Bingzheng Jiang

Toughening of poly(butylene terephthalate) with epoxidized ethylene propylene diene rubber

In this paper, unepoxidized ethylene propylene diene rubber (uEPDM) was first epoxidized with formic acid and H2O2, and then the epoxidized ethylene propylene diene rubber (eEPDM) was melt-mixed with PET resin in a Brabender-like apparatus. Toughening of PET matrix was achieved by this method. The dispersion of rubber particles and phase structure of the blends were also observed by SEM. It has been suggested that the epoxy groups in the eEPDM could react with PET end groups to form a graft copolymer which could act as an interfacial compatibilizer between the PBT matrix and eEPDM rubber dispersed phase. This is beneficial to the improvement of the impact performance of PBT

The ring-banded spherulite structure of poly (ε-caprolactone) in its miscible mixtures with poly (styrene-co-acrylonitrile)

The structure of the PCL spherulite in poly(epsilon-caprolactone)/poly(styrene-co-acrylonitrile) (PCL/SAN) blends was investigated by optical microscopy and small angle light scattering. The spherulite structure with a Maltese cross has been observed in pure PCL. Similar PCL/SAN blends exhibited not only spherulites with a Maltese cross, but also distinct extinction rings. The H(v) light scattering pattern especially caused diffraction rings in PCL/SAN blends but not in pure PCL. The spherical symmetry of spherulite PCL becomes more incomplete and the twist of the lamella becomes more irregular with increasing SAN content. It is found that the spherulite structure of PCL/SAN blends is dependent on the crystallization temperature and the concentration of SAN in PCL/SAN blends.

Phase behaviour and phase separation in polymer blends of poly(methyl methacrylate) with poly(vinyl acetate)

SummaryPhase behaviour and phase separation in a binary polymer blends of poly(methyl methacryate) (PMMA) with poly(vinyl acetate) (PVAc) was invistigated by cloud method and light scattering. A lower critical solution temperature (LCST) type phase diagram was found. The mixture system of PMMA/PVAc is miscible. Kinetic study on demixing at the two-phase region above the LCST was carried out by light scattering.

Statistical thermodynamics of polydisperse polymer mixtures

Abstract A statistical thermodynamics theory of polydisperse polymer blends based on a lattice model description of a fluid is formulated. Characterization of a binary polydisperse polymer mixture requires a knowledge of the pure polymer system and the interaction energy. It is assumed that the intrinsic and interactive properties of polymer (for example, T∗ , P∗ , ϱ∗, and e∗ ij ) are independent of molecular size. Thermodynamic properties of ternary and higher order mixtures are completely defined in terms of the pure fluid polymer parameters and the binary interaction energies. Thermodynamic stability criteria for the phase transitions of a binary mixture are shown. The binodal and spinodal of general binary systems and of special binary systems are discussed.

FRACTAL BEHAVIOR OF SPINODAL DECOMPOSITION IN POLYMER BLENDS

SummaryFractal behaviour of ramified domains in the late stage of spinodal phase separation in a binary polymer blend of poly(vinyl acetate) with poly(methyl methacrylate) was investigated by optical microscopic method. In the late stage of the spinodal decomposition, the fractal dimension D is about 1.64. It implies that some anomalous properties of irregular structure probably may be explained by fractal concepts.

Excimer fluorescence study on the miscibility of poly(vinyl methyl ether) and styrene-butadiene-styrene triblock copolymer

Abstract The excimer fluorescence of a triblock copolymer, styrene-butadiene-styrene (SBS) containing 48 wt% polystyrene was used to investigate its miscibility with poly(vinyl methyl ether) (PVME). The excimer-to-monomer emission intensity ratio I M I E can be used as a sensitive probe to determine the miscibility level in SBS/PVME blends: I M I E is a function of PVME concentration, and reaches a maximum when the blend contains 60% PVME. The cloud point curve determined by light scattering shows a pseudo upper critical solution temperature diagram, which can be attributed to the effect of PB segments in SBS. The thermally induced phase separation of SBS/PVME blends can be observed by measuring I M I E , and the phase dissolution process was followed by measuring I M I E at different times.

Dynamic scaling of the structure function for spinodal decomposition in critical and non-critical mixtures of poly(vinyl acetate)-poly(methyl methacrylate)

Abstract The dynamics of phase separation in a binary polymer blend of poly(vinyl acetate) with poly(methyl methacrylate) was investigated by using a time-resolved light-scattering technique. In the later stages of spinodal decomposition, a simple dynamic scaling law was found for the scattering function S(q, t)(S(q, t) ∼ I(q, t)):S(q, t)q −3 m S ( q q m ) . The scaling function determine experimentally was in good agreement with that predicted by Furukawa, S (X) ∼ X 2 (3 + X 8 ) for critical concentration, and approximately in agreement with that predicted by Furukawa, S (X) ∼ X 2 (3 + X 6 ) for non-critical mixtures. The light-scattering invariant shows that the later stages of the spinodal decomposition were undergoing domain ripening.

STATISTICAL THERMODYNAMICS OF POLYDISPERSE POLYMERS

Abstract A statistical thermodynamics theory of polydisperse polymers based on a lattice model of fluids is formulated. Pure polydisperse polymer can be completely characterized by three scale factors and the molecular weight distribution of the system. The equation of state does not satisfy a simple corresponding-states principle, except for a polymer fluid of sufficiently high molecular weight. The relationships between thermal expansion coefficient α and isothermal compressibility β with reduced variables are also predicted.

Statistical thermodynamics of a lattice fluid: pure polymer

A statistical thermodynamics theory of a polydisperse polymer based on a lattice model of a fluid is formulated. The pure polydisperse polymer is completely characterized by three scale factors and the distribution law of the system. The equation of state does not satisfy a simple corresponding state principle, except for the polymer fluid with sufficiently high molecular weight.