Micro-injection molding of thermoplastic polymers: Proposal of a constitutive law as function of the aspect ratios

摘要

Based on experimental measurements of the in situ conditions within polymer flow during micro-injection molding, a new geometrical parameter is defined to predict realistic dimensions of micro-parts (parts). To this aim, thin-walled parts of various aspect ratios length/thickness (L/h) were first molded, with two different polymers: (i) a polystyrene and (ii) a cyclo-olefin copolymer. It is shown that pressure drops (P-i), measured between the injection pressure and the various sensors present in the mold, are directly related to the square of the ratio of L/h. This approach has finally been successfully applied to the results of the literature, confirming its relevance. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45719.