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Wood‐plastic composites are attracting great interest from society due to their recycling nature and excellent processability. Also, nano silica can be used as reinforcing filler for wood‐plastic composites. However, it is difficult to achieve a fine nano silica dispersion within the wood‐plastic composites. In this article, the alkali treatment and sol‐gel method were combined to modify the wood flour(WF) in situ to prepare WF/silica hybrid, and the hybrid was used as reinforcing filler for polypropylene‐based wood‐plastic composites. The physicochemical properties of WF/silica hybrid were characterized by infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. Subsequently, the mechanical properties, Vicat softening temperature, oxidation induction time and thermal decomposition behavior of polypropylene‐based wood‐plastic composites were characterized. The test results were compared with polypropylene‐based wood‐plastic composites blended with nano silica. Compared with the wood‐plastic composites blended with commercial silica, the composites filled with hybrid filler have better mechanical performances and thermal stability. The addition of hybrid is also beneficial to improving the thermal oxygen resistance of the composites. We envision that the present work offers novel insights to prepare high‐performance wood‐plastic composites.

In this work, poly(vinyl alcohol) (PVA) biocomposites with regenerated cellulose-softwood pulp (RC-SP) as a green reinforcement were prepared via coprecipitation method. Simultaneous precipitation of the two components promotes uniform dispersion of the RC-SP and constructs strong molecular chain entanglements and hydrogen bonding network inside the composites. This physical cross-linking network reduces the water absorption and improves the water resistance of the composites. The incorporation of RC-SP not only improves the thermal decomposition properties of the composites, but also enhances the mechanical properties and dynamic mechanical properties, attributed to the strong interaction between the filler and the matrix. Moreover, the fabricated PVA/RC-SP composites exhibit good water-induced shape memory effect, and shape recovery rate of 10% RC-SP reinforced composite reaches 95.3% after immersing for 35 min. This work provides useful information for the implementation of co-precipitation method and the application of renewable cellulose resources.

Waste printed circuit boards powders (WPCBP), the critical by-products in the dispose process of waste electrical and electronic equipment, were selected as reinforcing fillers in polypropylene (PP) composites, which brought forward a new way to reuse WPCBP for a sustainable world. However, the multivalent metals in WPCBP could accelerate the degradation of PP molecule chains. In this study, nitric acid was selected as copper removal to pretreat WPCBP, and most of the metals were removed after decoppering pretreatment, which was evidenced by X-ray fluorescence (XRF). The ensuing compound was characterized by oxidation induction time, scanning electron microscopy, Fourier transform infrared spectroscopy, and mechanical analysis. As expected, the accelerate weathering behaviors of PP composite with nitric acid treated WPCBP were substantially improved, for instance, the notched impact strength and tensile strength of untreated PP/WPCBP composite after 21 days thermal aging were just 0.85KJ/m 2 and 9.3 MPa, while the PP composite with 6 wt % nitric acid-treated WPCBP was 3.47KJ/m 2 and 32.1 MPa. We envisage this facile strategy, that is, using proper concentration of nitric acid to pretreat WPCBP could improve the accelerate weathering properties of PP/WPCBP composites, which would broaden the potential applications of WPCBP in polymer compounds.