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Baghouil_30361200_2017.pdf
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- Abstract
- Epoxy resins are widely used nowadays as structural materials as well as functional materials. They are used in many fields ranging from the paint industry to construction and electronics. The versatility of these resins is due to their multiple interesting properties such as their good chemical and thermal resistance. However, they suffer brittleness which brought about numerous researches to study these resins in order to improve their toughness, in other words their resistance to crack propagation. In the same context, this work aims to improve the toughness of an epoxy resin. To achieve this, a thermoplastic blend in a film form is added to the resin. The epoxy resin studied in this work is the RTM6 which takes its name from the RTM process used in composites fabrication. The thermoplastics used are a phenoxy : the PKHH, a polyetherimide : the PEI Ultem 1000 and a hydroxyl terminated polyethersulfone : the PESOH. These pure components as well as PEI/PKHH and PESOH/PKHH blends in films form are added to the resin in order to investigate their influence on the latter’s toughness. A preliminary study characterizes morphologically and thermally the thermoplastic blends. Optical microscope observations, DSC and DMA analyses are performed allowing to observe the blends morphology and to determine their glass transition temperatures. Moreover, the effect of the composition and the process conditions on these characteristics is studied. These analyses show heterogeneous biphasic blends with a sign of partial miscibility. Then, the thermoplastics’ behavior in the resin is studied. Measures of the interdiffusion of thermoplastics filaments heated in a resin drop show that a heating rate of 2°C/min is the most suitable in order to allow the films diffusion in the resin during curing. Eventually, three point bending tests show that all the added films provide an improvement of the resin toughness, the best result being obtained for a PESOH/PKHH 50/50 blend. SEM analyses finally show that the films bring about a roughness that slows the crack propagation and that explains the improvement in toughness