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Microporous membranes of polyoxymethylene 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.1745
Subject(s) - extrusion , polyoxymethylene , lamellar structure , materials science , composite material , rheometry , microporous material , small angle x ray scattering , annealing (glass) , rheology , polymer chemistry , scattering , polymer , optics , physics
A two‐part study utilizing polyoxymethylene (POM) was undertaken to investigate a three stage process (melt extrusion/annealing/uniaxial stretching) (MEAUS) employed to produce microporous films. In this first part, three POM resins (D, E, and F) were melt extruded into tubular films (blowup ratio; BUR = 1), where resin D has a higher weight average molecular weight (M w ) than resin E, but both possess similar and relatively narrow molecular‐weight distributions (MWD). In contrast, resin F is characterized by a distinctly broader MWD while its M w is slightly higher than resin D. Specific attention was focused upon the morphological and crystal orientation results as a function MWD and M w . A stacked lamellar morphology was obtained in each case from the melt extrusion; however, the type of stacked lamellar morphology, planar or twisted, and the orientation state was found to depend upon both the resin characteristics and the melt‐extrusion conditions. Atomic force microscopy and wide‐angle X‐ray scattering were the main techniques utilized to study the melt‐extruded films while dynamic melt rheometry in conjunction with the Carreau‐Yasuda model aided in differentiating the melt‐flow behavior of the three resins. Small‐angle light scattering (SALS) was also employed to characterize the morphological state. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2944–2963, 2001