M. T. Garay

Unsaturated polyester resins cure : Kinetic, rheologic, and mechanical-dynamical analysis. I. Cure kinetics by DSC and TSR

The curing reaction of a polyester resin, using methyl ethyl ketone peroxide and cobalt octoate as promoter, has been studied by differential scanning calorimetry and thermal scanning rheometry under isothermal conditions. All kinetic parameters of the curing reaction, including the reaction order, activation energy, and the rate constant, were calculated and reported using different empirical relationships. The gel time, which is defined by several criteria, was used to determine the apparent activation energy of the process.

Unsaturated polyester resins cure: Kinetic, rheologic, and mechanical dynamical analysis. II. The glass transition in the mechanical dynamical spectrum of polyester networks

Unsaturated polyester networks with various structures built from an orthophtalic polyester, with methyl ethyl ketone peroxide as an initiator and cobalt octoate as a promoter, were studied with dynamic mechanical thermal analysis from -50 to 200 °C to characterize changes in the mechanical properties as a function of the temperature. From these measurements, the glass-transition temperatures of the different networks were determined, their dependence on conversion being fitted to an equation related to the Couchman and DiBenedetto equations. Finally, the different transitions were analyzed as a function of the cure conditions.

Investigation of conformational transition in poly(cyclohexyl methacrylate)

Abstract The variations of intrinsic viscosity and refractive index increment with temperature for poly(cyclohexyl methacrylate) in isobutyl methyl ketone have been studied. A conformational transition has been found in the range 10–30°C. The influence of the molar volume of the side-group on the conformational transition temperature has also been discussed with respect to results for related polymers.

Effect of temperature on the thermodynamic properties and unperturbed dimensions of poly(phenyl methacrylate) in methyl isobutylketone

Abstract The variation of the intrinsic viscosity of several fractions of poly(phenyl methacrylate) with temperature in methyl isobutyl ketone exhibits considerable anomalies. They have been explained in terms of a conformational transition of great magnitue due to the formation of specific interactions between phenyl groups.

Study of Polymer–Polymer Complexes of Poly(N‐Isopropylacrylamide) with Hydroxyl‐Containing Polymers

Abstract Interpolymer complexation between poly(N‐isopropylacrylamide) (PNIPAAM) and the hydroxyl‐containing polymers poly(p‐vinylphenol) (PVPh) and poly(2‐hydroxypropyl methacrylate) (PHPMA) has been studied. A common solvent for PNIPAAM and PHPMA has been selected from phase behavior studies of these polymers in aqueous–methanolic solutions. Precipitates of PNIPAAM/PVPh in methanol at room temperature and PNIPAAM/PHPMA in a mixture methanol/water (56/44) at −11°C have been isolated. The compositions of the resulting complexes have been determined. Calorimetric measurements indicate that all PNIPAAM/PVPh complexes present a similar T g, which does not depend on feed composition, and is higher than that of the component polymers, whereas PNIPAAM/PHPMA complexes present an intermediate composition‐dependent T g. Thermal stability of all complexes has also been studied.

Short-range order in blends of polycarbonates with polystyrenes

Abstract The local structure of a series of blends of bisphenol-A polycarbonate (BPA-PC) and tetramethyl BPA-PC (TMPC) with various styrene-based polymers (poly(para-chlorostyrene), polystyrene, poly(meta-chlorostyrene) and poly(ortho-chlorostyrene)) has been investigated. Measurements on the D7 diffractometer at ILL were carried out at room temperature. We show that while the amorphous halo of TMPC is only slightly perturbed by blending, major differences are observed in all BPA-PC blends. We conclude that inter-chain correlations in BPA-PC blends are considerably altered compared to the pure component.

Thermal Degradation of Copolymers of N‐Vinylcarbazole with Acrylic and Methacrylic Monomers

The thermal stability of several series of N‐vinylcarbazole and a methacrylic or acrylic monomer has been studied. The copolymers are more stable the higher the content of N‐vinylcarbazole, a few units of this monomer being capable of appreciably enhancing the thermal stability of the acrylic or methacrylic homopolymer. The degradation products have been analyzed by FTIR, and a degradation mechanism similar to that for the homopolymers has been proposed. The kinetic analysis based on a differential theoretical model, has allowed an estimate of the activation energy of the degradation process.