Jiangsu Co-Innovation Center for Efficient Processing and Utilization of Forest Resources, Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China.
Jiangsu Co-Innovation Center for Efficient Processing and Utilization of Forest Resources, Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China.
Int J Biol Macromol. 2023 Jul 1;242(Pt 3):124946. doi: 10.1016/j.ijbiomac.2023.124946. Epub 2023 May 24.
The development of biodegradable films with good UV-blocking and mechanical properties is of great significance for the alleviation of plastic pollution and the establishment of a sustainable society. Given that most natural biomass-derived films have poor mechanical and UV aging properties and are therefore of limited applicability, additives capable of mitigating these drawbacks are highly sought after. In particular, industrial alkali lignin, which is a byproduct of the pulp and paper industry, features a benzene ring-dominated structure with abundant active functional groups and is therefore a promising natural anti-UV additive and composite reinforcing agent. However, the commercial applications of alkali lignin are hindered by its structural complexity and polydispersity. Herein, spruce kraft lignin was fractionated and purified using acetone, subjected to structural characterization, and then quaternized based on the obtained structural data to increase water solubility. TEMPO-oxidized cellulose was supplemented with quaternized lignin at different loadings, and the mixtures were homogenized under high pressure to obtain uniform and stable lignin-containing nanocellulose dispersions, which were subsequently converted into films through suction filtration-based dewatering under pressure. The quaternization of lignin improved its compatibility with nanocellulose and endowed the corresponding composite films with excellent mechanical properties as well as high visible light transmission and UV-blocking performance. The film with a quaternized lignin loading of 6 % had UVA and UVB shielding efficiencies of 98.3 and 100 %, respectively, and featured a tensile strength (175.2 MPa) and elongation at break (7.6 %) that were 50.4 % and 72.7 % higher than those of the pure nanocellulose (CNF) film prepared under the same conditions, respectively. Thus, our work provides a cost-effective and viable method of preparing fully biomass-derived UV-blocking composite films.
具有良好的 UV 阻隔和机械性能的可生物降解薄膜的开发对于缓解塑料污染和建立可持续社会具有重要意义。鉴于大多数天然生物质衍生薄膜的机械和 UV 老化性能较差，因此适用性有限，因此非常需要能够减轻这些缺点的添加剂。特别是工业碱木质素，它是制浆造纸工业的副产品，具有以苯环为主导的结构，含有丰富的活性官能团，是一种很有前途的天然抗 UV 添加剂和复合增强剂。然而，由于其结构复杂和多分散性，碱木质素的商业应用受到限制。在此，使用丙酮对云杉硫酸盐木质素进行了分级和纯化，进行了结构表征，然后根据获得的结构数据进行季铵化以提高其水溶性。TEMPO 氧化纤维素中添加了不同负载量的季铵化木质素，然后在高压下将混合物均化，以获得均匀稳定的含木质素纳米纤维素分散体，随后通过加压抽吸过滤脱水将其转化为薄膜。木质素的季铵化提高了其与纳米纤维素的相容性，并赋予相应的复合薄膜优异的机械性能以及高光透过率和 UV 阻隔性能。季铵化木质素负载量为 6%的薄膜对 UVA 和 UVB 的屏蔽效率分别为 98.3%和 100%，拉伸强度（175.2 MPa）和断裂伸长率（7.6%）分别比在相同条件下制备的纯纳米纤维素（CNF）薄膜高 50.4%和 72.7%。因此，我们的工作为制备完全生物质衍生的 UV 阻隔复合薄膜提供了一种经济有效的可行方法。
