ISSN:
0449-2978
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
A series of polyurethanes (PU) prepolymers with NCO/OH ratios of 2.1:1 and 1.9:1 were prepared by reacting hydrogenated methylene di-p-phenyl diisocyanate (HMDI) with triol mixtures of TP740 (molecular weight 740) and TP1540 (molecular weight 1540). Stress-strain (S/S) and swelling equilibrium measurements were performed using thin-film samples prepared by moisture-curing the prepolymer at room temperature. The swollen PU networks gave an S/S curve which is fully described by rubber elasticity theory. The Mooney-Rivlin constant C1 (swollen) was found to increase directly while the molecular weight between crosslinks Mc decreases as the number of branches per cubic centimeter is increased. The solvent - polymer interaction parameter χ determined in benzene was 0.077 + 0.97vr, where vr is the volume fraction of rubber in the swollen network. The crosslink density v′, and Mc were calculated from the relations v′ = pNB and Mc = 0.667 B-1, where B denotes moles of branches per gram, and were found to be in good agreement with v′ and Mc established from S/S and swelling-equilibrium measurements. In calculating v′ and Mc, the water-PU crosslinking reaction at room temperature was assumed to occur mainly through the formation of a urea linkage.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1971.160090904
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