bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling permeation of modified atmosphere gas mixtures through a low density polyethylene package film
Authors: Llter M. , Özilgen M. , Orbey N. 
Published: April 2007

AbstractPermeation of individual gases through a low density polyethylene package film with CO2‐N2 and CO2‐O2‐N2 mixtures was simulated with a simple mathematical model. Permeabilities of carbon dioxide were of the order of 10 −12 m3/s m2atm/m with CO2‐N2 systems. Including oxygen in the system did not change carbon dioxide permeabilities. Permeabilities of oxygen were of the order of magnitude of 10−9m3/sm2atm/m with this system. When a CO2‐O2‐N2 mixture was humidified no substantial change was observed in CO2 permeability, but the O2 permeability decreased almost 10 times. These results and the mathematical model presented may help in the modified atmosphere package design to increase the shelf life of produce.
Preparation and anti‐microbial properties of friedel—crafts resins
Authors: Patel N. Z. , Patel J. N. , Ray R. M. , Patel R. M. 
Published: April 2007

AbstractFriedel‐Crafts resins were prepared by reacting chloroacetyl chloride, 1,2‐dichloroethane and dichloromethane with m‐xylene using carbon disulfide as solvent and anhydrous AlCl3 as catalyst. The resins were characterized by IR spectra and number average molecular weight measured by vapour pressure osmometry. The thermal properties were studied by thermogravimetry and differential scanning calorimetry. All the resins were tested for their microbial activity against Pseudomonas fluorescens, Bacillus subtilis and Aspergillus niger. The results show that most of the resins can be used as biocides.
An inverse gas chromatographic study of compatibility of food grade PVdC copolymer and low volatility plasticizers
Authors: Demertzis Panagiotis G. , Riganakos Kyriakos A. , Akrida‐Demertzi Konstantoula 
Published: April 2007

AbstractThe compatibilities of the systems poly(vinylidene chloride‐vinyl chloride 80:20)/polyadipate ester and poly(vinylidene chloride‐vinyl chloride 80:20)/tri‐isononyl trimellitate have been studied in the range 90–110°C using inverse gas chromatography (IGC). The retention behaviour of the polymer/plasticizer mixtures covering the entire composition range for each component was characterized for 10 probes of different chemical nature. In agreement with previous work, the IGC‐derived interaction parameters (X+23) showed an apparent dependence on the chemical nature of the probe, blend composition and temperature. The results predict good polymer/plasticizer compatibility up to c. 0–40 weight fraction of plasticizer for poly(vinylidene chloride‐vinyl chloride 80:20)/polyadipate ester blends and to c. 0.50 for poly(vinylidene chloride‐vinyl chloride 80:20)/tri‐iso‐nonyl trimellitate blends.
Radical polymerization of itaconic anhydride and reactions of the resulting polymers with amines and alcohols
Authors: Otsu Takayuki , Yang Jian‐Zhong 
Published: April 2007

AbstractItaconic anhydride was polymerized in the presence of a radical initiator under various conditions. The bulk polymerization at 75°C yielded polymer with molecular weight of more than 20000.The reactions of the resulting polymer with water and alcohols gave poly(itaconic acid) and its esters, respectively. The polymers prepared by such reactions were found to have similar thermal properties to those prepared by homopolymerizations of the respective itaconic acid derivatives.Poly(N‐substituted itaconomic acid)s, which are difficult to obtain by direct polymerization of their monomers, were prepared by the reactions of poly(itacononic anhydride) with amines.Copolymerizations of itaconic anhydride with electron‐donating monomers, styrene and isobutyl vinyl ether, gave alternating copolymers which were then converted by esterification to the respective copolymers of dialkyl itaconates with such electron‐donating monomers.
Chain‐extended polyurethanes—Synthesis and characterization
Authors: Ramesh S. , Rajalingam P. , Radhakrishnan Ganga 
Published: April 2007

AbstractThermoset polyurethane (PU) elastomers were prepared using hydroxyl‐terminated polybutadiene (HTPB), toluene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI). The effects of various diamines and diols on the mechanical and thermal properties of polyurethanes are discussed. The average molecular weight between crosslinks (M̄/c) was determined by swelling studies. The properties imparted by the extenders are explained on the basis of the groups present in the diamines and the number of methylene carbons in the diols.
Toughening of epoxy resins with thermoplastics. Ii. Tetrafunctional epoxy resin‐polyetherimide blends
Authors: Hourston Douglas J. , Lane Jaqueline M. , Macbeath Nigel A. 
Published: April 2007

