Study of poly‐ϵ‐caprolactone bulk degradation

The thermal stability of poly‐ϵ‐caprolactone samples obtained by ring‐opening polymerization in the presence of different metal alkoxides has been investigated. A significant degradation of the polyesters is observed under isothermal conditions at 120°C. The degradation is related to the nature of the endgroup, the presence of catalyst residues, and the presence of molecular oxygen. The hydroxyl endgroups play a determinant role in the process. They probably give rise, under the influence of catalyst residues, to hydroperoxides which are responsible for the polymer degradation by a radical reaction. It is shown that this is clearly different from the change in molecular weights distribution due to the well‐known ester interchange reaction (transesterification equilibrium). Resulting methods for the polymers stabilization are indicated. Copyright © 1976 John Wiley & Sons, Inc

Soluble bimetallic μ-oxo-alkoxides. 8. Structure and kinetic behavior of the catalytic species in unsubstituted lactone ring-opening polymerization

The bimetallic µ-oxo-alkoxides are highly active for lactone ring-opening polymerization. These compounds are aggregated in solution and their mean degree of association depends on the nature of alkoxide groups, metals, and solvent; it is modified by addition of suitable ligands or temperature variations. The course of the lactone polymerization is strongly related to the structural features of the catalyst. The determination of the mean number of growing chains per catalyst molecule, the study of the polymerization kinetics, and the knowledge of the catalyst behavior during the monomer conversion have contributed to an understanding of the polymerization mechanism

Molecular design of multicomponent polymer systems. X. Emulsifying effect of poly(styrene‐b‐methyl methacrylate) in poly(vinylidene fluoride)/noryl blends

The emulsifying activity of block copolymers is investigated in blends of incompatible engineering polymers such as polyvinyldene fluoride (PVF2) and Noryl (high impact polystyrene‐poly‐2,6‐dimethyl‐1,4‐phenylene oxide mixture). When the blends are modified by a poly(styrene‐b‐methyl methacrylate) copolymer, (PS‐PMMA) each block of which being selectively miscible with Noryl and PVF2 respectively, Phase dispersion, interfacial adhesion and ultimate mechanical properties are significantly improved; major effect is observed upon addition of 12 percent copolymer, resulting in intermingled and firmly adherent phases and a rough additivity of both tensile strength and elongation at break. All these features clearly demonstrate the important emulsifying effect of PS‐PMMA in these very attractive PVF2/Noryl blends. Copyright © 1986 John Wiley & Sons, Inc

Molecular design of multicomponent polymer systems, XI, emulsifying effect of poly(hydrogenated diene‐b‐methyl methacrylate) in poly(vinylidene fluoride)/polyolefins blends

[No abstract available

MOLECULAR DESIGN OF MULTICOMPONENT POLYMER SYSTEMS: EMULSIFYING EFFECT OF POLY( alpha -METHYLSTYRENE-B-METHYL METHACRYLATE) IN POLY(VINYLIDENE FLUORIDE)/POLY( alpha -METHYLSTYRENE) BLENDS.

peer reviewedA preliminary evaluation of the morphology and mechanical behaviour of poly(vinylidene fluoride)/poly( alpha -methylstyrene) blends provides clear evidence for the important emulsifying effect of a poly( alpha -methylstyrene-b-methyl methacrylate) copolymer. Moderate amounts (2 wt%) of the copolymer greatly improve phase dispersion and interfacial adhesion and also very significantly increase Young's modulus and ultimate tensile strength of the blends; even a synergy in the strength is observed

Anionic block copolymerization of methyl methacrylate in the presence of alkali and alkali–earth metal salts

[No abstract available

Bimetallic μ-oxoalkoxides. X. A new class of polynuclear complexes

Cryoscopic data, as well as electronic, NMR and mass spectra are presented for a variety of bimetallic μ-oxoalkoxides: they indicate that, like simple metal alkoxides, these compounds are associated in organic solution. The importance of these intermolecular associations is related to the nature of the metals, but also to the structure of the alkoxy groups. © 1976