Effects of glycerol content in modified polyvinyl alcohol-tapioca starch blends

The effects of glycerol content in modified polyvinyl alcohol-tapioca starch were investigated. A series of plasticized polyvinyl alcohol (PPVA) and TS blends were prepared. Prior to compounding process, PVA was plasticized with 15-40 phr glycerol as well as addition of calcium stearate (CaS) and phosphoric acid. Blends of PPVA at composition of 50%, 60%, 70%, 80% and 90% TS with 20 phr glycerol were compounded using twin screw extruder. Blends of PPVA-TS were then processed via injection molding to produce test specimen for mechanical testing. It was found that the addition of glycerol in the blending is compulsory in order to have a better flowability during the processing process. In spite of that, the amount of glycerol inside the blending must be in the optimum composition to ensure that the mechanical properties of the blends are not affected.