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Crystalline order in polyethylene: A 13C NMR CP/MAS solid-state T1 study

✍ Scribed by Axelson, D. E.

Publisher
Wiley (John Wiley & Sons)
Year
1982
Tongue
English
Weight
591 KB
Volume
20
Category
Article
ISSN
0098-1273

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✦ Synopsis

Abstract

The carbon‐13 spin‐lattice relaxation times T~1~ of the crystalline components of four solid ethylene‐octene copolymers have been studied as a function of thermal history, branching number, and branching distribution. Slowly cooled samples (1 deg/min from melt to room temperature) exhibited similar or longer T~1~s with respect to the same sample quench cooled (from the melt into 20°C water). The greater the degree of branching and the more homogeneous the branching distribution, the shorter were the observed crystal lattice T~1~s. Differences of up to a factor of 3 in T~1~ were observed for the same sample undergoing the two thermal treatments. Different degrees of branching homogeneity (for the same total number of branches) resulted in differences approaching a factor of 7 for samples with the same thermal history. These variations were attributed to the differing effects of side‐chain disruption of the crystal lattice.

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