AbstractA series of blends has been prepared by adding a polyetherimide (PEI), in varying proportions, to a tetrafunctional epoxy resin, tetraglycidyl‐diaminodiphenylmethane (TGDDM), cured with 4,4′‐diaminodiphenylsulphone (DDS). All the materials exhibited two‐phase morphologies which were characterised by dynamic mechanical thermal analysis and scanning electron microscopy. Addition of the thermoplastic gave a modest improvement in fracture properties (K1c and G1c), as determined by three‐point bending experiments, although no obvious correlation with the marked morphological changes was observed.
Recent developments in the gpc characterisation of polymeric materials
Authors: Meehan Elizabeth , McConville John A. , Warner Frank P. 
Published: April 2007

AbstractMixed gel GPC columns are specifically designed for the determination of polymer molecular weight distribution. The choice of column pore size distribution and particle size significantly affects resolution. Although optimum resolution is deirable, 5 μm particle size columns are not ideal for the analysis of polymers containing significant quantities of material above 1 million molecular weight as shear degradation of the polymer is likely to occur.Both narrow standard and broad standard methodolgies are suitable for the calibration of mixed gel GPC column systems. Using well‐characterised polydisperse polystyrene test probes, no difference in accuracy was found between the two procedures.
The application of luminescence techniques in polymer science
Authors: Soutar Ian 
Published: April 2007

AbstractThe luminescence phenomenon represents an extremely versatile and sensitive means whereby the physical behaviour of polymers may be examined at the molecular level. This review initially describes the ‘tools of the trade’ (the parameters which, in combination, confer high degrees of selectivity upon the technique) prior to discussion of their use. The account is illustrated by examples drawn mainly from the author's laboratory and includes applications of energy transfer, excimer formation and anisotropy experiments.
Alternating copolymers from the radical copolymerization of citraconic derivatives with isobutyl vinyl ether
Authors: Yang Jian‐Zhong , Otsu Takayuki 
Published: April 2007

AbstractRadical copolymerization of citraconic anhydride (CAn) with isobutyl vinyl ether (IBVE) was studied as well as the copolymerizations of N‐alkylcitraconimides, dialkyl citraconates and mesaconates with IBVE. All the copolymerizations attempted except one, incorporating N‐alkylcitraconimide, were found to give alternating copolymers with molecular weights of more than 10,000 in most cases. Of all the copolymerizations, the CAn‐IBVE system showed the highest reactivity. A charge transfer complex between these two monomers was confirmed to exist in this system. The equilibrium constant of the complex formation was determined by UV spectroscopy as 0–162 litre/mol in CHCl3 at 15°C.The alternating copolymer obtained from CAn with IBVE was converted to the corresponding copolymer of dialkyl citraconate by esterification.
Viscosity behaviour of acrylonitrile‐acrylate copolymer solutions in dimethyl formamide
Authors: Joseph Roychen , Devi Surekha , Rakshit Animesh Kumar 
Published: April 2007

AbstractThe viscosities of dimethyl formamide solutions of acrylonitrile‐acrylate copolymers were determined at 30,35,40 and 45°C using an Ubbelohde viscometer. The viscosities of homopolymer solutions were also studied. The homopolymers of aerylonitrile and also of methyl, ethyl and butyl acrylates were synthesised in the laboratory. The random copolymers were synthesised by a solution polymerisation technique keeping the acrylonitrile: acrylate ratio as 1:1, 1:2 and 1:3 (w/w). The intrinsic viscosity for each system was computed as a function of temperature. The activation parameters of viscous flow were calculated using the Frenkel‐Eyring equation. Voluminosity for all systems was also computed. From intrinsic viscosity and voluminosity data it was concluded that the polymer molecules are spherical in the dimethyl formamide solutions.
Organolithium route to poly(arylsilane)s
Authors: Albizane Abderrahman , Corriu Robert J. P. , Douglas William E. , Fisch Herbert 
Published: April 2007

AbstractVarious poly(arylsilane)s magnified imageThe poly(carbosilane)s prepared in this way are of higher molecular weight than when prepared by the Wurtz‐type condensation route previously reported. TG shows 40–50% overll weight loss attained at 500–600°C.
Unperturbed dimensions of a zwitterionic polymethacrylate
Authors: Huglin Malcom B. , Radwan Mostafa A. 
Published: April 2007

