ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
A simple radio-tracer method based on 14C is described for determining the diffusion coefficient of an additive in a polymer. Two theoretical models representing extreme cases for the diffusion system are discussed and shown to yield the same solution to within 10%. The diffusion coefficients of didodecyl 3,3′-thiodipropionate, N-octadecyldiethanolamine, and 1,1,3-tri(2-methyl-4-hydroxy-5-tert-butylphenyl)butane migrating in polyethylene, polypropylene, and poly-4-methylpentene-1 have been measured over temperature ranges of 50-80°C., within the range 20-200°C. In each case the variation of the diffusion coefficient D with temperature T can be represented by an Arrhenius equation D = D0 exp {-E/RT}, where the activation energy E is virtually independent of the size and shape of the diffusing molecule. The activation energy depends upon the polymer and is about 12.5, 21, and 14.5 kcal./mole for polyethylene, polypropylene, and poly-4-methylpentene-1, respectively.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1968.070120603
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