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The hydrolysis, sulfonation and crosslinking modification of a poly(styrene-co-acrylonitrile) copolymer in one step was studied. An extremely vigorous process has been developed for the preparation of a series of hydrophilic gels bearing strongly and weakly acidic groups on the same polymer backbone. The products were characterized using infra-red spectra, scanning electron microscopy, elemental...
The changes in intrinsic oxidation state ([=N-] and [-NH-] content) and protonation level ([N + ] ratio) of emeraldine (EM) base powders as a function of protonic acid loadings resulting from the protonation-deprotonation cycle have been assessed quantitatively by X-ray photoelectron spectroscopy. A hysteresis effect was observed for the protonation-deprotonation cycle involving HCl, but...
Using kinetic and mechanistic monitoring by high-performance liquid chromatography and 13 C nuclear magnetic resonance, we have shown that in formaldehyde-free conditions the reactivity of substituted phenols towards condensation reactions arises from several factors. In particular, the groups reacting among themselves may be of two types: either a non-substituted ortho or para aromatic...
We have studied the addition of formaldehyde to the various phenolic monomers present in a phenol-formaldehyde system under conditions of constant temperature, pH and catalyst type. The techniques used, carbon-13 nuclear magnetic resonance and high-performance liquid chromatography, enabled us to show the effect of aromatic ring substitution on the reactivity of sites that can potentially react....
A detailed re-examination of the photo-oxidation mechanism of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) at both long and short irradiation wavelengths under accelerated conditions is reported. The formation rate of polydimethylphenoxy (PDMP) radicals is observed both in the presence and in the absence of ultra-violet (u.v.) light by using electron spin resonance spectroscopy. In order to explain...
The kinetics of the aqueous polymerization of methacrylamide has been studied under an inert atmosphere employing the potassium peroxodiphosphate-cysteine hydrochloride redox pair. The order with respect to monomer and activator has been found to be unity and initiator showed half order. The polymethacrylamide samples collected under different kinetic conditions have been used for the determination...
A proposed evaluation of the extent of interfacial debonding in binary blends is based on the comparison of tensile (or yield) strength with model predictions. The predictive scheme employs a two-parameter mechanically equivalent model and data on the phase continuity of constituents acquired from percolation theory. The upper and lower bounds of strength are related, respectively, to interfacial...
Vapour-phase chemical polymerization of pyrrole was investigated in which a cotton thread coated with FeCl 3 oxidant was exposed to pyrrole vapour and the electrical resistance of this conductive polypyrrole supported on cotton thread was measured using a specially designed four-point probe. The relationships of the resistance of the polypyrrole supported on cotton thread with various experimental...
Blends of aliphatic polyamide PA 46 and aromatic polyamide PA 6I were obtained by coprecipitation from a common solvent and by melt mixing using a mini-extruder. The polyamides were found to be fully miscible by both blending methods. However, there are large differences in crystallization and melting behaviour when the blends obtained by the two methods of blending are compared to each other. ...
The morphology of multiphase polypropylene copolymers, called impact polypropylenes, was studied by 129 Xe nuclear magnetic resonance (n.m.r.) spectroscopy. The impact polypropylenes studied were composed of polypropylene homopolymer and ethylene-propylene rubber (EPR). The xenon atom is non-polar and is soluble only in the non-crystalline regions of semicrystalline polymers. ...
A vinyl ester resin (VER) with negligible carboxyl and hydroxyl groups was prepared from bisphenol A epoxy resin and α-methacrylic acid in combination with styrene. Simultaneous interpenetrating polymer networks (SINs) consisting of this VER and polyurethane (PU) could be obtained with negligible intercomponent chemical binding between the two networks. The synthetic courses of these SINs were monitored...
Differential scanning calorimetry (d.s.c.), dynamic mechanical thermal analysis (d.m.t.a.) and dielectric relaxation spectroscopy (DRS) have been used to study the α-relaxation in amorphous blends of poly(ether ether ketone) (PEEK) and poly(ether imide) (PEI). The composition dependence of the d.s.c. T g is well described by the Couchman and Gordon-Taylor equations while the isothermal dielectric...
Hydrogels were prepared by simultaneous graft copolymerization on amylose of 2-hydroxypropyl methacrylate with different acrylates (methyl acrylate, ethyl acrylate and butyl acrylate) using ceric ammonium nitrate as initiator. Similarly, another series of grafted samples with a 50 (mol/mol) composition of hydroxylic/non-hydroxylic monomers with 34 mol% of ethylene glycol dimethacrylate were prepared...
Freeze-drying of polylactide solutions in 1,4-dioxane has been studied as a way to produce microcellular foams. The thermally induced phase separation has been studied in relation to several processing and formulation parameters. The effects of polymer concentration, chain stereoregularity, polymer molecular weight and cooling rate have been investigated in connection with the porous morphology...
The kinetics of water uptake into the dry form of, and benzoic acid diffusion through, swollen inhomogeneous poly(acrylonitrile-acrylamide-acrylic acid) gels were investigated with gravimetry and ultra-violet visible spectroscopy, respectively. The goal is to understand the effects of ionizable moieties and water-polymer affinity on the rate of water diffusion during the formation of hydrogels from...
The evolution of the global orientation parameter for a series of aqueous hydroxypropylcellulose solutions both during and following the cessation of a steady-state shear flow is reported. Time-resolved orientation measurements were made in situ through a novel X-ray rheometer coupled with a two-dimensional electronic X-ray camera, and using an intense X-ray source at the LURE synchrotron. After...
Six thermotropic liquid-crystalline polymers (TLCPs) were spun on a CSI 194 Mini-Max extruder in their optimized spinning-temperature ranges. Based on the diameter and the diameter distribution of the resultant fibres, these TLCPs were classified into two groups with good and poor spinnability, respectively. The viscosity ratio of TLCP to matrix resin, η dm , in the optimized spinning-temperature...
Light scattering and viscosity measurements have been conducted on polystyrene samples (guest polymer) in pure toluene and in the isorefractive mixture toluene-poly(methyl methacrylate). The second polymer (host polymer) is present at constant concentration in the solution. In the dilute solution region in which the measurements are conducted, only when the solution flows does the host polymer provoke...
The influence of temperature on the photopolymerization kinetics of three analogous monomers, 2,2 -thiobisethanol diacrylate, 2,2 -oxybisethanol diacrylate and 1,5-pentanediol diacrylate, has been studied by isothermal differential scanning calorimetry in the temperature range of 30-100°C in air and in Ar atmosphere. The presence of the heteroatom markedly enhances the final conversion and maximum...
The polymerization of three analogous monomers--2,2 -thiobisethanol dimethacrylate, 2,2 -oxybisethanol dimethacrylate and 1,5-pentanediol dimethacrylate--has been studied in the temperature range 30-95°C by isothermal d.s.c. The temperature and heteroatom effects on the polymerization course were considered from the point of view of the occurrence and relative importance of hydrogen abstraction...
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