AbstractValues of intrinsic viscosity [ζ] measured in 2,2,2‐trifluoroethanol (TFE) and in 1·0M aq. NaCl solution mean square radii of gyration s2z and weight‐average molecular masses Mw measured in TFE at 298 K for 12 well fractionated poly[N‐(3‐sulphopropyl)‐N‐methacrylooxyethyl‐N,N‐dimethylammonium betaine] (PSPE) samples have been used to derive the unperturbed dimensions (<r20/M)1/2 via different extrapolation procedures.Cloud point curves for PSPE fractions in 0‐05M aq. NaCl yielded an upper critical solution temperature (0) of 308 K, which was confirmed turbidimetrically, visco‐metrically, and by light scattering, thus enabling the unperturbed dimensions to be determined directly.The mean value of (r20/M)1/2 by all procedures was 0‐052nm g‐1/2 mol1/2 which, in conjunction with the corresponding quantity calculated on the basis of free rotation, affords a value of 2‐83 for the steric factor α.From values of [ζ] in 2·0M aq. NaCl solution over the interval 283–343 K, the value of dlnr2o/dT was derived as −8·5 × 10−4 deg−1. The values of the long range interaction parameter β and the interaction parameter χ confirm that TFE is a thermodynamically better solvent than l·0M aq. NaCl solution for PSPE.
Anionic polymerization by tertiary amine/epoxide complex
Authors: Ikeda Isao , Mitsumoto Seiichi , Yamada Yuichi , Suzuki Kimihiro 
Published: April 2007

AbstractThe anionic polymerization of monomers such as acrylonitrile (AN) and ε‐caprolactone by triethylenediamine (TEM)/epoxide complex was investigated. They were not polymerized by TEM alone but polymerized easily with the addition of various epoxides. When glycidyl methacrylate (GMA) and allyl glycidyl ether (AGE) were used as the epoxide component, a double bond was introduced at the end of the polymer. Thus the macromonomers were prepared with the polymerization by TEM/GMA and TEM/AGE complexes. Macromonomers prepared with GMA were copolymerized with comonomers such as AN, styrene, acrylamide and methyl methacrylate to prepare the graft copolymers.
Effect of installation damage on the lifetime of upvc pipes subjected to cyclic pressures
Authors: Burn L. Stewart 
Published: April 2007

AbstractA survey of pipe installation damage in Australia has shown that when pipes are installed in water reticulation systems, they often have significant levels of damage or notches that can be considered as sharp, i.e. less than 25 μm notch tip radius. Experimental investigations of the effect of simulated sharp notches of varying depth on uPVC pipes subjected to a representative cyclic pressure regime show that there is a relationship between the depth of the notch and the cycles to failure. With damage less than 1·2 mm deep, corresponding to a stress intensity factor of 0·2 MPa,m, a fatigue crack threshold exists, below which cracks do not grow and consequently pipe lifetimes in excess of 100 years can be expected for pipes installed under such cyclic pressure conditions.
Electrically conductive composite of polyaniline and poly (p‐phenylene/diphenyl ether‐terephthalamide)
Authors: Bi Xian‐Tong , Xue Zhe‐Jian 
Published: April 2007

AbstractIn order to improve the flexibility and the anti‐static properties of poly‐(p‐phenylene‐terephthalamide) (PPTA), the copolymer of p‐phenylene diamine, p,p′‐diaminodiphenyl ether and terephthaloyl chloride (PPDTA) was synthesized. This copolyamide PPDTA was mixed with electrically conductive polyaniline (PAn) in concentrated sulphuric acid solution, and was processed to form film, or fibre, of the new composite PAn/PPDTA with high strength and good electrical conductivity. The composite is a lyotropic liquid crystalline polymer with electrical conductivity 10−1 S/cm. The surface morphology of the PAn/PPDTA composite consists of an oriented fibre‐like texture.
Morphology of block copolymers and associated networks
Authors: Jones Jennifer J. , Burford Robert P. 
Published: April 2007

AbstractInterpenetrating polymer networks (IPNs) of styrene‐butadiene‐styrene (SBS) block copolymers and polystyrene (PS) were prepared by sequential polymerisation. TEM micrographs of both the constituent block copolymers and their IPNs were obtained after staining with osmium tetroxide. It was found that images obtained after cryo‐ultramicrotoming of bulk samples were a more legitimate representation of block copolymer morphology than those obtained from solvent‐cast samples. Micrographs of both semi‐IPNs and true‐IPNs and bulk block copolymer reveal distinct microphase separation. An anisotropic domain morphology is found, with polybutadiene (PBD) being the continuous phase containing PS‐rich domains. Domain dimensions change with cross‐linking and block copolymer type. Image analysis and small angle X‐ray data were obtained to provide further quantitative information.
13C NMR spectral assignments of methacrylic acid/acrylonitrile statistical copolymers
Authors: Borbely Janos D. , Hill David J. T. , Lang Anthony P. , O'Donnell James H. 
Published: April 2007

