Lignocellulose fillers

Brookfield, Ct SPE, 2002, Paper 570, Session W7-Vinyl Plastics. Vinyl Composites, pp.4, CD-ROM, 012 AMINOSILANE SUPERFICIAL TREATMENT OF LIGNOCELLULOSIC FILLERS COMPOSITE PREPARATION AND MECHANICAL PROPERTIES... 

COMPOSITION OF WOOD-PLASTIC COMPOSITES CELLULOSE AND LIGNOCELLULOSE FILLERS... 

Effect of chemical treatment of lignocellulosic fillers on the acoustic properties of the composites... 

The reinforcement of the polypropylene with the lignocellulosic material results in the increase of ac conductivity (Figs. 10 and 11). The random distribution of the lignocellulosic fillers in the polypropylene matrix enables rearrangement of the fibres in a chain structure which ensures better carrier mobility in the presence of electric field. The frequency dependence of the electrical conductivity is described by the expression (Jonsher, 1997) ... 

The effect of chemical treatment is dominant in the low frequency range, i. e. from lO Hz to 1 kHz. It can be opposite for various kinds of lignocellulosic fillers. Figs. 16 and 17 show the frequency dependences of dielectric permittivity sf obtained at room temperature for the polypropylene composites containing crude, mercerized and modified lignocellulosic fillers derived from pine and beech wood as well as two kinds of rapeseed straw. The effect observed for the pine and beech wood (Fig. 16) consists in the increase of the dielectric permittivity s value. The modification with maleic anhydride causes greater increase than the mercerization. In the case of both kinds of rapeseed straw Kaszub and Californium (Fig. 17), the mercerization decreases the dielectric permittivity s value several times and the modification with maleic anhydride reduces s value to that measured for composites with crude pine and crude beech. One should take into account the location of the / wet- relaxation in the vicinity of room temperature to explain the opposite influence of chemical treatment... 

Averous, L. Le Digabel, F. (2006). Properties of Biocomposites Based on Lignocellulosic Fillers. Carbohydrate Polymers, Vol.66, No.4, (November 2006), pp. 480-493, ISSN 0144-8617... 

Yet another limitation associated with the use of lignocellulosic fillers is the fact that the processing temperature of composites must be restricted to just above 200°C (although higher temperatures can be used for short periods of time), because of their susceptibility to degradation and/or the possibility of volatile emissions that could affect the composite properties. This limits the types of thermoplastics that can be used to polymers like polyethylene, PP, poly-vinyl chloride and polystyrene, which constitute, however, about 70 per cent of all industrial thermoplastics. Nevertheless, technical thermoplastics like polyamides, polyesters and polycarbonates, which are usually processed at temperatures higher than 250°C, cannot be envisaged as matrices for these types of conposite. 

Transcrystallization of Isotactic Polypropylene on the Surface of Lignocellulosic Fillers... 

Felix and Gatenholm [20] were among the first researchers who showed results confirming the presence of TCL on the surface of lignocellulosic filler. In the manufacturing of polypropylene composites containing cotton fibers, they observed the presence of TCL around fibers. An interesting observation was that the presence of formed TCL improves the shear transfer between filler fiber and the matrix. 

The consequence of lignocellulosic material addition, not only in the form of fibers but also in the form of wood flour or wood particles, is the nucleating effect. Numerous reports prove that the presence of wood origin lignocellulosic filler has an influence on crystallization of polymeric matrix. 

Mucha and Krolikowski [39], studying the kinetics of isothermal crystallization of polypropylene, noticed that addition of a filler, e.g., wood flour, efficiently reduces the time of crystallization. This is desirable in the processing of composites as it reduces the injection-forming cycle and forms small spherulites improving the mechanical properties of composites. Transcrystalline structures are formed during polymer crystallization in the presence of lignocellulosic filler. 

The PLA has been associated with a great number of lignocellulose fillers such as paper waste fibers, wood flour, kenaf (Nishino et al. 2003), bamboo (Lee et al. 2004), papyrus (Nishino et al. 2007), jute (Plackett et al. 2003), or flax fibers (Van de Velde and Kiekens 2002). 

Fig. 17.3 Elaboration of lignocellulose fillers fractions wheat straw fractionation schema. Reproduced with permission (Averous and Le Digabel 2006). Copyright of Elsevier...

Averous L, Le Digabel F (2006) Properties of biocomposites based on lignocellulosic fillers. Carbohydr Polym 66 480-493... 

Le Digabel F, Boquillon N, Dole P et al (2004) Properties of thermoplastic composites based on wheat-straw lignocellulosic fillers. J Appl Polym Sci 93 428-436 Lee S -R, Park FI-M, Lim H et al (2002) Microstructuie, tensile properties, and biodegradability of aliphatic polyester/clay nanocomposites. Polymer 43 2495-2500 Lee SFI, Ohkita T, Kitagawa K (20(M) Eco-composite from poly(lactic acid) and bamboo fiber. Flolzforschung 58 529-536... 

Composite sample comprising lignocellulosic filler-beech wood sawdust, namely AAMSt/St/BWS, is more less transparent comparatively with sample comprising beech cellulose. Film sample based only the plasticized starch matrix with chemically modified starch microparticles in composition maintains relative transparency. 

B. Kord, and S. K. Hosseinihashemi, Effect of fungal decay on the hygroscopic thickness swelling rate of lignocellulosic filler-polyolefin biocomposites. Mechanics of Composite Materials 49 (6), 691-8 (2014). 

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