This research has been studied the preparation of natural rubber (NR) powder from NR latex by spray drying. The experiment was consisted of two parts. Firstly, it is to find the optimum condition for preparation of NR powder using 2ᵏ experimental design. The effects of various parameters: inlet air temperature at 130-170 ℃, feed rate at 3-6 ml/min, nozzle flow rate at 600-800 Lh⁻¹, %DRC at 10-40 % and sodium dodecyl sulfate content at 10-20 phr on yield of dried rubber were investigated. The optimum condition for spray drying was found to be at the inlet air temperature of 130 ℃, feed rate of 3 ml/min, nozzle flow rate of 600 Lh⁻¹, 15%DRC and 12 phr of SDS content. The total recovery of dried rubber showed 98.7% yield and 0.92% moisture content. In the second part, the mechanical properties of NR powder (unfilled and filled silica) were studied and used to compare with commercial block rubber. The tensile strength, modulus and hardness of the NR powder vulcanizate were improved compared with those block rubber vulcanizate. By comparing with those of the block rubber filled silica (STR/Si), the mechanical properties, such as tensile strength, elongation at break, modulus, hardness and tear strength of the NR powder filled silica (NRP/Si) were improved. Furthermore, the mechanical properties (modulus and hardness) of silica reinforced natural rubber composites obtained by spray drying of natural rubber latex mixed with silica (P(NR/Si)) showed higher mechanical properties than NRP/Si and STR/Si. The morphology of NR filled silica by using scanning electron microscope analysis showed that silica particles were dispersed more uniformly in P(NR/Si) than in STR/Si.
