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.

本研究开发了以亚麻籽胶（Flaxseed gum, FG）为基材的复合薄膜，以甘油作为增塑剂、戊二醛作为交联剂。为优化交联反应并降低基材亲水性，体系中添加了盐酸。在最优FG配方基础上，引入不同添加量的纤维素纳米晶（cellulose nanocrystal, CN）作为增强相。在pH 3.5条件下进行交联反应，可使FG基薄膜在水中的溶解度从100%降至53%，同时其热稳定温度从160 ℃提升至209 ℃。傅里叶变换红外光谱（FTIR）分析证实，FG分子的羟基间发生交联反应，导致-OH特征吸收峰强度降低。所有FG基薄膜均呈现弥散衍射图案。添加4%（w/w）的CN可使薄膜水溶性从53%进一步降至20.8%，吸水率从21.9%降至6.8%。最终，纳米复合薄膜的拉伸力学性能得到显著改善，所制备的所有配方均表现出令人满意的性能，其中向基材中添加8%（w/w）CN的效果尤为突出。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的应用前景广阔。