Characterization of Europium Complex-doped PMMA and PMMA-EVA Polymer Networks

Europium-β-diketone chelate doped poly(methyl methacrylate) and poly(methyl methacrylate)/poly(ethylene co-vinyl acetate) blends have been successfully prepared and characterized. The mechanical properties of the PMMA-EVA systems have been assessed in terms of tensile strength and impact strength. The thermal characteristics and the energy involved in thermal decomposition have been studied. The structural properties of the complex doped polymeric systems reveal that the complex exists in the same crystalline state in the doped systems as it does in the pure state. The orientations of the groups in the host matrix have been found to be affected by the complex loading. The optical properties of the system have been studied by photo luminescence spectroscopy. The fluorescence lifetime have been observed to decrease at greater loadings of the complex; an effect that has been attributed to concentration quenching. The complex doped PMMA/EVA polymer network developed is considered to be a potential candidate for the development of optoelectronic devices those possess superior mechanical properties.     

Polymers from Renewable Resources. XXVII. Studies on Synthesis,Characterization, and Thermal properties of Resins Derived from Cardanyl Acrylate-Furfural-Organic Compounds

Cardanol, the major constituent of cashew nut shell liquid (CNSL), is extracted from CNSL by vacuum distillation at 3–4 mm pressure of mercury and 230–240°C temperature. Cardanyl acrylate, a derivative of cardanol, is prepared by the Kaliyappan method. A number of resins have been synthesized by condensing cardanyl acrylate with furfural and selective organic compounds in the presence of acid as catalyst. The resins have been characterized by Fourier transform infrared spectra. Solvent absorptivity of the resins have been studied by taking toluene and dimethyl formamide as solvents. The thermal behavior of the resins have been studied. The overall activation energy and order of degradation of the resins have also been evaluated using the Freeman-Anderson method.     

超细TATB-BTF核-壳型复合粒子的制备

用喷雾干燥法制备了超细TATB-BTF核-壳型复合粒子。通过BTF在TATB表面结晶沉积,达到对超细TATB粒子进行包覆的目的。扫描电镜分析显示粒子表面形态发生了一定变化,表明TATB粒子表面有包覆层,用光电子能谱(XPS)对粒子表面各成分含量进行了分析。对复合粒子的热行为进行了DTA分析。结果表明,核粒大小是影响超细TATB-BTF核-壳型复合粒子包覆效果的主要因素。     

Thermal and mechanical properties of oxymethylene linked polymers

A series of novel polymers has been prepared by linking together copolymers of oxyethylene and oxypropylene with an oxymethylene link. Oxymethylene linked (OML) polymers have been made by a step polymerization reaction. Three different OML polymers have been synthesized starting from three different short chain triblock (ABA) copolymers of poly(oxyethylene) (A) and poly(oxypropylene) (B). These polymers have been characterized by gel permeation chromatography, differential scanning calorimetric analysis and Fourier transform infrared spectroscopy. The mechanical properties of the cast films and the rheological properties of aqueous solutions of these new polymers have been studied. It has been observed that it is possible to modulate the thermal and mechanical properties of these polymers by changing the starting materials. © 2000 Society of Chemical Industry     

Effect of chain structure on the melting of low molecular weight poly(ethylene oxide)

Linked poly(ethylene oxide) samples have been prepared by the condensation of α-methoxy-ω-chlorocarboxy-poly(ethylene oxide) with alcohols of various functionalities. Melting points (by dilatometry) and lamella spacings (by small-angle X-ray scattering) have been determined. The linked polymers have higher melting points than their unlinked precursors. The increased melting point is interpreted in the light of the model of Flory and Vrij.     

