Accession Number : ADA305783

Title :   Toughening Mechanism in Elastomer-Modified Epoxy Resins. Part 1.

Descriptive Note : Contractor rept. 23 Jun 80-31 Dec 81,

Corporate Author : GENERAL ELECTRIC CORPORATE RESEARCH AND DEVELOPMENT SCHENECTADY NY

Personal Author(s) : Yee, A. F. ; Pearson, R. A.

PDF Url : ADA305783

Report Date : AUG 1983

Pagination or Media Count : 132

Abstract : Several plaques of Epon 828, cured with piperidine, modified with Hycar(R), CTBN 1300x8, Hycar(R) CTBN 1300X13, and HyCar(R) CTBN 1300X15, and in some cases modified with bisphenol 'A' (BPA), yielded properly toughened epoxies with rubber particle diameters ranging from 0.1 to 10 micrometers. Fracture toughness experiments indicate that toughness was more a function of rubber content than the rubber particle size. Tensile volumetric behavior of the neat resin exhibits two regions: an initial region where the increase in volume strain was due to the Poisson's effect, and a second region where a slower rate of increase in volume strain was due to shear deformation. Tensile volumetric deformation of an elastomer-modified epoxy exhibits the same type of behavior to that of the neat resin at low rates (<3.2 x 10(exp -2/sec). But at very high strain rates, which correspond more closely to the strain rates at the crack tip, there exists an increase in volume strain beyond the Poisson's effect. TEM, SEM and OM studies indicate that the rubber particles had voided. When a thin section from the deformed region is viewed under crossed-polarized light, shear bands are seen connecting voided rubber particles. From this information cavitation and enhanced shear band formation is proposed as the toughening mechanism. jg p131

Descriptors :   *ELASTOMERS, *TOUGHNESS, *EPOXY RESINS, BANDS(STRIPS), SHEAR PROPERTIES, PARTICLE SIZE, POLARIZATION, HIGH RATE, POLYMERS, DEFORMATION, CRACKS, TENSILE PROPERTIES, RUBBER, FRACTURE(MECHANICS), STRAIN RATE, PARTICLES, THINNESS, EPOXY COMPOUNDS, VOLUMETRIC ANALYSIS, LOW RATE, POISSON EQUATION, BUTADIENES, CAVITATION, PIPERIDINES.

Subject Categories : Plastics
      Organic Chemistry
      Polymer Chemistry
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE