Toughened Epoxy Resins

Gilbert, A.H. Bucknall, C.B. Epoxy resins toughened with thermoplastic. In Makromol. Chem. Macromol. Symp, Vol. 45, 289-298. 

Figure 1.34. Change in the phase boundary (UCST) during the cure reaction for a system of a rubber (e.g. CTBN) dissolved in an epoxy resin. Toughening requires that phase separation be achieved during the cure cycle. After Pascualt et al. (2002).

Figure 6. Comparison of experimental and predicted values of Youngs modulus of epoxy resin toughened with rubber particles. Finite-element predicted values were calculated using two values of the Poisson ratio of the rubber phase and the predicted bounds using the Ishai and Cohen model (26).

Thermal Shock Behavior and Evaluation of Epoxy Resins Toughened with Hard Particulates... 

This chapter discusses the behavior, under thermal shock conditions, of epoxy resins toughened with ceramic particulates. Alumina Al203 and silica Si02, which are usually used as filler for insulation materials, and the new ceramic materials silicon carbide SiC and silicon nitride Si3N4 are employed. For these toughened epoxy resins, the thermal shock resistance is evaluated by using fracture mechanics. The difference between experimental and calculated values of the thermal shock resistance is discussed from a fractographic point of view. 

Synthesis and Analysis of Saturated, Reactive /I-Butyl Acrylate Polymers for Use in Epoxy Resin Toughening... 

The study considered here employed materials obtained from McDonnell Aircraft Co., through Dexter Hysol, under the Air Force program Development of Ultra Lightweight Materials . They contained the Courtaulds Research Apollo 45-850, consisting of 5 pm diameter carbon fibers in Dexter Hysol s HC 9106-3 di-, tri- and tetrafunctional epoxy resin, toughened by addition of the thermoplastic polyether sulfone (PES). The thermoplastic PEIS toughening agent, present in this epoxy matrix, is presumed to phase separate out once it has cured. These panels were fabricated in an autoclave by Dexter Hysol. 

Wu Wu, H., Xu, J., Liu, Y., Heiden, P. Investigation of readily processable thermoplastic-toughened thermosets. V. Epoxy resin toughened with hyperbranched polyester. J. Appl. Polym. Sci. 72 (1999) 151-163. 

Jin Jin, F.-L., Park, S.-J. Improvement in fracture behaviors of epoxy resins toughened with sulfo-nated poly(ether sulfone). Polym. Degrad. Stab. 92 (2007) 509-514. 

Pig. 2. Electron Micrograph of an OsO -Stained Microsection of Epoxy Resin Toughened with E-30... 

Another approach for toughening UP and VE resins which has had success with epoxy resins is the use of liquid rubber (or elastomer) additives. The chief benefit of emplojdng liquid rubbers (LR) versus a flexibilized resin is that decreases in hardness, stiffness and heat-deflection properties can be minimized. During cure, the liquid rubber phase separates from the resin and is concentrated in a particulate phase. Very little of the rubber remains in solution with the cured resin so the resin s heat deflection temperature is for the most part unaffected. The toughness of the two-phase, or composite, material will be a function of the microstructure, which in turn will depend on processing and cure conditions. The subject of epoxy resin toughening is covered in separate articles in this book. 

Mechanical testing was performed on epoxy resin toughened by incorporation of up to 17 vol% of PEI.1 The dynamic mechanical tests were carried out in DMTA at 10 Hz, in a single cantilever bending mode at r = -80 to 300°C. The flexural properties at 23°C were carried... 

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