新型界面微层结构对生物质基高分子复合材料性能影响的研究

After blended with polymers, biomass has a role in saving petroleum resource, reducing cost and improving the degradability of polymeric composites. At present, the un-compatible interface between hydrophilic biomass and hydrophobic polymeric continuous phase is the key science problem for the biomass-based composite. The processing method to use reactive compatibilizers for improving the compatibility of the interface is simple and effective. However, the current reactive compatibilizers have two problems that they are not compatible with two phases and that have low graft efficiency. In this proposal, polyurethane prepolymer will be used as a reactive compatibilizer to prepare a novel interface microlayer which is coated on the biomass during melt reaction. The inner layer of the interface microlayer is composed of urethane linkages which is formed from the reaction between multiisocyanates of polyurethane and the hydroxyl groups of biomass, and will improve the adhesion force between the microlayer and biomass; the mid-layer is the cross-linked polyurethane which is proposed to improve the graft efficiency of the polyurethane prepolymer and increase the numubers of interface molecules; the outer layer of the microlayer is composed of special polyols which are compatible with the continuous phase to improve the interface adhesion force between microlayer and polymeric continuous phase. The progress to form the microlayer structure will be studied, the structure of the hard domains and the softsegments of polyurethane prepolymer is designed to control the structure of the microlayer, and the relationship between the structure of the microlayer and the properties of the composite will be further studied, to provide a scientific guide to prepare biomass-based polymeric composite with excellence properties.

生物质与高分子材料复合后具有节约石油资源、降低成本和改善材料降解性的作用。目前，亲水性生物质分散相与疏水性高分子连续相存在的界面不相容性问题是生物质基高分子复合材料的关键科学问题。用反应性相容剂改善这类材料界面相容性的加工方法相对简单易行。然而，现有的反应性相容剂存在不能同时兼容两相和接枝效率低的问题。本申请拟用聚氨酯预聚体为反应性相容剂，在熔融反应中产生一种包覆于生物质上的新型界面微层。该微层的内层为多异氰酸酯官能团与填料的多羟基形成的氨酯层，用于提高微层与填料的界面粘附力；中层为聚氨酯交联体，用于提高聚氨酯的接枝效率，增加界面的分子数量；外层为与连续相相容的聚氨酯软段，用于提高微层与连续相的界面粘附力。申请者将研究微层结构的形成过程;通过设计预聚体的软段和硬段的结构来达到调控微层结构的目的;进一步研究界面结构与材料性能之间的关系，期望为制备高性能生物质基高分子复合材料提供理论依据。

目前，亲水性生物质分散相与疏水性高分子连续相存在的界面不相容性问题是生物质基高分子复合材料的关键科学问题。本项目使用聚氨酯预聚体在熔融反应中在生物质表面形成相容界面层，达到提高生物质基高分子复合材料的力学性能的目的。.我们发现：（1）预聚体的结构对形成包覆相容层具有决定性的影响。如果高分子预聚体的官能度小于2，则高分子预聚体在熔融反应的过程中难以在生物质填料表面形成交联包覆层，导致生物质与高分子连续相间的相互作用变弱并且高分子预聚体的反应效率大大降低。形成相容的交联的界面层的先决条件是高分子预聚体的官能度大于或等于2。.（2）高分子预聚体-高分子连续相的配对对制备强韧的高分子复合材料有重要影响。找到了几种效果良好的高分子预聚体-高分子连续相的配对：PCL基聚氨酯预聚体-PCL高聚物，聚己二酸-1,4-丁二醇酯（PBA）基聚氨酯预聚体-PLA高聚物，聚丁二酸丁二醇酯（PBS）基聚氨酯预聚体-PBS高聚物，PBA基聚氨酯预聚体-PVC高聚物，对苯二甲酰氯基预聚体(PCP)-PCL高聚物。.（3）研究了生物质填料（淀粉，木粉，纤维素，蛋白质粉和贝壳粉）种类对材料界面结构和材料的性能有重大影响。由淀粉填料制备的复合材料的韧性最高，因为淀粉颗粒表面提供出了高活性的羟基位点。贝壳粉基复合材料表现出高模量高韧性的特点，归因于贝壳粉的特殊结构。贝壳粉与聚氨酯预聚体作用后形成高强高模量的韧性复合材料。我们的创新之处是首次通过实验证实了该贝壳粉的特殊结构对制备高强高模量的韧性复合材料致关重要。.本项目的创新在于证实了聚氨酯预聚体的特殊结构对制备韧性的生物质基复合材料有着重要作用。