DTAC有机改性云南砚山膨润土的工艺研究

以经过钠化改性的砚山膨润土为原料,用十二烷基三甲基氯化铵(DTAC)进行有机改性,应用单因素及正交实验,研究了制备季铵型有机膨润土的最佳工艺条件,并用XRD和IR对合成的有机膨润土进行了结构表征。     

Compositional studies on technical cashew nutshell liquid (cnsl) by chromatography and mass spectroscopy

The composition of technical cashew nutshell liquid (CNSL), Anacardium occidentale, from four different sources has been examined. The C15 component phenols cardanol, cardol, 2-methyl cardol, and traces of anacardic acid have been determined by gas liquid chromatography (GLC), after hydrogenation and methylation, on the stationary phases Dexsil 300, SE52, SE30, and OV17, or alternatively the acetylated (unsaturated) phenols on Dexsil 300, SE52, or SE30. After thin layer chromatographic (TLC) separation of the component phenols, their saturated (15:0), monoene (15:1), diene (15:2), and triene (15:3) constituents have been determined by mass spectrometry (MS). In both the GLC and the MS procedures, the results have been corrected for differing relative responses. The more highly polymeric material present in technical CNSL from different sources has been determined by molecular distillation and by TLC. The fractions obtained by molecular distillation have been analyzed by GLC, the results of which show there is present some low polymeric material less volatile than the C15 component phenols, but the major portion of technical CNSL is volatile and can be analyzed by GLC. Part XI: Phenolic Lipids.     

Solution properties of dextran-polyacrylamide graft copolymers

Copolymers obtained by grafting polyacrylamide (PAA) onto polydextran (DEX) have been synthesised by ceric-ion-reduced redox initiation method. These copolymers have been characterized by light scattering, self-exclusion chromatography and viscometry in aqueous solutions. The short range molecular structure has been studied by small-angle X-ray scattering. From these results it is suggested that close to the anchoring point the grafted chains are extended while they take on a random conformation far from this point. A few investigations have been carried out in water/DMF (dimethyl formamide) mixtures. It is observed that the molecular weight depends strongly on the dimethyl formamide fraction. These results are discussed by contemplating the existence of PAA/DMF complexes.     

Strengthening of the adhesive bond using a mixture of adhesives between dissimilar adherends in a single lap joint

Abstract

Adhesive bonding is the best alternative to riveting in aircraft structures but the strength of the adhesive bonded joint is low and is limited by strength of adhesive. Strengthening of adhesive bonding is an important requirement. In this work, an attempt has been made to strengthen the adhesive bonding by mixing different quantities of brittle adhesive in the ductile adhesive and vice-versa. Two different adhesives, one brittle (AV138) and another ductile (Araldite-2015) adhesive have been considered. Initially single lap joint has been constructed between the CFRP and aluminium with individual adhesives, then the mixture of adhesives have been used in the bonded region in varied proportions. The X-ray radiography and ultrasonic testing have been performed to check the quality of bonding. Uniaxial tensile tests have been conducted on the lap joints along with Digital Image Correlations (DIC) to obtain the individual and mixed adhesive bond strength. The failure patterns have been identified using optical and scanning electron microscope. These studies indicate that strengthening of the adhesive bonding achieved by mixing of two adhesives and highest bond strength obtained when the mixture of AV138 and Araldite-2015 adhesives are used in equal proportions.     

Strain-rate dependent stress-strain properties of solution crosslinked poly(lsobutylene)-networks

Poly(isobutene) networks (butyl rubber) have been prepared by solution crosslinking. Networks have been characterized by swelling and mechanical measurements. The strain rate dependent stress strain behaviour is discussed in terms of a time dependent network unfolding process.     

Synthesis of linear polymers containing benzoxazine moieties in the main chain with high molecular design versatility via click reaction

Linear polymers with benzoxazine rings in the main chain have been synthesized applying click chemistry approach. These polymers possess molecular weights significantly higher than the benzoxazine polymers which have been chain extended via Mannich reaction. The number average molecular weight is estimated from size exclusion chromatography (SEC) to be between 20,000 and 40,000 Da. The structure of the polymers is confirmed by ¹H and ¹³C nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). Differential scanning calorimetry (DSC) is used to study crosslinking behavior of the polymers. The nature of the low temperature exotherm DSC peak observed in this work and the previous work of other authors is studied by model reactions. It is due to thermal coupling of the residual propargyl and azide end groups in the absence of active catalyst. In addition, a novel diazide-functional benzoxazine monomer has been prepared, showing a tremendous flexibility for applying click reaction to obtain various polymer architectures. Three types of polymers have been prepared from dipropargyl- and diazide-functional benzoxazine monomers. These polymers have been characterized by dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA).     

