New approach to processing of chlorine-containing wastes: Synthesis of 2,3-dichloropropene from 1,2,3-trichloropropane

Possibilities of utilization of by-products formed in manufacture of epichlorohydrin are considered. A promising way to utilize wastes from production of epichlorohydrin by synthesis of 2,3-dichloropropene from 1,2,3-trichloropropane is suggested.     

Electrohydrodynamic instability in some nematic cyanobiphenyls in an a.c. electric field

Electrohydrodynamic instability in homeotropically oriented nematic samples of 4'-n-octyl-4-cyano-biphenyl and 4'n-alkyloxy-4-cyanobiphenyl, (n = 8.9) have been studied in an a.c. electric field. The domain patterns during the instability in these compounds in a very low frequency a.c. field are very similar to those in a d.c. field. The domain patterns observed at higher frequencies have been identified as 'maltese crosses' or 'crossed isogyres'. The electro-convective 'isotropic' flows near the electrode play an important role in the observed instability.     

Combined supercritical-fluid chromatography/mass spectrometry in the analysis of diuron in plasma using on-line phase-system switching

On-line sample pretreatment by means of the phase-system switching approach is an interesting technique for the analysis of aqueous samples, e.g., plasma, by means of supercritical-fluid chromatography. In order to analyse plasma samples the following analytical procedure is used. The plasma sample is injected on to a short precolumn, which is washed with water and subsequently dried with nitrogen. Next, the solutes are desorbed with the supercritical mobile phase, analysed with packed-column supercritical-fluid chromatography and detected with either a UV detector or a mass spectrometer, equipped with a moving-belt interface. The herbicide diuron is selected as a test compound to study the feasibility of this approach. Using a selective detector the procedure is sufficiently sensitive to detect diuron in plasma, but not appropriate to detect the diuron metabolites in a post-mortem plasma sample. These have been identified with liquid chromatography/mass spectrometry. The detection limit of diuron in plasma using the procedure described is about 30 ng/mL.     

Effect of Conditions of Electric-Spark Dispersion of Zinc on the Quality of the Product Obtained

Influence exerted by additives introduced into the working solution, by iron or copper formedin electric-spark dispersion of these metals and zinc, on the quality of the products obtained in electric erosionwas studied.     

Banana-shaped mesogens: a new homologous series of compounds exhibiting the B7 mesophase

The synthesis and characterization of a new homologous series of compounds, the 2-cyano-1,3-phenylene bis[4-(4-n-alkoxyphenyliminomethyl)benzoates] derived from 2-cyanoresorcinol is reported. All the compounds are enantiotropic mesogens and exhibit the fascinating B₇ mesophase. The characterization of the mesophase was performed using polarizing optical microscopy, differential scanning calorimetry, X-ray diffraction and electro-optical studies.     

Photochemical attachment of polymers on planar surfaces with a covalently anchored monolayer of a novel naphthyl ketone photochemical radical generator

A monolayer of covalently anchored, novel, binaphthyl ketone is used as a surface‐confined photochemical radical generator (PRG) for anchoring a variety of polymers to silicon surfaces. The precursor PRG is synthesized by the application of a facile and novel method for the oxidation of sterically hindered benzylic hydrocarbons to carbonyl compounds. Oxidation was carried out with a stoichiometric amount of potassium peroxydisulfate, in the presence of a catalytic amount of copper sulfate in an acetonitrile/water mixture. The PRG synthesized is characterized by ¹H NMR, UV, and Fourier transform infrared (FTIR). The covalently attached monolayers are characterized by X‐ray photoelectron spectroscopy, ellipsometry, and water contact angle measurements. The method developed is applicable to the preparation of a monolayer of a variety of polymers on a wide range of substrates carrying surface hydroxyl groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5413–5423, 2004     

New liquid‐crystalline poly(ester amide)s: The role of nitro groups in the phase behavior

