Hongyun Qiu's research while affiliated with Jiangxi Academy of Sciences and other places

This study explored the effect of raw material morphology on the properties of bamboo–plastic composites produced using hot-pressing. To provide a reference for reducing the production cost and improve the product properties of the composites, polylactic acid (PLA)-based bamboo–plastic composites were prepared using bamboo chips with a shaved morphology (BS) and fiber morphology (BF) and PLA as the matrix material, via hot-pressing. The properties of the bamboo–plastic composites formed with BS and BF chips were studied and compared with those of composites with conventional granular morphology (BM) and powder morphology (BP). The results showed that when the content of the bamboo chips was at 50% (the same below), the mechanical properties of the BF/PLA composites were remarkably better than those of the other PLA-based composites. However, the BF/PLA composites showed a high degree of hydrophilicity, with a water contact angle of 70.0° and a water absorption of 10.8% at 288 h. More holes could be seen in the BF/PLA composites using a scanning electron microscope. Among the four types of PLA-based composites, better melt fluidity was found only in the BF/PLA composites, and the melting index was 65.3 g/min.

This study extracted Bambusa blumeana fiber using alkaline boiling and then applied double-roll pressing in order to develop it, explore the applications of its various parts, and improve its utilization potential. The results showed that the outer bamboo fibers are finer and straighter than the inner and middle fibers, and the fracture mode of the bamboo fibers is brittle. From the inside to the outside, the tensile strength of the fiber bundle gradually increases from the top to the bottom. Moreover, the tensile strength of the outside bamboo fiber is twice that of the inside, reaching a maximum of 982 MPa. The surface of the interior bamboo fiber is relatively smooth and can be used in textile and decorative fields. Compared with internal and central bamboo fiber, the outer fiber has higher thermal stability and higher crystallinity, which makes it more advantageous in the process of strengthening composite materials. Studying the structures of fibers from different parts of Bambusa blumeana can provide substantial scientific support for the differential applications of bamboo fibers.

In this study, a phenol–formaldehyde resin–montmorillonite intercalation composite solution was used as a modifier to treat Chinese fir via impregnation and compression. The basic characteristics and wettability of the PF (phenol–formaldehyde)–montmorillonite impregnation solution were analyzed. The effects of the solid content of PF, the quantity of montmorillonite, and the impregnation time on the impregnation weight gain of Chinese fir were studied through orthogonal experiments. The results showed that when the amount of montmorillonite was 1%, the wettability of the PF–montmorillonite impregnation solution performed the best, the curing time was short, and the curing strength was high. The optimal impregnation process consists of a PF solid content of 25%, an impregnation time of 120 min, and a montmorillonite ratio of 1%. Under these conditions, the modified Chinese fir was prepared via hot pressing. The effects of the addition of montmorillonite and different levels of compressibility on the physical and mechanical properties of modified wood were studied. The physical and mechanical properties were found to be better when the compression ratio was 33%: the density increased from 0.33 g/cm3 to 0.58 g/cm3; the surface hardness increased from 33.6 HD to 70.9 HD; the static bending strength increased from 60.4 MPa to 98.7 MPa; and the elastic modulus increased from 6 390 MPa to 11 498 MPa. After 30 days of release, the compression rebound rate was 3.97%. Meanwhile, the micromorphology and heat resistance of the impregnated compressed Chinese fir showed that the PF–montmorillonite impregnation solution entered into the cell cavity and intercellular space of the Chinese fir and formed a good composite, thus improving the water resistance, heat resistance, and physical and mechanical properties.