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Proceedings Paper

Microtomography of elastomers for tire manufacture
Author(s): John H. Dunsmuir; A. J. Dias; D. G. Peiffer; R. Kolb; G. Jones
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Paper Abstract

X-ray microtomography is used to image the internal structure of carbon black filled isobutylene-p-methylstyrene-p- bromomethylstyrene (PIB-PMS/BrPMS or ExxProTM) curing bladders before and after use-to-failure in the manufacture of automobile tires. Curing bladders operate under extreme conditions with extended mechanical cycling at high temperatures. Manufacturers typically do not run the bladders until failure but rather a pull policy is established which emphasizes the distribution of cyclic lifetimes. We examine the bladder elastomer structure at a resolution of about 10 microns with the objective of reducing the variability in performance. Using both edge crossing and absorption contrast we identify several types of heterogeneity including voids, foreign inclusions, and the distribution of curative agent from which we infer the uniformity of the cure. The results indicate several potential failure mechanisms. The small number of voids and foreign inclusions are mechanical defects that can initiate cracking. More widespread through the polymer matrix are small regions of polymer devoid of curative agent as shown by absorption edge imaging. These regions may be uncured polymer with poor mechanical and thermal properties that may lead to early failure. After several cure cycles the uncured regions are no longer present in the bladder tread area but they remain near the bead. At high cycles an approximately 500 micrometer thick zinc rich cap develops where the bladder contacts the inner tread area of the tire. This zinc rich cap may cause over-curing of the polymer resulting in crack initiation at the surface of the bladder that contacts the tire.

Paper Details

Date Published: 22 September 1999
PDF: 10 pages
Proc. SPIE 3772, Developments in X-Ray Tomography II, (22 September 1999); doi: 10.1117/12.363742
Show Author Affiliations
John H. Dunsmuir, Exxon Research and Engineering Co. (United States)
A. J. Dias, Exxon Chemical Co. (United States)
D. G. Peiffer, Exxon Research and Engineering Co. (United States)
R. Kolb, Exxon Research and Engineering Co. (United States)
G. Jones, Exxon Chemical Co. (United States)

Published in SPIE Proceedings Vol. 3772:
Developments in X-Ray Tomography II
Ulrich Bonse, Editor(s)

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