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

Abstract

The development of a facile and efficient approach to prepare high-toughness epoxy resin is vital but has remained an enormous challenge. Herein, we have developed a high-performance environment-friendly solid epoxy resin modified with epoxidized hydroxylterminated polybutadiene (EHTPB) via one-step melt blending. The characterization, mechanical performance, curing behavior, and thermal properties of EHTPB-modified epoxy resin were investigated. EHTPB-modified epoxy resin exhibited excellent toughness with a 100% increase in elongation at break of tensile than that of neat epoxy resin. The transfer stress and dissipated energy in the rubber phase were predominant mechanisms of toughening. The toughening effect of EHTPB on solid epoxy resin was better than that of some of the previously reported liquid epoxy resins. Meanwhile, at 10 wt % of EHTPB loading, the EHTPB-modified epoxy resin displayed high strength and 22 and 101% improvement of flexural strength and impact strength, respectively. Moreover, at 10 wt % of EHTPB loading, the activation energy of EHTPB-modified epoxy resin for curing reaction decreased from 73.89 to 65.12 kJÁmol −1 , which is beneficial for the curing reaction. Furthermore, EHTPB-modified epoxy resin had a good thermal stability and the initial degradation temperature increased from 249 to 313 C at 10 wt % of EHTPB loading. This work provides a simple-preparation and highly efficient and large-scale approach for the production of high-toughness environment-friendly solid epoxy resins.

Toughened epoxy‐liquid polybutadiene networks cured with anhydride with outstanding thermal and mechanical properties

“…Figure 3 illustrates the tan delta at low temperature. Pure epoxy network presented a large relaxation peak at −66°C, which is related to the β‐transition of the localized motion of glyceryl groups in the epoxy chain 35–36 . According to our previous work, the Tg of the pure HTPB appears around −22°C, whose region is similar to that corresponding to the β‐relaxation of ER matrix 17,23 .…”

“…Pure epoxy network presented a large relaxation peak at −66 C, which is related to the β-transition of the localized motion of glyceryl groups in the epoxy chain. [35][36] According to our previous work, the Tg of the pure HTPB appears around −22 C, whose region is similar to that corresponding to the β-relaxation of ER matrix. 17,23 The samples loaded with 5, 10, and 20 phr of PBNCO displayed wide tan delta peaks with maximum at around −59 C, −63 C, and − 58 C, respectively.…”

Amine/epoxy stoichiometric ratio dependence of crosslinked structure and ductility inamine‐curedepoxy thermosetting resins

“…By adjusting the curing conditions and the stoichiometric ratio, the reaction process, T g , Young's modulus, strength, and toughness (or strain energy) could be varied. In recent years, many attempts have been made to improve brittleness 12,13,14,15,16 . However, the effect of changes in the stoichiometric ratio on the crosslinked structure and mechanical properties, and the contributions of these factors to the ductility have not been fully elucidated.…”

Synthesis and application of thermal latent initiators of epoxy resins: A review

“…It is extensively used in coatings, adhesives, molding compounds, packaging for electronic devices, automobile materials, and fiber-reinforced composites. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Uncured epoxy resin initially has poor mechanical properties as well as poor chemical and thermal resistance. When epoxy resin reacts with a suitable curing agent, a three-dimensional cross-linked network structure is obtained.…”