Investigation on Model Molecules of the Reactions Induced by Triphenyl Phosphite Addition during Polyester Processing

Abstract

Reactions between model compounds were carried out at high temperatures (150−250 °C) in order to provide a correct simulation of the behavior of hydroxyl and carboxyl polyester chain ends in the presence of triphenyl phosphite (TPP). The reaction between TPP and alcohol (3-phenyl-1-propanol) leads to phenoxy/alkoxy substitutions on the phosphite. The elimination of phenol in open systems is considered as the driving force of this reaction. The occurrence of multisubstitutions between alcohol and phosphite is confirmed. On the other hand, carboxylic acid (4-tert-butylbenzoic acid) reacts with triphosphite to produce ester (or phenyl ester) and phosphonate. The driving force is the creation of a stable phosphoryl bond. NMR experiments lead furthermore to conclusive results concerning the higher velocity of the acid reaction with aliphatic phosphite than of the acid reaction with aromatic phosphite. In the reactions involving alcohol, acid, and phosphite, the conditions favoring ester formation are explained: The presence of TPP is seen to greatly promote the ester production.

Effect of additives on the melt rheology and thermal degradation of poly[(R)‐3‐hydroxybutyric acid]

“…The addition of triarylphosphites to molten polyesters has been shown to stabilize their thermal stability in several studies . The mechanism involves selective reactions between polymer chain ends and the phosphate, thus avoiding transesterification reactions and hydrolytic degradation.…”

Chain Extension and Thermal Behavior of Recycled Poly(Ethylene Terephthalate) Modified by Reactive Extrusion with Triphenyl Phosphite

“…The phosphorus content of purified samples increases with the mixing time which is in accord with Jacques's research results [3], indicating that the phosphorus is chemically bonded to the polymer chain. Chain extension reaction should be proceeded in the way shown in Fig.3 and Fig.4 [3,4]. As seen in Fig.3, the reactions between available hydroxyl group and phosphite could lead to triphosphite substitutions and chain extension.…”

“…S. M. Aharoni et al [2] suggested that the reactions proceeded in two steps and the phosphite acted only as a catalyst and the phosphorus atom was excluded from the polymer chain. While Jacques et al [3,4] concluded that TPP acted as a cross-linker and the phosphorus atom remained within the main chain. The proper reaction mechanism of R-PET in the presence of TPP was investigated in the paper by the phosphorus elemental analysis.…”

Preparation and characterization of high‐molecular‐weight poly(l‐lactic acid) by chain‐extending reaction with phosphites

“…16,17 Like the PET, PLLA has both hydroxyl and carboxyl end groups. We expected that PLLA would have a similar chain-extending mechanism by TPPi as for PET, as shown in Scheme 1.…”