Prediction of mechanical and thermal properties of wood plastic composites through theoretical and mathematical modelling / Ritu Gupta

Faculty of Computer Systems and Software Engineering

Thesis (Doctor of Philosophy in Computer Science) -- Universiti Malaysia Pahang -- 2014

Bibliography : p. 184-230

Wood plastic composites (WPC) have emerged as new option for composites in the composite industry. WPC have been accepted globally due to their remarkable advantages compared to synthetic fiber composites. In order to manufacture WPC with specific properties and quality, the industries at present employ trial-and-error method. Besides taking up a lot of time, a significant amount of materials is wasted with this method. However, this problem can be reduced to some extent through the use of simulation models for the prediction of the properties in the composites. Modeling and simulation allow users to visualize the effects of the parameters that are especially challenging for comprehension. In addition, the properties of WPC are dependent on the processing conditions. Hence, there are many parameters involved in the manufacturing process. Some of these parameters are important and are included in the simulation model to study and to understand their effects on the final WPC product. Thus, an integrated simulation model has been proposed to predict the thermal and the mechanical properties of WPC, which comprised of three main modules: a) the heat transfer model, b) the mechanical model, and c) the empirical model. The heat transfer model predicts the profile of temperature and the degree of cure via Melt Flow Index (MFI) and Young’s modulus for every layer during hot compression molding. Besides, a finite difference method was used to estimate the changes in the temperature in WPC during the compression molding process. Next, the mechanical model predicts the mechanical properties, such as Young’s modulus and tensile strength. Lastly, an empirical model to predict the Young’s modulus and the tensile strength based on the effects of the coupling agents. All the three models were validated with experimental results. The simulation model for heat transfer inside the board predicted the changes in temperature and the curing index of the composite across the thickness during the compression molding process. The proposed mechanical model successfully predicted the changes in tensile strength and Young's modulus with changes in the percentage of wood fiber. Furthermore, wood fiber was considered as a natural resource with nonuniform properties, as far as this study was concerned. Thus, the changes in the mechanical strength of WPC were predicted as the changes in the properties of wood fibers involved reduction in void volume, alkalization, and variations in moisture content. Moreover, the empirical model predicted the mechanical properties as a function of seven individual parameters for composites that were made of four types of fibers (Jute, Abaca, Hemp, and Pine) and Polypropylene. This model had been found helpful in predicting the effects of coupling agents on the mechanical strength of the composite. Therefore, this integrated research work with GUI should be able to aid the industry and the researchers concerning WPC