Mechanical properties and crystallization behavior of three kinds of straws/nylon 6 composites.

After alkali treatment, wheat straw, maize straw and rice straw were mixed with a mixture of nylon 6 (PA6) and prepared into composites using the melt blending method. The mechanical properties and crystallization behavior of three kinds of straw fiber/PA6 composites were studied using tensile and impact tests, differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results showed that increasing of the three kinds of straw fibers initially increased the tensile strength of the composites and then decreased, and that the tensile strength reached a maximum value when the wheat straw fiber content was 10%, which was 56.9% higher than that of the pure PA6. The impact strength of the composites initially decreased and then increased, with the maximum impact obtained for the composites with the wheat straw fiber content of 10%, which was 39.2% higher than that of the pure PA6. The introduction of the three kinds of straw fiber also induced the formation of α crystal formed in the PA6. With the increase of the straw fiber content, the grain size of the composite increased continuously, the crystallization temperature (Tc) decreased, the melting temperature (Tm) and crystalline changed slightly, and the maximum degree of crystallinity was obtained when the wheat straw fiber content was 10%.

New photocatalyst based on graphene oxide/chitin for degradation of dyes under sunlight.

Sunlight photocatalyst was fabricated by in situ synthesis of Cu2O in the regenerated chitin (RC)/graphene oxide (GO) composite film, where the porous chitin film was used as the microreactor for the formation of nano Cu2O. Nano Cu2O was immobilized and evenly distributed in the matrix and Cu2O tended to grow on the GO sheets. Cu2O inside the matrix excite and generate free photoelectrons and electron holes, which was responsible for the degradation of dyes, while GO transferred the yielded photoelectrons to prevent the generation of local high potential zone and induce the chain degradation at more points. So it was found that the porous chitin film could load Cu2O and graphene at the same time, controlling the size of Cu2O and leading to easy recycle and reuse of the photocatalyst. Moreover, the introduction of GO has dramatically improved the photocatalytic activity of Cu2O in the Cu2O/GO/RC film, showing great potential application in wastewater treatment utilizing solar energy.

Homogeneous synthesis of chitin-based acrylate superabsorbents in NaOH/urea solution.

A modified freezing-thawing cyclic (FTC) process was applied to dissolve the chitin in NaOH/urea solution. A transparent homogeneous solution was obtained. It was utilized directly for preparing the superabsorbent polymers (SAPs) by grafting copolymerization under static solution conditions without nitrogen protection. The acrylic acid was used conveniently without prior neutralization. The final products existed as hydrogels without excess reagent emissions. The adsorption capacity and yield of SAP that was prepared in the optimum conditions was 2833 g/g and 81.65%, respectively, higher than one-time FTC program prepared with 2527 g/g and 15.44%. Furthermore, it formed a uniform and transparent gel without any residual chitin particles. The regenerated chitin and SAPs were characterized by SEM, FTIR, XRD, and TG. The samples prepared by the new method presented a more amorphous state with good thermal stability, suggesting that this convenient preparation method for a potential industrial application's pathway.