Effects of processing conditions on mechanical properties and crystallinity of micro injection molded thermoplastics

A micro-injection molding machine was used to obtain micro-moldings of HDPE, POM, and PC, to study the effects of processing conditions on the mechanical properties of the moldings. A precise punch die was designed to prepare the dumbbell test specimens, and sample holders was designed to fit die pneumatic grips, to prevent slippage between sample and grips and to ensure that the long axis of the test specimen coincides with the direction of the pull force. The mechanical behaviour of the specimen, including stress-strain curve, modulus and yield stress, was correlated to DSC measurements. Significant drop in modulus was observed in micro specimens for the materials.