Temperature varied biochar as a reinforcing filler for high-density polyethylene composites

The poplar biochar (PB) was prepared at different pyrolysis temperatures and the hot pressing method was applied to prepare composites with PB based on high-density polyethylene (HDPE). The effects of pyrolysis temperature on the characterizations of PB were analyzed and the PB/HDPE composites were characterized by Xray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), Scanning electron microscope (SEM), and their mechanical properties. The results showed that the specific surface area and pore volume increased, polar functional groups and the polarity of PB decreased with the increase of pyrolysis temperatures. Moreover, the addition of PB had no effect on the microcrystalline structure but the intensity of the peaks of PB/HDPE composites was reduced. FTIR analysis of PB/HDPE composites showed no new functional groups which indicated that PB and HDPE did not react chemically with each other. Besides, the addition of PB did not change the melting temperature of HDPE but it promoted the early crystallization of PB/HDPE composites. The mechanical analysis showed that the flexural strength improved and the impact strength decreased of PB/HDPE composites by the addition of PB.