PREFACE

The 8^(th) International Symposium on Polymer Physics was held in Xiamen,China,in the period of June 8-12, 2008.This symposium was organized by The State Key Laboratory of Polymer Physics and Chemistry,China, MPI for Polymer Research,Germany,The University of Massachusetts,USA,and The Hokkaido University, Japan.It was sponsored by the National Natural Science Foundation of China,The Chinese Academy of Sciences (CAS),Institute of Chemistry,CAS,Changchun Institute of Applied Chemistry,CAS,Polymer Division,...

PREFACE

The 7th International Symposium on Polymer Physics was held in Suzhou, China, June 1-5, 2006. This symposium was organized by The State Key Laboratory of Polymer Physics and Chemistry, China, The University of Massachusetts, USA, MPI for Polymer Research, Germany, and The Hokkaido University, Japan. It was sponsored by The National Natural Science Foundation of China, The Chinese Academy of Sciences (CAS), The Institute of Chemistry, CAS, The Changchun Institute of Applied Chemistry, CAS, The Polymer Division, Chinese Chemical Society, and The Soochow University.

Evolution of Morphology and Structure During Crystallization and Melting in Syndiotactic Polypropylene

Structure and morphology development during isothermal crystallization and subsequent melting of syndiotactic polypropylene(sPP) was studied by time-resolved simultaneous small-angle X-ray scattering(SAXS) and wide-angle X-ray diffraction(WAXD) methods with synchrotron radiation and differential scanning calorimetry(DSC). The time and temperature dependent parameters such as long period, L , crystal lamellar thickness, l c, amorphous layer thickness, l a, scattering invariant, Q , crystallinity, X c, lateral crystal sizes, L 200 and L 020 , and unit cell parameters a and b were extracted from SAXS and WAXD profiles. Decreasing long period and crystal thickness indicate that thinner secondary crystal lamellae are formed. The decreases in unit cell parameters a and b during isothermal crystallization process suggest that crystal perfection takes place. The changes in the morphological parameters (the invariant, Q , crystallinity, X c, long period, L , and the crystal thickness, l c) during subsequent melting were found to follow a two-stage melting process, corresponding to the dual endotherm behavior in the DSC scan. We conclude that the dual melting peaks are due to the melting of secondary and primary lamellae(first peak) and the subsequent recrystallization-melting process(second peak). Additional minor endothermic peak located at the lowest temperature was also detected and might be related to melting of secondary, thinner and defective lamellae. WAXD showed that during melting, thermal expansion was greater along the b axis than that along the a axis.

The Crystallization Behavior Regulating Nature of Hydrogen Bonds Interaction on Polyamide 6,6 by Poly(vinyl pyrrolidone)

The crystallization behavior of polyamide 6,6(PA66) under complex flow field is of great importance for its final mechanical properties.Poly(vinyl pyrrolidone)(PVP) was applied as crystallization modifying agency to improve processability of PA66.The regulation nature on hydrogen bonds(H-bonds) interaction of PVP was studied upon cooling process.As revealed by in situ FTIR,the sample with 5 wt% PVP displays decreased enthalpy change(ΔH) for both the generation of H-bonds and the transition of H-bonds from “disordered” to “ordered” state,which illustrates the molecular mechanism for the regulation of crystallzation behavior.Moveover,2D-WAXD is applied to reveal the evolution of microstructure for sample under external injection field.Hermans orientation factor(f_(H)) decreases obviously with the addition of PVP,because the relaxation of chain segments is promoted as well the crystallization is retarded.The above crystallization and microstructure changes during the processing provokes the improvement of processability without the apparent sacrifice of mechanical properties.

SYNTHESIS OF EXFOLIATED ISOTACTIC POLYPROPYLENE/FUNCTIONAL ALKYL-TRIPHENYLPHOSPHONIUM-MODIFIED CLAY NANOCOMPOSITES BY IN SITU POLYMERIZATION

