INVESTIGATION OF STRUCTURE AND PROPERTIES FOR POLYMER SYSTEMS BASED ON DYNAMIC RHEOLOGICAL APPROACHES

The dynamic rheological measurements have been a preferred approach to the characterization of the structure and properties for multi-component or multi-phase polymer systems,due to its sensitive response to changes of structure for these heterogeneous polymers.In the present article,recent progresses in the studies on dynamic rheology for heterogeneous polymer systems including polymeric composites filled with inorganic particles,thermo-oxidized polyolefins,phase- separated polymeric blends and functional polymers with the scaling and percolation behavior are reviewed,mainly depending on the results by the authors' group.By means of rheological measurements,not only some new fingerprints responsible for the evolution of morphology and structure concerning these polymer systems are obtained,the corresponding results are also significant for the design and preparation of novel polymer-based composites and functional materials.

Study on the Novel Dicyanate Ester Resin Containing Naphthalene Unit

The novel dicyanate ester resin containing naphthalene unit (DNCY) was synthesized, and characterized by FT-IR, 1H-NMR, 13C-NMR and elemental analysis (EA). The thermal properties of DNCY resin was studied by thermal degradation analysis at a heating rate of 10 C /min-1 in N2 and air. The DNCY resin exhibited better thermal and thermal-oxidative stability than bisphenol A dicyanate (BACY) resin.

Rheological Behavior for Mica-filled Polypropylene Composite Melts

The study on rheological properties of a series of mica-filled polypropylene ( PP ) composites was carried out. The influence of surface-treatment of mica particles on dynamic rheological behavior of the composites were dealt with. The viscosity ( h ) and dynamic modulus ( G ) of the composite melts were higher than those of PP matrix, especially those for systems treated with silane, which was attributed to the interfacial adhesion enhancement. However, surface-treatment of mica by titanate resulted in lower h and G, as compared with the treatment by silane. The reason for this is believed to be the formation of the mono-molecular layer on the mica surface.

RING-OPENING POLYMERIZATION OF TRIMETHYLENE CARBONATE CATALYZED BY NOVEL SINGLE COMPONENT RARE EARTH CALIXARENE COMPLEXES

In this paper,ring-opening polymerization of trimethylene carbonate(TMC)with rare earth(Nd,Y,La)ρ-tert- butylcalix[n]arene(n=4,6,and 8)complexes as catalysts has been studied.Poly(trimethylene carbonate)(PTMC)with M_v of 21,400 was produced by bulk polymerization under the conditions as follows:[TMC]_0/[Nd](molar ratio)=1000,80℃, 8 h.Mechanism study reveals that the polymerization proceeds via a coordination mechanism.

The Dynamic Viscoelasticity of Polyethylene Based Montmorillonite Intercalated Nanocomposites

The viscoelastic behavior of melts for two systems composed of intercalated nanocomposites based on low density polyethylene and 3 wt% loading of cetyltrimethyl- ammonium bromide modified montmorillonite was studied. The results obtained through examining the dynamic storage module G' and dynamic loss module G' values of the composite revealed that the dynamic viscoelastic properties of composite strongly depended on intercalation of polymer, and exhibited dramatically change with altering intercalation conditions. Only when modified montmorillonite content was about 3 wt%, the composite showed a trend of pseudo-solidlike at lower frequencies.

Polymerization of n-Hexyl Isocyanate Initiated by Novel Rare Earth Tris(2,6-di-tert-butyl-4-methylphenolate)

The polymerization of n-hexyl isocyanate(HNCO) was carried out in the presence of a novel single initiator, rare earth tris(2,6-di-tert-butyl-4-methylphenolate)[Ln(OAr)_3]. The influences of reaction conditions such as the monomer concentration, the polymerization temperature and time, and the types of solvents on the polymerization of HNCO were studied. Polymerizations of phenyl, i-propyl, p-tolyl, n-butyl and n-octyl isocyanates with La(OAr)_3 were also examined.

Synthesis and Characterization of a Novel Aqueous Dispersion Poly[urethane-(disperse blue 14)-urethane] Dye

A novel polymeric dye of aqueous dispersion poly[urethane-(disperse blue 14)-urethane] was synthesized based on poly(propylene glycol) (PPG), 2, 4-tolylene diisocyanate (TDI), klimethylol propionic acid (DMPA), disperse blue 14 and triethylamine (TEA) depending on a modified acetone process. Fourier transform infrared spectroscopy (FTIR) was used to identify Lhe structure of the polymeric dye, indicating an obvious carbonyl stretching absorption in disperse blue 14. The polymer was also characterized by the analysis of DSC, TGA, WAXD and UV-Vis spectroscopy.

A Novel Approach for Observing Morphology of Polypropylene under Ultrasonic Vibration by SALS

In this paper, a set of ultrasonic vibration device connecting with small angle light scattering(SALS) for in-situ observing phase-transition of polymer under ultrasonic vibration was established. The experiments for verifying polypropylene(PP) indicated that ultrasonic vibration resulted in the decrease of the crystallization rate and made PP crystallizable at low temperature.

