Abstract The role of animal protein, casein, as compatibilizer and eco-friendly dispersant in composites comprising cellulose nanofibrils (CNF) and polylactic acid (PLA) was investigated. The effect of casein-mediated surface modification of PLA was validated with dynamic adhesion experiments that considered the contact area according to JKR approximation. In fact, a remarkable increase by ∼50% in the work of adhesion between CNF and PLA was observed after casein adsorption. It is likely that the improved adhesion gave rise to an enhanced dispersion of CNF and PLA within the composite matrix. Moreover, the mechanical properties of the respective nanocomposites were significantly improved. When compared to protein-free CNF/PLA nanocomposites, the systems containing casein indicated an enhanced extensibility (by 130%) and tensile toughness (by 60%) whereas tensile strength and Young's modulus were improved to a limited extent (6 and 12%, respectively). Finally, it is demonstrated that the surface modification of PLA with casein improves the compatibility between CNF and PLA, which is a prerequisite for the feasible preparation of 3D shaped cellulose-based packaging materials by direct thermoforming.

中文翻译：

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纤维素纳米纤维和聚交酯复合材料中蛋白质介导的界面粘附：增强材料开发的韧性

摘要 研究了动物蛋白酪蛋白作为增容剂和环保分散剂在包含纤维素纳米原纤维 (CNF) 和聚乳酸 (PLA) 的复合材料中的作用。酪蛋白介导的 PLA 表面改性的效果通过动态粘附实验进行了验证，该实验考虑了根据 JKR 近似的接触面积。事实上，在酪蛋白吸附后观察到 CNF 和 PLA 之间的粘附功显着增加了约 50%。改进的附着力很可能导致复合基质内 CNF 和 PLA 的分散增强。此外，各纳米复合材料的机械性能显着提高。与不含蛋白质的 CNF/PLA 纳米复合材料相比，含有酪蛋白的系统表明可扩展性（提高 130%）和拉伸韧性（提高 60%），而拉伸强度和杨氏模量的改善程​​度有限（分别为 6% 和 12%）。最后，证明了酪蛋白对 PLA 的表面改性提高了 CNF 和 PLA 之间的相容性，这是通过直接热成型制备 3D 成型纤维素基包装材料的先决条件。