Some factors affecting the flex life of polybutadiene rubber vulcanisate
- 15 Downloads
Flex life of three different grades of polybutadiene rubber (BR) with highly linear chains, linear chains and long-branched chains was measured. The rubbers were reinforced with a precipitated silica nanofiller, the surface of which had been pre-treated with sulphur-bearing bis(3-triethoxysilylpropyl-)-tetrasulphane (TESPT) coupling agent. The rubbers were cured by reacting the sulphur in TESPT with the rubber chains to produce vulcanisates. The mechanical properties of the rubber vulcanisates such as tensile strength, Young’s modulus, elongation at break, stored energy density at break and tear energy were subsequently determined. The flex life of the rubber vulcanisates was also measured at a constant maximum strain amplitude and a test frequency of 3.17 Hz at ambient temperature. Additionally, the flex life of some unfilled rubber vulcanisates of similar Mooney viscosities cured with elemental sulphur was also measured. For the silica-filled rubber vulcanisate, the rubber with the highly linear chains had the longest flex life and the one with long-branched chains, the shortest flex life. It seemed that a correlation between the flex life and the molecular chains structure might exist despite the crosslink density of the rubber vulcanisates being different and the compounds having silica in them. For the unfilled rubber vulcanisates, the rubber with highly linear chains had the longest flex life and the one with linear chains the shortest flex life. Therefore, it was concluded that the flex life of the rubber vulcanisate was determined, to a large extent, by the molecular chains structure of the raw rubber, irrespective of whether the rubber had reinforcing silica filler, different crosslink densities and different initial viscosities or not. A similar trend was also observed for some of the mechanical properties. For example, the elongation at break was lower and Young’s modulus higher for the silica-filled rubber vulcanisates with long-branched chains than those measured for the silica-filled rubber vulcanisate with highly linear chains.
KeywordsPolybutadiene rubber Chains’ structure Flex life Mechanical properties Crosslink density
The author(s) are grateful for financial support for the research, authorship, and publication of this article from University of Engineering and Technology, Lahore, Pakistan.
- 1.White JR, de Sadhan K (2001) rubber technologist’s handbook. Rapra Technology, Shrewsbury, p 328Google Scholar
- 2.Brown Roger (2006) Physical testing of rubber. Springer, Washington, p 245Google Scholar
- 3.Boyer HE (1986) Fatigue testing, atlas of Fatigue Curves. ASM International, Ohio, p 4Google Scholar
- 9.Chang S. Woo, Hyun S. Park, And Wan D. Kim (2013) The effect of maximum strain on fatigue life prediction for natural rubber material, 7(4), 621–626Google Scholar
- 11.British Standard 1673: part 3,1969, Methods of testing raw rubber and unvulcanized compounded rubber. Chemical analysis of acrylonitrile-butadiene rubber (NBR)Google Scholar
- 12.British Standard 903: Part A26,1995, Physical Testing of Rubber. Method for Determination of Hardness (Hardness Between 10 IRHD and 100 IRHD)Google Scholar
- 13.ASTM International D412, 2016, Standard test methods for vulcanized rubber and thermoplastic elastomers—tensionGoogle Scholar
- 14.ASTM International, D624, 2012, Standard test method for tear strength of conventional vulcanized rubber and thermoplastic elastomersGoogle Scholar
- 15.ASTM International D430, 2012, Standard test methods for rubber deterioration–dynamic fatigueGoogle Scholar