Injection molded foamed rice straw/LDPE with sodium bicarbonate and citric acid foaming agent : effect of foaming agent composition

Rice straw-LDPE foamed had been produced by incorporating foaming agent, which was the mixture of sodium bicarbonate and citric acid. The foam structure is produced when temperature is applied and the foaming agent decomposes. The effect of foaming agent composition on the morphology structure, density, water absorption behavior and hardness were studied. The compounding material which were rice straw, LDPE, starch, maleic anhydride and glycerol were mixed in the twin screw extruder. Then, the foaming agent was mixed with the compounded material and injected using the injection molding machine to produce foam product. Samples with foaming agent show the present of the foam structure that increases in size with foaming agent composition. The type of cell form is open cell. For the physical properties, as the amount of foaming agent increases, the density is decreased, the percentage of water absorbed increased and the hardness value is decreased.