Preparation and properties of modified poplar impregnated with PVA-nano silica sol composite dispersion system

The dilemma of insufficient wood resources and poor properties of fast-growing wood necessitates a breakthrough in the expansion and efficient utilization of wood resources to meet the real needs. With the aim of enhancing the properties of fast-growing poplar wood, a combination of PVA and nano-silica sol impregnation treatment was carried out to develop a novel functional wood material with good dimensional stability, compressive strength and thermal stability, while fully exploiting the unique structural properties of the wood itself. In this work, PVA-nano-silica sol composite wood was prepared by in-situ impregnation of poplar fast-growing wood via ultrasound-assisted and vacuum impregnation methods. Firstly, the effects of different treatments on the impregnation effect and strengthening effect of modified wood were explored. The results showed that the PVA-nano-silica sol dispersion system had no negative effect on the impregnation modification, and the compressive strength of modified wood was obviously improved compared with natural wood. Among them, the most effective modification was achieved under the condition of vacuum-assisted impregnation. The effect of compound impregnation modification on the structure of poplar fast-growing wood was analyzed by FTIR, XRD, SEM, and EDS, in which PVA and nano-silica sol can form a certain cross-linking system and form chemical bonds such as Si-O-C and Si-O-Si, enabling them to enter the structure of wood and react with wood cell walls effectively. The compressive strength of modified poplar wood was increased by 72.29% compared with natural poplar wood. According to the thermogravimetric analysis, the thermal stability of the modified poplar wood was improved to some extent. In view of all the results, the method proposed in this study provides an opportunity for the high value utilization of low quality wood, and this modified wood can be considered as a candidate for new lightweight and high performance materials in the construction field.