Characterization and comparison of metallocene-catalyzed polyethylene/thermoplastic starch blends and nanocomposites

This study presents characterization and comparison of the properties of metallocenec-atalyzed polyethylene (mPE)/thermoplastic starch (TPS) blends and nanocomposites, which contain maleic anhydride-grafted mPE (mPE-g-MA) compatibilizer and 20A-reinforced mPE-g-MA nanocompatibilizer, respectively. The results from X-ray diffraction (XRD) and transmission electron microscope (TEM) experiments revealed that mPE/TPS blend-based nanocomposites were achieved with the incorporation of the nanocompatibilizer. Clay 20A was also noted to preferentially locate within the interface between mPE and TPS, as well as within the mPE matrix in the nanocomposites. The crystallization temperature of mPE increased in the blends and nanocomposites, confirming the role of TPS and 20A as nucleating agents for mPE. However, the melting temperature and the glass transition temperature of mPE hardly changed in the blends and the nanocomposites. Clay 20A also served as a heat barrier, which greatly increased the thermal stability of the nanocomposites. There was a maximum increase of up to 36% and 40% obtained in tensile strength and Young's modulus, respectively, for the nanocomposites as compared to that of the blend counterparts. It was also determined that nanocomposites have a slightly lower water uptake character as compared to the blends. Hopefully, the results presented here can pave the way for further researches on the development and innovation of environmentally friendly polymeric systems. (C) 2008 Elsevier Ltd. All rights reserved.