Stepwise modification with 2,3-epoxypropyltrimethylammonium chloride cationization and rosin acid impregnation to improve water repellency and mold-proof property of bamboo

As its abundant reserves and good physical properties, bamboo is deemed to be a promising feedstock material for construction and home furnishing. However, the hydrophilicity of bamboo and its rich nutrients make it susceptible to mold infection. In this study, bamboo firstly reacted with 0, 3, 6, 9, and 12 wt times of 2,3-epoxypropyltrimethylammonium chloride (EPTAC) in NaOH/Urea solution, respectively, and then impregnated with rosin acid. Effects of modification on structure, thermal stability and water repellency of bamboo were identified by FT-IR, XRD, XPS, SEM, TGA, contact angle measurement and water absorption coefficient, respectively. A comparative study of mold-proof properties of original and modified bamboo was conducted as inoculation of Aspergillus niger, Penicillium citrinum and Trichoderma viride on samples. The results indicated that the sample obtained from a mass ratio (EPTAC to bamboo) of 9 had the highest substitution degree, charge content and ion exchange capacity as compared to samples obtained from other EPTAC dosages. After modification, the density of bamboo increased by 43.3%, which exhibited considerable thermal stability. Impregnating this sample with rosin acid improved its water-repelling and anti-swelling efficiency to 10.91% and 27.83%, respectively. Compared with the original bamboo, anti-mold property of EPTAC modified bamboo to three fungi was notably improved and achieved rate 1 mold coverings. Impregnation-modified bamboo with rosin acid enhanced the anti-mold property, achieving a rate of 0 mold covering. The research provides a feasible way to improve the mildew resistance of bamboo and promote the utilization of rosin.