Physicochemical changes in rice straw after composting and its effect on rice-straw-based composites.

ABSTRACT A composting method was applied to improve the processability of rice straw (RS) and its interfacial interaction with a biodegradable resin, hydrolyzed-soy-protein-modified urea formaldehyde adhesives. The composted RS was characterized by fiber testing, Fourier transform infrared spectroscopy, thermogravimetry, differential scanning calorimetry, and scanning electron microscopy. We found that the particle size of RS was reduced from 0.6-2.0 to 0.2-0.6 mm. The cellulose content decreased, and the lignin content increased; unstable bonds were decomposed after composting. All of the results were beneficial for improving the plasticity of RS. Composted RS with inoculant exhibited a higher peak degradation temperature (352 °C) than the untreated RS (347 °C). The porous structure and tissue in RS were destroyed by the microorganism. The best bonding results were obtained by the composted RS with inoculant. Compared with untreated composites, the modulus of rupture, modulus of elasticity, and tensile strength of the composites were improved by 14.94, 25.36, and 27.21%, respectively. In addition, a mechanism of the structural changes of RS during composting was also proposed. The full biodegradable composites have potential applications in agriculture toward the achievement of sustainable development. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44878. [ABSTRACT FROM AUTHOR]