Effect silica/carbon black ratio and types of accelerator for improvement in scorch time of cushion gum
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Date
2019-07
Authors
Nur Yusrina Binti Jamallullail
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Abstract
Effect of different ratio silica/carbon black on physical properties of cushion gum has been studied. Cushion gum is an uncured rubber sheet that acts as an adhesive layer between the precured tread liner and tire casing during tire retreading process. The aim of this research is firstly to determine the optimum ratios of silica and carbon black for scorch time improvement and secondly the suitable combination of primary and secondary accelerators that can improve the rubber compound properties. The rubber mixtures were prepared by using internal mixer where rubber and ingredients were mixed together. Then the premixed compounds were turned on into rubber sheet by using two roll mill. Sample S0CB35, S10CB30, S11.5CB35 and S13.5CB35 were tested to check their cuing characteristics, tensile properties, hardness properties. S10CB30 give the optimum properties due to combination ratio of silica and carbon black cause the intermingling of carbon black and silica particles which hinder the formation of hydrogen bonds between the silanol group of the latter’s particle. As a result, silica particles aggregate less, the filler disperses better in the rubber matrix which give rise to high tensile strength due to improved dispersion of silica particles in rubber matrix. There are three types of binary accelerator being studied which are MBT/TMTM, HMT/TMTM and TBBS/TBZTD. Binary accelerator MBT/TMTM give the highest mechanical properties due to its ability to form into higher crosslink density. Besides, it can decrease the cure time of rubber compound and increase the scorch time. By reducing the cure time, this reduce machine operating time used in production, and thus the time it needs power. On the whole, this is a significant reduction in energy requirements for a given production.