Simultaneously Enhanced Cryogenic Mechanical Behaviors of Cyanate Ester/Epoxy Resins by Poly(ethylene oxide)-co-poly(propylene oxide)-co-poly(ethylene oxide) (PEO-PPO-PEO) Block Copolymer and Clay

Cryogenic mechanical properties are important parameters for thermosetting resins used in cryogenic engineering areas. The hybrid nanocomposites were prepared by modification of a cyanate ester/epoxy/poly(ethylene oxide)-block-poly(propylene oxide)block-poly(ethylene oxide) (PEO-PPO-PEO) system with clay. It is demonstrated that the cryogenic tensile strength, Young's modulus, ductility (failure strain), and fracture resistance (impact strength) are simultaneously enhanced by the addition of PEO-PPO-PEO and clay. The results show that the tensile strength and Young's modulus at 77 K of the hybrid nanocomposite containing 5 wt% PEO-PPO-PEO and 3 wt% clay were enhanced by 31.0% and 14.6%, respectively. The ductility and impact resistance at both room temperature and 77K are all improved for the hybrid composites. The fracture surfaces of the neat BCE/EP and its nanocomposites were examined using scanning electron microscopy (SEM). Finally, the dependence of the coefficients of thermal expansion (CTE) on the clay and PEO-PPO-PEO contents was examined by thermal dilatometer. (C) 2015 Society of Plastics Engineers