Thermoset Blends of an Epoxy Resin and Polydicyclopentadiene

Abstract

The mechanical properties of two chemically distinct and complementary thermoset polymers were manipulated through development of thermoset blends. The thermoset blend system was composed of an anhydride-cured diglycidyl ether of bisphenol A (DGEBA)-based epoxy resin, contributing high tensile strength and modulus, and polydicyclopentadiene (PDCPD), which has a higher toughness and impact strength as compared to other thermoset polymers. Ultra-small-angle and small-angle X-ray scattering analysis explored the morphology of concurrently cured thermoset blends, revealing a macroscopically phase separated system with a surface fractal structure across blended systems of varying composition. The epoxy resin rich and PDCPD rich phases exhibited distinct glass transitions (T g 's): the T g observed at higher temperature was associated with the epoxy resin rich phase and was largely unaffected by the presence of PDCPD, whereas the PDCPD rich phase T g systematically decreased with increasing epoxy resin content due to inhibition of dicyclopentadiene ring-opening metathesis polymerization. The mechanical properties of these phase-separated blends were in reasonable agreement with predictions by the rule of mixtures for the blend tensile strength, modulus, and fracture toughness. Scanning electron microscopy analysis of the tensile and fracture specimen fracture surfaces showed an increase in energy dissipation mechanisms, such as crazing, shear banding, and surface roughness, as the fraction of the more ductile component, PDPCD, increased. These results present a facile method to tune the mechanical properties of a toughened thermoset network, in which the high modulus and tensile strength of the epoxy resin can be largely retained at high epoxy resin content in the blend, while increasing the fracture toughness.

High‐toughness, environment‐friendly solid epoxy resins: Preparation, mechanical performance, curing behavior, and thermal properties

“…As shown in the Figure (c), the rubber phase was distributed in the epoxy matrix and formed plastic cavitation. The plastic cavity is formed by rubber phase under the triaxial stress, and the rubber particles can transfer stress and dissipate energy as stress concentrators . For blend 10 wt % EHTPB, the plastic deformation of the fractured surface was a rough surface of terraces.…”

“…The glass transition temperature T g of epoxy is determined by the crosslinking density of the epoxy resins after curing . The T g of epoxy resin blended with different contents of EHTPB is shown in Figure (b).…”

“…The formation of a two‐phase system is the primary toughening mechanism during the co‐curing process of epoxy resins with liquid rubber. When the liquid rubber particles spread evenly among the epoxy resin, they can effectively absorb stress and play a role in dispersing energy to relieve stress concentration through rubber holes and shear deformation . Moreover, the other toughening mechanisms such as plastic void growth rubber particle bridging, crack deflection, crack bifurcation, and crack pinning are also widely accepted …”

Effect of Doping Microcapsules on Typical Electrical Performances of Self-Healing Polyethylene Insulating Composite

“…The thermal conditions and capillary action can cause the DCPD core material to flow into the defect site. The liquid DPCD contacts with the catalyst and reacts in the damaged area to form the PDCPD solid, whose thermal deformation temperature is 120 • C [40]. Moreover, the density and dielectric constant of PDCPD are similar to those of polyethylene.…”

Bond behavior of epoxy resin–polydicyclopentadiene phase separated interpenetrating networks for adhering carbon fiber reinforced polymer to steel

“…Through the construction of either true IPNs (in which the components are molecularly mixed) or phase separated IPNs, the blended network system can possess a unique combination of the neat component mechanical properties, either following the rule of mixtures or, at particular compositions, expressing a synergistic effect that is greater than the rule of mixtures [31,32]. The phase separated IPNs used in this study are comprised of diglycidyl ether of bisphenol A (DGEBA)-based epoxy resin and polydicyclopentadiene (PDCPD), which form micrometer-scale phase separated structures, and whose curing kinetics [33], morphology, tensile, and Mode I fracture properties [34] were studied previously, see Fig. 1 for illustration of the formation of this IPN system.…”