Compounding and Direct Compounding of Crimped Fiber Reinforced Thermoplastic Elastomers

The use of wavy fibers as reinforcement elements accounts for higher strengths and preserves the flexibility of elastomers. For this purpose, the manufacturing of wavy short fiber reinforced thermoplastic elastomers by injection molding was investigated. Thermoplastic elastomer and crimped staple fibers were separately compounded and molded (SCM) or directly compounded in the injection molding machine (DCM). Comparative tension bars were manufactured with compounds derived from straight fiber (tow, same fiber type). Selected specimens were dissolved in cyclohexane and the fibers were characterized regarding fiber length and degree of crimp (quotient of the extended fiber length and the crimped fiber length). Tensile tests were performed to evaluate the mechanical properties. The examination of the resulting fiber length and shape in the injection molded parts showed that every processing step (compounding or injection molding) and every raw fiber, whether straight or crimped, produced wavy fibers in the resulting granules or parts.