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:
Poly(vinyl chloride) polymers stabilized with tribasic lead sulfate discolor upon exposure to hydrogen sulfide gas as a result of lead sulfide formation. The discoloration occurs for samples in both cord and sheet forms and is shown to be a function of total H2S exposure, reaching a limiting value that is determined by the amount of lead stabilizer used in the polymer formulation. The permeation and diffusion constants for H2S through PVC stabilized with tribasic lead sulfate and with a liquid Ba-Cd-Zn formulation are found to be PPb = (6.0 ± 0.2) × 10-9, PBaCdZn = (5.2 ± 0.2) × 10-9 (both in cm3 gasċcm film/cm2 areaċsecċcm Hg), DPb = (1.3 ± 0.2) × 10-7 cm2/sec, and DBaCdZn = (6.4 ± 0.6) × 10-8 cm2/sec, all measured at 21°C. The stabilizing efficiencies of the formulations were assessed by HCl evolution measurements, which show that exposure to H2S decreases the initial polymer stability for both Pb-stabilized and Ba-Ca-Zn-stabilized formulations. Protection of stabilized PVC formulations from diffusing hydrogen sulfide is thus advisable for long-term stability as well as for color integrity.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1979.070230617
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