Production of continuous fiber reinforced composite with reactive thermoplastic resin and determination of the effects of flame retardants

In this thesis study, reactive thermoplastic based composite materials are produced with vacuum infusion method, a method used for the production of high strength composites. The mechanical performance of the composite structures is evaluated with various fibers which used from different producers and flame retardant additives. Continuous glass fiber reinforced unidirectional glass fabric of 1200 g/sqm that is manufactured by METYX Composites is used as the reinforcement component. In the first part of the study, mechanical properties of the laminates produced with thermoset and thermoplastic matrixes are compared. In the tensile tests of the composites produced with Şişecam fiber, PMMA matrix composite material showed higher tensile strength than Vinilester and Epoxy matrix composites. It was also observed that the elastic modulus was higher than that of Vinilester, Epoxy and Urethane acrylic matrix composites. In addition, it was observed that PMMA matrix composites showed higher compressive strength than Vinilester, Epoxy and Urethane acrylic matrix composites. In the interlaminar shear (ILSS) and in-plane shear tests (IPS), PMMA gave higher strength results than Vinilester. In the three-point bending test, PMMA showed higher bending strength than Epoxy. Similarly, it has been observed that in composites produced with 3B glass fiber, the PMMA matrix composite exhibits higher strength values than the thermoset matrices in tensile and ILSS tests. In many tests, PMMA matrix composite gives higher strength and modulus values than thermosets in two fiber types, but this difference is not higher than 10% at points where low strength and modulus values are observed. As a result of the shear tests (ILSS, IPS) in which the bond strengths between the fiber surface and the matrix are dominant, the commercially available glass fibers compatible with thermoset resins are also compatible with PMMA and they can be used with PMMA. As a result of parallel tests with thermoset resins, PMMA can be used as an alternative to conventional thermosets in the production of glass fiber reinforced composites. Experimental data obtained from this study provided us a useful composite design data. In the resin flowrate tests, it was found that the PMMA resin wetted the reinforcing fabrics about %35-39 faster than thermosets. In order to remove the composite from the mold, the resin curing time to be completed by standing in the mold was 12 hours in vinyl ester and acrylic resins, 24 hours in epoxy resin and 2 hours in PMMA resin. When it is necessary to apply post-cure to thermoset resins for 5-15 hours, PMMA can be used without post-cure process. It has been determined that the PMMA resins wet the fabric faster than the thermosets, the curing time required to remain in the mold is shorter than the thermosets, and no need for an additional postcure process provided opportunities for the production cycle in the composite production to take place in a shorter time. In another part of the study, phosphated, inorganic and halogenated-phosphated flame retardant additives are added in different proportions to PMMA composite materials produced by 3B glass fiber. In the UL-94 vertical burn tests, no flame retardancy was observed in other samples except TEP (phosphated) added specimens. In the tests where 15% of the TEP (phosphated) additive was provided, an effective increase in the flame retardancy was observed compared to the lower additive rates. However, it is foreseen that the contribution rate of 15% is not sufficient for UL-94 classification and the material can be classified if the contribution rate is increased. Composite materials were classified as HB (slow burning) in all additives and additive ratios in the combustion tests performed in the horizontal direction. HB classification did not change with additive rates. Mechanical tests have been carried out on composites produced by flame retardant addition, and it has been observed that the additives added at increasing rates generally reduce the mechanical properties. Observations made in interlaminar shear tests showed that the strength decreased by 24% in ATH (inorganic) admixtures, 27% in TEP (phosphated) admixtures and 21% in TCPP (halogenated-phosphated) admixtures. These data obtained from the shear tests show that the additives affect the fiber-resin compatibility by weakening the bond strengths at the fiber matrix interface. It has been found that halogen-phosphated flame retardants are better than inorganic flame retardants but less effective than phosphate flame retardants, in which inorganic flame retardants are not effective when incorporated at low rates, as compared to flame retardant additives in general. The addition of TEP (phosphated) additive with increasing amounts to the PMMA matrices will increase the flame retardancy but it will affect the fiber resin interface negatively. On the other hand, it was observed that the additives at the rates below 15% could not provide flame retarding properties. At the end of the study,it has been determined that the new generation of reactive thermoplastic resins will also provide the advantages of thermoplastic properties in the production of glass fiber reinforced composites. This resin, besides the advantages of thermoplastic properties (long shelf life, recycling, environmentally friendly, healthy working conditions, etc.) gives shorter production cycle.