ELECTROCHEMISTRY OF POLYANILINE UNDER LIGHT

The electrochemistry of polyaniline synthesized electrochemically in acidic solution under light irradiation has been studied as a function of the applied potentials, the concentration and acidity of electrolyte as well as pH at applied potentials in the rang+0.40 to-0.5V vs. SCE. It is concluded that under selected experimental conditions the reduced repeat groups in polyaniline are oxidized by air in the dark and that this oxidation process can be strongly photocatalyzed.

PREPARATION OF WATERBORNE ULTRAFINE PARTICLES OF EPOXY RESIN BY PHASE INVERSION TECHNIQUE

Waterborne ultrafine particles of epoxy resin were prepared by phase inversion technique. The results of SEM revealed that the particles diameter was in the range of 50 to 100 nm and the effects on amount of water required at phase inversion point were also discussed.

STUDIES ON THE BLEND OF POLYACRYLATE EMULSIONS AND TACKIFIER RESIN EMULSIONS

A series of polyacrylate emulsions were blended with tackifier resin emulsions such as modified rosin emulsion, C5 resin and C9 resin emulsion. The miscibility of the polyacrylates and tackifier resins was investigated by means of SEM and visual observation. The phase diagrams of the miscibility change systematically with the polarity of polyacrylates and tackifier resins. The influence of the content of the tackifier resins on the adhesion properties of the; polyacrylate emulsions were also studied. The results show that the 180 degrees C peel strength is improved as the amount of the tackifier resin increases and comes to a maximum at a specific content. The ball tack property decreases slightly and the hold strength changes complicatedly as the tackifier resin increases.

COPOLYMERIZATION OF PROPYLENE WITH HINDERED PIPERIDINE MONOMER OVER A HIGH ACTIVITY SUPPORTED ZIEGLER-NATTA CATALYST

Copolymerization of propylene and hindered piperidine monomers was carried out over a high activity supported Ziegler-Natta catalyst, using Al(C2H5)(3) as cocatalyst. Factors which affect the copolymerization were studied, The copolymers exhibited high light stability without adding extra light stabilizers. A self-stabilized polypropylene was prepared.

STUDY ON SYNTHESES AND PROPERTIES OF SOME NOVEL POLYIMIDES CONTAINING BISTHIAZOLE RINGS

Some novel polyimides containing bisthiazole rings were prepared by reacting 2,2'-diamino-4, 4'-bisthiazole (DART) with different aromatic dianhydride. The polyimides obtained had inherent viscosities of 0.37-0.82 dl/g. Thermogravimetric analysis of the polyimides showed good thermal stability, the temperature at 5% weight loss being from 450 degrees to 560 degrees C. The permeability of two polymer membranes to H-2, O-2 and N-2 was determined, respectively. Three kinds of polyimide films were converted into electrical conductor by pyrolysis at high temperature in nitrogen atmosphere. The maximum room temperature conductivity as high as 3.9x10(2) S/cm for PI him pyrolyzed at 1200 degrees C for 10 min was obtained, and it was very stable in air.

AN EXPERIMENTAL STUDY ON THE SOL/GEL PHASE TRANSITION OF LINEAR POLYMER IN THE PRESENCE OF CROSSLINKERS

The sol/gel phase diagrams were studied for two systems: polyacrylamide/Cr (III) and polyacrylamide/glyoxal. Sol or gel phase could be distinguished according to the concentrations of polymer and crosslinker. The boundary polymer concentration did not depend on the types of gelation and decreased with increasing polymer dimension (molecular weight and conformation). The gelation, which is basically interchain bonding, requires the occurrence of entanglement. The overlap concentration is thus considered as the minimum polymer concentration required for gelation.

STUDY ON THE SYNTHESIS AND CHARACTERIZATION OF THE SOLUBLE, HIGH MOLECULAR WEIGHT AND LAD D ERLIKE PO LYMETH YLSILSESQ UIO XANE

A new method for the preparation of a soluble ladderlike polymethylsilsesquioxane with high molecular weight ((?)=10~5—10~6) and low molecular weight distribution (D=Mw/Mn) in common solvents instead of the formerly used toxic methylisobutylketone has been developed. The structure and macromolecular regularity were characterized by IR, X-ray diffraction, and ^(29)Si-NMR spectroscopy. The thermal property was studied by TGA and DSC.

