Hybrid Wood Composites with Improved Mechanical Strength and Fire Retardance Due to a Delignification–Mineralization–Densification Strategy

Abstract

The shortage of wood resources and the policy of logging restrictions have hindered the development of the wood industry. The development of fast-growing wood can effectively solve the problem of wood shortages and the discrepancy between supply and demand; however, the softness and poor strength of fast-growing wood make it difficult to use directly and restrict its applications. Meanwhile, the inflammability of wood is also a crucial hindrance to its application. In this work, hybrid wood composites with high strength and excellent fire retardance were developed by using a combined strategy of “delignification–mineralization–densification”. Delignification promoted the deposition of minerals inside the wood, and the mineralization process was able to significantly increase the fire retardance performance of the hybrid wood. The densification treatment made the wood and minerals closely packed, which was conducive to the improvement of the strength and fire retardance performance of the hybrid wood. The resulting hybrid wood composites showed enhanced mechanical strength (the tensile strength, flexural strength, and compressive strength were 180.6 MPa, 159.8 MPa, and 86.5 MPa, respectively) and outstanding fire retardance, and this strategy provided a feasible pathway towards the high-value application of fast-growing wood.