1,4‐Bis(2,3‐dicarboxyl‐phenoxy)benzene dianhydride‐based phenylethynyl terminated thermoset oligoimides for resin transfer molding applications

Abstract

A series of thermoset oligoimides have been prepared by the thermal polycondensation of 1,4-bis(2,3-dicarboxyl-phenoxy)benzene dianhydride with three different aromatic diamines in the presence of 4-phenylethynylphthalic anhydride as an end capping reagent. The aromatic diamines included 4,4 0 -oxydianiline, 2,2 0 -bis(trifluoromethyl)benzidine (TFDB) and 2-phenyl-4,4 0 -diaminodiphenyl ether (p-ODA). Effects of the chemical structures and molecular weights of the oligoimides on their aggregated structures, melt processability as well as the thermal and mechanical properties of the cured films were then systematically investigated. X-ray diffraction results indicated that ODA series oligoimides and TFDB series oligoimides showed crystallinity; however, the asymmetrical p-ODA enables the p-ODA series oligoimides to exhibit amorphous forms. So the p-ODA based oligoimides with molecular weight of 750 g mol −1 showed much lower melt viscosity at a low temperature and the melt viscosity could maintain below 1 Pa s −1 after isothermal aging for 2 h at any temperature in the range of 220-280 C by rheological measurements.

Liquid Crystalline Polyimide Films with High Intrinsic Thermal Conductivities and Robust Toughness

“…4-Phenylethynyl phthalic anhydride (PEPA) is a kind of terminating agent for PI, and the terminal phenylethynyl group can cure PI by a chemical cross-linking reaction at high temperatures, 49 retaining the degree of order of PI molecular chains. 50 However, how to prepare LC-PI with a liquid crystal range containing the curing temperature and to achieve controlled curing within the liquid crystal range have become the key issues.…”

Effect of Nanoporous Molecular Sieves TS-1 on Electrical Properties of Crosslinked Polyethylene Nanocomposites

“…Crosslinking additives thermally decompose at high temperatures to form free radicals, which react with the monomer molecular chain to form macromolecular chain radicals in the presence of the LDPE monomer to initiate the polymerization reaction. In the absence of a monomer, it will further decompose into primary radicals (where j represents various primary radicals) [ 27 , 28 , 29 ]. At the same time, the primary radicals will react with the surrounding polymer long chain, so that it loses free electrons to form long chain radicals due to the high activity of the primary radicals further reacting with other polymer long chains; the formation of the reaction chain continues to increase, polyethylene molecular chains crosslink with each other to ultimately form a three-dimensional mesh structure, and the high activity of free radicals is finally consumed in chain reaction termination [ 30 , 31 , 32 , 33 ].…”

Phenylethynyl-terminated Imide Oligomers Modified by Reactive Diluent for Resin Transfer Molding Application

“…Asymmetric diamine, 2-phenyl-4,4'-diaminophenyl ether (p-ODA), was also suitable for synthesizing PETIs with greater processablity. [19,32] Fang et al [33] reported RTMable PETIs featured low melting viscosities at low temperatures. The melting viscosities of the PETIs maintain below 1 Pa•s for 2 h in isothermal rheological tests in the temperature range of 220−280 °C.…”