AbstractCopolymerization of methacrylic acid (M) and acrylonitrile (A) in bulk at 60°C gives a statistical copolymer. Through the use of 1H, 13C, DEPT and twodimensional NMR techniques, the observed resonances in the NMR spectra of these copolymers can be assigned, and thus provide detailed information about the microstructure of the polymer at the diad, triad and tetrad levels. Configurational effects have also been shown to play an important role, although in all cases the chemical shift differences resulting from configurational variation are smaller than those resulting from sequence variation.
Thermal decomposition of poly (1,6‐di‐n‐carbazolyl‐2,4‐hexadiyne)
Authors: Bradner F. P. , Shapiro J. S. 
Published: April 2007

AbstractThe kinetics of the thermal decomposition of the crystalline poly(1,6‐di‐N‐carbazolyl‐2,4‐hexadiyne) prepared by γ‐radiation induced polymerisation were studied over the temperature range 380‐450°C by means of a flow system, coupled to a gas chromatograph. Two major volatile reaction products were found: carbazole and 9‐methylcarbazole, leaving behind a carbonaceous residue. The reaction was found to be complex with two autoacceleratory regions followed by a very slow limiting rate after 65% weight loss. Whereas the magnitude of the first of these regions was found to be dependent on factors influencing the level of crystal purity and perfection, the second region was independent of these. A reaction mechanism is proposed, based on initiation by stress‐induced shearing of sidegroups, followed by concurrent molecular/radical non‐chain processes. The kinetics of the decomposition were found to be best described by the Avrami‐Erofeyev equation, and the Arrhenius parameters were determined for both autoacceleratory processes.
Dielectric properties of poly(vinyl chloride) in tetrahydrofuran and cyclohexanone
Authors: Salem M. B. , Oun A. M. , Omar M. M. 
Published: April 2007

AbstractThe dielectric absorption and dispersion of poly(vinyl chloride), MMv = 49 000, in THF and in cyclohexanone have been studied over a frequency range of 120 kHz to 11·0 MHz, at temperatures from −22·5 to 35°C, and at concentrations ranging from 4 to 12·0(w/v)% PVC/THF and from 2 to 8·0(w/v)% PVC/cyclohexanone. The viscosities of the two systems have also been measured at temperatures from 20 to 50°C. A single relaxation time was found (β = 0·8–1·0), which indicates that relaxation occurs by segmental rotation. The dielectric and viscous activation energies have been calculated. The dipole moment associated with the relaxation process has also been calculated. The relaxation time, dielectric and viscous activation energies and the dipole moment were found to be dependent on the type of solvent. The dipole moment also showed a molecular weight dependence. The influence of the concentration and temperature on the apparent dipole moment and on the relaxation time is discussed.
Dynamic properties of elastomers after water immersion
Authors: Oldfield David , Jackson Peter J. , Russo Sarina 
Published: April 2007

AbstractVulcanized bromobutyl, natural and nitrile rubbers were immersed in distilled water, or seawater, at 20, 40 or 60°C for up to 32 weeks and the resulting changes in weight and dynamic mechanical properties were monitored. Larger weight increases were observed for the specimens immersed in distilled water than for the equivalent specimens in seawater, and there was no sign of an equilibrium weight uptake being reached for the specimens immersed in distilled water at 60°C. Bromobutyl rubber showed increases in the magnitude of the loss tangent peak which could be related to the weight increases in both distilled water and seawater but the decreases in peak height observed for natural rubber and nitrile rubber were not well correlated with weight increases.
Thermal ageing studies of conducting polypyrroles
Authors: Moss Brett K. , Burford Robert P. 
Published: April 2007

AbstractConductive polymeric films have been of great interest recently, although one major drawback to their use is environmental stability. Polypyrroles doped with p‐toluenesulfonate, tetrafluoroborate and perchlorate anions were examined under elevated temperatures and environments. The use of d.c. electrical conductivity decay measurements and fitting of kinetic models allows changes in bulk properties to be examined. Surface characterisation performed by X‐ray photoelectron spectroscopy (XPS) enables detailed investigation into changes in chemical states of surface atoms. The mechanisms described for the change in electrical and structural properties may be attributed to polymer backbone oxidation through free radical oxygen insertion and electrolyte dopant degradation.
New chain transfer agents for free radical polymerizations
Authors: Meijs Gordon F. , Rizzardo Ezio , Le Tam P. T. 
Published: April 2007

