| Waterborne epoxy resin with excellent and environmental properties has attracted more and more widely attention with the strengthening to environmental protection. But some intrinsic defects of epoxy resin such as great brittleness, low temperature resistance in the curing state, limit its practical applications, so it has always been the research focus in this filed to undertake a modification to epoxy resin. Graphene oxide with excellent physical and chemical properties, as important part of carbon materials, is considered to be a great potential of reinforced materials. Meanwhile, the dispersion of graphene oxide in aqueous solution is better. In order to improve the mechanical properties of waterborne epoxy resin matrix material, graphene oxide was used in modify waterborne epoxy resin which regards water as solvent in this paper.In this paper, graphene oxide/waterborne epoxy resin emulsion was prepared by phase inversion method,then studied curing kinetics of graphene oxide/waterborne epoxy resin system and determined the optimum adding amount of graphene oxide by testing thermodynamic properties of the composite. Based on this the present study, with the example of waterborne epoxy resin system of 0.48wt% graphene oxide, explored the process temperature, heating rate and material thickness on the influence of the curing process through the macro dynamics simulation, then optimized the process and put forward new curing process conditions, and finally, verified the new process conditions by experiment.The research results of isothermal curing kinetics show that the SB autocatalytic model gives a better description of the curing process of blend system. The study results of thermal mechanical and thermogravimetric properties indicate thermal decomposition temperature and glass transition temperature increased first and then decreased with loading of graphene oxide increased. For the system of graphene oxide content was 0.36wt%, the temperature of the material loss 3% and loss 5% reached to 389.50? and 406.81?, respectively, compared with the pure waterborne epoxy resin system, which increased 31.00? and 25.08?respectively. While graphene oxide content was 0.48wt% of waterborne epoxy resin system,the glass transition temperature reached maximum value of 143.77?, which improved about 9? in compare with neat water epoxy resin.Macro kinetics study results indicated that the higher processing temperature and the faster heating rate and the greater thickness of material can make a more obvious thermal effect inner the material. There was a significant thermal stress occurring on the material surface at thermal shock and post-curing heat-up stage. A new curing process(358.15K/0.25h+341.15K/lh+413.15K/3h) of three stages contained a cooling stage, which adjusted continuous heating of two stages of traditional (353.15K/2h+413.15K/3h),was established by optimizing. Simulation results show that in the new optimized procedure, the thermal shock temperature was 20K lower, the time of thermal shock was 1000s earlier, and the total curing time was shorter about 0.5h than those for the conventional procedure. Based on this the present study,graphene oxide/waterborne epoxy resin composites were prepared by the new and conventional curing procedure, and tested the mechanical of materials.Mechanical experimental results demonstrated that the bending strength and elastic modulus of the specimen prepared by new curing procedure respectively reached 100.4MPa and 2749.6MPa, which increased by 14.9% and 7.3% when compared to the bending strength(87.4MPa) and elastic modulus (2562.2MPa) of the specimen prepared by the conventional curing procedure and the elastic modulus was 7.3% higher. Meanwhile, the bending strength(100.4MPa) of graphene oxide/ waterborne epoxy resin composite prepared by new curing procedure increased by 7.6% compared to solvent based epoxy resin composite (93.3MPa),which further verified the superiority of the new curing procedure. |
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