PAN基碳纳米微球的制备及表征

通过种子乳液聚合得到聚丙烯腈/聚甲基丙烯酸甲酯(PAN/PMMA)核壳结构的纳米微球。将经冷冻干燥后得到的PAN/PMMA纳米微球进行预氧化和炭化处理,成功制备出粒径为50 nm的碳纳米微球(Carbon Nanospheres,CNSs)。并利用光散射、傅立叶红外线光谱(FTIR)、透射电镜(TEM)等技术对所合成的PAN/PMMA纳米微球和CNSs进行分析。实验结果表明,PMMA的加入有利于降低PAN基CNSs的粒径,且炭化温度在500～600℃之间得到的CNSs的分散性最好。     

Multiferroic CoFe2O4-Pb(Zr(0.52)Ti(0.48))O3 core-shell nanofibers and their magnetoelectric coupling

Multiferroic CoFe(2)O(4)-Pb(Zr(0.52)Ti(0.48))O(3) core-shell nanofibers have been synthesized by coaxial electrospinning in combination with a sol-gel process. The core-shell configuration of nanofibers has been verified by scanning electron microscopy and transmission electron microscopy, and the spinel structure of CoFe(2)O(4) and perovskite structure of Pb(Zr(0.52)Ti(0.48))O(3) have been confirmed by X-ray diffraction and selected area electron diffraction. The multiferroic properties of core-shell nanofibers have been demonstrated by magnetic hysteresis and piezoresponse force microscopy, and their magnetoelectric coupling has been confirmed by evolution of piezoresponse under an external magnetic field, showing magnetically induced ferroelectric domain switching and changes in switching characteristics. The lateral magnetoelectric coefficient is estimated to be 2.95 × 10(4) mV/cmOe, two orders of magnitude higher than multiferroic thin films of similar composition.     

Synthesis,characterization and spectroscopic studies of two new schiff-base bithienyl pendant-armed 15-crown-5 molecular probes

Two new ligands provided with a 15-crown-5 as a receptor unit and bithiophen unit as an emissive probe have been synthesized and characterized in order to evaluate the coordination capabilities and their sensor effect. Ligand L1 presents an aromatic crown ether moiety that is directly linked to the imine-2,2′-bithiophene π–conjugated system, and ligand L2 is constituted by an aliphatic crown ether moiety that is linked to the same imine-2,2′-bithiophene system through a methylene unit. Solid metal complexes of Ni(II), Pd(II), Hg(II) and Na(I) have been synthesized using both macrocyclic compounds, and have been studied in solution in the presence of the same metal ions. All solid compounds have been characterized by common analytical and spectroscopic techniques. The sensorial effect has been studied using absorption, emission and MALDI-TOF-MS spectroscopies.     

Chemical and electrochemical polymerisation of diacetylenes containing thienyl moiety as the side group

Summary Two symmetrical diacetylene monomers containing thienyl moiety as the side groups, namely 1,4-bis(2'-thienyl)butadiyne and 1,4-bis(3'-thienyl)butadiyne, are reported which have been successfully polymerised electrochemically. They have also been polymerised chemically in solution using Lewis acid as initiator. The resulting polymers have been characterised by elemental analysis, infrared spectra, absorption spectra and by solid state NMR spectra. The polymers were found to have conjugated π-electron structure and both of them show high environmental stability. The properties of the polymers have been compared with that of poly(3-methylthiophene) which is a conventional and much studied conjugated polymer. The electrical conductivity of the polymers has also been investigated. Received: 9 September 1998/Revised version: 12 November 1998/Accepted: 19 November 1998     

Synthesis and properties of soy hull‐reinforced biocomposites from conjugated soybean oil

