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Graphene oxide (GO) modified epoxy resin (GH81) was prepared by mechanical grinding, and the dispersion of GO in the epoxy resin (H81) was analyzed by optical microscope, while the melting performances and curing behaviors of H81 and GH81 were researched through rheometer and differential scanning calorimeter respectively. The results show that GO is uniformly dispersed into the matrix resin，and the addition of GO hardly affects the melt viscosity and curing condition of the matrix resin at all. In addition, the 0° tensile strength, bending strength and compression strength of GH81 based carbon fiber reinforced composite (GH81-300) are 2270 MPa, 2239 MPa and 1529 MPa respectively, which is increased by 6.4%, 7.2% and 7.1% respectively, as compared with that of composite without GO.

A novel bio-based epoxy resin system with rosin-sourced acid anhydrides was established by formula design and selection according to the resin film’s forming performance and state with different storage time. The formula involves epoxy resin/curing agent/accelerator with mass proportion of 100/60/3-4. The curing property and the relationship between viscosity-temperature-time of resin were characterized by dynamic or steady state DSC analysis and cone plate viscometer, respectively. The results show the resin system can be cured at the range of 120-140℃, and the range of hot melt prepreg temperature is 60-85℃ with the viscosity from 1500mPa·s to 5000mPa·s. The processing time of hot melt prepreg is about 180min at 70℃. The curing mechanism of bio-based resin was also investigated through the samples with different curing time by IF and DSC.

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In this study, a novel bio-based thermosetting system has been developed from epoxy resin (EP), with rosin-sourced anhydrides (maleopimaric acid, RAM) as curing agent and imidazole type latent catalyst (two amino imidazole salt complex, IMA), to be used as matrix for hot-melt prepreg curing at mid-temperature. For comparison, the epoxy resin system with petroleum sourced hardener methylhexahydrophthalicanhydride (MHHPA) was also examined. The curing behaviour and mechanism were investigated by non-isothermal differential scanning calorimeter (DSC) analysis and Fourier transform infrared (FTIR) spectra. The results showed that the curing course of bio-based epoxy resin system containing RAM included two stages, which were the reaction between the free carboxyl group of RAM and oxirane ring under the acceleration of IMA, and the main reaction attributed to the reaction between anhydride and oxirane. According to Kissinger method, the reaction activation energy ( E ) of two stages were 68.9 and 86.5 kJ mol, respectively. The E of EP/MHHPA and EP/IMA resin system were 81.04 and 77.9 kJ mol. The processing property of EP/RAM/IMA system, i.e. the relationship between viscosity-temperature-time, was characterized by cone-plate viscometer aim to decide the processing parameter of prepreg preparation. The effect of RAM content on mechanical performance and dynamic mechanical property was investigated. Noteworthily, compared with the laminates with EP/MHHPA as matrix, the laminates with RAM as hardeners achieved a 44%, 73% and 70°C increase in bending strength, bending modulus and the glass transition temperature, respectively, due to the bulky hydrogenated phenanthrene ring structure incorporated into the cross-linking networks. When the fiber volume fraction reached 47%, the mechanical property of the laminates prepared with hot melt prepreg was superior or comparable to that of composites with pure petroleum sourced matrix. RAM as cross-linking agent of epoxy resin holds a great potential to satisfy the requirement of composites such as structure and secondary structure parts preparation. [ABSTRACT FROM AUTHOR]