Polymer
The effects of shear on molten polyethylene were studied. The experiment shows, that increasing shear gives rise to greater amounts of all-trans C-C bonds.
Structural relaxation of poly(methyl methacrylate) has been studied by differential scanning calorimetric (d.s.c.) and dynamic mechanical techniques, and the effect of temperature of ageing has been investigated. Isothermal ageings at temperatures between T g - 30 K and T g - 100 K lead to d.s.c. pre-peaks and a diminution of the mechanical loss tangent. The β relaxation is not affected...
This study investigates the compatibilizing effect of a poly(ester imide) (PEsI) on the blends of poly(ether imide) (PEI, Ultem 1000 from G.E.) and thermotropic liquid crystalline polymer (TLCP) (poly(ester amide), PEA, Vectra B950 from Hoechst Celanese). The compatibilizer, PEsI, was synthesized. Composite fibres were prepared by extrusion. Compatibility, thermal and rheological properties of...
Polyamides and polyimides having 4,4 -o-terphenyldiyl units in the main chain were synthesized. The polyamides were prepared from 4,4 -diamino-o-terphenyl and aromatic dicarboxylic acids or aromatic dicarbonyl dichlorides. The polyimides were prepared from 4,4 -diamino-o-terphenyl and aromatic tetracarboxylic dianhydrides. Copolyamides and copolyimides were also prepared using 4,4 -diamino-o-terphenyl...
Blends of a thermotropic liquid crystalline polymer (TLCP), [poly(ester amide), PEA, Vectra B950 from Hoechst Celanese] and poly(ether imide) (PEI, Ultem 1000 from G.E.) with the compatibilizer [poly(ester imide), PEsI] were extruded in a twin-screw extruder. The extruded strands were evaluated in terms of morphology and mechanical properties. The morphology of the compatibilized in situ composites...
The development of morphology from pellet-sized particles to submicrometre droplets during the polymer blending process is investigated for several polymer blends. In order to determine the morphology at short mixing times, a model experiment is developed that allows the matrix to be dissolved away so that the dispersed phase may be observed directly using scanning electron microscopy. The dispersed...
A systematic study of the terpolymerization of butyl acrylate/methyl methacrylate/vinyl acetate (BA/MMA/VAc) is being conducted. In the first stage of this study, bulk copolymerizations of BA/MMA, BA/VAc and MMA/VAc were performed. The polymers produced were characterized for conversion, composition and molecular weight. For the vinyl acetate-containing copolymerizations, during the first period...
Rotating frame 1 H n.m.r. spin-lattice relaxation times T 1 ρ have been used to study relaxation processes in partially crystalline polypropylene and polypropylene modified by a copolymer of ethylene and alkylaminoacrylate. Measurements were carried out within the temperature range of 250-420 K. Three relaxation times T 1 ρ were detected over the whole temperature...
Aqueous solutions of poly(vinyl alcohol) (PVA) were investigated by elastic and inelastic light scattering. In the initial stage of phase separation, a plot of the logarithm of scattered intensity against time formed a straight line when measurements were made in the sol region at less than the spinodal temperature estimated according to the method described by Cahn as being within the framework...
Microstructural details of poly(phenyl glycidyl ether) (PPGE) and its optically active form obtained by the aluminium isopropoxide (AIP)/ZnCl 2 ionic-coordinative initiator were analysed by nuclear magnetic resonance techniques. In order to assign the soluble fraction signals unmistakably, PPGE samples had to be synthesized using various cationic initiator systems. Several modifications...
Symmetrical aramid oligomers have been synthesized by dehalogenative polycondensation of two aryl dibromides containing primary amide structural units as monomers in the presence of electrogenerated zerovalent nickel acting as a catalyst. As the oligomers obtained were insoluble in organic solvents, they were characterized by solid-state n.m.r. spectroscopy, infra-red spectroscopy and elemental analysis...
Electrodeposited polypyrrole films prepared with paratoluenesulfonate (pTS), dodecylsulfate (DDS) and perchlorate anions were treated with acidic and basic solutions, and their structure was investigated by 13 C solid state n.m.r. spectroscopy. This technique has confirmed that pTS is completely removed from the film in both acidic and basic solutions whilst DDS is only partially removed and...
The electrical properties of poly(ethylene oxide) gels incorporated with CuCl 2 and polypyrrole were investigated with respect to temperature, concentration of CuCl 2 and the degree of crosslinking. Highly conducting gels were obtained even at low concentrations of CuCl 2 and polypyrrole. The activation energy for conduction and effect of crosslinking and swelling in methanol...
The strong colour of polydiacetylene polymer crystals is due to the backbone exciton. The energy of the exciton is strongly affected by Coulombic interactions with the surrounding crystalline environment. X-ray diffraction and optical absorption measurements of the blue phase polymer crystals of 4BCMU show that a change in the energy of the polydiacetylene backbone exciton can be related to a change...
Contemporary theoretical considerations of glass transitions in miscible binary polymer blends give the thermodynamic functions associated with the excess properties of mixing in liquid and glass states. A striking feature of the present analysis is that fewer assumptions are involved in the derivations. The values of the new parameters are reported for a number of polymer pairs, representing various...
The renaturation level of gelatin films was determined by calorimetry and polarimetry. Good agreement was observed for films made with conventional gelatins. A significant discrepancy was found on desiccated films (4% water), on films where KSCN had been added, and on films made with hydrolysed, chemically modified, or crosslinked gelatins. These results are discussed in relationship to the two techniques...
Rigid-rod networks containing 2,5-dialkyl substituted p-phenylene chains have been synthesized, either by the palladium-catalysed coupling of boronic acid end-group oligomers with tribromo aryls, or by the reaction of hydroxy- or acetoxy-terminated oligomers with tricar☐y or tricarbonic acid chlorides. The reaction products were characterized by nuclear magnetic resonance and Fourier transform infra-red...
The gas transport properties of three aromatic polyisophthalamides based on isophthaloyl chlorides and 4,4′-diaminodiphenylsulfone are reported at 35°C. The effects of bulky t-butyl and phthalimide substituents, at the 5 position of the isophthaloyl chloride moiety, on CO 2 , CH 4 , O 2 , N 2 , H 2 and He permeability, solubility and diffusivity were determined...
Thermally reversible macroporous poly(N-isopropylacrylamide) (polyNIPAAm) hydrogel has been synthesized in aqueous solution at a temperature above the lower critical solution temperature (LCST). Rapid swelling and deswelling kinetics of this macroporous hydrogel are characterized. Pore size measurement by a solute exclusion technique reveals that this macroporous hydrogel has a larger pore size distribution...
Small angle neutron scattering has been used to determine the dimensions and extent of aggregation of dilute solutions of sodium sulfonated polystyrene (SPS) ionomers of molecular weight 10 5 g mol −1 and sulfonation levels of 0.95 and 1.65 mol% in p-xylene. At concentrations below 0.1 × 10 −2 g ml −1 the 0.95 mol% SPS was present as mainly single chains of considerably...