The tensile and flexural properties of new thermosetting composites made by the free radical polymerization of a conjugated soybean oil (CSO)‐based resin reinforced with soy hulls have been determined for various resin compositions. The effects of reinforcement particle size and filler/resin ratio have been assessed. The thermal stability of the new materials has been determined by thermogravimetric analysis and the wt % of oil incorporation has been calculated after Soxhlet extraction (the extracts have been identified by ¹H‐NMR spectroscopy). The resin consists initially of 50 wt % CSO and varying amounts of divinylbenzene (DVB; 5–15 wt %), dicyclopentadiene (DCPD; 0–10 wt %), and n‐butyl methacrylate (BMA; 25–35 wt %). Two soy hull particle sizes have been tested (<177 and <425 μm) and two different filler/resin ratios have been compared (50 : 50 and 60 : 40). An appropriate cure sequence has been established by differential scanning calorimetry (DSC) analysis. The results show a decrease in the properties whenever DVB or BMA is substituted by DCPD. Also, larger particle sizes and higher filler/resin ratios are found to have a negative effect on the tensile properties of the new materials. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Ultrasound‐activated Knoevenagel condensation of malononitrile with carbonylic compounds catalysed by alkaline‐doped saponites

α,β‐Unsaturated nitriles have been synthesized by Knoevenagel condensation of a carbonylic compound with malononitrile, assisted by sonochemical irradiation. Two alkaline‐promoted clays (Li⁺‐ and Cs⁺‐exchanged saponites) have been employed as catalysts. The influence of the carbonylic compound (benzaldehyde or cyclohexanone) and the use of a solvent on the catalytic activity have been studied. Remarkable increase in the conversion values has been found when the reaction is activated by ultrasound, as compared with the thermal activation. In this green, solvent‐free procedure, α,β‐unsaturated nitriles have been produced in very high yields (97%) when the Cs⁺‐saponite is used as catalyst. Copyright © 2004 Society of Chemical Industry     

STUDY OF MICELLAR EXTRACTION IN THE SYSTEM (2-ETHYLHEXYL) PHOSPHONIC ACID MONO-(2-ETHYLHEXYL) ESTER - Co (II) - SURFACTANT

ABSTRACT

The equilibrium and kinetics of the extraction of cobalt (II) by P507 in Teric N9 micelles have been studied. The structure of the (2-ethylhexyl) phosphonic acid mono-(2-ethylhexyl) ester (known as P507), in Teric N9 micelles have been investigated using interfacial tension and fluorescence quenching measurements. It has been found that there is an interaction between these two components and mixed micelles are formed

The complex of Co²⁺ with P507 in Teric N9 aqueous solution has been shown to have a 1:3 stoichiometry and the equilibrium constant has been obtained by slope analysis. The rate of complex formation in the micelle media is very fast with the reaction going to completion in less than 0.2 seconds.     

ECTFE membrane preparation for recovery of humidified gas streams using membrane condenser

Polymeric flat membranes, using Ethylene–Chlorotrifluoroethylene copolymer (ECTFE), have been made by Thermal Induced Phase Inversion (TIPS). The non-toxic solvent glycerol triacetate (GTA) has been used as solvent. The morphology of the membranes has been analyzed by scanning electron microscopy (SEM). Asymmetric microporous sponge-like membranes have been produced and their properties in terms of contact angle, mechanical properties, pore size and porosity have been compared with the commercial PVDF hollow-fibers membranes. Both types of membranes have been tested using a membrane condenser, varying the feed temperature and feed flow rate, for the selective recovery of water from gaseous streams. The data obtained have been also supported by a simulation study of the process. The results showed that in both type of polymers used, the percentage of water recovered was similar, between 35% and 55%, much higher than the amount of 20% needed to make the plant self-sufficient. The obtained results and the outstanding chemical resistance properties suggested that the ECTFE flat membranes are very promising candidates for being employed in a membrane condenser, which is a new membrane based operation for water recovery from gaseous waste streams (i.e. flue gas).