Effect of fiber opening process on mechanical and insulating properties of glass fiber reinforced epoxy composites

In this study, chopped glass fibers with various fiber aspect ratios were opened via pressurized air application and obtained fiber bundles were used for reinforcing of epoxy matrix. Composites with fiber contents of 5%, 10% and 15% in weight were produced by hand lay-up technique and these samples were exposed to tensile, flexure and thermal insulation testing procedures. Results were compared with chopped glass fiber reinforced epoxy composites produced with identical process parameters. The results showed that opening process period was not related with fiber aspect ratio of chopped fiber and fiber length had an important effect on opening process period than that of fiber diameter. Long chopped fibers gave quick response to air pressure application. In general, openning process caused decrease on tensile and flexural strengths of composites but increase on thermal insulating characteristics. For 4.5 mm/13 μ samples, opened fiber reinforced composites exhibited high tensile resistance at low concentration values. Flexural strengths of composite were highly affected from fiber length parameter in both chopped and opened fiber reinforced composites and flexural behaviours of composites reinforced with (3 mm/13 μ) and (4.5 mm/10.5 μ) glass fibers having different fiber aspect ratios became more consistent after openning process. Thermal conductivity coefficients of composites decreased by using openned fibers as reinforcing agent and composites exhibited more insulating characteristics. © Chamber of Textile Engineers.