Study of enzymatic degradation and water absorption of nanocomposites starch/polyvinyl alcohol and sodium montmorillonite clay

The aims of the study were to investigate the effect of polyvinyl alcohol (PVA) and sodium montmorillonite clay content within the thermoplastic starch (TPS) blends on the rate and extent of starch enzymatic hydrolysis using enzyme -amylase. The results of this study have revealed that blends with a MMT-Na content at 5 wt% exhibited a significantly reduced rate and extent of starch hydrolysis. The results suggest that this may have been attributed to interactions between starch and MMT-Na that further prevented enzymatic attack on the remaining starch phases within the blend. The total solids that remained after 4320 min were 64 wt% (starch/PVA); 67 wt% (starch/PVA/1% MMT); 70 wt% (starch/PVA/3% MMT); 75 wt% (starch/PVA/5% MMT). The rate of glucose production from each nanocomposite substrates was most rapid for the substrate without MMT-Na and decreased with the addition of MMT-Na, for starch/PVA blend (29.01 μg/ml h), 27.32 μg/ml h (starch/PVA/1% MMT), 21.44 μg/ml h (starch/PVA/3% MMT) and 19.49 μg/ml h for (starch/PVA/5% MMT). Enzymatic degradation behavior of sodium montmorillonite-containing nanocomposites of poly(vinyl alcohol) with starch was based on the determinations of weight loss and the reducing sugars. The degraded residues have been examined by FT-IR spectroscopy and scanning electronic microscopy (SEM) and UV–vis spectroscopy. It has been established that the nanoparticles hinder degradation, while the susceptibility to enzymatic degradation varies in the order: starch/PVA > starch/PVA/MMT-Na.