Study of the effect of regrinding on the cumulative damage to the mechanical properties of fiber‐reinforced nylon 66

An experimental study of the tensile strength of nylon 66 regrind, with and without short-fiber reinforcement, is reported. For nylon 66 without reinforcement, a uniform increase in tensile strength has been observed with increasing number of moldings. This is due to a further condensation reaction which occurs during molding. For short fiber-reinforced nylon 66 composite, the tensile strength decreases with increasing number of moldings, which is attributed to the cumulative breakage of fiber length through mechanical working. A model based on fiber length analysis is proposed, and the semiempirical equation can be used to predict experimental results and balance cost–end use properties.