added to the blend in the hopper of the injection molder.
  • Blends 5 and 6 were actually sections of the fiber drum cut for testing. Blend 5 was from the drum bottom and blend 6 was from the drum wall. As blend 5 was not representative of the type of material that the composite would be replacing, it was eliminated from the rest of the study.
  • thermokinetic mixer K-mixer
  • K-mixer thermokinetic mixer
  • the average batch time was between 45 and 60 seconds.
  • Dump temperature was set at 200°C, and rotor tip speed was approximately 30 m/s maximum.
  • the resultant blends were injection molded into standard ASTM test specimens using a Cincinnati-Milacron 33 -ton reciprocating screw injection molder. Materials were injection molded with a flat temperature profile of 188°C (370°F), and injection pressures between 1000 and 1300 psi maximum. Once molded, specimens and remaining blend materials were stored over desiccant in sealed bags at 90°F and 20% relative humidity for 3 days before testing.
  • a portion of the blends were also used to produce curved cylindrical panels for a modified compression test as described earlier.
  • 360 g of the granulated material were placed in a mold in a
  • the compression tests on the composite material of the present invention and drum material formed was a direct relative comparison between the composite and the drum material. This comparison was made by forming a curved rectangular panel of composite material from a flat, square, pressed composite panel. This panel had the same dimensions (thickness, radius of curvature, length and width) as that of a section cut from the side of the fiber drum. Two pieces of material were placed with convex sides facing each other for stability. The sections were then compressed to failure and the resulting stress versus compression data were measured to obtain maximum axial load.
  • melt flow index was measured using a Kayness melt- indexer.
  • Melt temperature was 190°C and the cylinder load was 2160 g. Standard ASTM conditions for temperature call for 230° C. However, this is above the degradation temperature of the cellulosic fibers (approximately 200 °C), and 190°C is standard for similar types of thermoplastic materials.
  • the amount of material extruded out of the cylinder in 10 minutes was measured. The average of 3 trials per sample was determined for blends 2, 4, 7, and 8.
  • Figure 4 compares notched impact energy for each blend of drum materials and composite blend discussed above, while Figure 5 compares the un-notched impact energy for each blend of drum materials and the composite blend.
  • Figure 6 compares the cantilever modulus of elasticity for each drum material and composite blends.
  • Figure 7 compares the maximum cantilever strength for each drum material and composite blend.
  • Figure 8 compares the flexural modulus of elasticity for each drum material and composite blend.
  • Figure 9 compares the maximum flexural strength for each drum material and composite blend.
  • Figure 10 compares the tensile modulus of elasticity for each drum material and composite blend.
  • Figure 11 compares the maximum tensile strength for each drum material and composite blend.
  • Table 8 lists the results of a statistical analysis based on the student's t-test at the 95% confidence level. The table is used to determine if the mechanical property values of two different blends are statistically different from each other. The confidence level in effect determines the degree of rigor with which the comparison is made. A higher confidence level requires two values to have a higher degree of difference from each other in order to not be considered as equivalent values within the margin of error of measurement.
  • the numbers represent the result of a mathematical operation on the property values as part of the t-test. A number highlighted in bold italics indicates that the two property values that this t-test value represents are significantly different (statistically) from one another. Whether or not a t-test value is deemed significant or not depends on the test design, confidence level,
  • Jute fiber typically performs better than kenaf fiber as a reinforcement in polypropylene (compare blends 1 vs. 3 or 2 vs. 4). This is particularly evident when examining the maximum strengths of these materials. There is less of a difference in the modulus between composites of these two fibers. This is supported by the statistical analysis of table 3. These results follow behavior of individual kenaf and jute fibers, with the jute being stronger than kenaf, but both of relatively similar modulus. The effect of jute vs. kenaf fibers on impact energy is
  • Comparisons of blends 1 vs. 2 and 3 vs. 4 shows the effect of adding EPOLENE G-3002 coupling agent to the fiber/polypropylene composite at a level of 3% by weight of fiber.
  • the results clearly show the benefit of adding coupling agent on the maximum strength property of the composites.
  • the modulus is relatively unaffected by the presence of coupling agent. The statistical analysis supports these observations. These results are as expected, since at very low strains where the modulus is measured, the stif ⁇ hess depends mainly on the stif ⁇ hess of the fiber, and less on the stress transfer between matrix and fiber.
  • the maximum strength depends, in a large part, on the efficiency of transferring the stress from the relatively weak matrix to the much stronger fiber.
  • the coupling agent acts to increase the bonding and stress transfer between matrix and fiber, and thus will have little effect on modulus but a significantly greater effect on the maximum strength of the composites.
  • the effect of coupling agent on impact energies was to slightly increase the notched impact energy (which is a measure of crack propagation), and more significantly increase the unnotched impact energy (which is a measure of crack initiation), as compared to blends without coupling agent.
  • the composites in this Example 1 tend to follow the same trends illustrated in manufacturer reported properties of Fortilene 1602 (F1602-(Polypropylene-L) - 12 melt flow index polymer and) Fortilene 1986 (F1986-(Polypropylene-H) - 50 melt flow index polymer) as presented in TAbles 4 and 5 - namely, little disparity in modulus between the two polymers.
  • the reason for the smaller amount of disparity in modulus of the composites than would be expected based on matrix polymer considerations alone, can probably be explained by the fact that cellulose itself can act as a nucleation site for crystallinity. If this is the case, the high nucleation of densely filled composite systems such as these would negate the theoretical advantage of the more crystalline polymer.
  • the final properties tend not to be as different from one another as would be expected by considering matrix polymer effects alone.
