超声波辅助纳米Ag/TiO2浸渍木材的化学改性与微观构造表征

Chemical Modification and Microstructure Characterization of Nano-Ag/TiO_2 Impregnation of Wood Assisted by Ultrasonic

【目的】采用超声波辅助浸渍制备纳米Ag/TiO_2木基复合材料,分析其化学结构与微观构造,为防霉抗菌型纳米木基复合材料研发提供理论依据。【方法】以樟子松为原料,以纳米Ag/TiO_2为主要试剂,以六偏磷酸钠和KH560为分散剂,采用超声波辅助浸渍制备纳米Ag/TiO_2木基复合材料,分析超声功率、超声时间和纳米Ag/TiO_2浓度对木材载药量和抗流失性能的影响,以及浸渍前后木材的微观构造、轴向分布、化学结构、结晶度和热稳定性。【结果】1)随着超声功率增加,木材载药量呈先升高后降低的趋势,在功率为75 W时达到峰值,载药量较常压浸渍提高31.5%,抗流失率随着超声功率增加持续提高,在功率为300 W时,抗流失率较常压浸渍提高7%;2)超声时间对载药量的影响不大,对抗流失率的影响呈先升高后降低的趋势,在超声时间为30 min时抗流失率达到峰值77.73%;3)随着纳米Ag/TiO_2浓度增加,载药量持续上升,浓度为2.0%时载药量为3.363 kg·m-3,抗流失率则持续下降,浓度为0.5%时抗流失率为78.33%;4)超声波辅助浸渍处理后,纳米Ag/TiO_2成功进入木材内部并附着在细胞壁上,团聚现象减少,分散性显著增强,浸渍深度加深;5)纳米TiO_2与木材表面的羟基发生氢键缔合反应,偶联剂KH560不仅枝接在TiO_2上,而且与木材纤维素中的羟基发生反应;6)纳米Ag/TiO_2木基复合材料出现锐钛矿型纳米TiO_2特征峰,在超声波作用下,纤维表面生长疲劳裂纹,木材纤维素结晶度略有下降;7)纳米Ag/TiO_2使纳米Ag/TiO_2木基复合材料热稳定性增强,最大降解温度升高11.8℃。【结论】1)超声波辅助处理可提高木材的载药量和抗流失率,超声功率对抗流失率影响显著;2)纳米Ag/TiO_2成功进入木材细胞腔并附着于细胞壁上,部分与木材纤维素羟基发生反应;3)纳米Ag/TiO_2木基复合材料较素材热稳定性能提高。

【Objective 】 The nano-Ag/TiO_2 wood-based composite materials were prepared by ultrasound assisted impregnation,and the chemical structure and microstructure were analyzed in this study,with the aim to provide a theoretical basis for the new type of nano mildew wood composite research.【 Method 】 With six sodium hexametaphosphate and KH560 as dispersant,the Pinus sylvestris var.mongolica was reacted with nano Ag/TiO_2 to propagate nano-Ag/TiO_2 wood-based composite materials by ultrasonic assisted impregnation.The effects of ultrasonicpower,time and nano Ag/TiO_2 concentration on the loading amount and leach-resistance of nano-Ag/TiO_2 wood-based composite materials were studied,and the performance of the crystalline,axial distribution,chemical structure,thermal stability and microcosmic structure of nano-Ag/TiO_2 wood-based composite materials were also investigated.【Result】1） With the increase of ultrasonic power,the loading amount increased and then decreased.The loading amount of the 75 W ultrasonic wave treated samples increased by 31.5 %.With the increase of ultrasonic power,the leach-resistance continued to increase.The leach-resistance of the 300 W ultrasonic wave treated samples increased by7 %.2） Ultrasonic treatment time has little effect on the loading amount.With the increase of ultrasonic time,the leach-resistance increased and then decreased.The leach-resistance were reached the peak value of 77.73 % at 30 min.3） With the increase of nano-Ag/TiO_2 concentration,the loading amount continued to rise.When the concentration was2 %,the drug loading amount was 3.363 kg·m-3.The leach-resistance was decreased with the increase of nano-Ag/TiO_2 concentration.When the concentration was 0.5 %,the leach-resistance was 78.33 %.4） After ultrasonic assisted impregnation,nano Ag/TiO_2 successfully entered the interior of the wood and attached to the cell wall,the agglomeration phenomenon was reduced and the dispersion and immersion depth were significantly enhanced.5） The modified nano-particles predicted in the tracheid and attached to the cell walls through hydroxyl hydrogen bond association.KH560 coupling agent grafting not only in TiO_2,and reacted with the hydroxyl groups of wood cellulose.6） After penetrating into wood specimens,the nano-Ag/TiO_2 retained characteristic structures of anatase TiO_2 and thus retained photocatalytic activity.The decreased intensity of cellulose was due to the addition of nanoparticles having reduced the cellulose content in the specimen.7） The thermal stability of nano-Ag/TiO_2 wood-based composite materials enhanced and the maximum degradation temperature increased by 11.8 ℃.【Conclusion 】 1） Ultrasonic assisted treatment significantly increased the loading amount and the leach-resistance,and the ultrasonic power had a significant effect on the leach-resistance.2） After ultrasonic assisted impregnation,nano-Ag/TiO_2 successfully entered the interior of the wood and attached to the cell wall,some of nano-Ag/TiO_2 reacted with the hydroxyl groups of the wood,and the others were connected with wood by KH560.3） The thermal stability of nano-Ag/TiO_2 wood-based composite materials was improved.