高性能TEMPO功能化木粉-聚乙烯醇/锂铝水滑石复合材料的制备及性能

Preparation and Characteristics of High-Performance TEMPO-Functionalized Wood Powder-Polyvinyl Alcohol/Lithium Aluminum Hydrotalcite Composites

【目的】探究聚乙烯醇/锂铝水滑石(PVA/LDH)分散液对巴沙木加工剩余物理化性能的影响,为构建高性能木质复合材料提供理论依据,实现木材加工剩余物的高值化利用。【方法】受天然贝壳“砖-泥”有序结构启发,以巴沙木加工剩余物(木粉)为主要原料,经脱木素和氧化改性,获得2,2,6,6-四甲基哌啶-1-氧自由基(TEMPO)功能化改性木粉(T-WP),向其中加入不同比例PVA/LDH分散液,通过真空抽滤自组装过程将无机纳米片水滑石插层,构建天然有机聚合物与无机纳米片复合的高性能新型木质层状复合材料,基于FTIR、XPS、Zeta电位、力学性能等测试与分析,探究各组分间的相互作用及机械性能协同增强机制。【结果】1)木粉粒径100目时,纯T-WP薄膜的力学拉伸强度和韧性最大,分别为(225.25±0.82)MPa和(5.18±0.36)MJ·m^(-3)。2)PVA/LDH纳米片体系在T-WP上成功插层,并与T-WP分子链上的含氧官能团形成氢键、静电相互作用以及共价交联作用。3)对不同PVA/LDH添加量的T-WP-PVA/LDH复合材料进行力学性能分析,PVA/LDH添加量为20 wt%时,T-WP-PVA/LDH复合材料的拉伸强度和杨氏模量最大,分别为(287.29±4.91)MPa和(14.21±2.60)GPa,是纯T-WP的1.28和2.40倍。4)在相对湿度90%、温度25℃条件下放置16 h,T-WP-PVA/LDH复合材料的吸湿率为45.43%,力学拉伸强度为105.40 MPa;在湿润土壤中,T-WP-PVA/LDH复合材料表现出较好的可生物降解特性。【结论】T-WP-PVA/LDH仿生层状复合材料中,T-WP分子链上的活性含氧基团与PVA/LDH体系形成氢键、静电相互作用以及Al—O—C共价交联作用,构建协同增强体系,赋予T-WP-PVA/LDH复合材料优异的力学性能。木质层状复合材料优异的特性使其在包装、地膜、一次性餐盒等领域具有广泛应用前景,有望替代部分聚乙烯、聚丙烯等石油基产品。

【Objective】In this study,the influence of polyvinyl alcohol/lithium aluminum hydrotalcite(PVA/LDH)dispersion on the physical and chemical properties of Balsa wood processing residues was investigated,which provided theoretical basis for constructing high performance wood-based composite materials,contributing to realize the high-value utilization of wood processing residues.【Method】Inspired by the hierarchical“brick and mortar”structure of natural nacre,the Balsa wood processing residues(wood powders)were used as the main raw materials to obtain the 2,2,6,6-tetramethylpiperidine-1-oxylradi-cal(TEMPO)-functionalized wood powders(T-WP)through the delignification and oxidation modification process.Then,different proportions of PVA/LDH dispersion was added into the T-WP and a noval high-performance wood-based lamellar composites with natural organic polymers and inorganic nanosheets were assembled by intercalating inorganic LDH nanosheets through the vacuum filtration self-assembly process.What’s more,the FTIR,XPS,Zeta-potential and mechanical properties were tested and analyzed to investigate the interface interactions between the components and the synergistic enhancement mechanism of mechanical properties.【Result】1)When the particle size of wood powder was 100 mesh,the pure T-WP film showed optimal tensile strength of(225.25±0.82)MPa and toughness of(5.18±0.36)MJ·m^(-3),respectively.2)The PVA/LDH nanosheets were successfully intercalated on T-WP and formed hydrogen bonds,electrostatic interactions and covalent crosslinking with oxygen-containing functional groups on T-WP molecular chains.3)The mechanical properties of T-WP-PVA/LDH films with different PVA/LDH contents were analyzed,which illustrated that the T-WP-PVA/LDH film reached the optimal mechanical properties with 20 wt%PVA/LDH,for example,the tensile strength and Young’s modulus reached up to(287.29±4.91)MP and(14.21±2.60)GPa,which were 1.28 and 2.40 times that of pure T-WP film,respectively.4)Under the condition of 90%relative humidity and 25℃for 16 h,the hygroscopic rate and the tensile strength of the as-prepared T-WP-PVA/LDH film were 45.43%and 105.40 MPa;in moist soil,the T-WP-PVA/LDH film exhibited excellent biodegradability.【Conclusion】For T-WP-PVA/LDH bioinspired layered composites,the active oxygen-containing functional groups on T-WP molecular chains formed hydrogen bonding,electrostatic interactions and Al-O-C covalent cross-linking with PVA/LDH dispersion,establishing a synergetically reinforced biomaterials system,which remarkably enhanced the mechanical properties of T-WP-PVA/LDH films.Furthermore,these charming characteristics endowed the as-prepared wood-based layered composites with extensive application prospect in packings,mulching films and throw-away lunchboxs,which was expected to replace petroleum-based products such as polyethylene and polypropylene.