超高木质纤维含量木塑复合材料多尺度流变机理研究

Increasing the amount of lignocellulose fiber was an effective way to improve the wood feeling and decrease the production cost of the wood-plastic composites (WPC), which had been of great concern by the industry and academia. The rheological properties of wood-plastic composites filling with ultra-high (80%-90%) lignocellulose fiber (UHL-WPC) had been deviated seriously that of the traditional thermoplastic polymer composites, and the rheological mechanism of UHL-WPC was still unclear at present although it had been prepared successfully. This project introduced multi-scale rheological behavior academic theory of UHL-WPC based on the more obviously solid-like rheological behavior including discontinuous and instability during the extrusion process, that the rheological properties were the result of the integrated influence of wood-polymer nano-micro interface layer with multi-stage structure of lignocellulose fiber as the main body. In order to reveal the micro-mesoscopic-macro multi-scale rheological mechanism of UHL-WPC, the rheological behavior of UHL-WPC system was studied preferentially in different multi-scale interface under the complicated temperature-stress effect, and build the multi-stage rheological measurements and mathematical models to analyze the relations between the micro-structural viscoelasticity of lignocellulose fiber and nano-micro wood-polymer interface rheology with macroscopic rheological behavior of UHL-WPC. This study can provide scientific basis for the innovative design and preparation of UHL-WPC, breaking through the technical bottleneck of ultra-high filled WPC, and realizing the source innovation of WPC theory and technology.

增加木质纤维用量是提高木塑复合材料的木质感降低生产成本的有效途径，备受产业和学术界关注。超高木质纤维含量（80%-90%）木塑复合材料（UHL-WPC）虽已成功制备，但因其流变行为严重偏离传统聚合物复合材料的流变学规律，流变机理尚不清楚。本项目基于UHL-WPC在加工过程中表现出更明显的非连续、挤出畸变等类固体流变行为，提出超高木质纤维含量木塑体系多尺度流变学术思想，即以多级结构木质纤维为主体及木质纤维-聚合物微纳界面层综合作用下的多尺度流变机制。重点研究UHL-WPC在复杂温度-应力场作用下不同尺度界面流变行为，建立适用于UHL-WPC的流变表征方法和数学模型，分析木质纤维微观粘弹性及微纳界面流变与UHL-WPC宏观流变之间的构效关系，揭示其微观-介观-宏观多尺度流变机理，为超高填充木塑创新设计和制备提供科学依据，突破木塑复合材料超高填充的技术瓶颈，实现木塑理论和技术原理的源头创新。

大幅度提高木质纤维用量是提高木塑复合材料的木质感降低生产成本的有效途径，备受产业和学术界关注。超高木质纤维含量（80-90wt.%）木塑复合材料（UH-WPCs）虽已成功制备，但因其流变行为严重偏离传统聚合物复合材料的流变学规律，流变机理尚不清楚。本项目基于UH-WPCs在加工过程中表现出更明显的非连续、挤出畸变等类固体流变行为，提出超高木质纤维含量木塑体系多尺度流变学术思想，即以多级结构木质纤维为主体及木质纤维-聚合物微纳界面层综合作用下的多尺度流变机制。项目主要开展以下研究：一、探究了木质纤维层次结构、纤维相互作用、木质纤维-聚合物界面等因素对木塑复合材料流变行为的影响，为超高木质纤维含量木塑复合材料高效率和高品质的热塑化加工提供技术支撑，解决成型难的技术问题。二、发明了超高木质纤维含量高性能木塑复合材料及其制备方法，通过分步造粒法大幅度提高了木质纤维的用量，解决了超高含量木质纤维喂料困难和分散不均匀等技术难题，制备了系列超高木质纤维含量（≥80wt.%）的木塑复合材料，且具备良好的物理力学性能。三、以高性能超高木质纤维含量木塑复合材料为研究对象，首次纠正了现有酯化反应作为典型酸酐类相容剂在木塑复合材料中的界面作用机制，为本项目高性能超高木质纤维含量木塑复合材料制造及其加工关键技术提供了理论依据。四、发明了分层叠加法用于超高木质纤维含量木塑复合材料熔体的流变测试表征，构建了超高木质纤维含量木塑复合材料熔体蠕变本构方程，解决了传统流变测试方法无法采集高填充木塑熔体流变数据的技术难题。通过本项目的研究，为超高填充木塑创新设计和制备提供科学依据，突破木塑复合材料超高填充的技术瓶颈，实现木塑理论和技术原理的源头创新。