Phase transitions during shear flow of two phase polymer blends. II. Styrene‐acrylonitrile/poly(methylmethacrylate) transition to “Homogeneous” melt state
1987; Wiley; Volume: 27; Issue: 5 Linguagem: Inglês
10.1002/pen.760270508
ISSN1548-2634
AutoresJørgen Lyngaae‐Jørgensen, K. Søndergaard,
Tópico(s)Polymer Foaming and Composites
ResumoAbstract An advanced hypothesis derived in Part I (this issue) is tested with selected model blends. Blends of copolymers of styrene and acrylonitrile (SAN) and poly(methylmethacrylate), (PMMA) were studied because they are both amorphous, thermally stable, have large density differences, are easy to cut (in an ultramicrotome) and because comprehensive studies have been reported In the literature on this system. The melt viscosity of the blends were studied using a Rheometrics Mechanical Spectrometer and an Instron capillary rheometer. Light scattering measurements were performed during flow in order to measure the critical transition stress. The phase structure of quenched samples was studied by transmission electron microscopy on ultramicrotome cuts. It was shown that an Interpenetrating co‐continuous structure develops when flow is stopped, if a homogeneous phase Is formed during flow. Melt fracture limits the applicability of this approach to nearly compatible blends.
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