Effect of resin modifiers on the structural properties of epoxy resins

Abstract

Thermomechanical, mechanical and fracture mechanical properties of modified epoxy resins with two different modifiers are investigated. Carboxyl‐terminated butadiene‐acrylonitrile (CTBN) is used as toughening agent and hexanediole diglycidyl ether (HDDGE) as reactive diluent. Both modifiers are admixed in contents from 0 up to 100 phr (parts per hundred resin) and exhibit flexibilizing and toughening qualities. The glass transition temperature is strongly depressed by the admixed reactive diluent, whereas the tensile modulus exhibits greater dependency on the toughening agent contents. The tensile strength and strain at break values are higher for the formulations with diluent compared to resins with toughening agent. Up to a content of 45 phr both modified systems exhibit comparable fracture toughness values. Only the toughened systems comprise increasing values for modifier amounts higher than 45 phr. For the formulation with both modifiers (toughening agent and diluent) a significantly higher toughness but a reduced glass transition temperature was obtained. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45348.

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

“…The elongations at break of tensile and flexural of EHTPB‐modified epoxy resin (10 wt %) were both greater than those of the neat epoxy with approximately greater than 100% elongation, indicating that EHTPB provided ductility and enhanced toughness to the epoxy resin. As shown in Figure (c), the tensile strength and tensile modulus of blends gradually reduced with an increase in the EHTPB content, which is consistent with the prior literature . A marginal decrease in tensile strength was observed at no more than 10 wt % EHTPB.…”

“…In particular, the reactive liquid rubbers have been extensively used for enhancing the fracture toughness of epoxy resins, such as the carboxyl‐terminated butadiene acrylonitrile copolymer, amine‐terminated copolymer of butadiene and acrylonitrile, and hydroxyl terminated polybutadiene (HTPB) . Also, there are several studies on the toughening mechanism of liquid rubber toughened epoxy resins.…”

The role of interface on dynamic mechanical properties, dielectric performance, conductivity, and thermal stability of electrospun carbon nanofibers reinforced epoxy

“…A broad hump is observed especially at higher loadings for PCNF-E, which is possibly due to the heterogeneity of the system because of nonuniformly distributed and agglomerated CNFs. [49] Figure 4(C) supports this claim showing that the dispersion of CNFs in epoxy is not uniform for higher loadings and it is believed that samples have varying degree of heterogeneities for the 5 and 10 wt% PCNF-E. Interestingly, a shoulder peak at around 100 C was observed between 2 and 10 wt% PCNF-E loading after the peak deconvolution of tan δ peaks. This shoulder peak cannot be correlated to side chain β-relaxation because epoxies will usually show a low temperature β-relaxation (~À120 C) and a higher temperature glass transition (α-relaxation).…”

Laser confocal microscopical characterization of toughened epoxy resins: Correlations between structural features and mechanical properties

“…The glass transition temperature ( T g ), the tensile modulus (E t ) and the critical energy release rate (G IC ) values measured at ambient temperature are summarized in Table for formulations with different amount of toughening agent. Detailed results along with the relevant curves are described and discussed in Kregl et al . Admixing of toughening agent lowered the resin's glass transition temperature T g from 185 °C for the neat resin to 171 °C for the formulation with 100 phr modifier.…”