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Dynamic birefringence and conformation of poly- p-phenylene terephthalamide molecules in solution
Flow birefringence (FB) for samples of poly- p-phenylene terephthalamide (PPPhTPhA) dissolved in sulphuric acid has been investigated; intrinsic viscosities [η] of the solutions have been measured. Characteristic values of FB [ n] and orientation angles [ χ/ g] of the solutions were determined. Coef...
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Published in: | European polymer journal 1977, Vol.13 (6), p.455-458 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Flow birefringence (FB) for samples of poly-
p-phenylene terephthalamide (PPPhTPhA) dissolved in sulphuric acid has been investigated; intrinsic viscosities [η] of the solutions have been measured. Characteristic values of FB [
n] and orientation angles [
χ/
g] of the solutions were determined. Coefficients of rotatory diffusion
D
r
and molecular weights M of all the samples of PPPhTPhA were calculated using the values of [
χ/
g] and [η]. Dependences of [η] and
D
r
on M show that the conformation of the PPPhTPhA molecules in solution resembles a slightly bending rod.
Quantitative data on the equilibrium rigidity of the PPPhTPhA molecules were obtained from comparison of characteristic values of [
n] and [
χ/
g] at different M and from the dependence of [
n]/[η] on M, using the theory of optical anisotropy of persistent chains and also from the dependence of [η] on M. It was shown that the number of monomer units in a statistical segment of the PPPhTPhA chain is S = 200 ± 20; this corresponds to a segment length of (1300 ± 130) Å. The equilibrium rigidity of the PPPhTPhA chain is slightly lower than that of the PPBA molecules. Possible reasons for this difference are discussed. |
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ISSN: | 0014-3057 1873-1945 |
DOI: | 10.1016/0014-3057(77)90125-2 |