In-line Compounding of Long-fiber Thermoplastics for Injection Molding

Abstract

A new process has been developed for in-line compounding and injection molding in a single operation. Selected short-to long-fiber-reinforced thermoplastic mixtures are created and fed directly into the injection molding barrel while still hot. Compositions containing glass fibers of 3-12 mm in length have been molded successfully on a 230-ton injection press. The new processing system is adaptable to the existing injection molding machines. This novel technology permits molded articles to be produced at cost levels that are less expensive than those incurred when molding parts from the conventional long-and short-fiber-reinforced thermoplastic compounded pellets.

Effect of Flax/PP pellets’ morphology on the mechanical properties of injection-molded parts

“…This minimizes thermal degradation and improves mechanical properties. 24 Additionally, this process can be used to produce both SFT and LFT. 25 Another LFT manufacturing technique is referred to as the direct strand deposition.…”

A review of Long fibre thermoplastic (LFT) composites

“…D-LFT has gained tremendous attraction from the automotive sector and it was estimated that more than 90% D-LFT process was used for automotive parts [134]. The elimination of the intermediate processing step resulted in as much as a 50% reduction in raw material costs versus purchased pellets for injection moulding [110,168]. Although this approach also incurs added equipment costs these can be amortised at modest annual production volumes of 30,000 to 50,000 units [110].…”

“…The charge produced from in-line compounding is used for subsequent injection or compression moulding, as shown schematically in Figure 7. D-LFT eliminates the steps required for packing, handling, and shipping the LFT pellets [168,172] and enables the processing of the materials at low temperature [173]. The polymer matrix undergoes only a single melt history, which minimises degradation and improves the physical properties [168].…”

“…D-LFT eliminates the steps required for packing, handling, and shipping the LFT pellets [168,172] and enables the processing of the materials at low temperature [173]. The polymer matrix undergoes only a single melt history, which minimises degradation and improves the physical properties [168]. D-LFT has gained tremendous attraction from the automotive sector and it was estimated that more than 90% D-LFT process was used for automotive parts [134].…”

Dynamic mechanical properties, thermal, mechanical properties and morphology of long glass fiber-reinforced thermoplastic polyurethane/acrylonitrile–butadiene–styrene composites

“…In order to overcome this limitation, long glass fiber–reinforced thermoplastic (LGFT) composites have been developed so as to answer these new market requirements through a higher fiber aspect ratio (length–diameter ratio) theoretically leading to higher mechanical properties. 1 –5 The final length of glass fibers in the LGFT composites is also much greater than the final length of the composites, which have been conventionally manufactured by the twin-screw extrusion process. The main matrix resins of LGFT composites are polypropylene (PP) and polyamides (PA) 6 –12 Ward 7 et al reported the influence of microstructure on the mechanical property performance of long fiber–reinforced thermoplastic composites.…”