Abstract
Abstract It is well-recognized that different sulphur curing systems have greatly influenced to the final properties of the rubber vulcanizates. In this study, the properties of vulcanizates with conventional vulcanization (CV) and efficiency vulcanization (EV) systems were correlated in the aspect of stress relaxation and thermal stability. The stress relaxation behaviour and thermal stability were studied with the temperature scanning stress relaxation (TSSR) and with thermogravimatric analysis (TGA) techniques, respectively. Thermo-oxidative degradation of rubber chains in the CV system was greater than the EV system, leading to easier stress relaxation and poorer aging resistance of the CV system. Also, thermal stability of the rubber crosslinked with CV system was poorer than that with the EV system as corroborated by the activation energy of degradation. TSSR result correlated well with TGA result, and both revealed type of crosslinkages governed the thermo-oxidative degradation and thermal stability of vulcanizates.
Highlights
It is well known that unvulcanised NR has low strength, aging degradation of CV and EV crosslinked NR, and is unstable over a wide range of temperatures, and cannot found that the thermal ageing properties of NR vulcanizates recover its original shape after a large deformation[1,2]. depend strongly on crosslink density
It has been proven that the CV systems give a large proportion of polysulfidic linkages with bond obtained with a CV system, but the highest thermal stability was achieved with a semi-EV system due to high crosslink density with thermally comparatively stable mono- and disulfidic linkages
Rattanasom et al.[12] found that NR/tire tread reclaimed rubber blend vulcanizates had better heat aging resistance with an EV system than with CV, due to the better thermal stability of mono- and di-sulfidic crosslinks compared to polysulfidic linkages
Summary
It is well known that unvulcanised NR has low strength, aging degradation of CV and EV crosslinked NR, and is unstable over a wide range of temperatures, and cannot found that the thermal ageing properties of NR vulcanizates recover its original shape after a large deformation[1,2]. depend strongly on crosslink density. This Larpkasemsuk et al.[10] reported that for epoxidized natural is a chemical process, converting viscous rubber materials rubber the highest tensile strength and oil resistance were into three-dimensional elastic crosslinked networks by using chemicals and heat[3]. It has been proven that the CV systems give a large proportion of polysulfidic linkages with bond obtained with a CV system, but the highest thermal stability was achieved with a semi-EV system due to high crosslink density with thermally comparatively stable mono- and disulfidic linkages. Rattanasom et al.[12] found that NR/tire tread reclaimed rubber blend vulcanizates had better heat aging resistance with an EV system than with CV, due to the better thermal stability of mono- and di-sulfidic crosslinks compared to polysulfidic linkages. Various studies have reported on mechanical and thermal properties achieved with CV and EV systems but the discussions remained in contradiction
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