Abstract
In order to clarify the degradation mechanism of PET tire cord in rubber, hydrolysis reaction in a saturated steam atmosphere, ammonolysis reaction in ammonia gas and the deterioration of the cords embedded in rubber have been studied at high temperature conditions. In this report, the following results were obtained.
(1) The carboxyl end groups play a role as a catalyst in the hydrolysis reaction of PET in high temperature steam. The reaction is not diffusion-controlled but hydrolysis reaction itself.
(2) The rate of degradation is constant during the course of ammonolysis reaction, but depends on the initial content of carboxyl end groups which have remained unchanged during the reaction. The ammonolysis reaction consists of two step reactions, i.e. production of a water molecule by the neutralization reaction of free carboxyl group with ammonia, and formation of carboxyl end group from the hydrolytic scission reaction of the ester linkage, at the presence of the newly formed water molecule and the ammonia of the base catalyst.
(3) A significant decrease of the strength observed for PET tire cords embedded in rubber during the vulcanization of the rubber is mainly due to the hydrolytic decomposition reaction catalysed by ammine compounds of the additives in the rubber.
