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Crazing and Fracture in Polymers: Micro‐Mechanisms and Effect of Molecular Variables
Author(s) -
Kausch H.H.,
Halary J.L.,
Plummer C.J.G.
Publication year - 2004
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.200451003
Subject(s) - crazing , materials science , polymer , amorphous solid , composite material , toughness , molecular dynamics , fracture toughness , thermoplastic , polymer chemistry , chemistry , computational chemistry , crystallography
The influence of the primary molecular parameters chain configuration, architecture and molecular weight (MW) on the mode of mechanical breakdown is discussed for two series of (amorphous) thermoplastic polymers, methyl methacrylate glutarimide copolymers and amorphous semi‐aromatic polyamides. Structural and dynamic analyses and fracture mechanical methods applied to such adequately chemically modified (glassy) polymers permit us to show and to explain the effect of intrinsic variables on local molecular motions and on the competition between chain scission, disentanglement and segmental slip, which in turn determine the dominant mode of instability and plastic behaviour. Above a critical molecular weight, toughness depends most strongly on the entanglement density; a positive effect of the intensity of sub‐T g relaxations and in‐chain cooperative motions on the toughness of these materials is clearly evident.