AbstractThe palmitoyl ester of N‐hydroxypyridine‐2‐thione displayed useful chain transfer properties in free radical polymerizations of methyl methacrylate and styrene. Retardation, however, accompanied the lowering of molecular weight in methyl acrylate and vinyl acetate polymerizations.4‐Methyl‐3‐palmitoyloxythiazol‐2(3H)‐thione had good chain transfer activity with methyl methacrylate, styrene and methyl acrylate. Although benzyl thionobenzoate exhibited virtually ‘ideal’ behaviour (chain transfer constant Cx ∼1) in styrene and methyl acrylate polymerizations, it was ineffective in lowering molecular weight of poly(methyl methacrylate). Severe retardation was observed with vinyl acetate.Addition‐fragmentation pathways are postulated for chain transfer.
Development and characterisation of polypyrrole/metal junctions for electronic applications
Authors: Unsworth Joe , Jin Zheshi , Lunn Brett A. , Innis Peter C. 
Published: April 2007

AbstractPreliminary results are presented on the fabrication and analysis of junctions formed between metals and semi‐conducting and conducting polypyrrole. Rectifying junctions were observed between aluminium and indium with semi‐conducting polypyrrole in a sandwich geometry using current‐voltage (I‐V) and capacitance‐voltage (C‐V) analysis techniques, respectively. All planar junctions analysed were non‐rectifying, while both gold and platinum were observed to form ohmic junctions in both the sandwich and planar geometries. Preliminary analysis using ideal Schottky barrier theory was attempted with various junction parameters determined, with significant deviation from the ideal theory observed. It is proposed that this deviation is due to the synthesis history of the polymer and the presence of an insulating oxide layer between the polymer and the metal.
In‐chain functionalization by alternating anionic copolymerization of styrene and 1‐(4‐dimethylaminophenyl)‐1‐phenylethylene
Authors: Quirk Roderic P. , Zhu Linfang 
Published: April 2007

AbstractAnionic copolymerizations of styrene (M1) with excess 1‐(4‐dimethyl‐aminophenyl)‐1‐phenylethylene (M2) were conducted in benzene at 25°C for 24h, using sec‐butyllithium as initiator. Narrow molecular weight distribution copolymers with M̄;n = 16.1 × 103 g/mol (M̄w/M̄n = 1.04) and 38.2 × 103g/mol (M̄w/M̄n = 1.05), and 24 and 38 moles of M2 per macromolecule, respectively, were characterized by size exclusion chromatography, 1H NMR spectroscopy and DSC. The monomer reactivity ratio, r1 = 5.6, was obtained from the copolymer composition at complete consumption of M1, assuming that the rate constant k22 =0,i.e. r2 =0. The polymers exhibited Tg values of 128 and 119°C, respectively, which correspond to an estimated Tg = 217°C for the hypothetical homopolymer of M2.
Polyesters from lignin. 1. The reaction of kraft lignin with dicarboxylic acid chlorides
Authors: Guo Zhao‐Xia , Gandini Alessandro , Pla Fernand 
Published: April 2007

AbstractKraft lignin was treated with dicarboxylic aliphatic (sebacoyl) or aromatic (terephthaloyl) acid chlorides in N,N‐dimethylacetamide or N‐methyl‐2‐pyrrolidone as solvents in the presence of triethylamine or pyridine as catalysts. The polyester gels obtained were characterized by IR after specific extractions and the chemical incorporation of lignin was proved unambiguously. Their thermal behaviour was determined by DSC and TGA; they are amorphous and stable up to 200°C in a nitrogen atmosphere. The reactivities of the two types of hydroxyl group (aliphatic and phenolic) were assessed from model reactions carried out in the same conditions.
Synthesis and characterization of high molecular weight water‐soluble polymers
Authors: Hunkeler D. 
Published: April 2007

AbstractThe synthesis of high molecular weight acrylic water‐soluble polymers in heterophase water‐in‐oil polymerizations is discussed. A mechanism has been elucidated which includes elementary reactions in the continuous (organic) and dispersed (aqueous) phases, as well as the interfacial layer. The latter allows for the identification of interfacially active species which can concurrently enhance stability and increase the linear molecular weight of the polymer. Suitable species are found to contain multiple radically active functional groups on either the hydrophilic or hydrophobic moieties.A one‐point light‐scattering method is also developed which improves the accuracy in molecular‐weight estimation to /pi5%. compared with /pi10% for the conventional dilution procedure. This is demonstrated for high molecular weight polyacrylamides and is found to reduce the sample measurement time fourfold, to 20 min.