Micro-sized calcium carbonate was selected to develop polypropylene based microporous membranes through MEAUS process (melt extrusion – annealing – uniaxial strain). Different filler percentages were added to polypropylene (1, 5, 10 wt. % calcium carbonate) Parameters such as draw ratio during extrusion, annealing temperature, strain rate, and strain extension were kept as constant in order to analyze the effect of the calcium carbonate, and content of the obtained membranes. The stress applied involved a pre-orientation of the amorphous tie chains prior to crystal chain unfolding, which can be related to the first yield point. A logical pattern of increasing elastic modulus as filler content does is found in calcium carbonate compounds.
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