Microwave effects on montmorillonite reinforced polyvinyl alcohol-starch nanocomposite

Abstract

This study aims to investigate microwaves’ effects on montmorillonite (MMT) reinforced polyvinyl alcohol (PVOH)/starch blends. Microwave irradiation at a power range 50–250 W was applied to the nanocomposites. Generally, when MMT was added to PVOH-starch blends without microwave irradiation, the poor distribution of MMT particles in the polymer matrix impaired the mechanical properties of the composite. Microwave irradiation generally improved tensile strength of the nanocomposites. More powerful microwaves were needed for high amounts of MMT to obtain promising properties. A smooth morphology could be observed in SEM micrographs when the nanocomposites were subjected to microwaves, where the MMT particles were embedded into the polymer matrix. Infrared spectroscopy found a “red shift” effect where higher microwave power produced nanocomposites with overall lower wavenumbers, indicating better hydrogen bonding. This can be explained by high microwave power promoting the polar reorientation that enables better linkage between -OH groups from both the PVOH and starch. Finally, XRD analysis revealed that higher microwave power would improve the dispersion of MMT particles by reducing the agglomeration of MMT particles in the polymer matrix. In conclusion, the application of microwave irradiation is preferable to keep at 100-150 W to achieve better properties of PVOH-starch-MMT nanocomposites. J. VINYL ADDIT. TECHNOL., 23:E142–E151, 2017.