Synthesis and performance of flexible epoxy resin with long alkyl side chains via click reaction

Surfactant-Free Emulsion of Epoxy Resin/Sodium Alginate for Achieving Robust Underwater Superoleophobic Coating via a Combination of Phase Separation and Biomineralization

Underwater superoleophobic coatings exhibit promising prospects in the field of oil contamination resistance. However, their poor durability, stemming from the fragile structures and unstable hydrophilicity, greatly restricted their development. In this report, we proposed a novel strategy of combination water-induced phase separation and biomineralization to prepare the robust underwater superoleophobic epoxy resin-calcium alginate (EP-CA) coating by utilizing a surfactant-free emulsion of epoxy resin/sodium alginate (EP/SA). The EP-CA coating not only exhibited excellent adhesion to various substrates, but also had remarkable resistance to the physical/chemical attacks such as abrasion, acid, alkali and salt. It could also protect the substrate (e.g., PET substrate) from the damage of organic solution and the fouling of crude oil. This report provides a new perspective to fabricate robust superhydrophilic coating with a facile way.

Enhancement of Mechanical Properties and Bonding Properties of Flake-Zinc-Powder-Modified Epoxy Resin Composites

As a typical brittle material, epoxy resin cannot meet its application requirements in specific fields by only considering a single toughening method. In this paper, the effects of carboxyl-terminated polybutylene adipate (CTPBA) and zinc powder on the mechanical properties, adhesion properties, thermodynamic properties and medium resistance of epoxy resin were studied. A silane coupling agent (KH-550) was used to modify zinc powder. It was found that KH-550 could significantly improve the mechanical properties and bonding properties of epoxy resin, and the modification effect of flake zinc powder (f-Zn) was significantly better than that of spherical zinc powder (s-Zn). When the addition amount of f-Zn was 5 phr, the tensile shear strength and peel strength of the composites reached a maximum value of 13.16 MPa and 0.124 kN/m, respectively, which were 15.95% and 55% higher than those without filler. The tensile strength and impact strength reached a maximum value of 43.09 MPa and 7.09 kJ/m², respectively, which were 40.54% and 91.11% higher than those without filler. This study provides scientific support for the preparation of f-Zn-modified epoxy resin.

On Molecular Dynamics and Charge Transport in a Flexible Epoxy Resin Network

An epoxy based on diglycidyl ether of bisphenol A was reacted with a long-chain poly(oxypropylene diamine) hardener in the presence of an accelerator, resulting in a flexible epoxy network. Tensile properties were tested as a function of accelerator concentration. All systems exhibited high levels of extensibility, with strain at failure values in excess of 65%. Molecular dynamics in a formulation containing 10 phr of accelerator were then examined using dielectric spectroscopy over the temperature range of 103-433 K. At low temperatures, a molecular relaxation process (γ relaxation) was observed and shown to conform well to both the Arrhenius equation and activated tunnelling. A stronger relaxation appeared (203-303 K) just before the onset of charge transport, which dominated the behaviour at higher temperatures. The former takes an unusual bimodal form, which we consider a result of overlapping β and α relaxations, consequently termed αβ mode. Analysis of this mechanism revealed a Vogel-Fulcher-Tammann (VFT) behaviour. The temperature-dependent DC conductivity, σ_DC (deduced from the low-frequency charge transport contribution to ε_r″), also revealed VFT behaviour with an onset statistically equivalent to that of the αβ mode, therefore suggesting that charge transport, at this temperature regime, is strongly affiliated with cooperative molecular motion.