The present study investigates the effects of process parameters such as fabric structure, fabric orientation and compatibilizer concentration on the mechanical properties of fabric reinforced polypropylene composites. Two types of glass fabric reinforced composites with two different stacking sequences were prepared by compressing molding. The composites were prepared with and without compatibilizer for the purpose of analyzing interfacial-bonding. The composites were investigated in terms of tensile, flexural and impact strength for evaluation of the effects of the process parameters. The factorial approach is used to design the experimental layout. The test results revealed that Type-2 fabric reinforced composite in [0-90]4 orientation with 8 wt% compatibilizer possesses better mechanical properties. Tensile, flexural and impact strength were increased by 106%, 235% and 100%, respectively. Analysis of variance was used to identify the most significant factors which would affect the performance of composites. Morphological study explored the presence of strong interfacial-bonding between the materials.

Keywords: polypropylene, glass fabric, mechanical properties, morphological analysis, factorial design

Nowadays, advanced textile reinforced composites are broadly used in structural and automotive industries for load bearing applications in view of their good properties such as high specific strength and modulus, good dimensional stability, repair-ability, corrosion resistance and cost effectiveness.^1,2 Textile reinforced thermoplastic composites with these excellent features act as competitive materials for metals, alloys and thermoset counterparts.² The higher robustness feature of thermoplastic composites make them suitable for crash applications more than thermoset composites. However, improper fibre orientations,³ poor wettability of matrix over fibre,^4-6 and inappropriate processing techniques are the vital aspects that control the usage and performance of thermoplastic composite materials. In order to motivate the extensive usage of thermoplastic composites for engineering applications, it is important to broaden the understanding of their mechanical behaviour. In-depth and extensive knowledge of processing and optimization of product performance has been developed for short/long fibre reinforced thermoplastic composites. But still the situation for continuous and woven fabric composites has to improve.
Okereke3 studied the flexural response of glass fibre (GF) reinforced polypropylene (PP) composites with different ply orientations and noticed the influence of the plastic deformation of the matrix on the flexural behaviour of the composites. Ravikumar et al.⁴ investigated the effect of maleated PP on the mechanical properties of corn fiber/PP composites using the Taguchi technique and found considerable improvement in the properties of composites. Greater improvement in flexural, impact and tensile strength was noticed by Liu et al.,⁵ when maleic anhydride grafted polypropylene was added to the PP matrix. Sorrentino et al.⁶ achieved mechanical per-formance optimization through interfacial strength by adding maleated PP to the GF/PP composites.
The effects of process parameters on the mechanical properties of kenaf/PP composites were analyzed by Sallih et al.⁷ using the factorial approach. The optimization of process parameters for improving the flexural property of GF/PP composites was carried out using the Box-Behnken design.⁸ Vamshi Krishna et al.⁹ did evaluation of the mechanical properties of short GF/PP composites and observed the increase in the strength of the composite caused by an increase in fibre length. Lee et al.¹⁰ investigated the effect of coupling agent on the flexural, tensile and impact properties of silica reinforced polypropylene composites and reported that the PP composite mixed with 5 wt% silane prepared using the dry method exhibited the highest mechanical properties. The morphological and mechanical properties of natural fibre reinforced^11-15 as well as synthetic fibre reinforced^16-19 PP composites were studied by the researchers. The mechanical properties of GF/PP composites under different fibre orientations²⁰ and various surface treatment methods^21,22 were examined and enhancement in the properties of composites was observed. Despite numerous publications on short/long fibre reinforced PP composites, reinforcement of woven fabric in PP composites has seen only a limited application.
In this study, the effects of process parameters on the tensile, flexural and impact properties of plain woven glass fibre reinforced thermoplastic (GFRTP) composites, were investigated. The optimum process parameters were obtained using the full factorial design of experiments (DOE) approach, to fabricate the thermoplastic composites with better performance characteristics. Analysis of variance (ANOVA) was used for identifying the most significant factors which would affect the performance of composites. Using a scanning electron microscope (SEM), the morphological study was conducted on the samples before and after the tensile testing, for the analysis of the interaction between the matrix and reinforcement.