1999 рік

The effects of maleic anhydride (MA) content and its reactive functionality on the phase size and phase morphology of nylon 6,6/ polypropylene (PP) blends were studied. The blends were obtained by simultaneous compounding of maleated styrene–ethylene–butylene– styrene block copolymers (SEBS) containing different amounts of MA, with nylon and PP. The microstructures were examined using crosspolarized transmission optical microscopy (TOM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Both tensile and fracture properties of the maleated blends were reported and discussed in terms of the morphological features uncovered by these microscopic techniques. Tensile strength increased with MA-grafted SEBS content in the 75/25 nylon 6,6/PP blends but a reverse trend was observed in the 50/50 nylon 6,6/PP blends. It was thought that this was caused by the migration of the functionalized styrenic block copolymers from the PP phase to the dispersed nylon domains in the 50/50 nylon 6,6/PP blends. An optimized morphology was found when SEBS grafted with 0.74 wt% MA was blended with 75/25 nylon 6,6/PP. At this composition, SEBS inclusions were dispersed uniformly in the continuous nylon matrix and thin layers of SEBS molecules also existed at the nylon-PP interface. The latter gave a morphology similar to a core-shell rubber modified structure (i.e. SEBS shell and PP core) and imparted the highest fracture toughness to this blend with an optimal combination of tensile strength and ductility.

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Poly(5,6-dihexoxyisothianaphthene) (PDHOITN) is synthesized by introducing hexoxy groups on 5 and 6 positions on the repeat unit of poly(isothianaphthene) (PITN) in order to improve its solubility and processability. The PDHOITN film has a band gap of about 0.95 eV and exhibits a high contrast and reversible color change from bluish black at the neutral state to transparent light yellow (close to colorless) at the doped state. Both the neutral and doped states of this polymer can be dissolved in common organic solvents and cast into free standing film. After doping with ferric chloride, the conductivity of the film increases 5 × 10 ⫺5 to 2 × 10 ⫺2 S/cm.

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Polyhexamethylene guanidine hydrochloride and polyhexamethylene biguanidine hydrochloride were polycondensated in the melt of  n were determined by the viscosity of dilute polymer solution and VPO, respectively. Polyhexamonomers. The intrinsic viscosity and M methylene guanidine stearate and polyhexamethylene biguanidine stearate were synthesized using the precipitation reaction for the first time. NMR, FTIR, XPS and element analysis were used to analyze the chemical structure and element composition. The structure of the resultant polymers is coincident with the theoretic structure. The minimal inhibition concentration (MIC) was measured to characterize the antimicrobial activity of the products. The MIC is not larger than 200 mg ml 21. The polymeric guanidine and biguanidine are effective in controlling bacteria and fungi. The TG test shows that the resultant polymers are stable to heat.

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The adsorption parameters (a) for members of four classes of saturated hydrocarbons were compared with those observed for the corresponding ethers. The saturated hydrocarbon liquids exhibit a measurable affinity for polystyrene, as indicated by the linear relationships log a f ¼ log a i ¹ D s(N f ¹ N i), each characteristic of the homologous series being considered. These values increase from the linear series H(CH 2) nH (a i ¼ 0.10 ⫾ 0.02; D s ¼ 0.00 ⫾ 0.02) to those having the greatest affinity, members of the cyclic series (CH 2) n, where a i ¼ 0.863 and D s ¼ 0.0875. Even the latter, however, are considerably below the values for the corresponding cyclic ethers (CH 2) nO (a i ¼ 3.31; D s ¼ 0.0888), demonstrating the superiority of an oxygen atom and a methylene unit in affinity for the polymer’s phenyl group.

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Anthracene-photosensitized cationic polymerization of cyclohexene oxide at l ˆ 350 nm in conjuction with onium salts, namely Nethoxy-2-methyl pyridinium hexafluorophosphate (EMP ⫹PF6⫺) or diphenyliodonium hexafluorophosphate (Ph2I ⫹PF6⫺), in the presence of a stable radical, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), yielded polymers with alkoxyamine terminal groups. These polymers were found to be efficient initiators for stable free radical polymerization (SFRP) of styrene. IR, 1H-NMR spectral analysis and GPC studies of the obtained polymers show that block copolymers are readily formed as a result of combination of photosensitized cationic and stable free radical polymerization mechanisms.

