Production and characterization of fiber reinforced thermoplastic composite material

The most important advantage of the composite, a new set of material which is formed by creating an interface between at least two materials with different chemical and/or physical properties, is to exhibit superior properties than its constituents. Composite materials have wide application areas due to its higher mechanical, chemical and physical properties. Composites with chopped glass fiber have been using in many areas like automobile and marine industries, while continuous fiber composites have applications in the areas require higher mechanical properties. In today's plastic matrix composite applications, thermosetting polymers are preferred. This is because thermosetting polymers such as epoxy, vinyl ester and polyester have better wetting and easer adhesion on fiber materials, therefore strong connection between fiber-matrix interfaces ensure. Additionally, it is easy to process thermoset composites, even if with a simple methods such as hand lay-up technic. Thermoplastics, another type of plastic exhibiting better properties than thermosetting polymers, have been used in new applications with the purpose of improvement of plastic composites. Thermoplastic polymers have many advantages such as higher chemical resistance, higher strain, flexibility, light weight and recycling. However, the main problems in these are insufficient wetting and adhesion that would form interface, due to this expected performances from the mechanical properties, failure. Also production of thermoplastic composites is much more complex then thermosetting composite production and required mechanized processes (eg., injection molding, extrusion molding, etc.). Because thermoplastic raw materials are in the solid state, these raw materials have to be first melted and then consolidated with reinforcing materials. During this process, melt of thermoplastic matrix at high viscosity effect a negative role on matrix dispersion on fibers and arrange of reinforcement. Agglomeration in fibers and product homogenization are versions of failures in the meantime. Such difficulties caused by thermoplastic matrix have delayed the production of these composites until today. However, thanks to new developed chemicals as well as production technologies overcome these difficulties today and the advantages of thermoplastic matrix can appear on composites. By this way, the production in the today's industry of thermoplastic composite applications has been possible by extrusion and injection processes with the use of chopped glass fibers. However, the process that allows the production of continuous fiber composite is new developing in the world, and could not take a part in our industry yet. The reason for this is higher fiber concentrations in continuous fibers, so thermoplastic melt with higher viscosity could not penetrate to fibers uniformly throughout the process and fiber-matrix interfacial wetting and bonding problems occur. In this study, polyethylene and polypropylene, the cheapest thermoplastic polymers with lowest densities, were used as the matrix material. These were reinforced with continuous E-glass which offers optimum strength and cost results, basalt fiber as a new type of fiber alternative to E-glass and aramid fiber as a high performance fiber. To improve interfacial adhesion various compatibilizers were applied and some physical and mechanical tests were done. The ideal compatibilizer ratios were determined by comparing results and formation of interface was improved in polyethylene and polypropylene matrix composite materials.