ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
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:
Soft-segment molecular weight, soft-segment crystallization, hard-segment-type, and reactive diluent level were examined in urea and urethane acrylates. Increasing soft-segment molecular weight led to a decreased tensile modulus, increased strength, and increased elongation at break. Soft-segment crystallization increased the modulus below the melting temperature, but decreased the modulus above the melting temperature because crystallization interfered with cross-linking. Materials with hard segments that allowed for greater phase separation showed a higher modulus, higher ultimate stress, and higher ultimate elongation. Materials with reactive diluents 2-hydroxyethyl methacrylate (HEMA) and N-vinyl pyrrolidinone (NVP) showed qualitatively different behavior. HEMA caused the modulus and strength to increase with little effect on elongation up to concentrations of 50 wt %; at higher concentrations, the elongation decreased. NVP also increased the modulus and strength; however, at 40 wt % NVP, ultimate elongation increased in a well-phaseseparated system and decreased in a poorly phase-separated system. In tensile tests, samples with 40% NVP also showed substantial sample necking and drawing. © 1993 John Wiley & Sons, Inc.
Additional Material:
14 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1993.070491110
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