Rheological and Thermal Behavior of PVAc/Starch Blends Modified by Acrylic Acid

A novel plastic of polyvinyl acetate (PVAc) blended with starch was prepared in our research. Acrylic acid (AA) was added adequately in step of PVAc preparation as modifier, with emulsifier and initiator each occupied with 2.5 and 0.7 wt% of monomer. We used a capillary rheometer to evaluate rheological properties of PVAc and starch blends. The rheological behavior of the blends shows pseudoplastic and shear thinning. In this article, we also studied effects of AA content and temperature on viscosity. The results show that the viscosity of blends increased gradually as AA content increasing and it shows decreased as temperature increasing. The thermal behaviors of these materials were evaluated by differential scanning calorimetry and thermogravimetric analysis. The starch and AA content were considered to be the main influence factors. From the diagrams we concluded that the addition of adequate AA content could improve the compatibility and stability of the blends; however, the starch content was limited properly otherwise the stability of blends would be weakened. (C) 2013 Society of Plastics Engineers