Preparation of organosiloxane/silicate hybrid structures — Part I

Hybrid organosiloxane/sodium silicate structures have been prepared by the interaction of a‘QM’ polyorganosiloxane, produced by the trimethylsilylation of‘Suzorite’ (a phlogopite mineral), and a solution of sodium hydroxide in ethanol. These hybrid products lose volatiles on heating and give products which exhibit glass transition points at (～ 520°C). They show properties intermediate between those of typical organosiloxanes and silicates. They have both hydrophobic and hydrophilic properties as demonstrated by their solubility in water and acetone. This is dependent on the relative proportions of Na, Si(O_1/2)₄ and (Me)₃ SiO_1/2 groups present.     

Preparation and properties of layered silicate/polyimide hybrid films

Layered silicate/polyimide (PI) hybrid films were prepared from 4,4′‐oxydianiline, 3,3′,4,4′‐oxydiphthalic anhydride, and chemically modified montmorillonite via an in situ intercalation polymerization pathway. The X‐ray diffraction and transmission electron microscopy results indicated that the silicates were homogeneously dispersed as exfoliated layers in the PI hybrid film with 2% silicate. The mechanical properties and thermal stabilities of the PI hybrid films changed with the content of the layered silicates. The coefficient of thermal expansion and water uptake of the PI hybrid films decreased with increasing silicate contents because of the barrier effect of platelike silicate layers, which prevented the diffusion and penetration of water. The dielectric strength and electrical aging performance of the PI hybrid films could also be improved as the silicate layer highly dispersed in the films. For the hybrid PI film with 5% layered silicate, the time to failure during electrical aging exceeded 280 h, which was 2.5 times as long as that of pure PI film. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1176–1183, 2005     

Azides Part II — Mechanism of Fixation of Sulphonazido Dyes on Polyester Fibre*

Thermofixation of the reactive disperse azo dye, 2-hydroxy-5-methyl-4′-sulphonazidoazobenzene (I) containing a sulphonazido group, with polyester fibre leads to chemical bonding of the generated sulphonylnitrene with the fibre substrate. The nitrene interacts with the benzene ring of the polyester substrate through the formation of a sulphonamido link as well as through insertion followed by ring expansion of the adduct to yield the relevant N-sulphonyl-azepine. The mechanism is confirmed by means of a suitable model experiment of interaction of I with dimethyl terephthalate.     

Organic–silicate hybrid catalysts based on various defined structures for Knoevenagel condensation

Two types of organic–inorganic hybrid base catalysts are prepared. Organic-functionalized molecular sieves (OFMSs), particularly “amine-immobilized porous silicates”, are designed based on common idea to immobilize catalytic active sites on silicate surface. Silicate–organic composite materials (SOCMs), such as “ordered porous silicate–quaternary ammonium composite materials”, are the precursors of ordered porous silicates obtained during the synthesis. Both the OFMS and the SOCM are used as the catalysts for Knoevenagel condensation. Among the OFMSs, there is clear tendency that the use of molecular sieve with larger pore volume and/or surface area gives the product in higher yield. Aminopropylsilyl (AP)-functionalized mesoporous silicates such as AP-MCM-41 gives the product in high yield under mild conditions. No loss of activity is observed after repeated use for three times. The SOCMs are also active for the same reaction. The precursors of the mesoporous silicates are more active than those of microporous silicates. This material can be repeatedly used without significant loss of activity. High activity is not due to the leached species. The active sites of the SOCM catalysts are considered to be SiO⁻ moieties located on the pore-mouth. Activity of the SOCM increases when the reaction is carried out without solvent, whereas decrease in activity of the OFMS is observed in the solvent-free system.     

Hydrodynamics of disturbed flow and erosion–corrosion. Part II — Two-phase flow study

Erosion–Corrosion in turbulent, two-phase liquid/particle flow with recirculation, after a sudden pipe expansion is studied by the application of a numerical flow model along with two different erosion models. The flow model, which is based on a two-phase flow version of a standard two-equation model of turbulence and a stochastic simulation of particle-fluid turbulence interactions, is capable of successfully predicting local values of time averaged fluid velocities and turbulent fluctuations, as well as predicting particle dispersion and particle-wall interaction. The erosion models used are that of Finnie (1960) and a modified version suggested by Bergevin (1984). The agreement of the predicted and measured hydrodynamic parameters, for flow through a sudden expansion, was satisfactory. Predictions of erosion rates using Bergevin's modified model were in good agreement with the stainless steel erosion measurements for a 2% water/sand slurry flow. The erosion–corrosion model was successful in predicting the overall pattern and rates of metal loss for carbon steel.     

