Plant Fiber Reinforced Polyurethane Reaction Injection Molding Products Preparation And Mechanical Properties

Natural fiber especially hemp fiber has the high specific strength and modulus and polyurethane(PU) is a widely used resin material due to its good tough, quickly solidified and low cost. Natural fiber can effectively improve the performance of the PU materials, in addition natural fiber has advantages such as low density, low cost, extensive sources and biodegradability, so natural fiber reinforced PU composite not only has a certain practicality, but also has environmental friendly character.A new kind of polymer-based composites reinforced by good performance hemp fibers were prepared combined with the equipment of LFI-RIM-Star 16/40.By the analysis of mechanical property of this composite, practical conclusions were gained.The main content of this paper includes:(1) The technological process and forming principle of long fiber reinforced reaction injection molding (LFI) which is based on reaction injection molding (RIM) were introduced and the structure and mechanical characteristics of fiber reinforced polyurethane composite were described in detail, at the same time the composition and the working principle of Krauss-Maffei 16/40 LFI automatic production line were elaborated in this pape.(2) By analyzed the characteristics of LFI process and the quality defects found in production, improvement methods were given to improve product quality and process measure.(3) Fiber content, fiber length, modeling pressure and fiber surface treated were selected as the process parameters in experimental design whose main components was orthogonal test.The impact on tensile, bending, impact performance of natural fiber reinforced polyurethane composite was deeply analyzed and the optimum process parameters were gained by range analysis and variance analysis of test results, which can guide the practical manufacture. The mechanism of natural fiber reinforced polyurethane matrix was stated from the point of view of the microscopic structure of the composite.(4) Contrast tests were designed to discuss the performance differences between different fibres reinforced PU composite.