Enhanced hydrophobicity, dimensional stability and anti-mildew of bamboo by slightly acidic electrolyzed water pretreatment and wax annealing

Abstract

Bamboo, a sustainable natural resource, suffers from mildew attacks due to its inherent hydrophilicity and susceptibility to mildew, limiting its large-scale application. Here, a novel treatment method was conducted by combining slightly acidic electrolyzed water pretreatment with wax annealing. Bamboos were firstly impregnated with slightly acidic electrolyzed water (SAEW) for surface sterilization, then impregnated in paraffin/carnauba wax and beeswax/carnauba wax, finally, annealed at different temperatures to obtain waxy bamboo. The contact angle, water absorption, hygroscopicity, dimensional stability and bending property of the waxy bamboo were tested. The chemical composition and microstructure of the waxy bamboo were characterized. The anti-mildew evaluation of the waxy bamboo was conducted. The results showed that the contact angles as well as the surface energy of both the outer and inner layers of the waxy bamboo were the best at an annealing temperature of 70°C. The water resistance efficiency, anti-swelling efficiency, and bending property of waxy bamboo were the best at annealing temperature of 70°C. FTIR showed that SAEW treatment did not affect the chemical group connection between bamboo and waxes and micromorphology of waxy bamboo showed smoother coating at wax annealing at 70℃. The infection grade of untreated reached grade 4, and nearly all the waxy bamboo remained free from mildew and satisfied application shown on bamboo cutlery knives. Therefore, SAEW pretreatment combined with wax annealing process is an effective method for enhancing bamboo’s hydrophobicity, bending property, dimensional stability, and anti-mildew property, presenting significant potential for bamboo products applications.