High performance biodegradable starch-LDPE nanocomposites prepared via twin screw extruder

Official URL: http://risc01.sabanciuniv.edu/record=b1169196 (Table of Contents)

Developing biodegradable films with an optimum combination of desirable mechanical properties and biodegradation performance is the main objective of the present study. For this purpose, low density polyethylene (LDPE)/Starch blends reinforced with layered clays were prepared using twin screw extruder. The effect of compatibilizer, starch from and its content, clay type and processing methods on the physico-mechanical properties of blend was investigated and discussed in a comprehensive manner. The results have shown that in order to achieve good biopolymer dispersion with strong interfacial adhesion, starch should be converted into thermoplastic starch (TPS) and suitable comptibilizer should be employed. Maleic anhydride grafted polyethylene (MagPE) as compatibilizer worked best between LDPE and TPS. The highest amount of TPS that can be used in the blend formulations was found to be 40 wt%. Beyond that, the fracture mechanism changed from ductile to brittle fracture. The presence of clay, in general, enhanced the mechanical as well as barrier properties and biodegradation rate of the blands. The degree of enhancement influenced by the clay type and the phase where it was mainly dispersed. The presence of organoclay in LDPE matrix mainly improved the mechanical, tear and heat seal strength of the films, while the intercalation of Na –montmorillonite clay with starch molecules was found to be more effective in enhancing the moisture barrier properties. In biodegradation test, starch was degraded in the presence of enzyme and resulted in porous structure of LDPE films that is more susceptible to oxidative and hence biotic reactions.