Copolymerization of α-methylstyrene with N-alkylmaleimides

Summary Alternating copolymers of -methylstyrene (-MeSt) with N-alkylmaleimides (RMI; R=Et, n-Pr, iso-Pr, n-Bu, n-Hex) were prepared in Calvet differential microcalorimeter under different monomer-to-monomer ratios in the feed using AIBN as initiator. The equilibrium constants of CT-complex monomers have low values: 0.02–0.05 L.mol^-1 but the mechanism of copolymerization indicates the participation of CT-complex. Equilibrium constants and rate of decomposition under the TGA conditions are not dependent on steric factors, but the rate of copolymerization decreases with the increase of bulkiness of alkyl substituent. In high conversion copolymerization it was observed that in the presence of an excess of homopolymerizable RMI, alternating copolymers are quantitatively formed prior to the formation of poly(RMI).Dedicated to Professor Dragutin Fle on the occasion of his 70th birthday     

Tensile shear strength of wood bonded with urea–formaldehyde with different amounts of microfibrillated cellulose

Urea–formaldehyde (UF) adhesive mixtures with a 5% suspension of microfibrillated cellulose (MFC) at 0.5, 1, 3, and 5 wt% loading levels based on the solid weight (62.4%) of the UF adhesive were prepared. Beech lamellas with dimensions of 5 mm×20 mm×150 mm were prepared from beech lumbers using a planer saw. The UF adhesive (E0 class) was mixed with the MFC using a magnetic stirrer to achieve a proper distribution of the MFC in the UF adhesive. The tensile shear strength of single lap-joint specimens bonded with UF adhesive containing MFC was determined in accordance with EN 205 (2003). The specimens bonded with UF adhesive containing the MFC showed better tensile shear strengths as compared to the control. As compared to the control specimens, the tensile shear strength of the specimens increased by 5.7% as 3 wt% of the MFC was incorporated into the UF adhesive. However, a further increment in the MFC content up to 5 wt% decreased the tensile shear strength of the specimens (−14.3% of control specimen). The MFCs were well dispersed in the UF resin and were cross-linked to form a network to reinforce the bond line, improving bonding performance.     

Electroless Plating of Carbon Nanotubes with Copper

A simple chemical method was employed to coat carbon nanotubes with a layer of copper. Due to the hydrophobic nature, large surface curvature, small diameter and large aspect ratio, it is difficult to gain continuous electroless plating layer on the surface of carbon nanotubes. In this paper, a series methods (oxidization, sensiti-zation and activation) are used to add active sites before electroless plating, and the adjustment of the traditional composition of copper electroless plating bath and operating condition can decelerate electroless plating rate. The samples before and after coating were analyzed using transmission electron microscopy and energy-dispersive X-ray spectroscopy. The results showed that the surface of carbon nanotubes was successfully coated with continuous layer of copper, which lays a good foundation for applying carbon nanotubes in composites.     

Reaction of γ-Tocopherol with Hypochlorous Acid

In addition to being a very good antioxidant, γ-tocopherol is also an excellent electrophile trap. This is a study of the reactivity of γ-tocopherol with hypochlorous acid/hypochlorite, a potential biological foe that is both an oxidant and an electrophile. Aqueous sodium hypochlorite (1.72 mmol; pH 7.4) was stirred with γ-tocopherol (0.12 mmol) in hexane for 2 min at room temperature. The following products were isolated: γ-tocopheryl quinone (0.6%), tocored (10%), 3-chloro-γ-tocopheryl quinone (14%), an ether dimer of 3-chloro-γ-tocopheryl quinone (0.4%), two isomers of 5-(5-γ-tocopheryl)-γ-tocopherol (3 and 2% respectively), 5-chloro-γ-tocopherol (14%) and two chlorinated dimers (14 and 24% respectively) which were identified as diastereomers of (3R,10R)-11a-chloro-2,3,9,10-tetrahydro-3,5,6,10,12,13-hexamethyl-3,10-bis[(4R,8R)-4,8,12-trimethyltridecyl]-1H-pyrano(3,2a)-8H-pyrano(3,2g)-dibenzofuran-14(7aH)(14aH)-one. The chlorinated dimers, 5-chloro-γ-tocopherol, 3-chloro-γ-tocopheryl quinone and its ether dimer are new compounds.     

