Dual crosslinking of carboxylated nitrile butadiene rubber latex employing the thiol‐ene photoreaction |
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Authors: | Dietmar Lenko Sandra Schlögl Armin Temel Raimund Schaller Armin Holzner Wolfgang Kern |
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Affiliation: | 1. Polymer Competence Center Leoben GmbH, Roseggerstraβe 12, Leoben 8700, Austria;2. Semperit Technische Produkte GmbH, Triester Bundesstraβe 26, Wimpassing 2632, Austria;3. Chair of Chemistry of Polymeric Materials, University of Leoben, Otto Gl?ckel‐Straβe 2, Leoben 8700, Austria |
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Abstract: | At present, the most common used crosslinking process for carboxylated nitrile butadiene rubber (XNBR) latex is an accelerated sulfur curing system with zinc oxide. To avoid allergenic reactions related to residual accelerator levels in dipped XNBR latex articles such as medical gloves, a dual curing process has been developed combining thermal and photochemical crosslinking reactions. The two‐step procedure involves the formation of covalent and ionic bonds to ensure good mechanical properties of the final products. The photochemical thiol‐ene reaction is used to generate covalent crosslinks between the remaining C?C double bonds of the butadiene units whereas the carboxylic moieties are conventionally cured with divalent metal oxides (ZnO) under elevated temperature (formation of ionic crosslinks). The photochemical curing step is carried out both in the latex phase using a falling film photoreactor (prevulcanization) as well as in the solid phase by UV irradiation of dried XNBR films (postvulcanization). The mechanical properties and crosslink densities of the cured XNBR films are determined and the influence of selected curing parameters is assessed. The results give evidence that a combined approach of thermal prevulcanization and photochemical postvulcanization makes the production of latex articles (e.g., gloves) with tailored properties and good skin compatibility feasible. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 |
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Keywords: | elastomers mechanical properties crosslinking photochemistry |
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