  • Blends 2, 4, and 8 (50% kenaf/, 50% jute/, and 40% kenaf/ 12 melt flow index polypropylene, respectively), are quite similar.
  • Blend 7 (40% kenafi'50 melt flow index polypropylene) has a melt flow index 1.8 times that of blend 8, while the corresponding unfilled polypropylene has a nominal (190°C) melt flow index over 4 times that of F1906 (used in blend 8).
  • These composites have melt flow index values between 1 and 2.5, which is considerably less than the polymers alone.
  • Blends 2 and 7 are a direct comparison of the effect of fiber content (by mass) on properties. Both contain kenaf fiber with 3% G3002 with blend 2 at 50% by mass of fiber and blend 7 at 40% by mass of fiber. As would be expected for a less filled system, blend 7 shows higher values of impact energy. Composite failures is due to the initiation and propagation of cracks in the material. Fibers have regions of high stress concentration near their ends and tend to promote crack growth, which leads to a lower energy failure. It is easier for a crack to propagate along a fiber-matrix interface and in regions of high stress than it is through a plastic matrix. Also to be expected, blend 2 shows significantly higher values of strength and modulus for all three types of mechanical tests of this type.
  • Blends 9 (2% colorant) and 10 (5% colorant) can be compared to blend 2 to obtain a rough estimate of the effect of adding a colorant to the composite blend.
  • the data in Table 2 show that adding the colorant produces a significant drop in modulus and strength of about 10% on average. A greater decrease is indicated as percentage of colorant increases to 5%.
  • the appearance of such colored composites was that of a slightly brownish gray opaque tint with some surface fiber showing, with a smooth and glossy surface appearance. The 5% colored material had a whiter appearance than did the 2% material.
  • the results of the ambient water soak test are presented in Table 10 and graphically in Figures 12 - 17.
  • Table 10 The results of the ambient water soak test are presented in Table 10 and graphically in Figures 12 - 17.
  • Listed are the blends and their corresponding percent changes (from dry to wet) in weight, thickness, length and width of standard flexural bar specimens. Also shown are the changes in cantilever beam maximum strength and secant modulus. The percent changes in this case were calculated by comparing wet values to values obtained in the mechanical tests from the first part of the study.
  • the 24 hour water soak test included only blends 1-4 because there was not enough of the original blends 7 and 8 to do both a 24 hour and 3 week test. The 3 week test was chosen preferentially over the 24 hour test for blends 7 & 8 to emphasize long term effects.
  • the fiber drum samples were not subjected to the soak test since they lost their integrity within 24 hours.
  • the data indicate that after 24 hours, and especially after 3 weeks, of soaking in ambient water, there are differences between jute and kenaf and in blends with and without coupling agent. Overall dimensional changes are very low, typically below 5%, and without coupling agent, less than this. The values for changes in thickness and width are of an order of magnitude greater than that of the length. This is most likely due to the fact that fibers were generally aligned along the length of the test samples, and that width and thickness are dimensions in which fibers swell when absorbing moisture.
  • EPOLENE G-3002 significantly decreases the change in dimensions and mass, along with significantly decreasing the losses in modulus and strength. Coupling agents tend to promote belter bonding between fiber and matrix, and thus inhibit water molecule penetration and migration along the fiber-matrix interface. The compression test results are listed in Table 11.
  • both the jute and the kenaf composites performed in a similar manner.
  • the jute and kenaf composites show an approximately 40% increase in maximum axial load over the fiber drum. This indicates that this material should be able to perform at least as well as a similarly designed wound fiber drum in terms of ability to support axial loading.
  • the thickness of the supplied fiber drum material was found to fall within the specified range of thickness for the molded plastic parts to which they were compared (3.2 + 0.4 mm).
  • the fiber drum thicknesses were greater than the average thickness of the composite specimens by only a few percent. This is acceptable for experimental conditions in this study, since if the composite can perform better than a thicker drum section, then it should also perform better than a section of the same thickness.
  • the data shown in Table 11 lead to a number of conclusions.
  • the fiber drum material performed significantly better than either the jute or kenaf composite material in the Izod impact test. Although the Izod impact test standard used in this study was for plastic materials, this would tend to be a good indication of the relative performance of the drum material compared to the composite material. Polypropylene and fiber composites of the nature of those in this Example 1 tend to be somewhat more brittle than would be expected of the fibrous material composing the Sonoco drums.
  • the impact properties of these composites are by no means optimized due to the method of compounding used in Example 1.
  • the impact performance can be further enhanced to yield results exceeding the results for the fiber drum material by adding impact modifiers or increasing the fiber lengths of the fiber reinforcements by improved processing methods.
  • a few of the impact modifiers may include the addition of various rubber compounds and EVA, to name a few.
  • the modulus of the composite material is increased over that of the drum material by over 150% for the cantilever and tensile tests, and to over 200% for the flexural test.
  • the maximum strengths of the composite material is increased over that for the drum material by 130% for the tensile test to over 360% for the flexural test.
  • the results for the modulus and maximum strength correlate with the results of the compression test, since the inward failure of the proposed drum of the specified length to 20 radius ratio is dictated by stiffness more so than by buckling of the drum under axial load.
  • Composites of Jute/ or kenaf/virgin polypropylene homopolymer can be produced at levels of at least 50% fiber with typical plastics molding equipment.
  • Composites of this nature show significant improvements over wound fiber drum material in the areas of modulus, maximum strength, and maximum axial load in compression. Improvements of these properties range from 40% for axial compression load to up to 150%-350% for modulus and maximum strength in composites of jute with coupling agent.
