Effect of fiber length on short glass fiber reinforced epoxy composite materials

EFFECT OF FIBER LENGTH ON SHORT GLASS FIBER REINFORCEDEPOXY COMPOSITE MATERIALS(M.Sc. Thesis)Gözde DEM RC OĞLUGAZ UNIVERSITYINSTITUTE OF SCIENCE AND TECHNOLOGYJune 2006ABSTRACTIn this study, random chopped glass fiber reinforced epoxy compositematerials were produced. Then, the effect of change in glass fiberlength and glass fiber content on the composite structure wasexamined.For this objective, diglycidyl ether of bisphenol-A (DGEBA) type epoxyresine (NPEL 128) and cycloaliphatic amine type curing agent (ACR H-3895) were used as matrix system, chopped E glass fiber (BMC1) wasused as reinforcement system. By using molding technique, compositematerials were produced by adding 3 mm, 4,5 mm, 6 mm long choppedE glass fibers at different weight contents of %5, %10, %15 and %20 tothe matrix system.In order to determine mechanical properties of the composite materialsthree point bending and tensile tests were conducted. Thermalproperties of composite materials were analyzed by using differentialscanning calorimeter (DSC) and thermogravimetric analysis (TGA). Thefracture surface of the composite materials were examined by usingscanning electron microscope (SEM).Mechanical characterization studies showed that, the tensile andflexural strength and the modulus values of the composite materials,increased with increasing the fiber length and fiber content. Flexuraland tensile strain values decreased with increasing fiber content anddecreased with increasing fiber length.As a result of differential calorimeter (DSC) analysis; fiberreinforcement led to a slightly decrease in epoxy glass transitiontemperature (Tg). It was examined that, the differences in fiber lengthdid not affect Tg. Furthermore, glass fiber addition increased thethermal resistance of epoxy materials; the higher the fiber content ofthe composite material the higher the amount of increase in theirthermal resistance. The difference in fiber length did not affect theirthermal resistance. The results taken from the TGA thermogramssupported these results.On the basis of SEM micrographs from which fracture surfaces wereexamined, the glass fiber epoxy composites showed that good wettingof fiber with resin.Science Code : 912.1.092Key Words : Epoxy resin, short glass fiber, polymer composite,mechanical properties, thermal propertiesPage Number : 126Adviser : Prof. Dr. H. Vecihi PAMUKCo Adviser : Doç. Dr. Nursel D LS Z