Several commercial grades of homo-polymer and its blends were selected to prepare microporous membranes through melt extrusion-annealing-uniaxial stretching technique (MEAUS). Branched or very fluid polypropylene was employed to modify the polymeric composition. In some blends, micro-sized calcium carbonate was added. We analysed the influence of sample composition, extrusion draw ratio, and we performed a deep study concerning the uniaxial strain rate, using in some cases extreme strain rates and strain extents. The crystalline features were studied by Differential Scanning Calorimetry (DSC), and the morphology of porous structure was analyzed through Scanning Electron Microscopy (SEM). Thermal stability and thermomechanical performance was measured by thermogravimetric analysis (TGA) and dynamic-mechanical-thermal (DTMA) study. A close relationship was found between crystalline characteristics, porous morphology and the trends registered for permeability.

Several commercial grades of talc were selected to develop polypropylene based microporous membranes through MEAUS process (melt extrusion-annealinguniaxial strain). Talc commercial grades differed in particle size, aspect ratio, and crystalline morphology. Different filler percentages were added to polypropylene (1, 5, 10 wt.%) Parameters such as draw ratio during extrusion, annealing temperature strain rate, and strain extension were kept as constant to analyze the effect of the talc characteristics and content of the obtained membranes. Small particle size and high aspect ratio tend to provide membranes with small pore size, high porous area, and high Gurley permeability values.