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Microstructure, mechanical properties, and fracture behavior of liquid rubber toughened thermosets
Author(s) -
Zeng YiBing,
Zhang LianZheng,
Peng WeiZhou,
Yu Qiao
Publication year - 1991
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.1991.070420713
Subject(s) - materials science , composite material , natural rubber , thermosetting polymer , copolymer , acrylonitrile , microstructure , fracture toughness , ultimate tensile strength , nitrile rubber , toughness , epoxy , elastomer , phase (matter) , fracture (geology) , polymer , chemistry , organic chemistry
Phenolic epoxy resin was toughened by carboxyl‐randomized butadiene acrylonitrile copolymer (CRBN) for use as composite matrix. By adding different parts of butadiene acrylonitrile copolymer (BN‐26, without carboxyl contained) to CRBN, different sizes of rubber domains and different numbers of chemical bondings between the resin matrix and the rubber phase were obtained. It is found that small rubber particles (less than 0.1 μm) are cavitated during the crack development. The interaction between secondary crack zones caused by the cavitation makes the fracture toughness K IC of the materials high; by comparison, a local stress‐whitened zone is produced in the material with large rubber particles (more than 0.1 μm) when it is subjected to tensile stress. In this case, the flexure strength σ f of the material is great. Using ultrasection and TEM techniques, the stress‐whitened zone was shown to be caused by the special multiple‐phase structure of the material, in which many caves and “macrocrazes” coexist.