Toughened-hybrid epoxies: influence of the rubber-phase morphology on mechanical properties

C. I. VALLO; P. M. FRONTINI; LIJIANG HU; R. J. J. WILLIAMS

JOURNAL OF MATERIALS SCIENCE

SPRINGER

Lugar: Berlin ; Año: 1994 p. 2481 - 2486

0022-2461

A toughened-epoxy polymer based on diglycidylether of bisphenol A (DGEBA) cured withethylenediamine (EDA) and modified with a rubber based on an epoxy-terminatedacrylonitrile-butadiene random copolymer (ETBN), exhibited different morphologiesdepending on the rubber content. Up to 10% rubber, the morphology consisted of a randomdispersion of spherical domains rich in rubber, while at 1 5% rubber, large and irregulardomains were present, turning into a co-continuous structure at 20% rubber. Mechanicalproperties (elastic modulus, uniaxial compression yield stress, critical stress intensity factor,K~c and strain energy release rate, G~c ) of the toughened epoxies and hybrid-particulatematerials containing glass beads, were analysed. The best mechanical properties wereexhibited by hybrids with a random dispersion of rubbery domains in the epoxy matrix. Thepresence of large and irregular domains or co-continuous structures led to materials with poormechanical properties.