Studies on microdomain structure in segmented polyether polyurethaneureas by positron annihilation lifetime and small-angle X-ray scattering

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ENTROPIC CONTRIBUTION TO THE INTERACTION PARAMETER x IN THE POLYMER/OLIGOMER SYSTEM:A LATTICE CLUSTER THEORY CONSIDERATION

Entropic contribution to the interaction parameter (?) in the model incompressible polymer/oligomer system iscalculated by the lattice cluster theory(LCT).It is found that in the oligomer solvent,there exists a wide concentration rangethat the non-combinatorial“entropic interaction”term (?)φ_1φ_2 perceptibly counteracts the mean field combinary entropy△S_(MF).With the increase of the solvent size,both (?) and the ratio (?)φ_1φ_2/△S_(MF) first reach their maximum and finallybecome trivially to zero.It is worth noting that no any demixing was found in the current calculation.This makes thecontroversial idea“entropically driven demixing”even elusive.However,we propose that further work on compressiblepolymer solution with structured monomer will witness the demixing owning to an increased configurational correlation.

POLYMERIZATION OF A NEW SUBSTITUTED ACETYLENE BEARING A FURAN RING WITH PALLADIUM ACETYLIDE CATALYSTS

A substituted polyacetylene bearing a furan ring, poly(2-propynyl 2-furoate) (PPF), was synthesized for the first time with palladium acetylide complex catalysts in CHCl3 at 60°C to give a soluble and stable polymer with a yield of ca. 75%. Some features for polymerization of 2-propynyl 2-furoate are described and discussed. The resulting polymer was characterized by IR, GPC and 1H-NMR analysis.

Effect of Fluorination on Aggregate Structure of Perylene Diimide

The effect of fluorination on the aggregate structure of a novel fluorinated perylene diimide, N, N'-diperfluorophenyl-3, 4, 9, 10-perylenetetracarboxylic diimide 1, was investigated by UV-Vis absorptions and the conformation simulations from AM1 semi-empirical quantum mechanics modeling. The results showed that in the solid film 1 molecules stacked with the perfluorinated phenyl groups straightly over or below the perylene cores of the adjacent 1 molecules.

Synthesis and Application of a Novel Organosilane Modifier for Surface Paintability of Organosiloxane Sealants

A novel organosilane, N-n-butyl-γ-aminopropylmethyldimethoxysilane was synthesized through aminization reaction and the chemical structure of resulting products was characterized by 1HNMR, 13CNMR, FT-IR and elemental analysis. The results of test on probation for this organosilane proved that it was effective to modify surface-paintability of organosiloxane sealants.

CRYSTALLIZATION AND MELTING OF POLY(ETHYLENE OXIDE)CONFINED IN NANOSTRUCTURED PARTICLES WITH CROSS-LINKED SHELLS OF POLYBUTADIENE

Small fixed aggregates of a poly(ethylene oxide)-block-polybutadiene diblock copolymer(PEO-b-PB)in THFsolution were obtained by adding a selective solvent for PB blocks,followed by cross-linking the PB shells.Themorphologies of the nanostructured particles with a cross-linked shell were investigated by atomic force microscopy andtransmission electron microscopy.The average behaviors of the PEO crystallization and melting confined within thenanostructured particles were studied by using differential scanning calorimetry experiments.For the deeply cross-linkedsample(SCL-1),the crystallization of the PEO blocks was fully confined.The individual nanoparticles only crystallized atvery low crystallization temperatures(T_cs),wherein the homogenous primary nucleation determined the overallcrystallization rate.For the lightly cross-linked sample(SCL-2),the confinement effect was T_c dependent.At T_c(?)42℃,thecrystallization and melting behaviors of SCL-2 were similar to those of the pure PEO-b-PB diblock copolymer.At T_c>42℃,SCL-2 could form PEO lamellae thicker than those of the pure PEO-b-PB crystallized at the same T_c.

Dynamically Photocrosslinking of Polypropylene/EPDM Blends as a Thermoplastic Elastomer

The mechanical properties and the crystal morphological structures of the dynamically photocrosslinked polypropylene(PP)/ethylene-propylene-diene terpolymer(EPDM) blends have been studied by means of mechanical tests, wide-angle X-ray diffraction(WAXD), and differential scanning calorimetry(DSC). The dynamically photocrosslinking of the PP/EPDM blends can improve the mechanical properties considerably, especially the notched Izod impact strength at low temperatures. The data obtained from the mechanical tests show that the notched Izod impact strength of the dynamically photocrosslinked sample with 30% EPDM at -20 ℃ is about six times that of the uncrosslinked sample with the same EPDM component. The results from the gel content, the results of WAXD, and the DSC measurements reveal the enhanced mechanism of the impact strength for the dynamically photocrosslinked PP/EPDM blends as follows: (1) There exists the crosslinking of the EPDM phase in the photocrosslinked PP/EPDM blends; (2) The β-type crystal structure of PP is formed and the content of α-type crystal decreases with increasing the EPDM component; (3) The graft copolymer of PP-g-EPDM is formed at the interface between the PP and EPDM components. All the above changes of the crystal morphological structures are favorable for increasing the compatibility and enhancing the toughness of the PP/EPDM blends at low temperatures.

