| A new kind of pultruded carbon fiber/resins composites used for oil sucker rod was made to meet the demand in oil exploitation for light weight, high strength, fatigue-resistant, and correction-resistant with the oil well deeper and deeper, as well as the need for using in corrosive oil well in China. The important problems for the produce of pultruded composites were to deeper understand the cure characteristic of the matrix resins and the relation between micro-structure and mechanical performance in cured resins, to investigate the function of fiber and its interface with matrix resins in composites, how to optimize pultrusion technics, to study the structure and performance of the composites for successfully used as oilsucker rod. Herein, the matrix resins, initiator systems, pultrusion technics of composites, as well as the structure, performance and application of pultruded composites were investigated extensively in this paper.The microstructure in cured resins decides its mechanical properties. An important characteristic in cured vinyl-ester resin is micro-gels and bi-phase structure. The morphological structure of cured vinyl-ester resin and the formation of two-phase structures in vinyl-ester resin has been studied by using SEM and differential scanning calorimetry (DSC). The results demonstrated the existence of clusters of gel-particles with a size of about 20 μ m, each cluster of gel-particles containing many gel-particles with coral-like structures. The formation of gel-particles resulted in two-phase structure characterized by the two peaks in the rescanned isothermal DSC thermographs of the resin. The cure conditions (temperatures, post-cure) affected microstructure in the curd resins. The results of mechanical properties showed that the cure conditions affected its mechanical properties. The post-cure for the sample isothermally cured at 80℃ increased the tensile strengths and flexural strengths. On the contrary, the post-cure for samples isothermally cured at 120℃ decrease the tensile strengths and flexural strengths. The results of DMTA showed that glass transition temperatures (Tg) of cured resins had no direct relations with its mechanical properties.Initiators play an important role in the curing of vinyl-ester resins.Two kinds of initiators were used to investigate the effects of initiator system on the cure kinetics, microstructure and mechanical properties of vinyl-ester resins. Reaction kinetics was studied using isothermal differential scanning calorimetry (DSC). The result obtained from DSC data showed that the combination of different kinds of initiators could greatly decrease the induction times and exothermal peak times, increase the amount of isothermal reaction heat. The residual heat of isothermal cure of vinyl-ester resins obtained by DSC demonstrated the existence of micro-heterogeneity in the cured resins. And, the DSC data also showed that the highly cross-linked phase (the micro-gel phase) was more perfect for the resins cured with combination of initiator system. Little difference was found for the mechanical properties of resins cured under different conditions. On the other hand, the cure temperature had great effect on the mechanical properties of cured resins.The curing process of composite is a complicated one during which chemical reactions and physical changes take place. The DMTA of isothermal cure of vinyl-ester/carbon fiber composite showed that during the " induction time", the storage modulus increased slowly with time which was obviously resulted from the polymerization. But the reaction heat was too small to be detected by DSC. A kinetic model based on the irreversible thermodynamic fluctuation theory was used to study the isothermally curing process of vinylester resins/carbon fiber composite. Itwas found that the curing parameter: β was different within curing time and the relation of storage modulus and curing time could be described only within the time from lg(t/τ) =-0.4 to lg(t/τ) =0 which demonstratedthat during isothermal cure of composite, the change of storage modulus with time followed different mechanism which maybe resulted from that at the former stage, polymerization decided the change of storage modulus, however, at the latter stage, it was physical change that affected the change of storage modulus.The influents of the three-part temperatures, contents of the initiator, mould release agent and volume content of carbon fiber on the pultrusion composites were discussed through experiments, and the best value ranges of the above factor were discussed. The composites consisting of continuous carbon fiber/vinylester resins were fabricated by pultrusion processing, in which on-line treatment on the carbon fiber by thermal oxidization was carried out. The microstructures of the surface treatment of both treated and untreated carbon fiber and the fracture morphologies of the composites were analyzed by using SEM. Also, the quasi-static mechanical properties and the thermodynamics mechanical properties were measured with DMTA, respectively. The results showed that the surface roughness of the carbon fibers increased by the surface treatment, which resulted in the increase of interfacial adhesion strength between the carbon fiber and the resins, at the same time, the mechanical properties, especially the...
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