Joseph A. Sissano

Blends of amorphous-crystalline block copolymers with amorphous homopolymers. Morphological studies by electron microscopy and small angle scattering

A morphological study was performed with symmetric diblock ethylene-propylene copolymer (DEP) and the binary blends made from DEP and atactic polypropylene (APP) by use of small angle X-ray, light and neutron scattering, and also scanning and transmission electron microscopy. DEP contains a crystallizable polyethylene block and an amorphous atactic polypropylene block. Quenching the blends in liquid nitrogen preserved the morphology in the melt state. This quenching technique revealed that DEP forms a lamellar microdomain structure and blending DEP and APP includes morphological changes in the microdomain structures as well as macrophase separation. When the APP chain was shorter than the APP block, the addition of APP changed the morphology from a lamellar to a bicontinuous cylindrical and then a discrete cylindrical and finally to a spherical structure. On the other hand, when the APP chain was longer than the APP block, macrophase separation was observed and only a transition from a lamella to a bicontinuous cylinder occurred. These morphological transitions in the melt state can be correlated to differences in the crystallization kinetics of the blends.

Synthesis and properties of copolymers of ethylene/carbon monoxide with styrene/carbon monoxide

The terpolymerization of ethylene, styrene, and carbon monoxide was accomplished by two different palladium-based catalysts: a phosphine-based ligand system and a nitrogen-based ligand system. The range of possible compositions and the composition dependence of the properties of the resulting polymers were determined. These polymers were essentially carbon monoxide versions of the ethylene styrene interpolymers recently presented by Dow. A comparison between the two families of polymers is attempted.

Dynamic viscoelastic properties of poly(ethylene-propylene) diblock copolymer in the melt state and solutions

Abstract Dynamic mechanical properties of a symmetrical poly(ethylene-propylene) diblock copolymer with a molecular weight of 99 × 10 3 were investigated in the melt state, as well as in solutions in 1,2,4-trichlorobenzene. In the melt state, the frequency dependence of the elastic and loss moduli ( G ′ and G ″, respectively) exhibited a limiting behaviour of G ′ ≈ G ″ ≈ ω 0.5 in the terminal zone, a marker of inhomogeneity. Even solutions of 15 vol% polymer showed such inhomogeneity. These rheological data indicate that the diblock polymer is microphase separated and the phases are strongly segregated. The limiting behaviour in the terminal zone suggests that a lamellar structure is present in the melt.

Crystallization Kinetics and Microdomain Structures for Blends of Amorphous-Crystalline Block Copolymers with Amorphous Homopolymers

Blends of a symmetrical diblock poly(ethylene-b-propylene) (DEP) and an atactic polypropylene (APP) were studied by calorimetry, small angle neutron scattering, and electron microscopy. Addition of APP to DEP drastically changed the crystallization kinetics of the polyethylene block. The results were interpreted on the basis of the morphological studies of the microdomain structure in both the crystalline state and the melt state of the blends.

Thermodynamics of Random Copolymer Mixtures by Sans

A test of the theory of random copolymer miscibility is described in this paper. A series of random ethylene-butene copolymers were made by the saturation of polybutadienes of varying vinyl content, and the interactions in blends of these copolymers were measured by small angle neutron scattering (SANS). It was found that the standard random copolymer theory does not describe the data in that the interaction parameters were not proportional to the square of the difference in the compositions of the component copolymers. Rather, blends of ethylene rich copolymers had lower χ values than corresponding butene rich blends.