Designing of epoxy resin systems for cryogenic use

Short-channeled mesoporous Zr–Al-SBA-15 as a highly efficient catalyst for hydroxyalkylation of phenol with formaldehyde to bisphenol F

“…Based on the results discussed above, a plausible parallel-consecutive reaction mechanism for the synthesis of bisphenol F is presented in Scheme 2. At first, the formaldehyde is activated by a proton from the catalyst to form the hydroxymethyl carbocation (2). Then, the hydroxymethyl carbocation reacts with the carbon atom of phenol to form the hydroxyl oxygen cation (3) which is not stable; next, a proton transfers from carbocation (3) to catalyst and a 2-hydroxybenzyl alcohol (4-hydroxybenzyl alcohol) (4) is formed with regeneration of the catalyst.…”

“…Bisphenol F is an important monomer, which is widely used for producing epoxy resins and polycarbonates. Bisphenol F epoxy resin has lower viscosity and better resistance against solvents than bisphenol A epoxy resin [1,2], hence the production of bisphenol F has increased over the years [3], and the demand of bisphenol F is still expected to have steady growth in the future. Bisphenol F can be synthesized by hydroxyalkylation of phenol with formaldehyde in the presence of acidic catalyst as shown in Scheme 1.…”

Improving the fracture toughness properties of epoxy using graphene nanoplatelets at low filler content

“…29,30 Despite the numerous advantages of epoxy such as excellent mechanical properties and thermal stability, epoxies are fundamentally brittle due to their high cross-link density. [31][32][33][34] Low fracture toughness is one of the key drawbacks preventing the increased use of epoxies for a wider range of applications, and consequently toughening of epoxy resins has been at the forefront of many research studies since the early 1980s. 2,35,36 A common approach to increasing the toughness is the addition of a second-phase filler to the matrix at the micro-or nanoscale, resulting in composite materials which exhibit high specific strength and stiffness, and high fracture toughness.…”

Synthesis and Curing of Liquid‐Crystalline Epoxy Resins Containing a Biphenyl Mesogen

“…[13] The cured sample of dioxide monomer with mesogenic group has higher fracture toughness and elastic modulus than that of diglycidyl ether of bisphenol A (DGEBA) both at room temperature and under liquid nitrogen conditions. The internal stress which leads to fracture at cryogenic temperatures, mainly caused by the thermal contraction, may be decreased by incorporation of mesogenic groups.…”