Spectroscopy and spectrometry of lipids — Part 1

For a collection of articles on spectroscopy and spectrometry of lipids to be comprehensive, there is a requirement for a wide range of instrumentation and applications to be considered. In this dossier, the aim is to include as many aspects as possible that are relevant to modern approaches in lipid analysis. It is hoped that the articles will show how enormous advances have been made, and are continuing to be made, in this area. The range of techniques includes infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS), ultraviolet (UV) spectroscopy and electron spin resonance (ESR) spectroscopy. IR spectroscopy can be subdivided further into mid‐ and near‐infrared and Raman spectroscopy, and the former may be coupled to gas chromatography (GC). NMR spectroscopy encompasses high resolution (further split into ¹ H, ¹³ C and ³¹ P) and time‐domain. MS can be subdivided according to the type of ionisation (e.g. electron impact, chemical ionisation, fast atom bombardment) or separation technique (e.g. GC, liquid chromatography) to which it is coupled, but is more conveniently considered according to the type of lipid (fatty acid, triacylglycerol, complex polar lipid) to be analysed. Analysis of stable isotopes in fatty acids involves a highly specialised application of MS. There is a host of applications ranging from the measurement of broad quality control parameters to highly specific determinations for research purposes, and includes both qualitative and quantitative information. Quality control applications include chemical parameters such as peroxide value by IR (as a possible replacement for more timeconsuming traditional methods) and physical parameters such as droplet size distribution by time‐domain NMR. Structural determinations of fatty acids and lipids by the various MS methods tend to be targeted towards specific research objectives.     

Preparation procedures for woven cotton and polyester/cotton fabric. Part 2 — oxidative desizing with hydrogen peroxide

Oxidative desizing with sodium hydroxide in the presence of hydrogen peroxide has been investigated as a preparatory treatment for dyeing and printing cotton and polyester/cotton woven fabric. Using statistically designed experiments, the effect of time and temperature of treatment, and peroxide and sodium hydroxide concentrations on degree of desizing, whiteness, fabric absorbency and mote removal has been determined. The major factor determining desizing rate was sodium hydroxide concentration. As peroxide concentrations increased above 0.1% o.w.f. of 35% solution desizing was retarded. Desizing was thus seen to be a hydrolytic process initiated by hydrogen peroxide. Whiteness achieved during desizing was not correlated with sodium hydroxide concentration and adequate whiteness was not achieved with the 100% cotton fabric. Whiteness of the blend was significantly influenced by all the desizing factors, while absorbency was affected by treatment time and temperature. Pure cotton was not rendered absorbent at all at below 65°C, in contrast with enzymatic desizing. Treatment for a short time in the temperature range 65–95°C gave a generally unsatisfactory level of mote removal.     

Segmented organosiloxane copolymers. 1. Synthesis of siloxane—urea copolymers

Siloxane—urea linked segmented copolymers were synthesized from ,ω-bis(aminopropyl)poly dimethylsiloxane oligomers and various aromatic and cycloaliphatic diisocyanates such as MDI, TDI and H-MDI. Molecular weights of the siloxane oligomers were varied in the range of 1000–4000 g mole⁻¹ and high molecular weight linear copolymers were obtained by employing homogeneous solution polymerization techniques. The solvent used during the reactions has a very critical role on the average molecular weight of the final product. Bis(2-ethoxy ethyl) ether (EEE) and THF were most useful. Chain extenders such as aliphatic or cycloaliphatic diamines were also used in some reactions and in this case polar cosolvents such as NMP were also required. The yields were usually very high and the amorphous products obtained from the simple stoichiometric linking reaction were soluble in various common organic solvents. Formation of urea linkages during the polymerization were followed by FTi.r. spectroscopy. The copolymers were characterized by g.p.c. and intrinsic viscosity measurements, FTi.r., n.m.r. and thermal analysis. All these results together with mechanical characterization described in the accompanying second paper of this series indicate the formation of novel, segmented elastomeric siloxane—urea copolymers.     

