Resin Matrix Composite is widely used in the top aerospace and shipping industry, as well as in the automotive, construction, sports products and other fields because of its specific strength, high specific modulus, low coefficient of expansion, corrosion resistance, electrical insulation, etc., especially the rapid development of pressure cylinders, and ever-increasing composite cylinders use. By the chemical analysis tools of infrared spectroscopy, DMA, mechanical testing on the casting body with composite cylinder using E-51 / DDM epoxy resin systems under different curing system, the influence on the resin system lays fixed foundation on the application of epoxy resin in composite cylinder.

1. Introduction

        In the resin matrix composite, resin serves to connect fiber, transmit stress, the resin performance has a direct impact on the overall properties of the composites. Resin performance itself is affected by many factors, such as raw materials, matching, crafts molding, curing conditions, wherein the curing is an important part on the molding process. Resin curing is a crosslinking reaction of polymer materials, that is the linear molecular structure of the resin turns into the reticular macromolecular structure. The same resin system upon heat curing, due to the curing time, curing temperature differences, can be formed into different,even greatly different molecular structure of physical and mechanical properties. Short time or low temperature, the resin can not be completely cured, on the contrary, overlong time or overtemperature causes unnecessary energy waste, and even damages its performance. Generally, the elongation of resin slightly higher than fibers is the best selection criterion. Actually, at the expense of the other conditions to obtain far higher than the operating requirements is kind of performance wasted. Therefore, looking for the best curing temperature system is extremely necessary according to the application requirements.

2. the experimental process

        1. Raw materials

        Mixed epoxy resin: homemade; aromatic amine curing agent: chemically pure and made by Shanghai SSS Reagent Co., Ltd; accelerating agent: made by Shanghai SSS Reagent Co., Ltd.

        2. DSC Thermal analysis on the resin system 

        Compound liquid cement according to matching epoxy resin: curing agent: accelerating agent = 110: 35: 0.5, measure the exothermic situation in resin curing at different heating rates (instrument: PE-7 series differential scanning calorimetry made in Germany). According to DSC analytic curve, the reaction exothermic peak started at about 80℃ and by regression analysis at l℃/ min heating rate, the heat peak temperature is 128℃. Based on the experiment, take 80℃ and 130℃ as the highest point curing temperature, develop two curing temperature curve, and manufacture castings, study resin performance under different curing system and compare these two curing system.

        3. Castings test 

        (1) Castings manufacture

        Pour the well-prepared and vacuum degassing liquid cement into previously coated with release agent and preheated steel mold cavity, remove the liquid cement bubbles, respectively, according to two different temperature curves heating cure. After cooling and mold released, polish them and get castings FH80 and FHl30, and test the performance.

        (2) Casting Performance Test

        Curing test: According to GB / T2576-1989, use solvent extraction.

        Molecular structure analysis: Infrared spectroscopy measurement.

        Mechanical properties test: Tensile test according to GB / T2568-1995, bending test according to GB / T2570-1995.

        Glass transition temperature: Use dynamic modulus analysis. temperature rise rate of 5℃/ min; dynamic testing on stress 8.0×104Pa; static test on stress 1.0×105Pa; test frequency 1.0Hz.

        4. test equipment

        PE-7 Series thermal analyzer: made in German. Infrared spectroscopy: PEKIN-ELMER2000FT-IR type made in Germany. INSTRON4505 type universal material testing machine made by Instron Corp, British.