SYNTHESIS AND-CHARACTERIZATION OF THE SOLUBLE, HIGH MOLECULAR WEIGHT AND LADDERLIKE POLYHYDROSILSESQUIOXANE AND ITS COPOLYMERS

The high molecular ladderlike polyhydrosilsesquioxane （LPHSQ） and its copolymer, ladderlike random copolymethylhydrosilsesquioxane （LR-PMHSQ） and ladderlike block copolymethylsilsesqui-oxane（LB-PMHSQ） have been synthesized by a preaminolysis reaction of the corresponding trichlorosilane with 1 ,4-phenylene diamine（PDA） then by hydrolysis and polycondensation reactions The thermographs of these polymers measured by DSC method indicate that these macromolecular backbones are very rigid as seen from the DSC curves which are almost horizontal from room temperature until 350;without noticeable glass transition. The content of Si—H group in the polymers can be regulated by changing the composition of the two copolymerized monomers. So the ladderlike polymers including its copolymers can be the useful precursors for the functional polymers, especially such as fishbone-like liquid crystalline polymers.

CATALYTIC BEHAVIOR OF A SILICA-SUPPORTED POLYTITAZANE-PLATINUM COMPLEX FOR THE HYDROGENATION OF PHENOL

A new kind of inorganic polymer, viz, silica-supported polytitazane (Ti-N), and its platinum complex (Ti-N-Pt) were prepared. Cyclohexanone can be obtained in a maximum yield of about 62.2% in the hydrogenation of phenol over Ti-N-Pt at room temperature under atmospheric pressure. The effects of mole ratio of N/Pt in the complex, concentration of the catalyst and reaction temperature on the catalytic activity and selectivity have been studied. The complex can be reused several times without loss in its catalytic activity.

SYNTHESIS, STRUCTURE AND ELECTRICAL PROPERTIES OF POLY(PHENYLENE VINYLENE) FILM DOPED WITH FERRIC CHLORIDE

Poly(phenylene vinylene) (PPV) him was synthesized via a soluble precursor polymer. Strong fluorescence at 500-600 nm was observed in both precursor and PPV him. Room-temperature conductivity of PPV him doped with FeCl3 depends on the elimination temperature, the concentration of FeCl3 and doping time. The maximum conductivity of doped PPV at room-temperature can reach about 40 S . cm(-1). The temperature dependence of conductivity was controlled by 1D-VRH (1 Dimension Variable Range Hopping) model with T-0 value of 3.9 x 10(3) K. Non-Ohmic conductivity resulting from Schottky effect was observed and the value of converted voltage from Ohmic region into non-Ohmic region at the current-voltage characteristic was found to be dependent upon the work function of electrodes.

FOURIER TRANSFORM INFRARED STUDIES OF POLY (ETHYLENE TEREPHTHALATE) FILM IN THE GLASS TRANSITION REGION

Three specimens from a solution-cast poly (ethylene terephthalate) (PET) film, one being liquid-N_2 quenched from 92℃(Q), one being slowly cooled from 92℃(SC) and one being quenched and sub-T_g annealed at 67℃(AN), have been studied by specimen difference spectra Q-SC and AN-Q and temperature difference spectra T-70 and T_2-T_1 for every 2℃ steps on heating to 90℃ at 2℃ /min. SC and AN showed more gauche conformers than Q. That means that the PET chain has more trans conformers at higher temperatures and some of these are frozen during quenching through T_g. A band at 1340 cm^(-1) has been found to be complex containing overlapping bands reflecting trans in crystalline regions and trans in amorphous regions. The temperature difference spectra on heating through T_g showed that the spectral changes in Q are gradual while a rather abrupt change occurs in AN at 80—82℃ for the bands at 1340, 1042 and 1020 cm^(-1). No new conformational structure or new vibrational mode is involved. A kind of locking mechanism is suggested which hinders the molecular vibrational changes in AN below T_g until a sudden release occurs at T_g. These locking sites can be nothing else than sites of tighter local packing of chain segments. Consequently it is believed that inter-chain van der Waals attraction energy plays a dominating role in the volume relaxation and sub-T_g annealing of quenched amorphous polymers.