SYNTHESIS, CHARACTERIZATION OF CHIRAL POLY(ESTER AMIDE)S DERIVED FROM L-ISOLEUCINE

A series of new optically active aromatic poly(ester amide)s containing a chiral group in the side chain prepared from the p-toluenesulfonic acid salt of o,o'-bis(leucyl)-hexanediol (TS-+LHD+TS-) and p-phthaloyl chloride and styrene-2,5- dicarbonyl chloride styrene have been synthesized by interfacial polymerization. The structure of the monomer is elucidated by FT-IR and elemental analysis. The thermal properties of the polymers were studied by DSC and TGA. The chiroptical properties of the above polymer have also been studied by circular dichroism (CD) spectroscopy. Results indicated that these polymers form helical structures.

Preliminary Study on the Dynamic Properties of PMVS Filled with Surface-treated Silica

Dynamic properties of polymethylvinylsiloxane (PMVS) filled with surface-treated silica (SiO2) were studied using an advanced rheometric expansion system (ARES). The results revealed that the coupling agent, bis (3-triethoxysilylpropyl) tetrasulfane (TESPT) exerted a pronounced effect on the storage modulus (G'), and the effect of TESPT involved a frequency-dependent relation.

In-situ Enhanced Toughening of Poly（ethylene terephthalate）/elastomer Blends via Gamma-Ray Radiation at Presence of Trimethylolpropane Triacrylate

Gamma-ray radiation has always been a convenient and effective way to modify the inter- facial properties in polymer blends. In this work, a small amount of trimethylolpropane triacrylate （TMPTA） was incorporated into poly（ethylene terephthalate） （PET）/random terpolymer elastomer （ST2000） blends by melt-blending. The existence of TMPTA would induce the crosslinking of PET and ST2000 molecular chains at high temperatures of blend- ing, resulting in the improvement in the impact strength but the loss in the tensile strength. When the PET/ST2000 blends were irradiated by gamma-ray radiation, the integrated me- chanical properties could be enhanced significantly at a high absorbed dose. The irradiated sample at a dose of 100 kGy even couldn＇t be broken under the impact test load, and at the same time, has nearly no loss of tensile strength. Based on the analysis of the impact- fractured surface morphologies of the blends, it can be concluded that gamma-ray radiation at high absorbed dose can further in situ enhance the interfacial adhesion by promoting the crosslinking reactions of TMPTA and polymer chains. As a result, the toughness and strength of PET/ST2000 blend could be dramatically improved. This work provides a facial and practical way to the fabrication of polymer blends with high toughness and strength.

Preparation and Characterization of Aromatic Polybenzoxazoles Copolymers Containing 2,6-Naphthalene Units

A series of polybenzoxazoles(co)polymers bearing crankshaft units in the main chain was synthesized by the conventional solution polycondensation of 4,6-diaminorescinol dihydrochloride, terephthalic acid(TA) and 2,6-naphthalene dicarboxylic acid(NDA). All of the polymers show lyotropic liquid crystal behavior in polyphosphoric acid(PPA) and methanesulfonic acid(MSA). The polybenzoxazoles exhibit an excellent thermal resistance although the crankshaft monomer has been introduced into the polymer backbone. The temperature for the 5% weight loss of all the polymers is above 600 ℃.The X-ray diffraction analysis results show that the series of the polymers has a high crystallinity. The introduction of NDA makes a slight decrease in the thermal resistance of the polymers. The maximum absorption peak in the UV-Vis spectra can be adjusted according to the amount of 2,6-naphthalene units in the polymers, which indicates the potential application of the polymers as optoelectric materials.

A Layer-Structured Metal-Organic Framework-Derived Mesoporous Carbon for Efficient Oxygen Reduction Reaction

Developing highly active and durable electrocatalysts for the oxygen reduction reaction （ORR） is crucial to large-scale commercialization of fuel cells and metal-air batteries. Here we report a facile approach for the synthesis of nitrogen and oxygen dual-doped meso-porous layer-structured carbon electrocatalyst embedded with graphitic carbon coated cobalt nanoparticles by direct pyrolysis of a layer-structured metal-organic framework. The elec- trocatalyst prepared at 800℃ exhibits comparable ORR performance to Pt/C catalysts but possesses superior stability to Pt/C catalysts. This synthetic approach provides new prospects in developing sustainable carbon-based electrocatalysts for electrochemical energy conversion devices.