Pultrusion process is used to develop continuous fiber-reinforced composites based on thermosets as well as thermoplastic polymers (Akil et al., 2011; Velde and Kiekens, 2001). Long components having a fixed cross-sectional profile can be made using this process. However, some researchers have tried using it as a compounding process prior to injection molding. A schematic of the pultrusion process depicting various parts of the setup is depicted in Fig. 9.5. The lignocellulosic fibers to be reinforced are pulled through a preheater and a heated strand die, during which fibers are impregnated with the desired thermoplastic biopolymer (Kabir et al., 2012). The pultruded biocomposite strands thus obtained are either pelletized and injection molded or hot pressed into desired products. This process ensures minimum fiber length damage and helps in fabrication of long fiber-reinforced pellets. Ganster and Fink (2006) employed pultrusion process for compounding of spun cellulose fibers (viscose, lyocell, and carbamate) with PLA and other synthetic
Processing of lignocellulosic fiber-reinforced biodegradable composites
Figure 9.5 Schematic of pultrusion process for development of LFBC pellets.
polymers (PP, PE, HIPS). Yang et al. (2012) also employed this process to obtain jute-reinforced PLA (long fiber) pellets prior to injection molding. The jute fibers were impregnated at different temperatures (235, 250, and 280°C) and it was reported that 250°C is the optimum impregnation temperature.