高填充木塑复合材料的流变性和挤出模拟研究

Wood plastic composites (WPC) is a new kind of environment-friendly material with lignocellulosic materials or wood fiber and thermoplastics as its main ingredients by melting compounded. Approximately 80% WPC products were compounded by profile processing technology. With better property than wood and plastics, the composites have been widely applied in many fields. Among the many factors that lead to this development, the competitiveness of high loading level wood and recycled polyole?ns over conventional materials is an important factor. Along with the expansion of domestic WPC industry，it becomes important research topic which is urgent to be solved to develop profile processing technology with competitive efficiency and technical stability. This project focus on the rheological properties related to the profile processing technology of highly filled WPC (for example, the rheological behavior related to melted mixing in torque rheometer chamber, method to evaluate the processability of WPC formula and the effectiveness of typical WPC additives, the rheological basis to establish constitutive equation). Scientific rheological method will be established to characterize the rheological behaviors of highly filled WPC system. The rheological behaviors and extrusion processability of typical WPC formula will be systematic studied to conducted comprehensive investigations on the fundamental ?ow behavior of the highly ?lled plastics and practical methods for evaluating the ?ow performance for process development. Finite element method (FEM) was used to simulate the extrusion process, then validate and correct the constitutive equation. Finally the rheological fundament and optimized methodology of numerical simulation for materials, profile die passage and process designs of highly filled WPC will be developed.

木塑复合材料(WPC)是一类以木质纤维为填充或增强材料，以聚烯烃等热塑性塑料为基体，经熔融复合而制成的新型复合材料,约80%的WPC制品由挤出工艺成型。随着国内WPC产业规模和应用领域的迅速扩大，高木质纤维添加量、废旧塑料利用等技术的发展，提高WPC挤出技术的效率、稳定性、适应性已成为亟待解决的重要研究课题。本项目针对高填充WPC复合体系的流变性问题(复合混炼过程中的流变性、WPC配方、挤出工艺性和助剂性能的流变性评价，本构方程的建立)，研究建立能够灵敏而特征性地表征高填充WPC复合体系流变行为的方法和测试条件，系统研究常用木塑复合体系流变性和挤出工艺性，揭示流变行为变化的原因和规律，形成挤出WPC配方和助剂性能的流变评价方法，进一步用有限元法(FEM)分析模拟挤出工艺过程，进行挤出实验验证和修正，最终建立高填充WPC材料设计、模具设计、工艺设计等系统的优化方法和流变学依据。

木塑复合材料(WPC)是一类以木质纤维为填充或增强材料，以聚烯烃等热塑性塑料为基体，经熔融复合而制成的新型复合材料,约80%的WPC制品由挤出工艺成型。随着国内WPC产业规模和应用领域的迅速扩大，高木质纤维添加量、废旧塑料利用等技术的发展需要，提高WPC挤出技术的效率、稳定性、材料适应性已成为亟待解决的重要研究课题。本项目针对高填充WPC复合体系的基本流变性问题(复合混炼过程中的流变性、流变性调控、挤出工艺性和助剂性能的流变性评价，本构方程的建立，挤出模拟与优化)进行了系统的深入研究，综合运用挤出流变方法、转矩流变方法和旋转流变仪，从不同角度建立了能够灵敏而特征性地表征高填充WPC复合体系流变行为的方法和测试条件；系统研究了常用木塑复合体系的流变性和挤出工艺性，弄清了高填充木塑复合体系的流变行为变化规律和主要影响因素。取得了四个方面的创新研究成果：形成了高填充木塑复合体系流变性与工艺性的实用调控技术；建立了挤出WPC配方与助剂性能的流变评价方法；用管模挤出流变测试方法测得60%木粉的HDPE复合体系本构方程，并用有限元法(FEM)分析模拟和调适挤出工艺过程，结合经验对优化结果进行实验验证；以羟基化碳纳米材料为模型探索了天然纤维高分子共价键表面改性新技术。建立了高填充WPC材料设计、工艺设计、流变性调控等系统的应用性基础研究成果。