Rheological Study of Epoxy Systems Blended with Poly(ether sulfone) of Different Molecular Weights

Miscibility, thermal degradation and rheological analysis of epoxy/MABS blends

The effect of the addition of the methyl methacrylate acrylonitrile butadiene styrene (MABS) copolymer on the miscibility, thermal degradation and rheological properties of epoxy systems is described. Epoxy resin/MABS blends containing 5, 10, 15 and 20 phr MABS were prepared using the solution mixing technique. Homogenous blends obtained using this technique have undergone a polymerization reaction induced phase separation process by the introduction of the curing agent 4,4'-diaminodiphenyl sulfone (DDS). The isothermal rheology at four different temperatures, 150, 160, 170 and 180 °C, was used to examine the effect of MABS on the gelation and vitrification time. The evolution of storage modulus, loss modulus and tan delta was found to be closely related to the evolution of complex phase separation. The increase in the complex viscosity during curing was determined by in situ rheometry and theoretically analysed by fitting with the Williams-Landell-Ferry equation. An exponential increase in complex viscosity was observed, which was induced by cross-linking. The variation of T_g before and after curing was studied using DSC analysis and dynamic kinetic modeling of the curing process was carried out by utilizing dynamic DSC scans. Thermal stability studies of completely cured epoxy/MABS blends using thermogravimetric analysis revealed that all the blends and neat epoxy exhibited single step degradation. Thermal degradation kinetics was calculated using the Coats Redfern equation.

Polyether Sulfone-Based Epoxy Toughening: From Micro- to Nano-Phase Separation via PES End-Chain Modification and Process Engineering

The toughness of a high-performance thermosetting epoxy network can be greatly improved by generating polyether sulfone-based macro- to nano-scale morphologies. Two polyethersulfones (PES) which only differ by their chain-end nature have been successively investigated as potential tougheners of a high-T_g thermoset matrix based on a mixture of trifunctional and difunctional aromatic epoxies and an aromatic diamine. For a given PES content, morphologies and toughness of the resulting matrices have been tuned by changing curing conditions and put into perspective with PES chain-end nature.

Preparation of epoxy/acrylonitrile-butadiene-styrene copolymer/short carbon fiber composites with a self-made conical mixer

Acrylonitrile-butadiene-styrene copolymer (ABS) was introduced to modify the epoxy resin (EP) by the solution mixing method. The results showed that the modulus was decreased with the addition of ABS. Short carbon fibers (SCF) were chosen as the reinforcement agent to prepare high-performance EP/ABS/SCF composites. Meanwhile, a self-made conical mixer was applied to improve the dispersion behavior of the SCF in EP. The properties of both EP/ABS matrix and EP/ABS/SCF composites were investigated and discussed. The results showed that the tensile strength and impact strength of EP/ABS matrix are remarkably improved in the presence of 4,4-diaminodiphenyl methane (DDM), which reached the maximum value at 4 wt% ABS. The introduction of ABS and SCF eventually can maintain the excellent original properties of EP and greatly improve the tensile modulus of EP/ABS/SCF composites with the specialized self-made conical mixer.

Dual effects of mesoscopic fillers on the polyethersulfone modified cyanate ester: enhanced viscoelastic effect and mechanical properties

Enlarging the filler content and decreasing the filler size contribute to enhancing both viscoelastic effect and mechanical property of polyethersulfone modified cyanate system.