Nanocomposite Films Based on Flaxseed Gum and Cellulose Nanocrystals

Flaxseed gum (FG)-based films were developed with the addition of glycerol as a plasticizer and glutaraldehyde as a crosslinking agent. HCl was added to improve crosslinking and decrease the hydrophilicity of the matrix. Different cellulose nanocrystal (CN) amounts were used as reinforcements in the optimum FG formulation. The crosslinking process at pH 3.5 led to a lower solubility of FG in water (from 100% to 53%) and an increase in thermal stability (from 160 ºC to 209 ºC). FTIR analysis confirmed a reduction in the -OH band due to crosslinking between the hydroxyl groups of FG. A diffuse diffraction pattern was observed for all FG films. The addition of 4% w/w of CN contributed to reduction of water solubility (from 53% to 20.8%) and absorption (from 21.9% to 6.8%). Finally, an improvement was observed in the tensile mechanical properties in the nanocomposites, showing satisfactory results for the proposed formulations, mainly with 8% w/w of CN added to the matrix. Overall, this study demonstrated that FG/CN nanocomposites are promising materials to be use as a sustainable biopolymer for application as bioplastics.

本研究以亚麻籽胶（Flaxseed gum, FG）为基底材料，以甘油作为增塑剂、戊二醛作为交联剂制备FG基复合膜。为优化交联反应进程并降低基体亲水性，体系中添加了盐酸。在最优FG配方基础上，掺入不同用量的纤维素纳米晶（cellulose nanocrystal, CN）作为增强相。在pH 3.5的条件下完成交联反应后，FG在水中的溶解度从100%降至53%，基材的热稳定温度从160 ℃提升至209 ℃。傅里叶变换红外光谱（FTIR）分析证实，FG分子间的羟基发生交联反应，导致-OH特征吸收峰强度降低。所有FG基膜均呈现弥散衍射图谱。掺入4%（w/w）的CN可进一步降低复合膜的水溶性（从53%降至20.8%）与吸水率（从21.9%降至6.8%）。此外，纳米复合膜的拉伸力学性能得到显著改善，所制备的配方均表现出良好效果，其中向基体中添加8%（w/w）CN的改性效果尤为突出。综上，本研究证实FG/CN纳米复合材料作为可持续生物聚合物用于制备生物塑料具有可观的应用前景。