CONFORMATIONAL CHARACTERISTICS OF POLY(ACRYLIC ACID) AND POLY(METHACRYLIC ACID)

A full-relaxation optimization of molecule and the Dreiding force field are employed to obtain the geometry parameters and the conformational energy surfaces of meso or racemic dyad of poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA). Three different carbonyl-bond orientations of side-groups resulted in the differences in depth of potential wells in their energetic contours for a meso or a racemic dyad. These discrepancies are interpreted as a result of various fine structures corresponding to grid search conformations as well as thereby different interactions. The analysis on the most stable conformations of PMAA confirmed that the ester groups are nearly perpendicular to the plane defined by the two adjacent skeletal bonds but may possibly change their relative orientations to meet the requirement of lower energy during the conformational state transition. For each polymer, two global energy maps of a meso and a racemic dyad were finally constructed from the superposition of energy data for the three kinds of side-group orientations by the Boltzmann factors. From an ensemble average, the proposed scheme with three rotational isomeric states (RIS) allowed us to access the experimentally unperturbed dimensions of PAA chain via the configurational statistical mechanics. Although the calculation was based on the short-range, local interactions, it was interested to note that the experimental characteristic ratios just fell within the range calculated for atactic chains.

EFFECT OF ULTRASONIC WAVE ON THE ELECTROPOLYMERIZATION OF PYRROLE

Electropolymerization of pyrrole under ultrasonic field at 20kHz was performed in a series of aqueous and propylene carbonate (PC) solutions. The ultrasonic wave with moderate intensity at the power of 44W, which is the power threshold of the ultrasonic generator used in this work to produce cavitation effect, enhance the conductivity and tensile strength of the polypyrrole films as prepared. However, too high intensity of the ultrasonic wave is harmful to the polymerization.

INTERFACIAL MOLECULAR DESIGN OF A RIGID- PARTICLE TOUGHENED POLYAMIDE 6 COMPOSITE

The effects of interfacial modifier on the mechanical properties of kaolin-filled polyamide 6 (PA6) have been studied. The interracial interaction between polyamide 6 and kaolin has been character ized by means of infrared spectroscopy (IR) and scanning electron microscopy (SEM). The results show that the role of the interracial modifier lies in forming an elastic interlayer with good adhesion between kaolin and PA 6. A composite with high impact strength, high tensile strength and high elastic modulus can be obtained by inserting the elastic interfacial modifier into the rigid-particle-filled polymer system.

CATALYTIC BEHAVIOR OF SILICA-SUPPORTED POLY-γ- AMINOPROPYL- SILOXANE-Co-Ru BIMETALLIC COMPLEX FOR THE HYDROFORMYLATION OF CYCLOHEXENE

The cobalt and ruthenium bimetallic complex of poly-γ-amino-propylsiloxane( abbr. as Si-CH_2-Co-Ru) was prepared, and it was found that it can catalyze the hydroformylation of cyclobexene effectively with the conversion amounting to over 90%. Cyclohexanecarboxaldehyde was first formed in the hydroformylation, and then further hydrogenated to form cylcohexanemethanol. The coversion was affected obviously by the Co/Ru ratio.When Co/Ru molar ratio was 100-150, i.e. in the very low content of noble metal Ru, the catalytic activity of Si-NH_2 -Co-Ru was also very high. The product composition was affected by CO/H_2 ratio in the reaction gas. Aldehyde can be got high selectively by controlling CO/H_2 ratio. Compared with other catalyst system, the Si-NH_2-Co-Ru catalyst has higher catalytic activity and efficiency with very low Ru/Co ratio. The total turnover number was more than 28,800 (based on the amount of ruthenium used).

