Piero Manaresi

Thermal degradation of poly(butylene terephthalate)

Abstract The thermal degradation of poly(butylene terephthalate) between 240° and 280°C has been studied by measurements of intrinsic viscosity, carboxyl end groups and weight loss. A first-order mechanism of fission, followed by elimination of butadiene, is proposed. The values of the kinetic constant and activation energy are in good agreement with those obtained for simple esters and poly(ethylene terephthalate).

Kinetics of graft polymerization of styrene on cis-1,4-polybutadiene

Abstract By measurements of polymerization rate, grafting efficiency and number-average molecular weight of free and grafted polystyrene, the α-dicumyl peroxide initiated polymerization of styrene on cis -1,4-polybutadiene at 100°C and at low extents of reaction was studied. The polymerization rate and the polystyrene molecular weights decreased with the rubber content of the solution. The grafting efficiency was found to be substantially independent of the peroxide concentration, but to increase with rubber content. A rigorous mathematical model of the reaction was developed, from which it has been possible to confirm the proposed mechanism and to establish the value of many kinetic constants.

Refractive index of poly(thiocarbonate)s and poly(dithiocarbonate)s

Abstract The refractive indices and densities of recently synthesized poly(thiocarbonate)s and poly(dithiocarbonate)s were measured, and were used to determine the group contributions of thiocarbonate (OCOS) and dithiocarbonate (SCOS) groups to the molar refraction. The high refractive indices observed make these polymers, particularly the poly(dithiocarbonate)s, potentially interesting for optical applications (i.e. lenses and optical fibres).

Models for the formation of poly(butylene terephthalate): Kinetics of the titanium tetrabutylate-catalysed reactions: 2

Abstract In order to investigate the mechanism of catalysis of titanium tetrabutoxide on the polycondensation of poly(butylene terephthalate), this reaction has been studied with the aid of model molecules. The catalytic and retarding effects of benzoic acid have also been taken into account. Appropriate kinetic equations are derived and discussed and the results compared with experimental data obtained at different temperatures and molar ratios of reactants.

Polyethylene like polymers. Aliphatic polyesters of dodecanedioic acid 1. Synthesis and properties

A series of aliphatic polyesters has been synthesized starting from 1,12-dodecanedioic acid and aliphatic diols, bearing from 2 to 12 carbon atoms. These polymers, which were fully characterized in terms of chemical structure, molecular weight and thermal behaviour, were obtained as crystalline materials with melting points ranging from 70 to 90 °C and with a relatively high molecular weight. All the monomers used can be obtained from biomasses, as a consequence these materials can be an interesting alternative to synthetic polymers produced from petrochemical processes based on nonrenewable resources.

Solid state polycondensation of poly(butylene terephthalate)

Abstract Solid state polycondensation of poly(butylene terephthalate) has been studied under vacuum at 200°C for various particle sizes. The effect of the process on intrinsic viscosity and number of end groups has been examined. The results suggest that the increasing of the number average molecular weight can be explained by a mechanism involving hydroxyl groups, which approach each other by diffusion until a limiting value of their concentration is attained.

Effect of sodium sulfonate groups on the ionic conductivity of a copolyester of thiodipropionic acid

Abstract New copolyesters of thiodipropionic acid and triethylene glycol containing various amounts of -SO3Na groups were developed. Both these copolymers and their electrolytes, the latter obtained by dissolving NaClo4 in the polymeric matrix, were characterized in terms of ionic conductivity in the 25–80 °C temperature range to evaluate the effect on conductivity of ionic groups covalently attached to the polymer backbone. A small number of -SO3Na groups were found to improve the electrical properties of the copolymers, even though the conductivity values were not high enough to allow their use in electrochemical devices without further dissolution of sodium salt. On the other hand, a large content of sulfonate groups increases significantly the viscosity of the copolymeric matrix and reduces the electrical performances of the electrolytes.

Rheological characterization of highly branched poly(ethyleneterephthalate)

Linear and highly branched poly(ethyleneterephthalate) samples were synthesized and characterized in terms of intrinsic viscosity, molecular weight and melt viscosity over a wide range of shear rates at several temperatures, in the range from 265° to 295 °C. Linear samples exhibited Newtonian behavior over a wide range of shear rates, while the branched ones became shear thinning at relatively low shear rates. Our experimental data, as well as data previously reported, were found to be described by a proposed correlation between the melt viscosity ratio and a branching index. Moreover, the activation energy for melt flow was found for the highly branched samples to be a little higher than that of the linear samples.

A general intrinsic viscosity-molecular weight relationship for linear polydisperse polymers—3. Applicability to the evaluation of the mark-houwink-sakurada k and a constants

Abstract An empirical equation relating the intrinsic viscosity of a polymer and its number-, weight- and z-average molecular weights has been used to evaluate the K and a constants of the Mark-Houwink-Sakurada relationship, in cases where data either from monodisperse samples or from samples with known molecular weight distribution are not available. It is shown that accurate K and a values are obtained, provided the ratio of z- to weight-average molecular weights is not too high.

Models for the formation of poly(butylene terephthalate): effect of water on the kinetics of the titanium tetrabutylate-catalysed reactions: 3

Abstract In an effort to investigate the mechanism of catalysis of titanium tetrabutoxide on the polycondensation of poly(butylene terephthalate), alcoholysis and hydrolysis reactions were studied with the aid of model molecules. The retarding effect of water has also been taken into account. Appropriate kinetic equations are derived and discussed and the results compared with experimental data obtained at different molar ratios of reactants.