超声-抗菌石蜡处理对竹材防霉性能的影响

为增强竹材的防霉性能,以毛竹作为研究材料,先对竹材进行超声预处理,制备了抗菌石蜡乳液对竹材进行浸渍改性处理,并对改性后竹材的含水率、吸水率、防水效率和防霉性能进行了测试。选用天然植物中的2-羟基-1,4萘醌作为防霉剂,选用司班80(Span80)和吐温80(Tween80)作为58号食品级石蜡的复配乳化剂,考虑了亲水亲油平衡(HLB)值对石蜡乳化的影响,制得稳定的抗菌石蜡乳液。利用抗菌石蜡乳液对超声处理后的竹片进行浸渍处理,采用L₉(3³)正交试验设计,以石蜡乳液固含量、干燥温度和干燥时间为因子,以含水率和浸泡768 h后的防水效率为测试指标。结果表明,当Span80和Tween80的质量比为2∶3、HLB值为10.72时,石蜡乳液的稳定性最好。对改性后竹材含水率的影响从大到小依次是石蜡乳液固含量、干燥温度、干燥时间。当石蜡乳液固含量为5%、干燥温度为70℃、干燥时间为1.5 h时,试件含水率最低为4.11%。浸泡768 h后对竹材防水效率影响从大到小依次是干燥温度、石蜡乳液固含量、干燥时间;当石蜡乳液固含量为15%、干燥温度为40℃、干燥时间为1.5 h时,试件防水效率最高为32.15%。超声处理并不能有效阻止竹材的霉变,超声联合抗菌石蜡乳液改性后的竹材防霉性能有明显提高,改性竹材在28 d霉变试验后表面无菌丝、霉点。

Effect of ultrasonic-antibacterial paraffin treatment on the antifungal performance of bamboo

Moso bamboo specimens were firstly subjected to ultrasonic pretreatment,and then immersed into the antifungal paraffin wax emulsion.The moisture content,water absorption and waterproof efficiency of the modified bamboo were examined,and the anti-mildew properties were also tested.The 2-hydroxy-1,4-naphthoquinone in natural plants was used as the antifungal agent,and Span80 and Tween80 were used as the antifungal emulsifiers of 58#food-grade paraffin by considering the influence of HLB(hydrophile-lipophile balance)value on paraffin emulsification.The stable antifungal paraffin wax emulsion was prepared and used to treat the bamboo slices with the help of ultrasonic wave.The L 9(33)orthogonal test was designed by taking the solid content of paraffin wax emulsion,drying temperature,and drying time as factors.The moisture content and the waterproof efficiency of the modified bamboo were evaluated after 768 h of soaking in water.The results showed that the surface tension of the antifungal paraffin wax emulsion decreased firstly and then increased with the increase of HLB value.When the mass ratio of Span80 to Tween80 was 2∶3 and the HLB value was 10.72,the paraffin emulsion had the best stability.From the scanning electron microscope(SEM),it can be seen that the higher the solid content of the antifungal paraffin wax emulsion,the thicker paraffin layer was formed on the surface of the bamboo.The higher the drying temperature,the more unfavorable formation of continuous paraffin layer on the surface of the bamboo.The order of influence of factors on the moisture content of the modified bamboo was as follows:paraffin emulsion solid content,drying temperature,drying time.The minimum moisture content of 4.11%was obtained under the condition of the paraffin emulsion solid content of 5%,the drying temperature of 70℃and the drying time of 1.5 h.When samples were soaked in water for 768 h,the order of factors affecting the bamboo waterproof efficiency was as follows:drying temperature,solid content of paraffin wax emulsion and drying time.When the solid content of paraffin wax emulsion was 15%,the drying temperature was 40℃,and the drying time was 1.5 h,the waterproof efficiency of the specimen was 32.15%.The ultrasonic treatment cannot effectively prevent the mildew of bamboo itself,but the antifungal performance of the bamboo was improved obviously by the treatment of ultrasonic wave combined with paraffin emulsion impregnation.There was no mycelium or mildew spot on the surface of the modified bamboo after the 28-day mildew test.