ISSN:
0098-1273
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Proton spin-lattice relaxation experiments on the bis-(p-toluenesulfonate) of 2,4-hexadiyne-1,6-diol (TSHD) as a function of temperature (25 to 353 K), of frequency (22 and 44 MHz), and of conversion to polymer were performed to determine the molecular motions in this crystal and to follow the conversion via the changes in the relaxation time T1. It was found that T1 is dominated below 125 K by weakly hindered (ΔE = 2.8 kJ/mole) tunneling (Λ = 220 MHz) CH3 groups, at about 160 K by order-disorder fluctuations around the phase-transition temperature ϑc which depends strongly on the conversion, and above 200 K by the motion of the whole side group. T1 can be used as sensitive probe for the conversion: The change in T1 at about 44 K is directly proportional to the conversion, whereas the change at high temperatures (e.g., 353 K) occurs essentially at low conversions (≤10%). This is explained by distorted (stressed) areas around the isolated polymer chains, which are estimated to be about 16 times the size of the chains. After an induction period the stresses are relieved by further polymerization.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1980.180180307
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