Toughening of Epoxy Resin: The Effect of Water Jet Milling on Worn Tire Rubber Particles

Abstract

In this work a cycloaliphatic amine-cured epoxy (EP) resin was modified by micron-scale rubber particles (RP). Nominal RP, in sizes of 200 and 600 µm respectively, were produced using worn truck tires and ultra-high-pressure water jet cutting. The RP were dispersed into the EP resin using different mixing techniques (mechanical, magnetic, and ultrasonic stirring) prior to the introduction of the amine hardener. The dispersion of the RP was studied using optical light microscopy. A longer mixing time reduced the mean size of the particles in the EP compounds. Static (tensile and flexural), dynamic (unnotched Charpy impact), and fracture mechanical (fracture toughness and strain-energy release rate) properties were determined. The incorporation of the RP decreased the stiffness and strength values of the modified EPs. In contrast, the irregular and rough surface of the RP resulted in improved toughness. The fracture toughness and strain-energy release rate were enhanced up to 18% owing to the incorporation of 1% by weight (wt%) RP. This was traced to the effects of crack pinning and crack deflection. Considerably higher improvement (i.e., up to 130%) was found for the unnotched Charpy impact energy. This was attributed to multiple cracking associated with RP-bridging prior to final fracture.

Microwave devulcanization of ground tire rubber and applicability in SBR compounds

“…GTR can be blended with thermoplastic or thermoset polymers with or without compatibilization . However, devulcanization is expected to bring a breakthrough for GTR recycling.…”

Modified Epoxy for Fibre Reinforced Polymer Strengthening of Concrete Structures

“…Cured epoxy is brittle, therefore modifications made to neat epoxy should be able to toughen it by improving its ductility and strength [60], [69]. In relation to bonding materials for FRP, problems such as thermal incompatibility to the concrete substrate, minimum application temperature, as well as curing condition, eventually affect the performance of the repaired structure [63], [70]- [72].…”

Effect of crumb rubber addition on the deformation and fracture behavior of ductile epoxy matrix

“…However, the brittle nature and low resistance to crack growth of epoxies are the main concerns for their use in many applications. As a result, epoxy is usually reinforced with soft or rigid nano-2-8 or micro-fillers [9][10][11][12][13][14][15][16][17] to enhance its toughness. Rubber is one of such fillers that has been used to toughen the epoxide system.…”

“…While reactive liquid rubber is used in the first approach, 9,15-17 preformed rubber particles are preferred in the second strategy. [10][11][12][13][14] The latter is better in the sense that different mechanical/thermomechanical/microwave/ultrasonic/chemical treatments are possible to achieve better compatibility and adhesion between the rubber particles and epoxy resins. 10,12,[18][19] Toughening occurs due to the energy dissipation associated with shear yielding, cavitation/debonding of rubber particles, microcracking, crack deflection, and plastic zone branching ahead of the crack tip.…”

“…Since then, many studies have been performed to improve the mechanical performance of epoxy using crumb rubber particles. [12][13][14][27][28][29] The recycled crumb rubber is primarily used in civil engineering constructions, 24 artificial turf fields, 30 utilitarian composites, 14 and automobiles. 31 It should be noted here that in most of the reported studies, crumb rubber particles are primarily utilized as a softer phase to improve the toughness and other mechanical properties of the relatively harder epoxy phase.…”