Syntheses and characterizations of copolymers of dicyanoquinone methides with α-acetoxystyrenes

Summary 7,7-Dicyanoquinone methides (1a-b) copolymerized spontaneously with substituted -acetoxystyrenes (2a-b) in benzene at 60 °C to give alternating copolymers (poly(1a-b-co-2a-b)) with the molecular weights of 8–60×10⁴ in 42–66% yields. When these copolymers were heated under nitrogen, they eliminated acetic acid quantitatively at around 200 °C to be converted to the copolymers (poly(3a-d)) with olefinic bonds, which were characterized by infrared and nuclear magnetic resonance spectroscopy. Alternating copolymers and the corresponding copolymers with olefinic bonds were amorphous, and capable of being cast from their chloroform solutions into transparent, tough films.     

Fibre-forming properties of melts of polypropylene—Copolymer of ethylene with vinyl acetate blends

The rheological properties of melts of PP—CEVA blends include a decrease in the viscosity and an increase in the elasticity due to the specific features of fibre formation in flow of melts of the blends. The orientational draw ratio of composite PP—CEVA monofilaments increased in comparison to the λ of monofilaments of the starting polymers. Fibres with higher (by 1.6 times) strength and higher (by 2 times) initial modulus than for fibres of the starting PP can be obtained by spinning from a melt of PP—CEVA mixture. Ukraine State Academy of Light Industry, Kiev. Translated fromKhimicheskie Volokna, No. 1, pp. 18–20, January–February, 1999.     

Reaction of Sillimnite with Alumina at Elevated Temperatures

The reaction of sillimanite with alumina at temperatures 1650℃ an 1750℃ has been investigated.The results have shown that,in the laboratory test conditions,the higher the alumina content,the lower will be the amounts of glass-phse of the fired body and the higher will be the formation of mullite .In the present tests,however,the reaction in concern has not been completed,the reaction in concern has not been completed.Some uncombined residual alumina still exist in the form of corundum.     

Chinese Petroleum Enterprises Meet with Query of Monopoly

Previously when the voices of anti-mo-nopoly were on the rise,some peoplewould always stand out arguing in fa-vor of monopoly groups while this timeas the voices of anti-monopoly once     

Rheological behavior of liquefied α-cellulose with phenol

The steady rheological behavior of phenol-liquefied cellulose product (LCP) at varying liquefaction times was investigated at three testing temperatures. The LCP presented interesting rheological behavior. When liquefaction time was longer than 45?min, the LCP showed stronger shear-thinning behavior with increasing temperature, and the viscosity at high testing temperature was higher than that at low testing temperature at low shear rates. An experiment with a heating and cooling cycle indicated that LCP would form reversible association structures when temperature increased. The mechanism of the reversed rheological behavior of LCP may be attributed to the association of alkyl chain parts of liquefied cellulose when heating.     

Reactions of α -sulfone disulfides with sulfinate anions

Degenerate substitution reactions (at carbon) between the appropriate sulfinic acid salts and tosylmethyl methyl or mesylmethyl methyl disulfides have formed symmetrical disulfone disulfides in moderate yields. These products form in a redox process involving sulfinate anions following partial skeletal disassembly arising from rupture of the SS bond. The reaction of mesylmethyl methyl disulfide and sodium methanesulfinate provides a natural product, dysoxysulfone, in low yield.     

Studies on Macro-kinetics of Gas Phase Polymerization of Butadiene with Rare-earth Catalyst

The study of the kinetics of gas phase polymerization of butadiene with heterogeneous catalyst based on neodymium (Nd) was carried out. The effects of reaction temperature, reaction pressure, dispersing medium, and types of catalyst on kinetics of polymerization were investigated. A kinetic model with two kinds of active sites was proposed. The results show that the effects of the reaction temperature and the types of dispersing medium and catalyst on the kinetic performance of polymerization are significant, and that the combined model of first and second order decay of active site of catalyst can be used to describe the phenomena.     

Synthesis of solid resorcinol–formaldehyde resin modified with styrene with the use of a shale phenol fraction with a boiling temperature higher than 270°C

The synthesis of modified solid resorcinol–formaldehyde resins based on resorcinol and a fraction of water-soluble shale alkylresorcinols (T_b > 270°C) was studied. Styrene was used as a modifier. Data on the quality of the target products depending on a molar ratio between the initial components were acquired.     

