多糖纳米填料对复合可食用膜机械、阻隔性能的影响规律及相关机制研究

Inorganic nano-fillers could form well dispersed percolation networks with synthetic polymer film matrices and bring ideal ‘tortuosity path’ due to their strong absorbability and high impermeability, which could endow packaging films with excellent mechanical strength and barrier performance. However, the traditional percolation network model and the improvement in mechanical properties and barrier performances faced with many challenges when aiming at edible films because of the complexity of self-structures and interactions between natural biopolymer-based nano-fillers and film-forming. The objective of this project was to systematically analyze the influences of physical forms, charge characteristics, and crystal structures of polysaccharide nano-fillers’on the macromolecule conformation, the interface morphology, the dispersing status of polysaccharide nano-fillers within film matrices. The corresponding percolation network models based on filler properties and filler-matrix interactions were then designed and built according to the above analyses. based on these models and the mechanical properties and barrier performances of the correspending nanocomposite edible films, the influences of polysaccharide nano-fillers’ physicochemical properties, interactions between polysaccharide nano-fillers and film-forming matrices, and coexisting competitive relationships between fillers and plasticizers on the mechanical properties and barrier performances would be comprehensively elucidated. Information obtained from this project would be critical to the design of high-performance polysaccharide nano-fillers-based nanocomposite edible films, and would promote large-scale application of edible film as a substitution of traditional plastic packaging films in real prctice.

无机纳米填料强的吸附性和高的不可渗透性使其与合成高聚物膜基质间可形成分散良好的渗透网络结构并带来理想的“弯曲路径”，赋予包装膜优异的机械强度和阻隔性能。但当以可食用为目标时，同为生物大分子的纳米填料与成膜基质自身结构及其相互作用的复杂性使传统的渗透网络模型及预期的机械、阻隔性能改善受到诸多挑战。据此，本课题拟以系统分析不同物理形态、电荷特性、结晶结构的多糖纳米填料复合对可食用膜基质高分子构象、界面形态及基质中填料聚集分散、定向非定向分布模式的影响为基础，构建基于填料特性及填料-基质相互作用的差异化渗透网络结构模型，结合复合可食用膜机械、阻隔性能的实测数据，全面阐明多糖纳米填料物化形态、填料-成膜基质间相互作用强度以及填料与增塑剂共存竞争关系对膜机械、阻隔性能的影响规律及机制。为高性能多糖纳米填料复合可食用膜的高效制备以及推进可食用膜真正替代传统塑料包装、实现大规模应用提供理论依据。

无机纳米填料强的吸附性和高的不可渗透性使其与合成高聚物膜基质间可形成分散良好的渗透网络结构并带来理想的“弯曲路径”，赋予包装膜优异的机械强度和阻隔性能。但当以可食用为目标时，同为生物大分子的纳米填料与成膜基质自身结构及其相互作用的复杂性使传统的渗透网络模型及预期的机械、阻隔性能改善受到诸多挑战。在项目实施的过程中，首先通过控制纤维素的来源及水解条件制备了一系列结构差异明显的纤维素纳米晶（cellulose nanocrystals，CNC），并将上述CNC以不同添加量添加至多糖膜中得到可完全降解的纳米复合膜。确定了CNC的结构特性和添加量的变化对CNC的分散状态及其与基质间的相互作用的影响情况，并详细表征了CNC的添加对复合膜应用性能的影响规律。通过实验测定结果及Halpin–Kardos和Ouali理论模型的预测结果，初步分析了多糖复合膜机械性能显著提升的机制。其次，以加工过程中胶原纤维结构变化重组规律研究为基础，确定pH及热处理改变胶原纤维溶胀、解聚的规律，不溶性微米/纳米纤维素、可溶性多糖与胶原纤维共混网络改善胶原纤维膜机械性能的机制，同时，针对化学交联剂戊二醛处理带来的胶原纤维膜延展性的不足，通过考察两种天然蛋白交联剂原花青素和谷氨酰胺转氨酶的作用效果，确定了最优交联策略；进一步，明胶具有良好的成膜性，可以作为塑料基材的替代品，但在应用于食品包装时缺乏足够的耐水性来抵抗较高的湿度。将玉米醇溶蛋白进行定制化设计，确定了玉米醇溶蛋白在提升明胶膜疏水性能上的提升效果，并且创新了一种在乙醇体系中添加TG酶的技术，进一步获得了疏水性能的提升。本研究结果可为合理利用多糖/蛋白填料强化可食用膜基质提供了理论基础，同时也在一定程度上推进了可食用膜替代传统塑料包装膜、实现大规模应用的步伐。

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