LONG FIBER COMPOSITE REINFORCEMENT USING THERMOPLASTIC POLYMER DISPERSIONS

摘要

Long glass fiber (LGF) reinforcement of polypropylene is commonly used to improve mechanical properties in molded articles across a wide range of application areas. Fibers are typically incorporated into thermoplastic resin within a continuous pultrusion process, whereby a group of glass fibers are drawn through molten polymer using a die configured at the end of an extruder. An alternative technique for binding glass fibers in highly concentrated rovings based on simple immersion processes within aqueous polymer dispersions is described. Following water evaporation, strand cooling, and pelletization into defined lengths, the resulting LGF concentrates are suitable for injection molding using existing process equipment. Glass fiber loadings exceeding 90 weight percent can be generated within polymer dispersions selected for compatibility with the targeted base resin. Measured viscosity variation over time can be utilized as a means to assess subsequent handling characteristics for a given bath type at larger scales, with preferred polymer dispersions identified for the process based upon Versify? elastomeric resins. The method is equally applicable to alternate long fiber material types including metals utilized for electromagnetic compatibility applications, and shielding levels equivalent to conventional methods are demonstrated. Such an approach to forming concentrates can be similarly applied to particulate fillers, pigments, and other additives.