Diphenyl(4-hydroxyphenyl) hexadecyl phosphonium bromide(POH)-modified montmorillonite(POHMMT) was used to prepare a novel TiCl4/MgCl2/POHMMT compound catalyst and exfoliated iPP/POHMMT nanocomposites were prepared by the in situ intercalative polymerization of propylene with the TiCl4/MgCl2/POHMMT compound catalyst. The POH surfactants don't change the catalytic characteristic of the Z-N catalyst and the obtained PP presents high isotacticity,normal molecular weight and molecular weight distribution. The WAXD, SAXS and TEM results demonstrate the highly exfoliated iPP/POHMMT nanocomposites were produced by the in situ polymerization with this novel catalyst, while the intercalated iPP/ Na+MMT nanocomposites were produced with the TiCl4/MgCl2/Na+MMT compound catalyst. Through this approach, in situ propylene polymerization can actually take place between the silicate layers and lead not only to PP with high isotacticity and molecular weight, but also to highly exfoliated PP nanocomposites.

Surface structure change properties:Auto-soft bionic fibrous membrane in reducing postoperative adhesion

Peritoneal adhesion is the most common adverse effect following abdominal surgery or inflammation.The occurrence in clinical trials has been successfully reduced using barriers.However,the shortcomings of frequently used adhesion barriers,such as rapid degradation rate of gel barrier and inadequate operation ability of solid barrier,cannot be ignored.In this study,a fibrous membrane with an ECM-like structure was prepared.The adhesion properties were reduced significantly by changing the surface structure.The fibrous membrane caused less inflammatory response and much less peripheral adhesion and intestinal obstruction compared to the casting film and the commercial film with smooth surface,though with the same components.Because of the auto-soft bionic structure and similarity in the mechanical modulus of the tissues,the fibrous membrane was more flexible when it adhered to the tissues,showed excellent effectiveness and biocompatibility.In addition to the rat and miniature pig models,a randomized,placebo-controlled,and multicenter clinical pilot study with 150 patients confirmed that because of its flexibility,biodegradability,and similarity to mechanical modulus and structure with tissues involved,the fibrous membrane served as a favorable implant for preventing post-operation adhesion.

Glass transition: from interaction potential changes to the corresponding structural and relaxation responses along the path of reaching the final equilibrium

Glass transition involves a many-body interaction and relaxation process. The split of relaxation spectrum and the extremely slow dynamics bring into considerations of non-linearity and non-equilibrium. Some of our recent findings in two measurable colloidal systems are reviewed, one with a simple attractive interparticle potential and the other with a competitive(repulsive vs. attractive)inter-particle interaction. With an approach from interaction potential changes to the corresponding structural and relaxation responses, along the path of reaching the final equilibrium, we illustrate some interesting physics in glass formation process. Also,some reviews on the popular glass transition theories are made to remind readers to avoid artifacts and misinterpretations.

Phase Behavior Actuating Morphology and Rheological Response of Polybutadiene/Polyisoprene Blends under Small Amplitude Oscillatory Shear

The morphology evolution and the corresponding linear viscoelastic behavior of the phase-separating polybutadiene(PB)/low vinyl content polyisoprene(LPI) blend have been investigated by phase contrast optical microscopy(PCOM), small-angle light scattering(SALS) and rheometry. Two kinds of structure evolutions and rheological responses have been observed. It is found that the co-continuous structure generally gives a power law behavior of the dynamic storage modulus versus frequency and the coarsening of co-continuous structure leads to a decrease of the storage modulus. For the droplet-matrix structure, a platform modulus is observed at the mediate frequencies, followed by the typical terminal relaxation behavior of storage modulus at the extremely low frequencies. The decreasing platform modulus and increasing terminal modulus with the growth of droplets are observed and can be well interpreted by the simplified Palierne model. The platform modulus and terminal modulus at a given frequency are found to be scalable with the phase separation time. Besides, the characteristic relaxation time and domain size of the droplets have been obtained by rheology. And it seems that the rheologically determined droplet dimensions are consistent with the ones determined by PCOM and SALS.

PREFACE

The 9^(th) International Symposium on Polymer Physics was held in Jinan,China,from June 6^(th) to 10^(th),2010.This symposium was organized by The State Key Laboratory of Polymer Physics and Chemistry,China,MPI for Polymer Research,Germany,The University of Massachusetts,USA,and The Hokkaido University,Japan.It was sponsored by the National Natural Science Foundation of China,The Chinese Academy of Sciences(CAS), Institute of Chemistry,CAS,Changchun Institute of Applied Chemistry,CAS,Polymer Division,Chinese Chemical Society,and Shandong University.