other compouding ingredients such as sulphur,zinc oxide,stearic acid,N-isopropyl-N'-phenyl-p-phenynediamine (IPPD),benzothiazolil disulpide(MBTS), and precipitated silica(grade valcasil-S) were supplied by bayer Co.(M) sdn.Bhd.,petaling Jaya,selangor,Malaysia.