竹粉表面修饰对高填充木塑结构-性能的调控机理研究

Starting from the efficient processing and high performance of highly filled wood-plastic composites (WPC), this project uses alkyl ketene dimer (AKD) and alkenyl succinic anhydride (ASA) as surface modifiers with strong chemical binding capability, moderate permeability, high coverage efficiency, and non-pollution to modify bamboo flour. The purpose is to reduce the surface energy of bamboo flour, to improve its dispersibility in and compatibility with polypropylene (PP) matrix, and finally to enhance the processability and physical-mechanical properties of WPC. This study will concentrate on optimizing process parameters for bamboo flour modification, creating an efficient, cheap, and environmentally-friendly surface modification technique, toughening PP to achieve improved rheological properties and better compatibility with bamboo flour. The modified bamboo flour will be compounded with toughened PP to fabricate highly filled WPC. The structure and performance of the WPC will be characterized. The effect of surface modification with AKD and ASA on surface energy of bamboo flour will be studied at ambient and processing temperature, respectively. The three-dimensional dispersibility and distribution of bamboo flour in PP matrix will be investigated. At room temperature, correlation between the surface energy characteristics of bamboo flour and PP and the mechanical properties of WPC will be revealed, and at processing temperature, correlation between the surface energy characteristics of bamboo flour and PP and the rheological properties/processability of WPC melts will be revealed as well. This study could explore new ways and provide theoretical basis to promote the efficient processing and high performance of highly filled WPC.

本项目从高木质纤维含量木塑复合材料（WPC）的高效加工和高性能化出发，采用化学结合能力强、渗透性适中、表面覆盖效率高、无污染的烷基烯酮二聚体（AKD）和烯基琥珀酸酐（ASA）对竹粉进行表面化学改性，降低其表面能，改善其在聚丙烯（PP）基体中的分散性和相容性，提高WPC的加工性能和物理力学性能。重点研究改性参数和工艺的优化，建立高效、经济、环保的木质纤维表面改性方法，增韧改性PP以制备具有高流变性能又能与竹粉形成良好界面结合的改性PP，进而制备高竹粉含量WPC，并对其结构性能进行表征。研究表面改性对竹粉在室温和成型加工温度下表面能的影响，竹粉在PP中的三维分散与分布状态，最终揭示室温下，竹粉与PP的表面能特性与WPC力学性能的相关性，成型加工温度下表面能特性与WPC熔体流变/加工性能的相关性，为推动高木质纤维含量WPC的高效加工和高性能化探索新的途径，提供理论基础。

为了探究木质纤维表面修饰对高填充木塑复合材料（wood plastic compisites，简写WPC）结构-性能的调控机理研究，本项目首先通过不同部位竹材制备出了聚丙烯（polypropylene，简写PP）基WPC，并对WPC的性能及其影响因素进行了系统分析，揭示了化学成分、微观结构对纤维形态及WPC性能的影响规律，为高性能竹塑复合材料的制备提供了理论基础；探究了一种新的木质纤维改性方法，在球磨中通过机械/化学法，利用制备的混酸酐与纤维素颗粒反应制备表面改性的混合酸酐纤维素酯，并将表面改性的纤维素颗粒与PP基体复合制备WPC，对其加工性能、结晶行为、力学性能和吸水行为等进行分析，揭示了混酸改性纤维素酯对PP的增强机理；通过弹性体烯烃嵌段共聚物（Olefin block copolymer，简写OBC）共混和马来酸酐（maleic anhydride，简写MAH）接枝改性的方法制备了高韧性和高力学强度的PP基WPC，并对其尺寸稳定性、动态力学和断裂形貌进行分析，揭示了OBC和MAH对PP的增韧机理；通过烷基烯酮二聚体（Alkyl ketene dimer，简写AKD）乳液喷淋和溶液浸泡处理木质纤维并制备了PP基WPC，对WPC的机械性能和加工性能进行了分析，探究了AKD的改性机理及处理工艺对WPC性能的影响规律；制备了一系列纤维含量高达70~85%的高填充PP基WPC，探究了纤维含量和AKD改性对WPC力学性能和加工性能的影响规律，为高填充WPC的制备提供了理论基础；通过氧气和六甲基二硅胺烷等离子气体处理木粉并制备了PP基WPC，对WPC的机械性能和加工性能进行了分析，揭示了木质纤维表面能对WPC性能的影响规律。在综合分析、系统总结上述研究结果的基础上，建立了表面修饰对高填充WPC结构-性能的调控机理。