Hydroformylation of olefins with water-soluble rhodium catalysts in the presence ofα-cyclodextrin

Hydroformylation of hex-1-ene using a water soluble rhodium catalyst HRh(CO)[PPh₂(m-C₆H₄SO₃Na)]₃ (HRh(CO)(TPPMS)₃) (I), gives lower yields when-cyclodextrin is added to the biphasic reaction system implying an interaction between the cyclodextrin and rhodium catalyst.     

Copolymerization of butadiene and isoprene with TMEDA as modifier

以正丁基锂(n-BuLi)为引发剂,N,N,N',N＇-四甲基乙二胺(TMEDA)为调节剂,环己烷为溶剂,通过负离子聚合制备了丁二烯和异戊二烯的共聚物.结果表明,随着TMEDA用量的增加,聚合速度加快,丁二烯单体竞聚率增加,异戊二烯单体竟聚率减少,二者差值逐渐增大,在TMEDA/n-BuLi(摩尔比)不小于0.8时,这种变化趋势变缓,表明共聚物分布不均匀程度增加.     

Electrochemical Analysis of Ion-Exchange Membranes with Respect to a Possible Use in Electrodialytic Decontamination of Soil Polluted with Heavy Metals †

Abstract

Transport numbers in different metal chloride solutions were estimated using the emf method for two ion-exchange membranes: Ionics CR67 HMR412 (cation-exchange membrane) and Ionics AR204 SXRA 7639 (anion-exchange membrane). The cation-exchange membrane was found to work nearly ideally for NaCl and CaCl₂ solutions even at high concentrations, whereas deviation from ideality was seen for ZnCl₂ and CuCl₂ solutions. The anion-exchange membrane showed transport numbers for the anion around 0.95 for NaCl, CaCl₂ and ZnCl₂ solutions for the concentration range investigated. Electrodialytic desalting experiments taken as a simplified simulation of the electrokinetic decontamination method showed that it was possible to remove all ions in the simulated soil volume, with a sharp increase in the potential difference over the soil volume as a result, and that it was possible to control the metal content in the different solutions in the electrodialytic decontamination method.

     

Improved Dyeing with Redox Systems: IV—dyeing of nylon-6 with disperse dyes

The dyeing of nylon-6 fabric with Terasil Red 2GL (CI Disperse Red 72), in the absence and presence of redox systems based on ammonium persulphate [(NH₄)₂S₂O₈] as oxidant and potassium pyrosulphite (K₂S₂O₅), glucose (C₆H₁₂O₆) or thiourea (CH₄N₂S) as reductant, was studied. It was found that for a given set of dyeing conditions the colour strength, expressed as K/S, follows the order

Increasing the (NH₄)₂S₂O₈ concentration (0.00–0.03 m ) as well as the duration (15–60 min) and temperature (65–95° C) of the dyeing process caused significant enhancement in the colour strength and dye fixation. It is postulated that the presence of (NH₄)₂S₂O₈ alters the mode of dye interaction. In the presence of the oxidant component, i.e. (NH₄)₂S₂O₈ , attachment of the disperse dye to the nylon-6 substrate seems to involve covalent bonding in addition to the usual hydrogen bond. This is indicated by the significant colour strength remaining after DMF extraction for dyeings obtained using different disperse dyes and in the presence of (NH₄)₂S₂O₈. A free-radical mechanism for the covalent bond formation between nylon-6 and the disperse dyes is tentatively suggested.     

Kinetics and Mechanism of Copolymerization of α-terpineol with Methylmethacrylate in Presence of Azobisisobutyronitrile as an Initiator

The radical copolymerization of -terpineol with methyl-methacrylate in xylene at 80±0.1C for 50 minutes in the presence of azobisisobutyronitrile (AIBN) follows ideal kinetics and results in the formation of a functional and random copolymer. The activation energy is 33 KJ/mole. The IR spectrum and NMR spectra of the copolymer(s) shows the bands at 1750 and 3400 cm^–1 for ester group of methylmethacrylate and alcoholic group of -terpineol and peaks at 3 to 4 for methoxy group and at 6.5 to 7.5 due to alcoholic group of methylmethacrylate and -terpineol repectively. The values of reactivity ratios, calculated by Kelen–Tüdos method, are r ₁ (MMA) = 0.18 and r ₂ (-terpineol) = 0.046. The Alfrey-Price; Q–e parameters for -terpineol has been calculated as 0.149 and 2.486. The mechanism of copolymerization has been elucidated and it is concluded that the double bond present in the monocyclic ring of -terpineol is an active site for copolymerization and the alcoholic group of -terpineol remain to give functional copolymer.