New hydrogen‐bonded liquid‐crystalline poly(ester amide)s (PEA)s were obtained from 1,4‐terephthaloyl[bis‐(3‐nitro‐N‐anthranilic acid)] (5) or 1,4‐terephthaloyl[bis‐(N‐anthranilic acid)] (6), with or without nitro groups, respectively, through the separate condensation of each with hydroquinone or dihydroxynaphthalene. The dicarboxylic monomers were synthesized from 2‐aminobenzoic acid. The phase behavior of the monomers and polymers were studied with differential scanning calorimetry, polarized light microscopy, and wide‐angle X‐ray diffraction methods. Monomer 5, containing nitro groups, exhibited a smectic liquid‐crystalline phase, whereas the texture of monomer 6 without nitro groups appeared to be nematic. The PEAs containing nitro groups exhibited polymorphism (smectic and nematic), whereas those without nitro groups exhibited only one phase transition (a nematic threaded texture). The changes occurring in the phase behavior of the polymers were explained by the introduction of nitro groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1289–1298, 2004     

The effect of compatibilization and rheological properties of polystyrene and poly(dimethylsiloxane) on phase structure of polystyrene/poly(dimethylsiloxane) blends

The compatibilization effect of polystyrene (PS)‐poly(dimethylsiloxane) (PDMS) diblock copolymer (PS‐b‐PDMS) and the effect of rheological properties of PS and PDMS on phase structure of PS/PDMS blends were investigated using a selective extraction technique and scanning electron microscopy (SEM). The dual‐phase continuity of PS/PDMS blends takes place in a wide composition range. The formation and the onset of a cocontinuous phase structure largely depend on blend composition, viscosity ratio of the constituent components, and addition of diblock copolymers. The width of the concentration region of the cocontinuous structure is narrowed with increasing the viscosity ratio of the blends and in the presence of the small amount diblock copolymers. Quiescent annealing shifts the onset values of continuity. The experimental results are compared with the volume fraction of phase inversion calculated with various theoretical models, but none of the models can account quantitatively for the observed data. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 898–913, 2004     

Viscoelastic behavior of polypropylene/nitrile rubber thermoplastic elastomer blends: Application of Kerner's models for reactively compatibilized and dynamically vulcanized systems

The viscoelastic properties of binary blends of nitrile rubber (NBR) and isotactic polypropylene (PP) of different compositions have been calculated with mean‐field theories developed by Kerner. The phase morphology and geometry have been assumed, and experimental data for the component polymers over a wide temperature range have been used. Hashin's elastic–viscoelastic analogy principle is used in applying Kerner's theory of elastic systems for viscoelastic materials, namely, polymer blends. The two theoretical models used are the discrete particle model (which assumes one component as dispersed inclusions in the matrix of the other) and the polyaggregate model (in which no matrix phase but a cocontinuous structure of the two is postulated). A solution method for the coupled equations of the polyaggregate model, considering Poisson's ratio as a complex parameter, is deduced. The viscoelastic properties are determined in terms of the small‐strain dynamic storage modulus and loss tangent with a Rheovibron DDV viscoelastometer for the blends and the component polymers. Theoretical calculations are compared with the experimental small‐strain dynamic mechanical properties of the blends and their morphological characterizations. Predictions are also compared with the experimental mechanical properties of compatibilized and dynamically cured 70/30 PP/NBR blends. The results computed with the discrete particle model with PP as the matrix compare well with the experimental results for 30/70, 70/30, and 50/50 PP/NBR blends. For 70/30 and 50/50 blends, these predictions are supported by scanning electron microscopy (SEM) investigations. However, for 30/70 blends, the predictions are not in agreement with SEM results, which reveal a cocontinuous blend of the two. Predictions of the discrete particle model are poor with NBR as the matrix for all three volume fractions. A closer agreement of the predicted results for a 70/30 PP/NBR blend and the properties of a 1% maleic anhydride modified PP or 3% phenolic‐modified PP compatibilized 70/30 PP/NBR blend in the lower temperature zone has been observed. This may be explained by improved interfacial adhesion and stable phase morphology. A mixed‐cure dynamically vulcanized system gave a better agreement with the predictions with PP as the matrix than the peroxide, sulfur, and unvulcanized systems. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1417–1432, 2004