Jp. Mercier

Bio: Jp. Mercier is an academic researcher from Université catholique de Louvain. The author has contributed to research in topics: Crystallization & Polycarbonate. The author has an hindex of 16, co-authored 29 publications receiving 1344 citations.

Bisphenol‐A polycarbonate–poly(butylene terephthalate) transesterification. I. Theoretical study of the structure and of the degree of randomness in four‐component copolycondensates

Abstract: This article is the first of a series devoted to various aspects of exchange reactions in molten bisphenol-A polycarbonate–poly(butylene terephthalate) mixtures. The statistical aspects of exchange reactions between two polycondensates of different chemical structure are considered. This theoretical approach enables us to calculate the mean lengths of the various sequences as well as several expressions for the degree of randomness in four-component copolycondensates from triad or dyad concentrations as determined by NMR spectroscopy.

Bisphenol‐A polycarbonate–poly(butylene terephthalate) transesterification. II. Structure analysis of the reaction products by IR and 1H and 13C NMR

Abstract: The structure of the four-component copolyester resulting from the exchange reaction between molten bisphenol-A polycarbonate and poly(butylene terephthalate) is analyzed as a function of the reaction time by infrared and nuclear magnetic resonance spectroscopy. By applying a statistical method developed earlier, the mean chain length of the various sequences as well as the degree of randomness is computed. The exchange reaction leads initially to the formation of a block copolyester with reduced solubility. As the reaction proceeds, a soluble random copolycondensate is progressively formed.

The Trans-esterification of Bisphenol-a Polycarbonate (pc) and Polybutylene Terephthalate (pbtp) - a New Route To Block Copolycondensates

Abstract: In this work, the exchange reaction taking place in molten blends of bisphenol-A polycarbonate and polybutylene terephthalate was studied. A direct transesterification mechanism catalyzed by titanium residues, present in commercial PBTP, was deduced. The transesterification reaction can be -stopped at various levels by additives capable of complexing the titanium catalyst. This work enhances the possibility of a new approach in macromolecular engineering by directly combining polycondensates in a processing machine such as an extruder.

Polymer Crystallization By Chemical Nucleation

Abstract: Several attempts1–5 have been made to control the rate of crystallization and the morphology by the addition of very finely-divided substances which promote abundant nucleation. However, these studies have mostly been carried out on an empirical basis and, except in a few cases (self-seeding6, epitaxy2–5), the mechanism of action of these nucleating agents is poorly understood despite several attempts at modelling1,2. This is particularly so in the case of most technical nucleating agents such as mica, talc and organic salts. We report here that the mechanism of action of organic nucleating agents such as sodium benzoate and its derived salts completely differs from the generally accepted model, at least in the case of polyesters. The nucleating agent reacts as a true chemical reagent with the molten macromolecules and produces ionic end groups which constitute the true nucleating species.

Structural and mechanical properties of biopolymer gels

Abstract: The structural and mechanical properties of gels formed from biopolymers are discussed both in terms of the techniques used to characterise these systems, and in terms of the systems themselves The techniques included are spectroscopic, chiroptical and scattering methods, optical and electron microscopy, thermodynamic and kinetic methods and rheological characterisation The systems considered are presented in order of increasing complexity of secondary, tertiary and quaternary structure, starting with gels which arise from essentially ‘disordered’ biopolymers via formation of ‘quasicrystalline’ junction zones (eg gelatin, carrageenans, agarose, alginates etc), and extending to networks derived from globular and rod-like species (fibrin, globular proteins, caseins, myosin) by a variety of crosslinking mechanisms Throughout the text, efforts are made to pursue the link (both from experiment and from theory) between the structural methods and mechanical measurements As far as we are aware this is the first major Review of this area since that of J D Ferry in 1948 — The interest shown by polymer physicists in more complex biochemical systems, and the multi-disciplinary approaches now being applied in this area, make the format adopted here, in our opinion, the most logical and appropriate