  • Composites of this nature perform at levels significantly lower than that of the fiber drum material when subjected to Izod impact tests. The drum material shows improvement over the composite
  • Jute fibers prepared according to the present invention act as better reinforcing fibers as
  • jute fiber composites When subjected to an ambient water soak test, jute fiber composites also show smaller dimensional and mass changes, as well as smaller decreases in cantilever modulus and maximum strength, than do composites made with kenaf
  • non-nucleated 12 melt flow index polypropylene homopolymer in terms of mechanical properties and process ability. In this case the effect of high fiber loading outweighs the effects of polypropylene crystallinity variations.
  • FIG 18 a generalized chart illustrating the relationship between fiber loading and composite strength is shown.
  • the relationship between fiber length/mean critical fiber length and efficiency is illustrated in Figure 18.
  • About 90% of theoretical strength is achieved at 1.5 times the mean critical fiber length - after which very little improvement occurs. This is probably in the neighborhood of an aspect ratio of 100 - or 5 mm fiber length.
  • pullout length is inversely proportional to the shear-bond strength.
  • the critical length/diameter ratio is twice the pullout length/diameter ratio.
  • filler material at low loading levels will have the effect of shifting the curve upwards, because of an increase in composite tensile modulus due to the addition of filler. This provides better stress transfer across fibers than does the matrix itself.
  • Injected jute-like fibers have a specific gravity close to unity, which is significantly lower than that of other competitive synthetic reinforcing material.
  • the reinforcing value of jute-like fibers per unit weight is significantly higher than that of glass fiber - 2.5 specific gravity vs 1.29 for jute and a higher tensile strength and tensile modulus.
  • a specific gravity of filler which is close to the specific gravity of the plastic material does not add much weight by volume, as opposed to glass, which will add significantly to weight by volume. Jute-like fibers also hold strength-for- weight advantages over other materials.
  • Table 12 compares the tensile, flexural, and impact properties, along with water absorption and specific gravities, of the neat polypropylene, the 50%-kenaf composite, and several commonly utilized injection molded filled/reinforced polypropylene materials. The comparison is meant as a general indicator and not as an exact comparison, which would be possible only if all the specimens were prepared and tested under identical conditions.
  • the tensile and flexural properties of the kenaf-filled polypropylene show significant improvement over those of the unfilled polypropylene.
  • the tensile modulus of the kenaf-fiber system is approximately equivalent to that of the 40%-mica polypropylene or to a 30% chemically coupled glass-fiber polypropylene composite (from the data on 30%- and 40%-glass- filled polypropylene), but significantly higher than that of the talc and calcium carbonate-filled
  • the kenaf filaments were obtained from Agro-Fibers, Inc., and cut into lengths of about 1 20 cm.
  • the fibers, polypropylene (Solvay 1602), and a maleated polypropylene (Eastman Chemical Co. G3002) were blended in a thermokinetic mixer,
  • the blend contained 50% kenaf fibers, 1.5% maleated polypropylene, and 48.5% polypropylene (weight percent). Data for talc and CaCO 3 from Modern Plastics Encyclopedia. 607 (1989). Data for glass and mica from "Materials Selector 1993," Maeter. Eng.. 174 (1992).
  • a composite made of polypropylene and kenaf fibers extracted from a commercial crop has mechanical properties comparable with those of commercial polypropylene composites.
  • the low density of the kenaf-polypropylene composite offers materials cost savings, but the high water absorption of the composite means that care is required in the selection of applications.
  • Mold design can, where possible incorporate these concepts to achieve certain fiber orientation. Fiber orientation is achieved at the injection nozzle and can be maintained throughout the flow under conditions of injection from thick to thinner part. Mold design can be optimized to achieve this intended effect. In one instance, to pick one of many, in a die containing ribbing, the channels used to create the ribbing can be used to concentrate and channel injected material to other parts of the die. This produces fiber alignment and greater strength.
  • Random fiber orientation is enforced through the addition of micro spheres [explain micro spheres, what they are and how to add them] that provide enhanced fiber distribution - essentially better micro-packing. This has the effect of providing better stress transfer from fiber to fiber. The fiber resists strain locally, inducing a much higher stress in the fiber than in the surrounding matrix.
  • Transverse (orthogonal) orientation of the fibers results in failure at between 0.6% (557 aspect ratio) and 1.0% (185 aspect ratio) of the strain, and at between l/8th (557 aspect ratio with 1.6% strain at failure) and l/6th (185 aspect ratio with 1.4% strain at failure) of the stress applied to oriented fiber composite.
  • Water abso ⁇ tion is a function of the bond, coating and crystallinity of the polypropylene. The more amo ⁇ hous the polypropylene, the less water abso ⁇ tion will occur. Note that with high degree of orientation and high fiber loading the more ductile, amo ⁇ hous polypropylene composite behaves almost identically to the more crystalline polypropylenes. With a more ductile matrix, transverse alignment will still result in a small increase in tensile strength such that, in a brittle matrix, it will cause a decrease in tensile strength with fiber loadings. This is probably because of stress concentration in the transverse direction.
  • Jute or kenaf/polypropylene composites can even better serve in the materials for drum containers in the food shipping industries, with further modifications.
  • the impact performance of the composite of the present invention could be increased by the addition of elastomeric impact modifiers in the polypropylene matrix material. This method could prove cost prohibitive on a commercial basis, however.
  • Another means to improving the impact properties of this type of composite is to increase the minimum fiber lengths by appropriate processing conditions while maintaining adequate dispersion. This could be accomplished by the use of less intensive mixers such as continuous kneaders or appropriately configured twin screw extruders.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Wood Science & Technology (AREA)
  • Forests & Forestry (AREA)
  • Mechanical Engineering (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

