The application of highly soluble amine-terminated aromatic polyimides with pendent tert-butyl groups as a tougher for epoxy resin

Chitosan toughened epoxy resin by chemical cross-linking: Enabling excellent mechanical properties and corrosion resistance

There is a growing demand for the development of epoxy resin modified with biomaterials, aiming to achieve high toughness. Herein, chitosan crosslinked epoxy resin (CE) was synthesized by diisocyanate as a bridge. With 4,4'-diamino-diphenylmethane (DDM) as the curing agent, thanks to the unique cross-linking structure of the CE resin and the presence of carbamate groups, the cured CE/DDM exhibited superior properties compared to commercially available epoxy resin (E51). The tensile strength of the cured CE-3/DDM reached 90.17 MPa, the elongation at break was 11.2 %, and the critical stress intensity factor (KIC) measured 1.78 MPa m1/2. These values were 21.4 %, 151.6 %, and 81.6 % higher than those of the cured E51/DDM, respectively. It is worth noting that the addition of biomass material chitosan did not reduce the thermal stability of the resin. Additionally, the CE coatings on the metal substrate exhibited exceptional corrosion resistance, as evidenced by higher impedance values in electrochemical impedance spectroscopy (EIS) and polarization voltages in the Tafel curve compared to those of the E51 coating. This study opens up a novel approach to modifying epoxy resin with biomass materials with high toughness and corrosion resistance, without sacrificing other performance.

Cure kinetics and properties of high-performance epoxy thermosets cured with active ester-terminated poly (aryl ether ketone)

Benzene-1,3,5-triyl tribenzoate (TBB), both 3,5-bis(benzoyloxy)benzoate-terminated poly (aryl ether ketone) oligomers (BPAPK and TMPK), containing active ester (Ph−O−(C=O)− structure), were prepared and served as curing agents for dicyclopentadiene novoalc epoxy (DCPD). The curing kinetics and properties of three epoxy thermosets were systematically investigated. The model reaction of TBB and glycidyl phenyl ether was designed to understand the curing mechanism of oxirane ring with active ester. TMPK/DCPD displays the lowest reaction activation energy, which is the result of the combined influence of free volume and diffusion. In addition, TMPK/DCPD has the highest Tg value (218°C), which enhances 34.6% and 42.5% compared with BPAPK/DCPD and TBB/DCPD, respectively. Meanwhile, TMPK/DCPD also shows superior dielectric and water resistance properties due to no secondary alcohol generated after curing and hydrophobic tetramethyl-substituted biphenyl structure. Herein, TMPK/DCPD as high-performance epoxy thermosets has potential applications in electronic packaging fields.