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The coil-globule transitions of random (statistical) and alternating copolymers of styrene and methyl methacrylate in their theta solvents, cyclohexanol and 2-ethoxy ethanol were studied by using dynamic light scattering technique. The dimensions of the copolymeric chains show smooth and continous contractions below θ temperatures. The hydrodynamic size, R h , of a random copolymer P(St-co-MMA)...
We have developed a new method for preparing conducting polyaniline (Pani) films and investigated their chemical and physical properties by means of UV-Vis, FT-IR, EPR, XPS, and dc conductivity measurements. Conducting polyaniline films are prepared by casting from the solution of polyaniline with lithium salt. The free-standing films have relatively high dc conductivity without further treatment...
The diffusion coefficient, D, of a typical UV-absorbing stabiliser has been measured in a series of poly(ester-block-ether) copolymers (PEBEs) with different fractions of the polyether blocks, by using ultra-violet microscopy to monitor the concentration profile of the additive diffused into the edge of a thin film of polymer over a range of temperatures. For all samples, D shows an Arrhenius dependence...
SEM micrographs of carbon black polymer composites have been analysed in terms of their fractal geometry. Acetylene black/ethylene butylacrylate copolymer samples have a fractal dimension of about 1.8 at low filler concentrations that increases to 2.1 at high concentrations. The numerical values indicate a cross-over from diffusion limited cluster aggregation (DLCA) to reaction limited cluster aggregation...
Crosslinkable polymer with host-guest and side chain system was investigated to increase the content of NLO chromophores in second order nonlinear optics. Though very low poling temperature has been applied, the observed UV absorption difference before and after poling was large due to low glass transition temperature of the polymer and high content of chromophores introduced by side chain and guest...
A series of hyperbranched polyacrylates were synthesized by self-condensing vinyl polymerization (SCVP) of 2-[(2-bromobutyryl)oxy]ethyl acrylate (BBEA). A tetrafunctional atom transfer radical polymerization (ATRP) initiator (THABI) capped with bromoisobutyrate, which has higher reactivity than the initiating site of monomer, was used as core-forming molecules. The structure and properties of the...
New toughened poly(butylene terephthalate) (PBT) materials were obtained by melt blending with poly(ethylene-octene) copolymer (PEO) and maleic anhydride grafted PEO (gPEO) in a twin screw extruder followed by injection moulding at two injection speeds. The presence of either PEO or gPEO did not influence either the nature of the PBT phase or the crystallisation of PBT. Low injection speeds (7cm ...
A study was carried out on the mechanical properties of silica filled styrene-butadiene rubber systems in relation to the secondary structure formed by silica particles in the systems, which was controlled by a surface chemistry of silica particles and by a strain applied to the samples. The breakdown of the secondary structure was successfully detected by transmission electron microscopy (TEM) observations...
Rodrun 5000/Vectra B950 blends were obtained by direct injection moulding at two injections rates. The blends were partially miscible and unreacted under the processing conditions used. Higher orientations and properties were obtained at the lower injection rate due to the higher overall orientation obtained. The produced orientation and the negative volume of mixing of the blends led to a range of...
A novel temperature-switchable vapor sensor was prepared by radiation-induced polymerization of N-isopropylacrylamide (NIPAAm) in an alcohol solution of calcium chloride (CaCl 2 ). The conductivity of the sensor material largely increased in water and ethanol vapors, but decreased against acetone, tetrahydrofuran, and chloroform vapors. The data showed a high level of reproducibility. In addition,...
Circumferentially notched specimens of a first generation and a third generation pipe-grade of high density polyethylene with similar weight average molar masses have been subjected to constant tensile loads at 80 o C. A transition from full ligament yielding to failure by stable sub-critical crack growth was observed as the applied load was decreased. The specimen lifetimes in this latter...
Three new polyfunctional TEMPO-based initiators have been synthesised by reaction of some mesitylene cores and 2,2,6,6-tetramethyl-1-(2-hydroxy-1-phenylethoxy)-piperidine. They have been employed in the living/controlled radical polymerisation of styrene to provide three- and six-arm star macromolecules. These polymers have molecular weight ranging from 6000 to 11000g/mol and narrow molecular weight...
Polymer layered silicate nanocomposites have been studied for nearly 50 years, but few references deal with the importance of how the organoclay was processed into the plastic of choice. Many articles focus on the importance of the chemistry used to modify the surface of the clay, usually montmorillonite, without including the role of processing. This paper demonstrates the importance of both the...
Differential Scanning Calorimetry has been used to study the isothermal crystallization kinetics and melting behaviour of PET. Kinetic analysis indicated that the overall crystallization of PET involved two processes, attributed to primary and secondary crystallization. Secondary crystallization occurred consecutively with primary and both processes obey different Avrami time dependences. The primary...
Strain induced crystallisation of poly(ethylene terephthalate) (PET) designed for stretch-blow moulding is studied combining well-controlled tensile tests, different quenching protocols and X-ray diffraction technique. As well known [Polymer, 33 (1992) 3182; Polymer, 33 (1992) 3189], crystallisation begins when a minimum strain has been reached. However, crystallisation is a progressive phenomenon...
Novel ethylene-propylene random copolymers with isotactic sequence of propylene were synthesized with a MgCl 2 -supported Cr(acac) 3 catalyst. The propylene content was controlled by the monomer concentration. The crystallinity of these copolymers showed a minimum around 50mol% content of propylene or ethylene. According to differential scanning calorimetry and wide-angle X-ray diffraction,...
Studies on the thermal behaviour of copolymers, poly(N-isopropyl acrylamide), PNIPA, grafted with different amounts of poly(ethylene oxide), PEO, were conducted in aqueous solutions by fluorescence and EPR spectroscopies. The grafting reaction had been conducted under various reaction conditions and the number of PEO grafts per a PNIPA chain varied from 6 to 10. A fluorescence probe, 4-(dicyano methylene)-2-methyl-6-(p-dimethyl...
The influence of electropolymerisation time, t p , on the synthesis, structure and morphology of polyfurane films doped with perchlorate anions, PFu/ClO 4 , was analysed. The analysis of the nucleation mechanism revealed a mixture of progressive and instantaneous nucleation of small hemispherical nodules controlled by spherical diffusion.The morphological study revealed an ordered...
Phosphonates, O,O-di-1-phenylethyl phenylphosphonate (1), O,O-di-tert-butyl phenylphosphonate (2), and O,O-dicyclohexyl phenylphosphonate (3), were examined as non-salt-type latent initiators in the polymerization of isobutyl vinyl ether (IBVE), phenyl vinyl ether (PVE), and tri(ethylene glycol) divinyl ether (DVE-3). The polymerization of IBVE and PVE did not proceed below 90 and 120 o C,...
The synthesis of diblock copolymers using atom transfer radical polymerization (ATRP), of methyl methacrylate (MMA), and butyl acrylate (BA), is reported. These copolymers were prepared from bromo-terminated macroinitiators of poly(MMA) and poly(BA), using copper chloride, CuCl,/N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDETA), as catalyst system, at 100 o C in bulk and in benzonitrile...
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