Abstract
AbstractSeveral commercial grades of talc were selected to develop polypropylene based microporous membranes through MEAUS process (melt extrusion—annealing—uniaxial 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.
Highlights
Membranes have gained an important place in chemical technology and are used in a broad range of applications
Several works account for the needing of a highly oriented row lamellar structure in neat polypropylene films, so as membranes could be obtained in stages of MEAUS processes; the minimum orientation factor should be above 0.35.[21,23] In the precursor films, the orientation and position of the crystal blocks control the lamellae separation process, which leads to pores formation
The addition of talc constraint the orientation of neat polypropylene, being this effect more marked as more amount of talc is added to polypropylene
Summary
Membranes have gained an important place in chemical technology and are used in a broad range of applications. The use of mineral fillers can provide to the membrane an increase in rigidness, an enhancement of the hydrophilic surface characteristic and can affect to the final porous morphology of the membranes, as most of the fillers have some nucleating ability in the crystallization processes of polyolefins.[7,8,9,10,11,12]. This work is the first stage of this study, in where the key point is the combination of an advanced modification of the extrusion process (rapid air cooling) of the extruded exit along with the addition of talc of mineral filler. Several types of talc, differing in particle size, morphology and aspect ratio will be added at different concentration polypropylene, to analyze the effect of these characteristics on physical and transport properties of membranes produced through MEAUS process.
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