Natural rubber powder (NRP) is widely used as an additive in polymer industries because of its mechanical properties with high tensile modulus. It gives improvements of ductility, impact strength and also the decrease of crystallization of polymer blended with NRP. NRP was successfully prepared by spray drying method. The advantages of spray drying method were able to control the particle size with of ease of scaling up. However, NRP could not be directly produced due to inherit properties of rubber that were adhered together. Therefore, the coating or encapsulation of rubber particle by sol-gel method was reported to produce NRP. In addition to the spray drying, the sol-gel process was used to encapsulate rubber particle with silica (SiO₂). The sol was prepared and mixed with the pre-vulcanized latex suspension. The solid content of the mixture was controlled at 20 wt%. Then, the mixture was fed through the spray dryer. The appropriate conditions of the spray drying and the mixing ratio between SiO₂ and rubber particle to prepare the non-agglomerated NRP were investigated. The amount of SiO₂, morphology, size and size distribution of rubber particle were investigated by using TGA, SEM-EDX and laser light scattering technique, respectively. Thereafter, the obtained composite powder was blended with polylactide (PLA) by twin screw extruder. Their mechanical properties as impact value, tensile strength and elongation at break were measured by impact tester and universal testing machine. At the feed solid content at 20 wt%, NRP encapsulated with silica was successfully prepared by spray drying. Composite powder from this process could improve impact value of polymer.