STUDIES ON MISCIBILITY OF POLY (ε-CAPROLACTONE) AND ALIPHATIC POLYCARBONATE BLENDS AND DETERMINATION OF THEIR INTERACTION PARAMETER

In this paper the miscibility of poly (ε-caprolactone) (PCL) and aliphatic polycarbonate (APC) is studied by using DSC. The results show that PCL and APC are miscible in all ranges of composition. The interaction parameter between the polymers is calculated from the melting point depression data. Using optical microscope, the shapes of the PCL spherulites in the blends are observed.

EFFECTS OF COUPLING AGENTS ON THE RHEOLOGICAL BEHAVIOR OF KAOLIN FILLED POLYAMIDE 6

An experimental study was carried out to investigate the effects of coupling agents on the rheological properties of kaolin filled polyamide 6(PA6). We have investigated the state of dispersion and interfacial interaction of the filled systems, using 'h:anning electron microscopy (SEM) and Molau test, respectively. It is found that the addition of the coupling agents to the PA6/ kaolin (20 wt percent) significantly decreases the melt viscosity and the melt elasticity (first normal stress difference). Moreover, the states of dispersion and the polymer/filler interactions have significant influences on the rheological properties of kaolin/PA6 systems. The rheological behavior of KH550 kaolin /PA6 system is different from that of KH560 kaolin/PA6 system, although chemical reactions have taken place between the surface of KH550 kaolin (or KH560 kaolin) and PA6 matrix during melt processing. This is attributable, in part, to the differences in the state of dispersion of kaolins in PA6 matrix and, to a great extent, to the differences in the extent of chemical reactions that have taken place between the filler and polymer matrix.

MODIFICATION OF EPOXY RESINS WITH PHENOLIC HYDROXYL-TERMINATED POLYSILOXANE

Phenolic hydroxyl-terminated polysiloxanes were incorporated into epoxy resins to reduce the internal stress owing to the mismatch in coefficient of thermal expansion (CTE). Polysiloxane-epoxy resin block copolymers were made by a pre-reaction step prior to the curing. In the cured resin, the domain size of the polysiloxane phase depended on the structure of the phenolic hydroxyl-terminated polysiloxane. It was found that the modulus of the cured resin depended largely on the level of the modifier, while the CTE was affected greatly by the structure of the polysiloxane. By means of incorporating a few percent of methylphenylsiloxane unit into the polydimethylsiloxane chain, or by introducing; more compatible end-capping groups, the compounds of more effective low stress modifiers were synthesized.

BAND-LIKE TEXTURE OF ETHYLCYANOETHYL CELLULOSE MESOPHASE

In the ethyl-cyanoethylcellulose ((E-CE)C)/dichloroacetic acid (DCA) cholesteric liquid crystalline solution, the hand-like texture is formed when the mesophase aggregates with the disk-like texture grow to big enough and merge with each other with increasing concentration. The band-like texture is composed of parallel equidistant bright and dark alternative strips which are about 0.2-2.0 μm in width. In the band-like texture, the layers of ordered polymer chains are perpendicular to the solution film and the axes of helicoids are parallel to it. The width of the strips is different in different zones. Under the effect of an external magnetic field, the strips in the band-like texture first become wider and then narrower gradually.Moreover, the axes of helicoids in the (E-CE) C/DCA mesomorphic solution change from the direction normal to the magnetic field to the agreement with the magnetic field direction.

AROMATIC AND HETEROCYCLIC NITRILES AND THEIR POLYMERS ⅩⅥ. THE POLYMERIZATION KINETICS OF 4, 4′-BIPHENYLDICARBONITRILE CATALYZED BY LEWIS ACID-METAL SYSTEM

The polymerization kinetics of 4, 4′-biphenyldicarbonitrile using cuprous chloride-zinc system as catatyst was investigated. the concentration of unreacted cyano group was measured by infrared spectroscopic analysis using potassium ferricyanide as the internal reference. It was found that the polymerization rate is directly proportional to the concentrations ofcyano group, cuprous chloride and zinc, and the activation energy of the polymerization is as Tow as 18.4 KJ/mol. In addition, the other kinetics parameters were obtained and discussed.