The specific volume of partially crystalline specimens of polypropylene, poly(butene-1), and poly(pentene-1) from about 160°K to above the melting point has been studied. In addition, proton spin magnetic resonance of a partially crystalline poly(butene-1) specimen has been observed over the 77°K to 320°K temperature range. Percent crystallinities as functions of temperature for polypropylene and poly(butene-1) calculated from the specific volume data are compared. The poly(butene-1) specimens show higher densities than the polypropylene samples at 170–180°K although the crystalliniites of the former are 25–40% lower than the latter. In addition, the temperature dependence of the specific volume from 160–280°K is greater for poly(butene-1) than for polypropylene. Somewhat similar trends are noted in a comparison of the NMR (nuclear magnetic resonance) second moment versus temperature curves for these two materials.
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Sauer et al. (1959) studied this question.
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