Integrated analysis of liquid composite molding (LCM) processes
Liquid composite molding (LCM) processes have been proven to be cost effective for producing lightweight and high-performance composites. In this study, an integrated analysis was carried out to study two processes in this category, including the resin injection pultrusion (RIP) process and the vacuum assisted resin transfer molding (VARTM) process. RIP has attracted much attention in the last decade, due to its great potential for producing composite-profile with constant cross-sectional area, high productivity, low cost, and zero volatile organic compounds (VOC) emissions. In this study, a friction coefficient model and a volume change model of a vinyl ester resin were developed. An analytical model was developed to predict the resistance force in the injection die. The volume change model and the friction coefficient model, combined with the temperature and resin conversion profiles along the die, were used to predict the resistance force in the heating die. The comparison between the analytical and numerical results with the experimental data showed that the models and the simulation tool developed in this study are capable of predicting the pulling force in the entire die with good agreement. Recently, because of the growing interest of low temperature manufacturing processes such as VARTM, low shrinkage molding compounds with the ability to be processed at low temperature have attracted considerable interest from the composite industry. However, most low profile additives (LPAs) do not work well for the shrinkage control of unsaturated polyester (UP) in low-temperature processes because of the lack of strong temperature changes during molding. In this work, a novel nanotechnology was developed to achieve zero volume shrinkage of low profile UP resin system cured at room temperature by controlling the selectivity of nanoclay during reaction-induced phase separation. TEM observation of the cured sample showed that nearly all of the nanoclay platelets resided in the LPA-rich phase. Nanoclay presence increased the reaction rate in the LPA-rich phase because nanoclay could act as a co-promoter in the UP curing system, which could result in the earlier microvoid formation and better shrinkage control. The resulting VARTM panels with improved volume shrinkage control showed better surface quality improvement.
School:The Ohio State University
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:liquid composite molding resin injection pultrusion vacuum assisted transfer vinyl ester unsaturated polyester low profile additive
Date of Publication:01/01/2004