Reinforcements in plastics

In general, natural fibers are subdivided as to their origin, coming from plants, animals, or minerals (Fig. 2). Plant fibers usually are used as reinforcement in plastics. The plant fibers may be hairs, fiber sheafs of dicotylic plants, or vessel sheafs of monocotylic plants (bast and hard fibers). 

The mechanical properties of composites are mainly influenced by the adhesion between matrix and fibers of the composite. As it is known from glass fibers, the adhesion properties could be changed by pretreatments of fibers. So special process, chemical and physical modification methods were developed. Moisture repel-lency, resistance to environmental effects, and, not at least, the mechanical properties are improved by these treatments. Various applications for natural fibers as reinforcement in plastics are encouraged. 

Asbestos It is not the name of a distinct mineral species but is a commercial term applied to fibrous varieties of several silicate minerals such as amosite and crocido-lite. These extremely fine fibers are useful as fillers and/or reinforcements in plastics. Property performances include withstanding wear and high temperatures, chemical resistance, and strengths with high modulus of elasticity. When not properly handled or used, like other fibrous materials, they can be hazardous. 

Fillers and reinforcements, in Plastics Compounding Redbook, Leonard, L. (Ed.), Advanstar Communications, Cleveland, OH, 2000, pp. 47-58. 

Schlumpf H P (1990) Fillers and reinforcements, In Plastics additives handbook, Gachter R and Muller H (Eds), Hanser Publishers Munich, pp 525-591. 

Schlumpf H P, Filler and Reinforcements in Plastic Additives, Ed. Gaechter R, Mueller H, Hanser Verlag, Munich, 1993. 

Corbiere-Nicollier, T., Gfeller Laban, B., Lundquist, L., Leterrier, Y., Manson, J.A.E., Jolliet, O., 2001. Life cycle assessment of bioflbres replacing glass fibres as reinforcement in plastics. Resources Conservation and Recychng 33, 267—287. 

Corbiere-NicoUier T, GfeUer Laban B, Lundquist L, Leterrier Y, Manson JAE, Jolhet O. Life cycle assessment of biofibres replacing glass fibres as reinforcement in plastics. Resour Conserv Recycl 2001 33 267-287. 

H.P. Schlumpf, Fillers and Reinforcements , in Plastics Additives, 4th ed., R. Gachter and H. Muller, Eds., Carl Hanser Verlag, Munich, 1993. 

Good fiber-matrix interface is essential in the use of natural fibers as reinforcement in plastics to ensure performance and stability (Mwaikambo and Ansell 1999). 

Ihere is a growing trend to use natural fibers as fillers and/or reinforces in plastic composites as thermosetting and thermoplastic materials. Ihe use of lignocellulosic materials as reinforcements has received increasing attention due to the improvements that natural fibers can provide such as low density, biodegradabihty and highly specific stiffness, as well as the fact that these materials are derived from renewable and less expensive sources [11-... 

T. Corbiere-Nicolher, B.G. Laban, L. Lundquist, Y. Leterrier, J.-A.E. Manson, and O. Jolliet, Life cycle assessment of biofibers replacing glass fibers as reinforcement in plastics. Resour. Conserv. Recy. 33(4), 267-287 (2001). 

Choppers n. Chopper guns, long cutters, roving cutters cut glass fibers into strands and shorter fibers to be used as reinforcements in plastic. 

Short-cut staple n. Staple fiber less than 0.75-in. long. Typically used in wet-laid non-woven processes to make fabrics, or as reinforcement in plastics, concrete, asphalt, and other materials. 

Similar to in-situ modifications, post modifications (changes to cellulose after growth) could provide the opportunity to tailor-design the material in order to achieve specific properties, which is particularly relevant if cellulose is to be included in blends and composites with other materials. These changes may be chemical or physical. For example, chemical changes may be necessary as cellulose is a hydrophilic molecule, which is a problem for cellulose fibers if they are to be used as reinforcement in plastics [122]. 

Mineral fillers require surface modification when used as reinforcements in plastics. Surface treatment improves mechanical strength and... 

The primary mineral fillers and reinforcements in plastics are calcium carbonate, kaolin, talc, mica, wollastonite and silica. Calcimn carbonate is by far the mineral most commonly used to fill plastics. This is mainly because it is low in cost, widely available and provides a good balance of properties. Calcium carbonate may be pure or in combination with magnesium carbonate as a dolomitic limestone. Dolomitic limestone is harder than pure calcium carbonate and is preferred when abrasion resistance is needed, as in floor tiles. 

However, an important problem in using natural fiber as reinforcement in plastic is the poor adhesion between natural fibers and polymer matrix. In order to optimize this fiber/matrix interface and to promote adhesion, various chemical treatments can be applied on surface fibers [19-25]. Physical treatment includes heat, plasma, corona and surface fibrillation [26]. 

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