Generalized age-adjusted effective modulus method for creep in composite beam structures. Part I — Theory

The age-adjusted effective modulus method for approximate analysis of structures exhibiting linear aging creep law and underlying Ba?ant's theorem is generalized to a form which is more accurate for composite beam structures in flexure. A rigorous derivation of a linear algebraic relationship between the internal force histories and the deformation histories of the beam is given using the integral operator symbolics.     

Catalytic membrane reactor for oxidative coupling of methane. Part II —Catalytic properties of LaOCl membranes

This work presents the potential of a LaOCI porous membrane reactor for the reaction of oxidative coupling of methane. The sol-gel method provided LaOCl membranes supported on alumina tubes which presented mesoporous texture. Actually, the severe operating conditions of this reaction caused textural instability which restricted any transport effects to the macroporous domain. However, despite moderate separation effects between methane and oxygen, beneficial effects of the membrane reactor have been observed, subject to surface composition, structural and feeding configuration requirements.     

Segmented organosiloxane copolymers: 2 Thermal and mechanical properties of siloxane—urea copolymers

The structure-property behaviour of new siloxane-urea containing segmented copolymers has been investigated. Amino-propyl terminated poly(dimethylsiloxane) oligomers of from 900–3660 M_n were reacted with various diisocynates to form segmented copolymers with urea linkages. The length of the hard segments in these copolymers corresponds approximately to the length of the diisocynate unit employed. A number of mechanical and thermal properties were investigated for these phase separated materials. It was found that the performance of these copolymers was effected by varying the hard segment type and/or content and that high strength necessitates a microphase texture. The two phase nature of these copolymers was verified by dynamic mechanical, thermal and SAXS studies. The phase separation was found to occur in these copolymers even with 6% hard segment by weight. In conclusion, these materials displayed a behaviour similar to the segmented polyurethanes and were found to be superior to the unfilled silicone elastomers.     

Hydrodynamics of disturbed flow and erosion—corrosion. Part I — Single-phase flow study

Numerical simulations of turbulent flow have been used to determine the flow structure in a sudden pipe expansion, in order to explain the effects of disturbed flow on mass transfer controlled erosion–corrosion. Previously determined rates of mass transfer through the liquid boundary layer have been directly related to the predicted levels of near-wall turbulence. When rust films are present, the turbulent fluctuations affect both the mass transfer through the boundary layer and the removal of the film. The determining resistance to mass transfer, under the conditions examined, was that of the rust film.     

Preparation of polystyrene/toluene‐2,4‐ di‐isocyanate–modified montmorillonite hybrid

A novel selective interlamellar modification of cetyltrimethylammonium bromide‐exchanged montmorillonite (MMT) by toluene‐2,4‐di‐isocyanate (TDI) has been successfully obtained, and a polystyrene/TDI‐modified MMT hybrid has been prepared. After the interlamellar modification, TDI was grafted to hydroxyl groups of the MMT, and the orientation of cetyltrimethylammonium in the interlayer space changed from a bilayer lying flat structure to a double‐layer inclined one. The structures of the TDI‐modified MMT and the hybrid were characterized by Fourier transform infrared (FTIR) spectra, powder X‐ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. A schematic model of the TDI‐modified MMT structure was also presented. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2201–2205, 2000     

Preparation of dendritic adamantane‐based polymers/layered silicate nanocomposites

An adamantane‐based atom transfer radical initiator (Adm‐Br) was prepared by the treatment of 1‐[[N‐[2‐Hydroxy‐l,l‐bis(hydroxymethyl)ethyl]amino]carbonyl]adamantane with bromopropionyl bromide. The resulting initiator was subsequently used in the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) to form (Adm‐p‐MMA), which was successfully used, as a macroinitiator, in further ATRP reactions with 3‐O‐methacryloyl‐1,2 5,6‐di‐O‐isopropylidene‐α‐d ‐glucofuranose (gly), a glycomonomer, to afford the Adm‐p‐MMA‐b‐gly polymer. The new Adm‐p‐MMA‐b‐gly polymer subsequently was employed to form a nanocomposite with chitosan‐modified, Nanofil clay (NC). The resulting Adm‐p‐MMA‐b‐gly/NC composite material was progressively hydrolyzed to regenerate the OH groups of the glucose units within the Adm‐p‐MMA‐b‐gly copolymer. The polymer/NC nanocomposites were characterized by X‐ray diffraction, thermal gravimetric analysis, differential scanning calorimetry, and transmission electron microscopy. POLYM. ENG. SCI., 54:2669–2675, 2014. © 2013 Society of Plastics Engineers