Toughening of carbon fiber/epoxy composite by epoxy-polysulfone semi-IPNs with a morphology spectrum

Abstract

The aim of this thesis is development of epoxy/PSf semi-IPNs and toughening carbon fiber/epoxy composites based on the morphology spectrum concept. In particular, the system with low thermoplastic contents was investigated because thermoset materials with high thermoplastic modifier contents display poor thermal and mechanical properties. In Chapter 2, the morphology spectrum formation of the epoxy/PSf semi-IPNs in the carbon fiber/epoxy composite is studied. The epoxy/PSf semi-IPNs with the morphology spectrum are prepared by the PSf film insertion method into the center of prepregs. Morphology was observed by SEM and the formed PSf concentration gradient in the composite is observed by EPMA. The mode I fracture toughness ($G_{IC}$) is evaluated by the double cantilever beam (DCB) specimen. In Chapter 3, the semi-IPNs with the morphology spectrum are prepared by the PSf particle dispersion method. To evaluate the effect of PSf surface area on the phase separation, two kinds of PSf particles are used. Morphology was observed by SEM and the formed PSf concentration gradient in the composite is observed by EPMA. $G_{IC}$ was evaluated by the double cantilever beam (DCB) specimen. In Chapter 4, according to the results of toughening effect by the PSf film and particle modified composite at previous Chapters, composite pressure bottle was designed and manufactured by filament winding. After structure analysis of pressure vessel by the ABAQUS software, we can conclude that toughening was needed at Y-joint of pressure vessel. To evaluate toughening effect at Y-joint by the PSf modified epoxy composite, the cylinder type composite by filament winding was designed and modified DCB specimen was designed and attained from the cylinder type composite. PSf was applied at interplay of the cylinder type composite by film and particle (large size: 50~150 μm) form same as Chapter 2 and 3.