Des structures renforcées de fibres comprennent un polymère thermoplastique (53) et contiennent 30 à 60% en poids de filaments de renforcement disposés au hasard ou alignés dans de telles structures, sont produites en continu et présentent des résistances à la rupture en flexion, à la traction et à la flexion ainsi qu'une rigidité élevées, et un fluage et un coût relatif faibles. Cette résistance et cette rigidité élevées résultent des fibres naturelles (51) et de la matrice thermoplastique (53), rendues compatibles en humidifiant ou recouvrant ces fibres (51), qui mesurent 1 mm à 20 cm de long, avec des agents de couplage (55) à base de polypropylène maléaté et, éventuellement, avec un faible volume des résines phénoliques ou époxy. Ce matériau mixte est ensuite traité par moulage (65) dans des conditions telles que sa température reste inférieure à 230 °C et la pression inférieure à 28000 psi.
PCT/US1995/010098 1994-08-08 1995-08-08 Materiaux composites a base de fibres de jute et de kenaf et procedes de production WO1996005347A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US28721794A 1994-08-08 1994-08-08
US08/287,217 1994-08-08
US45813495A 1995-06-02 1995-06-02
US08/458,134 1995-06-02

Publications (1)

Publication Number Publication Date
WO1996005347A1 true WO1996005347A1 (fr) 1996-02-22

