Abstract:
The objective of this research is to prepare polymer blends from natural rubber (NR) mixed with potato starch (PS) at various ratios from 100/0, 90/10, 80/20, 70/30, 60/40 and 50/50. The experiment can be divided into 3 parts. For the first 2 parts, it was NR/PS film with and without glycerol. For the first part, polymer blend was prepared by mixing the suspension of starch with NR latex, which was called as latex mixing. Then the dried polymer was mixed with rubber chemicals using a two-roll mill. While for the second part, NR was mixed directly with PS using an internal mixer called as dry mixing. Then the obtained mixture was mixed with rubber chemicals using a two-roll mill. And for the third part, the silane coupling agent Si-69 was replaced glycerol. The compound was compression-molded at 155 oC to form film for further testing in physical, mechanical and heat properties. From the investigation of the film with naked eyes, it can be seen that NR film mixed with PS prepared from a dry mixing showed less phase separation than that obtained by latex mixing. Moreover, it was found that adding glycerol reduced the agglomeration of PS. From the swelling test, it was found that PS caused the NR film to absorb water and the % water absorption increased with increasing PS. At the same NR/PS ratio, the NR/PS film prepared by latex mixing had higher water absorption than the one prepared by dry mixing. Moreover, the % water absorption increased with the presence of glycerol. The addition of PS caused the reduced mechanical properties. The more PS, the lower mechanical properties. However, it was found that the NR/PS film prepared by dry mixing had higher tensile strength and tear resistance but lower hardness than the one prepared latex mixing. The addition of glycerol improved tensile strength and tear resistance but reduced hardness of the NR/PS film. For thermal decomposition, it was found that the addition of PS to NR film in both with and without glycerol resulted in NR, which is the main phase, prone to decompose at higher temperature. Lastly, when replacing glycerol with silane coupling agent Si-69, it was found that the NR/PS film showed better water absorption and tensile strength but lower tear strength.