About the Mechanism of Stress-Strain State of Epoxy Resin by Carbon Nanotubes

Abstract

Epoxy resin (ER) and composite materials based on it play an important role in engineering and technologies. The wide use of epoxy resins derived from their strength and unique combination of performance characteristics. The article considers 2 aspects influencing the strength of ER: rates of strain and modification of ER by the carbon nanoparticles (CNT). The experiments were conducted on the ER of brand and Etal Inject-T hardener. The strain of samples was carried out at speeds of 1 mm/min, 2 mm/min, 5 mm/min and 20 mm/min. The experiments showed that the stress-strain curve consists of three successive zones—elastic, plastic and elastic-plastic strain at small strain rates of 1-5 mm/min. With increasing of strain rate the zone of plastic strain is gradually transformed in elastic-plastic, the average modulus of elasticity increases. At the strain rate above the critical value (about 20 mm/min.) the zones of plastic and elastic-plastic strain disappear, only the zone of elastic strain remains, while the sample is destroyed by the formation of cracks and chips. The initial and functionalized CNTs of Taunit-M brand were used in the experiments. It is found that the initial CNT, introduced in ER do not affect the course of the stressstrain curve, and functionalized CNT with a mass content of 0.05% give different effect on the strain zones: the effect is not felt in the zone of elastic strains, give hardening up to 25% in the plastic zones and elastic-plastic strain. With the increase in input of functionalized CNTs up to 0.2%, the hardening effect of ER was reduced almost in 2 times in the zones of plastic and elasticplastic strain.