Family

ID=26964337

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1995/010098 WO1996005347A1 (fr) 1994-08-08 1995-08-08 Materiaux composites a base de fibres de jute et de kenaf et procedes de production

Country Status (1)

Country Link
WO (1) WO1996005347A1 (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998013424A1 (fr) * 1996-09-25 1998-04-02 Universidad De Oviedo Materiaux composites thermoplastiques/lignine et procede de production
WO2000029183A1 (fr) * 1998-11-12 2000-05-25 Flz Faserlogistikzentrum Gmbh Granulat, et procede et dispositif pour sa production
EP1009705A1 (fr) * 1997-01-21 2000-06-21 The Dexter Corporation Non tisses obtenus par voie humide de fibres naturelles depulpees, et composites les contenant
FR2871164A1 (fr) * 2004-06-02 2005-12-09 Gaillon Soc Par Actions Simpli Composition thermoplastique destinee a la fabrication d'elements plats alveolaires par extrusion puis calandrage et elements ainsi obtenus
US7513967B2 (en) * 2000-09-27 2009-04-07 Toyota Boshoku Kabushiki Kaisha Molded fiber materials and methods and apparatus for making the same
WO2009082350A3 (fr) * 2007-12-21 2009-08-27 Antal Boldizar Procédé de fabrication de pastilles composites polymère/fibre naturelle et/ou de pastilles agent de couplage/fibre naturelle et pastilles obtenues par le procédé
US8071491B2 (en) 2001-11-07 2011-12-06 FledForm Technologies, LLC Process, composition and coating of laminate material
US8158539B2 (en) 2001-11-07 2012-04-17 Flexform Technologies, Llc Heat deflection/high strength panel compositions

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5268050A (en) * 1991-06-05 1993-12-07 Ferro Corporation Process for using an extruder die assembly for the production of fiber reinforced thermoplastic pellets, tapes and similar products
US5288772A (en) * 1992-06-23 1994-02-22 Clemson University Pre-treated cellulosic materials for producing molded composite articles therefrom and process

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5268050A (en) * 1991-06-05 1993-12-07 Ferro Corporation Process for using an extruder die assembly for the production of fiber reinforced thermoplastic pellets, tapes and similar products
US5288772A (en) * 1992-06-23 1994-02-22 Clemson University Pre-treated cellulosic materials for producing molded composite articles therefrom and process

