Polymer
A poly(ether imide) (Ultem), which is an amorphous engineering thermoplastic, was melt blended with two liquid crystalline polymers: one based on p-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid (Vectra A900) and the other based on phenylhydroquinone, ethylphenylhydroquinone and terephthalic acid (Granlar). The miscibility of these two blend systems was studied by means of differential scanning...
The chloromethylation of poly(methylsilane) is readily achieved using chloromethyl methyl ether in a tin(IV) chloride-catalysed reaction in chloroform solution at 0°C. A convenient, less hazardous reaction, in which chloromethyl methyl ether is prepared in situ, is also reported. The accompanying variations of the polymer molecular-weight parameters are recorded for chloromethylations extending...
Relaxation/transition behaviours for copolyesters made from poly(ethylene terephthalate) (PET) andp -acetoxybenzoic acid (POB) have been characterized by thermally stimulated current (TSC) measurement. The sequence distribution, in terms of the degree of blockiness, in dual chemidomains of POB/PET copolyester is simulated from a model developed by us to predict the probability between block sequence...
The critical concentration, c * , at which overlapping between macromolecular chains occurs, has been studied using dynamic (viscometry) and static (light scattering) methods. With the same polymer-solvent system this critical concentration has a higher value when viscometry is used, compared to the concentration obtained when using a light scattering technique. This difference is attributed...
For the purpose of developing an effective surface finish for copper, imidazole-silane copolymers were synthesized by radical copolymerization of 1-vinylimidazole and methacryl or styryl silane coupling agents. It was found that the reactivity of 1-vinylimidazole was very low as in the case of the copolymerization with styrene or other vinyl monomers. Monomer reactivity ratios obtained from Kelen-Tudus...
Drawn multifilament poly(ethylene terephthalate) yarn was heat-set isothermally at temperatures between 180 and 258°C in the slack and taut conditions. The apparent crystal widths of these samples in the undeformed state and when axially stretched by 5-40% were monitored by X-ray diffraction. Significant reduction of crystal width occurred in the [010] direction in samples heat-set at high temperatures...
A 1 3 C nuclear magnetic resonance study (with cross polarization and magic angle spinning) is presented of commercially available cellulose acetate and cellulose propionate as powder samples and also in different membranes. Some physical properties of the films are interpreted in the light of data obtained for the principal components of the shielding tensor of 1 3 C nuclei...
A model was developed for interdiffusion at interfaces of polymers with dissimilar physical properties. This model is based on the assumption that the monomeric friction coefficients of the two polymers are identical but a strong function of the matrix composition. The composition dependence of the monomeric friction coefficient was evaluated from the blend zero-shear viscosity using the reptation...
The intrinsic viscosity of poly(ethyl methacrylate) in isopropyl alcohol (propan-2-ol) around the theta (θ) temperature was measured using a capillary viscometer. Contraction and collapse were observed below the θ temperature. Because of experimental difficulties around the cloud point, mathematically curve-fitted experimental points were obtained instead of experimental data at lower temperatures...
The current demand for environmentally degradable composites has initiated the use of novel biodegradable copolyamides reinforced with E-glass fibres by using the hand lay-up technique. Differential thermal analysis, wide-angle X-ray diffraction patterns and density measurements were employed for the characterization of polymeric composites. The thermal properties of composites, namely T g ...
After synthesis, poly(seleno-p-arylene diamine)s were doped with chlorine. The polymers were studied before and after doping by X-ray photoelectron spectroscopy (X.p.s.), electron spin resonance (e.s.r.) and conductivity measurements. It is suggested that chain ends may be partly terminated by groups containing oxygen. After doping, there is charge transfer complex formation as shown by X.p.s. analysis...
The aqueous electrochemically initiated polymerization of pyrrole has been successfully performed on graphite fibres from a solution containing the monomer and toluene-4-sulfonic acid sodium salt. The effects of the initial monomer concentration, supporting electrolyte concentration and applied voltage on the rate of electropolymerization of pyrrole have been investigated in an attempt to ascertain...
In an earlier paper we considered the effect of polypropylene modified with maleic anhydride (MAGPP) on the properties of in situ composites based on polypropylene (PP) and a thermotropic copolyesteramide (Vectra B). In this paper we consider the effect of MAGPP on the properties of in situ composites based on PP and two different thermotropic copolyesters. It was observed that the MAGPP was nearly...
Inverse gas chromatography has been used to measure the thermodynamic interaction between poly(4-hydroxystyrene) (P4HS) and poly( -caprolactone) (PCL) at 190°C. The retention behaviour of the homopolymers and three blends (0.25, 0.5 and 0.75 P4HS volume fraction) was characterized for 13 probes. The polymer-polymer interaction parameter χ 2 3 calculated from the Scott-Flory-Huggins...
A two-dimensional ultrathin film was defined as being a film thinner than the dimension of an unperturbed Gaussian chain in the three-dimensional state. The segment density of an unperturbed chain in equilibrium in the two-dimensional solid state was investigated using a Monte-Carlo simulation. When the film thickness exceeds 30% of twice the radius of gyration of a three-dimensional unperturbed...
Potentiometric and calorimetric measurements on aniline polymerized by persulfate reveal an induction period, which may be decreased or eliminated by the addition of ceric (Ce I V ) ion. The addition of the second oxidizer appears to promote nucleation. The molecular weight and electrical conductivity of the resulting polyaniline were measured. Substantial shortening of the reaction...
Polymer-supported chiral oxazaborolidines bound to the polymer via the boron atom, have been prepared from a series of crosslinked polymers synthesized using 2-vinylthiophene. The polymer-supported oxazaborolidines were used to catalyse the reduction of prochiral ketones using the borane-dimethyl sulfide complex, a reduction which also occurs in the absence of catalyst to give racemic products. ...
The following theoretical equation has been obtained for measuring the rate of slow crack growth in polyethylene in terms of the crack opening displacement rate : = σ y (1 - γ 2 ) 2 ηd 0 E 2 σ 2 c K 4 Here σ y is the yield point, K is the stress intensity, η is the intrinsic viscosity of the fibrils in the craze, E is Young's modulus,...
The preparation of a new perfluoroalkylated diamine, 5-[1H,1H-2-bis(trifluoromethyl)heptafluoropentyl]-1,3-phenylenediamine, is described. Poly(amic acid)s and polyimides were prepared from this new diamine and polyimides were evaluated as films for electronics applications. The polyimides evaluated were found to yield low dielectric constant and low moisture absorption, but were found to have exceptionally...
The crystalline structures of a range of specially synthesized random copolyesters of poly(ethylene terephthalate) (PET) and poly(ethylene naphthalene-2,6-dicarboxylate) (PEN) have been studied. It is shown that this system has a crystallization and melting behaviour typical of random copolymers. Significant crystallinity can be induced in the copolymers of all compositions by hot drawing, even...