Manfred Fedtke

Curing of glycidyl ethers with aromatic amines: model studies on the effects of tertiary amines as accelerators

Abstract The effect of N , N -dimethylbenzylamine on the reaction of glycidyl ethers with primary aromatic amines has been investigated using diglycidyl ether of bisphenol A and 4,4′-diaminodiphenylmethane. With the help of model reactions of phenyl glycidyl ether and aniline, etherification and homopolymerization were found to interfere with the epoxy-amine reaction. Products arising from etherification were identified.

Epoxy resin curing by dicyandiamide using model compounds

SummaryThe reaction behaviour of different accelerated homogeneous epoxy-dicyandiamide systems was studied using phenyl glycidyl ether as a model and as solvent N,N-dimethylformamide. N,N-dimethylbenzylamine, imidazole, 2-methylimidazole were applied as accelerator. The reaction course was followed by HPLC and 13C-NMR measurements. A reaction mechanism involving a tautomerisation of dicyandiamide depending on temperature is suggested.

Curing of epoxy resins by dicyandiamide

SummaryThe reaction course, the final structure and the thermal behaviour of dicyandiamide cured epoxy resins were studied by HPLC, Carbon-13 NMR (liquid and solid state), IR, gel time determination, DSC and evolved gas analysis. N, N-dimethyl-benzylamine, imidazole and Monuron were applied as three different accelerator types. Dimethylformamide was used as solvent to obtain homogeneous reaction mixtures. Two reaction pathways depending on tautomeric dicyandiamide structures are suggested explaining the reaction mechanism.

Reaction of glycidyl ethers with aliphatic alcohols in the presence of benzyl dimethylamine

Abstract In the reaction of phenyl glycidyl ether with aliphatic alcohols in the presence of benzyl dimethylamine, four different oligomers are found at temperatures above 100°C. In the temperature range of 100–180°C, the length of oligomer chains decreases with increasing temperature. In bifunctional epoxide-alcohol systems the number of branched products increases simultaneously. These small branched oligomers are terminated by non-reactive end groups, preventing network formation above 140°C. At lower temperatures (

Oligomerization of phenyl glycidyl ether in the presence of ZnCl2

SummaryIn the presence of ZnCl2 phenyl glycidyl ether reacts to different products owing to the ring-opening reaction of the oxirane and the cleavage of the ether bond. Using HPLC and offline mass spectrometry most of the reaction products could be identified.A reaction scheme and the supposed reaction mechanism were described involving the formation of chlorine — containing oligomers and low molecular weight by — products resulting from the cleavage of the ether bond of the monomer. Conclusions were drawn for original polyfunctional epoxy resin systems.

New aspects in acceleration of glycidyl ether oligomerization by imidazole compounds

SummaryUsing simple model compounds the oligomerization of glycidyl ethers accelerated by imidazole and imidazole derivatives was investigated. The formation of oligomers depending on 1,3-diphenoxy-2-hydroxypropane as their starting compound was predominant.In the case of imidazole 1,2-dihydroxy-3-phenoxypropane and the resulting oligomers are further formed. It seems to be obvious that this reaction also occurs in the absence of water.An over-all reaction mechanism including both the main products of the glycidyl ether oligomerization formed and the different imidazole compounds investigated is proposed.

Effects of reactive diluents in curing of epoxies as revealed by model reactions

SummaryThe tertiary amine induced oligomerization of diglycidyl ether of bisphenol A (DGEBA) containing epoxide-based diluents as well as the model reaction with phenyl glycidyl ether (PGE) itself were investigated. The oligomer products obtained were separated by HPLC. The structure of these oligomers was elucidated by spectroscopic methods. Reactive diluents such as phenyl glycidyl ether and cyclohexyl glycidyl ether (CHGE) influence the cure time and the network formation of the final crosslinked product.

Oligomerization of N-ethylglycidyl aniline induced by tertiary amines

SummaryThe homopolymerization of N-ethylglycidyl aniline in the presence of N,Ndimethylbenzyl amine was determined by HPLC and titrimetric methods. A product spectrum of oligomer distribution was observed. It was clearly demonstrated that the formation of this oligomer distribution was only possible in the presence of moisture. Furthermore, the formation of N-ethyl-N-propane-2,3-diol aniline was identified.