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Effect of Multiple Extrusion on Impact Fracture of Three Poly(propylene) Impact Copolymers
Author(s) -
Jancar J.,
Tochacek J.
Publication year - 2013
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.201300084
Subject(s) - materials science , composite material , extrusion , izod impact strength test , charpy impact test , spherulite (polymer physics) , melt flow index , plastics extrusion , polypropylene , crystallization , nucleation , copolymer , microstructure , polymer , chemical engineering , ultimate tensile strength , thermodynamics , engineering , physics
Summary The effect of structural changes induced by multiple extrusion on the impact fracture behavior of three reactor poly(propylene) impact‐copolymers (ICPPs) was investigated. The morphogenesis of the complex ICPP structure was controlled by the competition between the intraspherulitic phase separation and crystallization. The rubbery inclusion size was controlled by the rate of spinodal decomposition at the onset of crystallization. The following fast spherulite growth fixed the size and spatial distribution of these inclusions. The Charpy notched impact strength ( a k ) and critical strain energy release rate ( G c ) measured under impact loading decreased significantly with the number of extruder passes. A measurable reduction of the size of the crack tip plastic zone ( R p ) with the number of extruder passes was observed using high speed digital camera. While the melt flow index (MFI) dependence of a k exhibited ICPP specific shape, the MFI dependences of G c fell on a single master curve at both 23 and −20 °C.