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Tensile, impact and fatigue behavior of an amine‐cured epoxy resin
Author(s) -
Kim S. L.,
Skibo M. D.,
Manson J. A.,
Hertzberg R. W.,
Janiszewski J.
Publication year - 1978
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760181410
Subject(s) - materials science , epoxy , composite material , ultimate tensile strength , fracture toughness , amine gas treating , toughness , modulus , stoichiometry , elongation , fracture mechanics , chemistry , organic chemistry , environmental engineering , engineering
Abstract Although crosslinked networks are commonly used as adhesives and composite matrixes, structure‐property relationships are not as well established as with thermoplastics. For this reason, an extensive study was begun to systematically examine effects of stoichiometry, morphology, and distribution of crosslink density on viscoelastic behavior and ultimate properties. The system selected was based on a bisphenol‐A‐type epoxy cured with methylene dianiline. This paper describes and discusses results obtained for resins in which the amine/epoxy ratio ranged between 0.7 and 2.2. In agreement with reports by others, the tensile strength, modulus, and ultimate elongation were relatively insensitive to stoichiometry but did not show slight maxima or minima when the amine was somewhat in excess. Impact strengths, tensile energies‐to‐break and fracture toughness were, in contrast, quite sensitive, though the patterns of each differed significantly. Both fracture toughness and the stress intensity factor required to drive the crack at a given rate varied directly with the amine/epoxy ratio, as did estimates of the characteristic flaw size. Fatigue striations were observed on the fracture surfaces and corresponded to the incremental advance of the crack in one loading cycle.