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998013424A1 (fr) * 1996-09-25 1998-04-02 Universidad De Oviedo Materiaux composites thermoplastiques/lignine et procede de production
EP1009705A1 (fr) * 1997-01-21 2000-06-21 The Dexter Corporation Non tisses obtenus par voie humide de fibres naturelles depulpees, et composites les contenant
EP1009705A4 (fr) * 1997-01-21 2001-08-01 Dexter Corp Non tisses obtenus par voie humide de fibres naturelles depulpees, et composites les contenant
US6762138B2 (en) 1997-01-21 2004-07-13 Ahlstrom Windsor Locks Llc Wet-laid nonwoven web from unpulped natural fibers and composite containing same
WO2000029183A1 (fr) * 1998-11-12 2000-05-25 Flz Faserlogistikzentrum Gmbh Granulat, et procede et dispositif pour sa production
US7513967B2 (en) * 2000-09-27 2009-04-07 Toyota Boshoku Kabushiki Kaisha Molded fiber materials and methods and apparatus for making the same
US8071491B2 (en) 2001-11-07 2011-12-06 FledForm Technologies, LLC Process, composition and coating of laminate material
US8158539B2 (en) 2001-11-07 2012-04-17 Flexform Technologies, Llc Heat deflection/high strength panel compositions
FR2871164A1 (fr) * 2004-06-02 2005-12-09 Gaillon Soc Par Actions Simpli Composition thermoplastique destinee a la fabrication d'elements plats alveolaires par extrusion puis calandrage et elements ainsi obtenus
WO2009082350A3 (fr) * 2007-12-21 2009-08-27 Antal Boldizar Procédé de fabrication de pastilles composites polymère/fibre naturelle et/ou de pastilles agent de couplage/fibre naturelle et pastilles obtenues par le procédé

Similar Documents

Publication Publication Date Title
Akter et al. Plant fiber-reinforced polymer composites: a review on modification, fabrication, properties, and applications
Jaafar et al. Important considerations in manufacturing of natural fiber composites: a review
Stark Wood fiber derived from scrap pallets used in polypropylene composites
JP5938299B2 (ja) 繊維強化樹脂組成物
CA2560349C (fr) Procede de production de materiaux composites hybrides renfermant des fibres organiques et des fibres inorganiques
US8852488B2 (en) Manufacturing process for high performance short ligno-cellulosic fibre—thermoplastic composite materials
US9309392B2 (en) Reinforced polymer composites from recycled plastic
AU2013328401A1 (en) Plant fiber-reinforced thermoplastic resin composition
US20070259167A1 (en) Wood/plastic composites with glass fiber reinforcement
KR20110007137A (ko) 비혼화성 중합체 블렌드의 인성을 증가시키는 방법
Kaczmar et al. Use of natural fibres as fillers for polymer composites
WO1996005347A1 (fr) Materiaux composites a base de fibres de jute et de kenaf et procedes de production
Chaitanya et al. Processing of lignocellulosic fiber-reinforced biodegradable composites
Ejeta et al. The Influence of Filler Concentrations and Processing Parameters on the Mechanical Properties of Uncompatibilized CS/HDPE Biocomposites
Divya et al. Evaluation of mechanical properties of wood particles reinforced polymer composites
Radzi et al. The effect of kenaf filler reinforcement on the mechanical and physical properties of injection moulded polypropylene composites
Balasuriya et al. Morphology and mechanical properties of reconstituted wood board waste-polyethylene composites
Hon et al. Interfacial phenomena of newspaper fiber-reinforced polypropylene composite, part I: the development of interfacial interaction
Alodan et al. Effect of fiber loading on physical, mechanical, and thermal properties of low density polyethylene/palm tree waste fiber composites
Baptista et al. Microstructure of thermoplastic composites reinforced with wool and wood
Faruk et al. Natural fiber reinforced thermoplastic composites
Paul et al. The role of interface modification on the mechanical properties of injection-moulded composites from commingled polypropylene/banana granules
Vishnu et al. Areca fiber reinforced LLDPE biocomposite
Chaitanya et al. Kenaf fiber reinforced polypropylene composites fabricated by injection molding
Hanif et al. Effect of phthalic anhydride on tensile properties and thermal stability of recycled high density polyethylene/wood fiber composites

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): CA JP MX

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
122 Ep: pct application non-entry in european phase
122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: CA

点击 这是indexloc提供的php浏览器服务，不要输入任何密码和下载