Adhesive properties of water-soluble and biodegradable hot-melt adhesive based on partially saponified poly(vinyl acetate)

Partially saponified low molecular weight (LMW) PVAc was synthesized and blended with a tackifier for use as hot-melt adhesive with water-solubility and biodegradibility. The water-solubility of the partially saponified LMW PVAc was determined as a function of the degree of saponification. PVAc prepared in this study had good water-solubility because its molecular weight was very small and it had lots of hydroxy groups in the polymer chain. As the degree of saponification increased, the solubility of PVAc in water increased. The glass transition temperature and viscoelastic properties of partially saponified PVAc were measured and analyzed by using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). As the temperature increased and the degree of saponification decreased, melt viscosity decreased. The single lap-shear strength and biodegradability of the hot-melt adhesive on based PVAc were systematically evaluated. As the degree of saponification of the polymer increased, the single lap-shear strength of the hot-melt adhesive and the tendency for cohesive failure to occur decreased. The higher the degree of saponification, the faster the rate of biodegradation of the adhesive in natural water.