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Microporous membranes of isotactic poly(4‐methyl‐1‐pentene) from a melt‐extrusion process. I. Effects of resin variables and extrusion conditions
Author(s) -
Johnson Matthew B.,
Wilkes Garth L.
Publication year - 2001
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.10164
Subject(s) - extrusion , lamellar structure , materials science , composite material , tacticity , microporous material , annealing (glass) , morphology (biology) , polymer chemistry , polymerization , polymer , biology , genetics
A study utilizing isotactic poly(4‐methyl‐1‐pentene) (PMP) was undertaken to investigate a three‐stage process (melt‐extrusion/annealing/uniaxial‐stretching) (MEAUS) employed to produce microporous films. The results of this study will be reported in the course of two articles. In this first part, three PMP resins were melt‐extruded into tubular films (blowup ratio; BUR = 1), where the resins each differ in weight‐average molecular weight (M w ). Specific attention was focused upon the morphological and crystal orientation results as a function of the melt‐relaxation times as influenced by the resin characteristics and the processing parameters. The results of a number of melt‐extrusion conditions are presented. A stacked lamellar morphology was obtained in each case; however, the type of stacked lamellar morphology, planar or twisted, and the orientation state was found to depend upon both the resin characteristics, specifically M w , and the melt‐extrusion conditions. Atomic force microscopy and wide‐angle X‐ray scattering (WAXS) were the main techniques utilized to study the melt‐extruded films, while oscillatory shear measurements, in conjunction with a Carreau–Yasuda analysis, aided in differentiating the melt‐flow behavior of the three resins. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2095–2113, 2002