Natural weathering of rape straw flour (RSF)/HDPE and nano-SiO2/RSF/HDPE composites

The use of wood polymer composites (WPCs) in industries has been growing, and this is fueled in part by the use of WPCs in the construction industry. Rape straw flour (RSF)/high-density polyethylene (HDPE) composites as WPCs can also be applied in the construction industry. As a result, the durability of RSF/HDPE composites after natural exposure becomes a concern. Fourier transform infrared (FTIR) spectroscopy is used to monitor the development of degradation products, such as carbonyl groups and vinyl groups, and to determine changes in HDPE crystallinity. Differential scanning calorimetry (DSC) is also used to analyze changes in HDPE crystallinity. The results indicate that the carbonyl index was roughly lower for the RSF/HDPE composites than for the nano-SiO2/RSF/HDPE composites, and the concentration of vinyl groups was generally much larger for the RSF/HDPE composites than for the nano-SiO2/RSF/HDPE composites. At the same time, carbonyl index and vinyl index decrease with an increasing depth of composites, particularly decreasing strongly from 100 to 200 μm. The crystallinity of the samples increase because of natural aging, and the values of crystallinity derived by DSC are smaller than those derived by FTIR.