effect of urea bond on structure and properties of toughened epoxy resins

In this article, modified poly(oxypropylene) diamines were synthesized and used as a new flexible curing agent for epoxy resins. The purpose of modification is to introduce urea group into epoxy resins. The reaction rate, mechanical properties, glass transition temperature (Tg), and fracture surface...

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Bibliographic Details
Published in:Journal of applied polymer science 2010-11, Vol.118 (4), p.2195-2201
Main Authors: Fang, Jianglin, Zuo, Ruilin, He, Peng, Quan, Yiwu, Chen, Qingmin
Format: Article
Language:English
Subjects:
Applied sciences
Bonding
Chemical properties
Diamines
Elongation
epoxy resin
Epoxy resins
Exact sciences and technology
Fracture mechanics
Hydrogen bonding
modification
Polymer industry, paints, wood
Properties and testing
Scanning electron microscopy
Technology of polymers
toughness
urea
Ureas
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Summary:In this article, modified poly(oxypropylene) diamines were synthesized and used as a new flexible curing agent for epoxy resins. The purpose of modification is to introduce urea group into epoxy resins. The reaction rate, mechanical properties, glass transition temperature (Tg), and fracture surface morphology of these toughened epoxy resins were investigated. Because of urea groups, the reactivity between poly(oxypropylene) diamines and epoxy resins was significantly enhanced. At the same time, the urea groups resulted in strong intersegmental hydrogen bonding between modified poly(oxypropylene) chain, which reduced the compatibility of poly(oxypropylene) with epoxy resins and resulted in higher Tg of toughened epoxy. The modified sample had tensile strength of 15.8 MPa and ultimate elongation of 118% at room temperature, whereas the unmodified sample only had 6.2 MPa and 70%. The scanning electron microscope analysis showed that the modified system displayed tough fracture feature, whereas the unmodified system showed typical brittle fracture.
ISSN:0021-8995
1097-4628
1097-4628
DOI:10.1002/app.32594