摘要:

Ionic conductivities of salt complexes of polyoxyethylene (PEO)-containing star-shaped block copolymers and copolymers with uniform grafts were measured. The results were compared with the thermal characteristics and crystallinity of the complexes obtained from DSC and WAXD analysis. The conductivity increases with PEO content of the copolymers, more noticeably at PEO contents over 50%. For the complexes of the star-shaped block copolymers of styrene (S) and ethylene oxide (EO), conductivity decreases in the following order of salts: KCNS > NH4CNS > NaCNS. The room temperature conductivity of the KCNS complex with EO/K ratio = 20 can reach a value of 2 × 10−5S cm−1at 57% PEO content of the copolymer. The complex with FeCl2displays a conductivity even higher than that of the NaCNS complex. Addition of γ-butyrolactone reduces the crystallinity and enhances markedly the ionic conductivity. For complexes of the copolymers with uniform PEO grafts the conductivity decreases in the following order of salts: KCNS > LiClO4> FeCl2. Complexes with LiClO4exhibit a maximum conductivity at EO/Li = 20. For different kinds of copolymers with uniform PEO grafts, conductivity of the complexes increases in the order: PS-g-PEO < PMMA-g-PEO < polymethyl acrylate-g-PEO.

ISSN:0360-2559    

DOI:10.1080/03602558908048604

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Soluble high-temperature polymers containing a tetraphenylthiophene unit were successfully prepared. Four types of tetraphenylthiophene monomers—diamine, diisocyanate, dicarboxylic acid chloride, and dibromide—were synthesized starting from tetraphenylthiophene, which was readily obtained by the reaction of benzyl chloride and sulfur. Aromatic polyimides and copolyimides were prepared by the reactions of tetraphenylthiophene diamine with tetracarboxylic dianhydrides, tetraphenylthiophene diisocyanate with tetracarboxylic dianhydrides, and tetraphenylthiophene diamine with tetracarboxylic dithioanhydrides. Aromatic polyamides and copolyamides were obtained from the reaction pairs of tetraphenylthiophene diamine and dicarboxylic acid chlorides, tetraphenylthiophene dicarboxylic acid chloride and diamines, and tetraphenylthiophene dibromide, diamines, and carbon monoxide. Similarly aromatic polyamide-imides were prepared by the reaction of tetraphenylthiophene diamine with 4-chloroformylphthalic anhydride, and tetraphenylthiophene diisocyanate with trimellitic anhydride. The reaction of tetraphenylthiophene dicarboxylic dichloride with bisphenols and aminophenols afforded aromatic polyesters and polyamide-esters, respectively. Aromatic polyazomethines were prepared by the reaction of tetraphenylthiophene diamine and dialdehydes. All the polymers were obtained in high molecular weights, and all were soluble in organic solvents and had high glass transition temperatures around 300°C.

ISSN:0360-2559    

DOI:10.1080/03602558908048605

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This paper describes a novel gas dispersion system for use in highly viscous/polymeric fluids using a plasticating extruder. The unique but not yet widespread method employs a rotating submerged orifice constructed on an extruder mixing head. The gas is injected directly into the mixing zone of the extruder radially through the rotating orifice. This generates large deformation of the bubbles formed at the orifice by virtue of the shear stress in the surrounding fluid. As a result, very fine bubbles (0.1–3 mm) may be generated in continuous-phase viscosities as high as 500 Pa·s. Results on the isothermal bubble formation in a model polymeric system show that the bubble size produced is a strong function of the screw speed and is also affected by the gas injection rate, melt pressure, continuous-phase viscosity, and to some extent by the size of the orifice used. A progressive diminution in the bubble size was recorded with increasing screw speed irrespective of the conditions employed. Depending upon the conditions employed (screw speeds, fluid pressures, continuous-phase viscosity, etc.), the dispersions generated may be controlled to the desired degree of fineness within certain limits. Only low gas injection rates (0.5–3.5 cc/s) using an isolated orifice were employed in this study. It is expected, however, that an understanding of the processes of formation at a single orifice will serve as a useful preliminary to investigations employing multiple orifices. The new process is discussed in the light of existing technologies, and its salient design features are described and illustrated. An outstanding feature of the process is its ability to produce the desired dispersion at relatively much lower but constant system pressures. This feature is especially attractive as it holds the potential for a practical gas subdivision device which offers the minimum of energy outlay. Linear low density polyethylene (LLDPE) was used as a model dispersion resin in this study although other resin systems may be employed without the loss of generality.

ISSN:0360-2559    

DOI:10.1080/03602558908048606

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Grafting of cotton stalk pulp with methylmethacrylate monomer using a ceric salt redox system is carried out. The effect of different variables—for example, monomer dose, reaction time, reaction temperature, acid concentration, initiator concentration, and liquor ratio—are studied. The effect of the presence of different amounts of residual lignin in cotton stalks pulp on the grafting process is demonstrated. Residual lignin percentage in the pulp plays an important role in determining the grafting rate. A sharp decrease in the grafting rate is observed by increasing the residual lignin percent in pulp from 1.64% to 4.96%. As the residual lignin percentage in the pulp is increased to 12% in pulp, the grafting reaction is nearly stopped. Optimization of the grafting conditions is clarified.

ISSN:0360-2559    

DOI:10.1080/03602558908048607

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Alkaline phosphatase, ALPase (E.C. 3.1.3.1) was immobilized onBombyx morisilk fibroin fiber by covalent bond formation. Two different immobilization procedures (i.e. diazo and cyanogen bromide, CNBr, methods) were tried. The immobilization conditions such as pH, enzyme concentration, reaction time, and temperature were examined in detail, and optimum conditions were obtained. The immobilized enzyme activity was characterized with Michaelis constant,Km, and maximum activity,Vm.The optimum pH of the activity of the fixed enzyme tended to shift to the acid side. Thermal stabilities of the enzyme were improved above 50°C. In addition, the immobilized enzyme maintains activity over a long period.

ISSN:0360-2559    

DOI:10.1080/03602558908048608

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0360-2559    

DOI:10.1080/03602558908048609

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0360-2559    

DOI:10.1080/03602558908048603

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor