| Compare to short fiber and long fiber reinforced thermoplastic composite (SFT and LFT), continuous fiber reinforced thermoplastic composites (CFT) have more excellent mechanical properties, can be used as structural materials; coupled with lightweight, corrosion resistance, etc., CFT is an alternative material to take the place of steel. So, research and development of new CFT materials is extremely essential, especially high-performance thermoplastic resins (eg, special engineering) and new molding process (such as pultrusion, winding, etc.).In using process, materials will face the applied load and the erosion of different environments. To study the variation laws of performance of material under these factors, can bring an important guiding significance to practical application.In this paper, polypropylene, short and long fiber reinforced polypropylene thin layer were used as interleave to improve interlamination toughness of continuous fiber reinforced polypropylene laminated composites. The results showed that interlaminar shear strength was increased11.5%,27.6%and38.6%, respectively, but the improvement of flexural strength was not very significant. Then an attempt to soften fiber reinforced interleave at200℃was carried out in order to insert fabric. The result was very satisfactory, compare to add un-softened thin layer, flexural strength was increased39.0%and42.9%, respectively.In this paper, short-term creep behaviors of continuous glass fiber and basalt fiber reinforced polyphenylene sulfide composites under different temperatures and applied loads were studied. With the increase of temperature and applied stress, the creep strain increased. When fiber weight content were30%and40%, creep resistance of laminated composite was at the same level; and when fiber weight content was50%, creep resistance improved more significant. Moreover long-term creep behavior could be predicted through time-temperature superposition.Continuous glass fiber reinforced polypropylene pultruded bars were prepared successfully from two-step process by using an self-designed pultrusion equipment with only single heated mold. The optimization parameters of pultrusion process were determined: preheating temperature was160℃, molding temperature was200℃and pultrusion speed was0.3m/min. Then, temperature adaptability and corrosion behavior in simulated seawater of pultruded rods were investigated. After heat treatment, flexural strength and modulus of pultruded bars were both increased7-8%. After temperature cycle and freeze-thaw cycle, flexural strength and short beam shear strength were both decreased, but not much. It indicated that hydrothermal stability of pultruded bars was good.Diffusion behavior of prepared seawater in pultruded bars was pseudo-Fickian behavior at room temperature and high temperature; and under high pressure condition, diffusion behavior of prepared seawater was linear Fickian behavior. The diffusion coefficient of simulated seawater was5.52×10-6,1.89×10-5and3.03×10-4mm2/s respectively under25℃,50℃and5MPa conditions.With the immersion time increased, mechanical strength of composite gradually reduced. It was found that prepared seawater diffused into pultruded bars reduced the interfacial bond between fiber and matrix, thus strength of pultruded bars descended. At the same condition and time, water absorption of pultruded bars decreased and strength retention enhanced after end-capping treatment by using polypropylene melt. End-capping treatment increased water diffusion resistance, and improved durability of composites effectively.Service life of pultruded bars was predicted from short-term corrosion behavior in simulated seawater based on Arrhenius equation. The result showed that compared to normal temperature and pressure, the degradation rate of high-pressure and high-temperature accelerated corrosion was an order of magnitude larger. It was found that the predicted time to reach50%retention of flexural strength was about14year under local environment condition。... |
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