Vernetzung durch Diels-Alder-Polyaddition

Abstract

The known types of the Diels-Alder polyaddition reaction which lead to linear polymers are discussed. A correlation is established between these reactions and the crosslinking of unsaturated polyesters and of polybutadiene by the addition of oligomer biscyclopentadienyl compounds. A number of biscyclopentadienyl oligomers with a latent diene reactivity is described.
During heat cure of oligo-bis-dienes these compounds also serve as dienophiles. For the polymeric structure of the macromolecular network a structure analogous to polycyclopentadiene, but crosslinked with bivalent radicals R is assumed. Since this type of heat cure proceeds without the aid of polar groups, molding and heat cure lead to tough and flexible synthetic resins, which excel by low dielectric losses and by a low dielectric constant.
Low polarity bis-dienes with perchlorinated aromatic bridge radicals at elevated temperatures are much more stable than chlorine-free bis-dienes against oxidation and are self-extinguishing. Laminates reinforced with glass fibres, which contain these resins as bonding material are well suited as base plates for printed circuits.