N,N‐dimethylaminopyridine as initiator in the copolymerization of diglycidylether of bisphenol A with six‐membered cyclic carbonates

Abstract

N,N-Dimethylaminopyridine (DMAP) was used as initiator to cure mixtures of diglycidylether of bisphenol A (DGEBA) and 1,3-dioxan-2-one (TMC) or 5,5dimethyl-1,3-dioxan-2-one (DMTMC). The curing was studied by differential scanning calorimetry (DSC) and Fourier transform infrared in the attenuated-total-reflection mode (FTIR/ATR). FTIR/ATR was used to monitor the competitive reactive processes and to quantify the evolution of the groups involved in the curing. We observed the formation of five-membered cyclic carbonates and anionic carbonate groups that remain unreacted at the chain ends. The formation of these groups was explained by the attack of the anionic propagation species on the methylene carbon of the carbonate group, which leads to an alkyl-oxygen rupture. By performing the cure in the thermobalance we could evaluate the loss of CO 2 produced in the samples containing carbonates. The kinetics were studied by DSC and analyzed with isoconversional procedures. The addition of carbonates slows down the curing rate. Thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA) experiments were used to evaluate the properties of the materials obtained.

Crosslinking of mixtures of DGEBA with 1,6‐dioxaspiro[4,4]nonan‐2,7‐dione initiated by tertiary amines. I. Study of the reaction and kinetic analysis

“…But since curing reaches completion at lower temperatures as the s(gBL) content increases, it would seem that the addition of s(gBL) has an accelerative effect on the curing of DGEBA under anionic catalysis with a small amount of initiator. A similar behavior was reported in the anionic copolymerization of DGEBA with cyclic carbonates, 20,21 and resembles the observed effect in the cationic copolymerization of DGEBA with s(gBL). 5 Formulation 142, with an excess of s(gBL), has been studied to ascertain the observed apparent accelerating effect.…”

Modification of epoxy–anhydride thermosets using a hyperbranched poly(ester‐amide): I. Kinetic study

“…Chen and co‐workers, reported the use of a newly synthesized epoxy monomer with cleavable tertiary ester groups, which could be used in epoxy formulations. We have reported the modification of epoxy formulations with a variety of lactones or cyclic carbonates, which resulted in the incorporation of ester or carbonate groups into the network structure, thus enhancing the thermal degradability of the resulting materials.…”

Modification of epoxy–anhydride thermosets with a hyperbranched poly(ester amide). II. Thermal, dynamic mechanical, and dielectric properties and thermal reworkability

“…However, the use of cycloaliphatic monomers restricts their application and curing versatility. Some of us have reported the modification of epoxy formulations with a variety of lactones4–6 or cyclic carbonates;7 this results in the incorporation of ester or carbonate groups into the network structure and, thus, enhances the thermal degradability of the resulting materials. The main drawback in this case is the reduction of the glass transition temperature of the fully cured material ( T g ∞ ) via the decrease in the crosslinking density and the flexibility of the units introduced into the network structure.…”