Preparation of natural rubber powder modified with bis(triethoxysilylpropyl)tetrasulfide treated silica by spray drying process

Abstract

In polymer industry, Natural rubber powder (NRP) is broadly used because of its stability and useability. Although, NRP is difficult to be produced due to the rubber adhered together. Consequently, silica was used to encapsulated the rubber particle to avoid adhesion of rubber. However, there is a polarity difference between silica and rubber. Silica can be made hydrophobic via surface modification with silane coupling agent, bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT). This research study aimed to prepare uniform silica-coated NRP via a combination of silane modification and spray drying technique. The effect of the mass ratio of TESPT and silica is 1%, 5%, 8%, 10%, and 12% were investigated in the modification of silica step. The results found that 8% of TESPT is most suitable for modifying silica as evidenced by its highest grafting efficiency. The second step is the preparation of NRP. The effect of TESPT and the mass ratio of silica to natural rubber at 3:1, 2:1, 1:1 and 0.5:1 to the properties of NRP were investigated in this step. The findings of this study demonstrated the feasibility of the production of uniformly spherical NRP. Moreover, the results indicated that TESPT can improve the compatibility between NR and silica resulting in higher bound rubber content and the mass ratio of silica to NR ranging from 3:1 to 1:1 the most of NR particles were sufficiency encapsulated in silica particle.