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What is the development process for this product? First of all, raw materials are selected properly, among them: mixed epoxy resin: homemade; aromatic amine curing agent: chemically pure, marketable; accelerator, commercially available. According to the epoxy resin: curing agent: accelerator=110:35:0.5, the glue solution was prepared and the curing exotherm of the resin was measured at different heating rates. (The instrument is a German-made PE-7 series differential scanning calorimetry. instrument). According to the DSC analysis curve, the exothermic peaks of the reaction started at about 80°C, and the regression analysis showed that the temperature peak was 128°C at a heating rate of 1°C/min. Therefore, the experiment takes 80°C and 130°C as the highest point of the curing temperature. Two curing temperature curves are formulated and the casting body is prepared. The properties of the resin under different curing systems are studied and two curing systems are compared.
The casting test was then performed. The preparation process of the casting body is as follows: the glue liquid prepared by mixing and vacuum degassing is poured into the steel mold cavity preliminarily coated with the mold release agent and preheated to remove the air bubbles in the glue liquid, according to two kinds respectively The different temperature rising curves heat up and solidified. After cooling and demoulding, the two casting bodies FH80 and FHl30 are ground to obtain a performance test. The performance test process of the casting body is: solvent extraction method for curing degree test, according to GB/T 2576-1989. The molecular structure analysis was performed by infrared spectroscopy. The mechanical properties were measured by tensile test according to GB/T2568-1995, bending test by GB/T2570-1995, and the glass transition temperature by dynamic modulus analysis (heating rate 5°C/ Min, dynamic test stress 8.0×104 Pa, static test stress 1.0×105 Pa, test frequency 1.0 Hz).
The test equipment is relatively advanced, among them: PE-7 series thermal analyzer, German production, infrared spectrometer PEKIN-ELMER 2000 FT-IR type, German production, INSTRON 4505 type universal material testing machine, British production. The materials produced by the rigorous test results are excellent: at 130°C curing temperature, the curing degree and tensile and bending strength of the resin are not further improved, and even the mechanical strength is slightly decreased; the curing reaction process has time-temperature equivalence, When the maximum temperature is 80°C, the curing time can still reach a higher degree of curing and good mechanical properties; selecting the appropriate curing accelerator and the appropriate amount can effectively reduce the activation energy of the curing reaction of the epoxy resin system, so that Fully cured at lower temperatures; excellent overall performance, low cost, and the test performance of high pressure gas cylinders used in the manufacture of composite materials meets the design requirements.
In the resin matrix composites, the resin plays a role of connecting the fibers and transferring stress, so the quality of the resin directly affects the overall performance of the composite. The resin performance itself is affected by many factors, such as raw materials, proportioning, process molding, curing conditions, etc. Among them, curing is an important part of the molding process. The curing of the resin is the cross-linking reaction of the polymer material, ie, the resin changes from a linear molecular structure. Reticulate macromolecular structure. When the same resin system is heat-cured, the molecular structure with different physical and mechanical properties and even a very large difference can be formed due to the difference in curing time and curing temperature. Recently, experts in the industry in China have studied the curing of composite gas cylinders using E-51/DDM epoxy resin systems cured under different curing systems through physical and chemical analysis methods such as infrared spectroscopy, DMA, and mechanical testing. The effect of resin properties laid the foundation for the application of epoxy resin in composite gas cylinders.