ISSN:
0032-3888
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
A range of additives at 7 to 20 wt% loading can increase the stiffness and strength of crosslinked epoxy resins by up to 60%, yet the tensile specimens also fail in a ductile fashion. In additive formulations where little chemical bonding occurs between the additive and the epoxy matrix (e.g., the reaction product of 4-hydroxyacetanilide and 1,2-epoxy-3-phenoxypropane), the increase in modulus is directly related to the decrease in free volume available for segmental mobility. The increase in strength results from a combination of the increased modulus and an increased fracture energy, A ductile mode of failure occurs because the cured plastic exhibits a large increase in free volume on straining (low Poinsson's ratio). The strain-induced increase in free volume effectively takes the sample through the glass to rubber transition. In more highly reactive formulations (e.g., the reaction product of 4-hydroxyacetanilide and vinyl cyclohexene dioxide), chemical bonding effects complicate this simple free volume interpretation, but the occurrence of a ductile failure mode is again related to the free volume increase with strain.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760272108
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