Digitale Medien
Springer
Journal of materials science
8 (1973), S. 1673-1689
ISSN:
1573-4803
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Maschinenbau
Notizen:
Abstract Values quoted forΔH α, the activation energy of the high temperatureα-relaxation in polyoxymethylene (POM), range from 20 to 92 kcal mol−1. This paper seeks to rationalize the discrepancy by remeasuringΔH α using time-temperature superposition of torsional creep and dynamic compliances for a POM specimen annealed at 160° C. Superposition of loss compliance curvesJ″ (ω, T) is possible over the range 20 to 120° C but creep compliance curvesJ(t, T) fail to superpose above about 70° C. The creep anomaly is explained in terms of the McCrum-Morris reduction equations in which the unrelaxed complianceJ U T increases with temperature more rapidly than the relaxed complianceJ R T . The activation energyΔH α has a constant value of 21±1 kcal mol−1 below about 70° C. Above about 70° C,ΔH α increases steadily up to 33±2 kcal mol−1 at 120° C.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF02403516
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