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The conformational changes of the backbone as well as the side chains of poly(di-n-hexylsilane) during the isothermal crystallization from the disordered phase was investigated. The backbone reorganization was detected by fluorescence and UV, while the side-chain reorganization was detected by IR. It was found that the backbone reorganization begins to occur prior to the side-chain reorganization. This trend is observed for all the crystallization temperatures investigated. At lower temperatures, the difference in the time of reorganization was not very large, but at higher temperatures the difference becomes larger.

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a,q-Hydroxy-terminated vinyl prepolymers were prepared by radical polymerization of methyl methacrylate, butyl acrylate, styrene and vinyl acetate in the presence of allyl alcohol. The butyl acrylate prepolymer of molecular weight 3100 and functionality 2.2 was prepared by the following condition; [BA] ¼ 3.85 mol/l, [ACPROL] ¼ 0.128 mol/l and [AA] ¼ 0.90 mol/l at 110°C. The polyurethane reactions of the resulting telechelic polymers with hexamethylene diisocyanate were carried out to obtain vinyl polymer-based polyurethanes.

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Broad line proton magnetic resonance (PMR) has been used for the study of molecular motion in wholly aromatic thermotropic liquidcrystalline (LC) copolyester at high temperatures up to 340°C. Specimens were thin highly oriented fibers produced from a copolymer of hydroxybenzoic acid and hydroxynaphthoic acid (HBA/HNA). In the vicinity of the thermotropic transition temperature a fine structure of PMR spectra was revealed for as-spun fibers. Annealing leads to smoothing of this structure. Theoretical spectra were calculated and compared with the experimental ones. This made it possible to obtain information on large-scale segmental motion of macromolecules in the LC phase. Heat treatment leads to retardation of the chain cooperative mobility. Dynamic inhomogeneity of the fibers at high temperatures is discussed.

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The transport of nitric oxide (NO) in various plasticized and unplasticized polymeric films (silicone rubber, plasticized and unplasticized polyurethane, plasticized poly(vinyl chloride) and plasticized cellulose triacetate) is examined, and apparent NO diffusion coefficients are reported for each of the polymer compositions studied. Diffusion coefficients are found to range from ca. 2.5 × 10 26 cm 2/s in low weight percent plasticizer films to 3.0 × 10 25 cm 2/s in silicone films. The variation in NO diffusion rates through different polymer systems is explained by considering the characteristics of the polymers and, when applicable, the influence of plasticizer content. The newly measured values reported here should promote the rational choice of appropriate polymeric matrices for specific NO mass transfer applications.

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Regioregular organocobalt polyethers (3 and 4) and polyesters (5–8) have been prepared by the polycondensation of regioisomerically pure (h 4-tetraarylcyclobutadiene)cobalt-containing bis-phenols (9 and 10) with aliphatic or aromatic comonomers. The diols (9) offered rigid-rod p-terphenyl-like structural units, while their isomers (10) led to 90° kinks in polymeric backbones. The polymers (3, 5 and 7 ¼ 'odd’ series) were derived from the bis-phenols (9), while their isomers (4, 6 and 8 ¼ 'even’ series) resulted from 10. Most of the polymers (3–8) exhibited good solubilities in common organic solvents. In the case of the isomeric polyesters with aromatic backbones (7 and 8), the latter were more soluble, indicative of their higher configuration entropies. Glass transition temperatures of the 'odd’ and 'even’ isomers were similar, irrelative to the kinks in their backbones, but they showed good correlation with aliphatic-to-aromatic mass ratios and rigidities of the main chains. The polymers of the 'odd’ series exhibited crystalline and liquid crystalline (polyesters, 7) phases, while their 'even’ isomers remained amorphous. Correlations between mesomorphic properties and the structure of the repeating units have been discussed.

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