The influence of tertiary aromatic amines on the BPO initiated cure of unsaturated epoxy polyesters with styrene studied by non-isothermal DSC

Abstract

The influence of tertiary aromatic amines on the course of BPO initiated cure reaction of unsaturated epoxy polyesters with different styrene content has been studied by non-isothermal differential scanning calorimetry. Unsaturated epoxy polyesters prepared from cyclohex-4-ene-1,2-dicarboxylic anhydride, maleic anhydride and suitable aliphatic glycol: ethylene glycol or 1,4-butanediol or 1,6-hexanediol were dissolved in vinyl monomer (styrene) resulting in a styrene content of 20-80% by weight. The styrene solutions of polyesters were subjected to the cure reaction with suitable curing agent: benzoyl peroxide (BPO) used in various concentration (0.5-3.0 wt%) or the mixture of BPO/stoichiometric ratio of chosen tertiary aromatic amines: (N,N-dimethylbenzylamine (BDMA) or 2,4,6-tri(dimethylaminomethyl) phenol (DMP-30). The curing characteristic such as: temperature of the cure initiation (T onset ), peak maximum temperature (T max ), final cure temperature (T end ), heat generated during the cure reaction (DH) were evaluated. It has been found that the course of the cure reaction depended on the styrene content in prepared compositions and the initiating system used. The performed investigations confirmed that one of the applied tertiary aromatic amine: BDMA was an effective promoter for BPO decomposition process, causing a decrease in characteristic curing temperatures of unsaturated epoxy polyesters with styrene. The organic peroxide-amine interactions caused the promotion of BPO decomposition to benzoyloxy radicals at lower temperatures and thus accelerated the copolymerization process. However, DMP-30 was a very sluggish promoter for BPO decomposition, probably due to the presence of both hydroxyl group, their ortho-position to two of three amine groups and their branched structure. The redox reaction between BPO and DMP-30 probably resulted in non-radical products or radical formation which was incapable of initiating the polymerization reaction.

Thermal, viscoelastic, and mechanical properties of DCPD-containing polymers

“…During the reaction, water was removed continuously from the system by azotropic distillation (xylene). After that, xylene was distilled under reduced pressure and the obtained product was chemically modified in order to prepare novel DCPD-modified unsaturated epoxypolyesters according to a previously reported procedure [15][16][17]. The theoretical structure of novel DCPDmodified unsaturated epoxypolyesters is presented in Scheme 1.…”

Diphenylsilane‐Manganese Acetylacetonate Redox Initiating Systems: Toward Amine‐Free and Peroxide‐Free Systems

“…[ 1–7 ] Being highly relevant under mild conditions, the two‐component (2K) mixing of reducing and oxidizing agents in redox initiated polymerization has been broadly investigated in the materials science. [ 8–12 ] However, the currently used efficient redox initiating systems (RISs) are commonly comprised of amine‐dibenzoylperoxide (BPO) systems [ 13–21 ] which now represent serious potential issues: toxicity of the amines, risk associated with peroxides handling and storage, pressing regulations on peroxides, etc. [ 22,23 ] Advancement of more secure RIS to meet the prerequisites of room temperature polymerization has in this manner been the quest for researchers.…”

Effect of Post-Cure on the Static and Viscoelastic Properties of a Polyester Resin

“…Moreover, organic peroxides (initiators) can also initiate the reaction by adding metallic salts or amines (initiator + promoter system) at room temperature (RT). Unlike other thermosetting resins, no byproducts are formed during the curing reaction, and these resins can be molded, cast, and laminated at low pressures and temperatures [ 13 , 14 , 15 , 16 ]. However, many of the processing problems arise precisely in this curing process, which are generally ignored in the production planning phase.…”