Edze Jan Tijsma

Synthesis, Structure, and Properties of Polymers Based on Pivalolactone

Abstract Since the introduction of poly(ethy1ene terephthalate) (PET) and polyamide 6, many attempts have been made to synthesize other polymers with a large variety of properties. One of the polymers which has been studied extensively is polypivalolactone (PPVL), formed by ring-opening polymerization of pivalolactone (PVL). PPVL is a highly crystalline aliphatic polyester (≥75% crystallinity) with mechanical properties comparable with those of PET and polyamide 6. Although the technology and expertise to prepare PPVL on a commercial scale was already available in the early 1970s, most of the projects concerning PPVL, especially in fiber applications, were discontinued on the basis of economic considerations.

Mechanical properties and chemical stability of pivalolactone-based poly(ether ester)s

The processing, mechanical and chemical properties of poly(ether ester)s, prepared from pivalolactone (PVL), 1,4-butanediol (4G) and dimethyl terephthalate (DMT), were studied. The poly(ether ester)s could easily be processed by injection moulding, owing to their favourable rheological and thermal properties. The tensile response of a poly(ether ester) with a butylene terephthalate (4GT) content of 72 mol%, which exhibited the phenomena of necking and strain-hardening, was related to the morphology of these copolymers. The influence of the short 4G-PVL segments was reflected in a high Youngs modulus and yield stress, and resulted in a tough behaviour for the poly(ether ester), with an ultimate elongation of 500%. The poly(ether ester)s were stable towards treatment at room temperature with water or weakly acidic or alkaline solutions. Conditioning at 90°C in water for 264 h resulted in a water uptake of 1 wt%, whereas the rate of hydrolysis was 0.0003 (expressed in An rel h-1) for the poly(ether ester) with a 4GT content of 72 mol%. Although a decay in the mechanical properties for the PVL-based poly(ether ester) after exposure to water at 90°C was observed, these materials were assumed to have a higher hydrolytical stability than other poly(ether ester)s