NR/PP thermoplastic vulcanizates: Selection of optimal peroxide type and concentration in relation to mixing conditions

Thitithammawong, A. and Nakason, C. and Sahakaro, K. and Noordermeer, J.W.M. (2007) NR/PP thermoplastic vulcanizates: Selection of optimal peroxide type and concentration in relation to mixing conditions. Journal of Applied Polymer Science, 106 (4). pp. 2204-2209. ISSN 0021-8995

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Abstract:	Thermoplastic vulcanizates (TPVs) from natural rubber (NR) and polypropylene (PP) were studied, prepared by dynamic vulcanization during melt mixing, using various peroxides to crosslink the rubber phase. The objective was to find a proper balance between degree of crosslinking of the rubber and degradation of the PP-phase, and the tendency of the peroxide to form smelly by-products, in particular acetophenone. Four types of peroxides were investigated: 2,5-dimethyl-2,5-di(tert-butyl-peroxy) hexyne-3 (DTBPHY), 2,5-dimethyl-2,5-di(tert-butyl-peroxy) hexane (DTBPH), di(tert-butylperoxyisopropyl) benzene (DTBPIB), and dicumyl peroxide (DCP), at two mixing temperatures: 160 and 180°C for a 60/40 NR/PP TPV. The maximum and final mixing torques are clearly related to the intrinsic decomposition temperature of the particular peroxide used, where DCP and DTBPIB turn out to be effective at 160°C, whereas the other two require a higher temperature of 180°C. The best mechanical properties, tensile strength, elongation at break and compression set are obtained at lower mixing temperature with DCP and DTBPIB, presumably due to less degradation of the NR and PP. Unfortunately, these two peroxides form more smelly by-products than DTBPHY and DTBPH. Dependent on the requirements of the pertinent application, a balanced selection needs to be made between the various factors involved to obtain an optimal product performance of these NR/PP TPVs.
Item Type:	Article
Copyright:	© 2007 Wiley InterScience
Faculty:	Engineering Technology (CTW)
Research Group:	Elastomer Technology and Engineering (ETE)
Link to this item:	http://purl.utwente.nl/publications/72221
Official URL:	http://dx.doi.org/10.1002/app.25935
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