Hot compaction and mechanical properties of ramie fabric/epoxy composite fabricated using vacuum assisted resin infusion molding

Abstract

Recently, natural fiber has been a focus for environmental and recyclable polymer composite, because of its excellent properties, such as low cost, low density, high specific strength and modulus. Vacuum assisted resin infusion (VARI) molding is an attractive manufacturing technique for natural fiber reinforced polymer composites with high quality and low cost. Because of low applied pressure of VARI and special compacting property of natural fiber fabric, how to increase natural fiber content of composite is a critical issue for improving the mechanical performances of composite fabricated by VARI. In this paper, ramie fabric/epoxy resin composite laminate was prepared using VARI. In order to increase ramie fiber content, pre-compaction operation on dry ramie fabric stack was carried out before injecting epoxy resin into the fiber fabric. Vacuum pressure compaction and hot compaction with high pressure and temperature were respectively used to compress the fiber stack, and the compaction responses of fabric stack under different vacuum pressure loading cycle and hot compaction conditions were studied. The morphology, structure and tensile property of ramie fiber before and after pre-compaction procedure were investigated and the compaction mechanism under different conditions was discussed. Moreover, the composite laminates using compacted ramie fabric were manufactured using VARI, and tensile, flexural and interlaminar shear properties were measured. It is found that hot compaction can significantly increase ramie fiber content and the mechanical properties of composites. However, when the temperature and pressure of hot compaction are beyond certain values, the mechanical properties of ramie fiber and its composite obviously decrease, indicating that hot compaction conditions have optimizing scope.