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Proton spin–lattice and spin–spin relaxation times in isotactic polypropylene. II. Effects of stretching ratio and temperature
Author(s) -
Tanaka Hiroshi
Publication year - 1983
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1983.070280514
Subject(s) - crystallinity , amorphous solid , materials science , relaxation (psychology) , tacticity , proton spin crisis , atmospheric temperature range , polypropylene , proton , analytical chemistry (journal) , condensed matter physics , spin–lattice relaxation , spin glass , lattice (music) , spin (aerodynamics) , nuclear magnetic resonance , crystallography , polymer , thermodynamics , chemistry , composite material , physics , organic chemistry , nuclear physics , psychology , social psychology , acoustics , polymerization
Proton spin–lattice, T 1 , and spin–spin, T 2 , relaxation times of uniaxially stretched polypropylene film were measured at 40°C using a wide line pulse spectrometer operating at 19.8 MHz. T 1 l , the longer T 1 , increases almost linearly with increasing stretching ratio, and T 2 a , T 2 of the amorphous region, decreases gradually as the stretching ratio is increased. These results can be interpreted in terms of the increased constraints to molecular motion in the amorphous region. The fraction of the rigid protons in the sample, F c , increases with increasing stretching ratio, while the crystallinity calculated from the density, X d , does not change largely. The difference between F c and X d , therefore, increases as the stretching ratio is increased. This indicates that the physical structure of the highly stretched sample is far from the ideal two‐phase model. The influence of the stretching temperature was also investigated. There are only slight increases in T 1 l and in F c for the samples stretched in a temperature range from 80°C to 150°C, whereas the considerable increase in T 2 a occurs. The most notable change introduced at a high temperature stretching is the increase in the chain mobility in the amorphous region.