The blooming of compounding ingredients onto natural rubber vulcanized surface / Ummu Qani'ah Yasin

Blooming is a diffusion process whereby compounding ingredients in rubber compound migrate to the rubber surface and give problems such as poor appearance and loss of adhesion. Blooming of compounding ingredients onto un-filled vulcanized rubber surface were studied using simple weight changes. In this project, 2 types of natural rubber compounding formulations were used. The first type was the compounding ingredients, which were sulphur, paraffin wax and Zinc Diethyldithiocarbamate (ZDEC); being loaded with high loading content (lOpphr) was mixed into the natural rubber individually. The second type was all these compounding ingredients were mixed together with natural rubber. All the formulations were cured using dicumyl peroxide vulcanization with 6 different dicumyl peroxide loadings. The rubber compounds were cured at 150°C and stored under different temperatures to allow the blooming process. The amount of bloom was measured by scrapping the rubber surface in function of time while the blooming rate was measured by divided the equilibrium point (where the amount of bloom do not show any increment) with square root of time. The amount of bloom and blooming rate were found to be affected by the temperature and dicumyl peroxide (DCP) loading. Blooming rate of sulphur, paraffin wax and ZDEC were increased as the loading of DCP increase. Blooming rate of sulphur and ZDEC also increase as the temperature increase except paraffin wax. Based on the results of FTIR and EDX, paraffin wax was found as the dominant compounding ingredients in blooming process. Besides that, crosslink concentration also affects the blooming rate of sulphur, paraffin wax and ZDEC. As the crosslink concentration increase, the blooming rate increase.