ISSN:
0449-2978
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Mechanical relaxation data as a function of temperature (ca. 1 Hz) have been obtained for several samples of isotactic polypropylene crystallized from the melt, which exhibit both α and β forms as well as varying degrees of lamella orientation. The samples ranged in morphology from an unoriented sample showing only the α form to one highly oriented having approximately 90 per cent the β form. Results for the logarithmic decrement Δ and loss modulus G″ are that the low temperature (ca. -75°C) and glass temperature (ca. 0°C) relaxations show little or no sensitivity to orientation in the α form, but that the intensity of the two processes is different in the α form than in the β form for samples of nearly equal overall per cent crystallinity. In both Δ and G″, the low-temperature peak decreased and the glass temperature peak increased in intensity as the fraction of β form crystallinity present increased. Data for the high-temperature relaxation (ca. 80°C) indicate a dependence upon orientation and/or crystal form in addition to a dependence upon per cent crystallinity.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1969.160070210
