Consolidation of fiber-reinforced composites with thermoplastic matrices.

摘要

A continuous fiber-reinforced polymer (CFRP) composite is a material composed of reinforcing fibers that are held together with a polymer matrix. Thermoplastics are rarely used in CFRP composites. Two reasons for this include the high viscosity of thermoplastic materials and the lack of processing information available for continuous fiber-reinforced thermoplastics. Because of the high viscosity of thermoplastics, the rate-limiting step in producing continuous fiber-reinforced thermoplastics is the slow permeation of the resins through the fiber bed. Therefore, it is important to quantify the permeation process.; There is little experimental or theoretical work reported on the transverse permeation of thermoplastics through beds of fibers. With this in mind, the fundamental objective of this thesis was to answer three questions: (1) Can the transverse permeation process during thermoplastic composite processing be modeled with semi-empirical and theoretical models? (2) Which model more accurately models the permeation process? (3) Are the models valid for different materials and processing conditions?; To answer these questions, several permeation experiments were performed, and semi-empirical and mechanistic models were used to describe the permeation process. A variety of thermoplastics, fibers, preforms, and processing conditions were used in the permeation experiments. The semi-empirical model was referred to as the Semi-empirical model, and the mechanistic models were referred to as the Vijaysri and Bruschke models, respectively. Compression molding, a common composite processing technique, was used to study the permeation.; There was good agreement between all the models and the experimental results. The Semi-empirical and Bruschke models gave matching predictions that were slightly better than the Vijaysri model. With this in mind, it was recommended to use the Bruschke model to quantify the transverse permeation of thermoplastic through beds of fibers. The reason for this recommendation was that the Bruschke model, unlike the Semi-empirical model, did not require an empirical constant as an input parameter. Another goal of this thesis was to derive a model to predict the void content of thermoplastic composites. The Bruschke model was used as a basis for the void content model. There was good agreement between the theoretical and experimental void contents.