Comparative Investigation of Nanographene and Nano-Zinc Oxide Combined with an Antioxidant on the Photostability and Surface Properties of Natural Fiber Thermoplastic Composites (NFTCs)

In the present study, a wood-plastic composite with polypropylene reinforced with wheat straw, in a ratio of ۶۰ to ۴۰, was made by the pressing method. Additives of ۱% Irganox ۱۰۱۰ antioxidant (A), ۰.۵% nanographene (NG), ۲% nano-zinc oxide (ZnO), ۰.۵% nanographene - ۱% antioxidant (NA) and ۱% antioxidant - ۲% nano-zinc oxide (ZA) were used, and the effect of these additives on weathering and color changes, chemical changes and contact angle of the resulting composite was investigated. Chemical changes and surface degradation resulting from weathering were also analyzed using Fourier transform infrared spectroscopy (FTIR) before and after ۲۱۶۰ hours of weathering. The results of colorimetry showed that after weathering, the lightness index increased significantly in all samples. The lightening of the surface of the composites after weathering was attributed to the oxidative degradation of lignin and the formation of water-soluble groups and washing by rain and exposure to cellulose. The results of FTIR spectra of the samples showed the degradation of the polymer matrix, which indicates the lack of effect of these additives in preventing the degradation of the polymer matrix and was consistent with the colorimetry results. Also, the results indicated the oxidation of graphene due to ultraviolet radiation. The increase in intensity in the vinyl groups of the polymer matrix in the control sample was attributed to the dominance of Norrish II reactions and subsequently the formation of vinyl groups resulting from the degradation of polypropylene.

کلیدواژه ها:

Irganox ۱۰۱۰ ، Ultraviolet absorber ، Thermal stability ، Weathering ، Natural fiber thermoplastic composite