The Effects of Crumb Rubber on the Properties and Microstructure of Modified Starch Degradable Composites

Modified starch (MS) degraded composites were prepared via a molding method with starch as a substrate and a blending process with crumb rubber (CR) and added plasticizers such as glycerol, urea, and formamide. The mechanical properties and water absorbability of the MS degraded composites were measured. The functional group variations were confirmed by Fourier transform infrared spectroscopy (FT-IR), and the changes of the functional groups were investigated with a stereoscopic microscope to analyze the microstructure of the composites. The results indicated that the addition of CR substantially improved the performances of degradable composites. When the CR content was 50 wt% of the MS, the interfacial properties of the reinforced materials and the dispersing degree of the filler were improved. Compared with the composite without additive, the tensile strength and bending strength of the composites were increased by 107% and 49.5%, respectively. The minimum water absorption ratio was reduced by 78% compared with the composite without the additive.