Preparation and Study on the Properties of LDPE-Thermoplastic Starch Blends; Part II: Water Absorption Behavior

In this work, water absorption behaviour of biodegradable low density polyethylene-thermoplastic starch (LDPE-TPS) blends is investigated. Thermoplastic starch was prepared by melt mixing starch and glycerol (35 wt.%) using an internal mixer at 140 °C and rotor speed of 60rpm for 8 minutes. LDPE/TPS blends containing various amounts of starch (10-40 wt.%) were prepared with (3 wt.%) and without PE-g-MA using single screw extruder. Water absorption test was carried out at room temperature and using related standard methods. The results indicate that with increase in TPS content and also increasing the immersion time, water absorption increase unit the constant value is obtained. After 21 days of the immersion time, 10.5% and 16.3% increase in water absorption were obtained for uncompatibilized and compatibilized blends containing 40 wt.% TPS, respectively. The results also show that after immersion tests, the tensile properties such as ultimate tensile strength and Young's modulus decrease.