Effects of Treatment Temperature on Properties of Starch-based Adhesives

Starch-based adhesives were developed by hydrolyzing starch with polyvinyl alcohol under alkaline and acidic conditions at various treatment temperatures. The chemical and physical structures of the corn starch and hydrolyzed starch were characterized with Fourier Transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and scanning electronic microscopy (SEM). Thermal degradation and bond strength were also evaluated. The results indicated that the bond strength of starch adhesives reached a maximum value at 40 °C. The FI-IR results showed that the amount of hydroxyl groups first increased and then decreased with increasing treatment temperature. When the treatment temperature was 55 °C the crystallinity of treated starch was the lowest and the thermal resistance also the weakest; it decreased by 10.1% and 13.6% respectively compared to untreated starch. Obvious erosion could be observed from the SEM images of treated starch. In addition, the interaction of polyvinyl alcohol (PVA) and starch also could be observed, and the results indicated that the compatibility between starch and PVA became better and better as the treated temperature was increased.