Research On Flax Nonwoven Reinforced Composite Materials

This article mainly researched the technology of making the flax fiber reinforced composites, tested and analyzed the mechanic properties. In the article the characteristics of the flax fiber were introduced and the length, fineness and the strength were tested. The property of flax fiber as the basic unit can largely affect that of the end products. Through the needle punching technology, we made more than ten kinds of flax non-woven fabrics including the different laying types (parallel laid and cross laid) and the different punching density (from once to seven times). Before taking part in the process of making the composites, the flax non-woven fabrics were tested in the following aspects: the thickness, weight per m2 and the tensile property. As for the tensile property, the one of the parallel laid non-woven fabric was discriminative compared with that of the cross-laid non-woven fabric.We use the method of Vacuum assisted Resin Transfer Molding, VARTM in abbreviation to make the composites in which the unsaturated resin was used. The process of making the sheets depended on the penetration of resin into the fiber and the combination of the two as well. Generally speaking, it was ideal when the resin combined the fiber firmly by chemical reaction. Thus we should think about the interface of the two kinds of materials such as their consistence. We should also think about the fluidity of the resin in the fabrics and the conditions and the time of the consolidation as well. After having done numerous experiments, we found the best method to make the ideal composites.After making the different composites, we tested the tensile and bending properties according to the GB standards. Through analyzing the conclusion was drawn that the mechanic properties of the flax non-woven fabrics primarily affected those of the composites. When the parallel-laid fabrics were pulled or bended along the same direction of laying most fibers could burden the load. As a result, the longitudinal tensile property of parallel -laid technology was better than that of the cross-laid technology. Compared with the cross-laid composites, the longitudinal andthe lateral properties of the parallel-laid composites were more discriminative. At the same time, by making good use of the scanning electronic microscope, we observed and analyzed the details of the tensile broken surfaces and the bending broken traces, by which we could know the combination of the resins and the fibers much clearly. This was very useful for the analysis of the mechanical properties of the composites. Through watching a series of photos in different amplifying multiple we know that the interface of bleached flax reinforced epoxy resin composites was better than others, which jumped together with the conclusion in the mechanical properties.In order to compare the properties we made the composites of different fibers namely the rude flax and the bleaching flax with different resins namely the unsaturated resin and epoxy resin. After testing and studying the mechanic property, we found that the property of the bleached flax fiber reinforced epoxy resin composites was better than the others. We also drew a conclusion that it was fixer for epoxy resin to combine the flax fibers.This project made good use of the resource advantage, saved the cost, reduced the producing period and at the same time there wasn't chemical waste so that it could protect the environment. The composites reinforced with flax fiber have wide developing prospect, which can be used in automobile, architecture, decoration and other fields. So it was of great importance to develop composites reinforced with flax fiber.