bluuebunny/crossref_metadata_2025 huggingface dataset:
A dynamic mechanical study on unidirectional carbon fiber‐reinforced polypropylene composites
Authors: Sengupta P. K. , Mukhopadhyay D.
Published: April 2003

Fiber‐reinforced polymer composites show high specific strength and stiffness. The alignment of reinforcing fibers results in anisotropy of the material. This anisotropic behavior has been studied through dynamic mechanical analysis of unidirectional carbon fiber‐reinforced polypropylene (CFRPP) composites measured in both parallel and transverse directions to fiber arrangement. Several parameters such as storage modulus (E′), loss modulus (E″), loss factor or damping factor (tan δ), and complex viscosity (MU*) have been determined over a wide range of frequencies and at a fixed temperature. Relaxation and retardation spectra have been constructed for these composites. Modulus enhancement occurs due to stiffness imparted by the fiber and efficient stress transfer at the interface. Relaxation of the polymer matrix ceases with increase in the volume fraction of the fibers. α′‐relaxation is observed for the composite having a 13% volume fraction of fibers and is ascribed to relaxation in the crystalline phase where the additional crystallinity arises out of the transcrystalline growth at the fiber–matrix interface. There exists a good correlation between theroretical curves with the experimental ones. Relaxation and retardation spectra and the dynamic parameters determined for these composites show a good correlation with the volume fraction of fibers as well as the direction of the applied load. © 1994 John Wiley & Sons, Inc.
Silicon‐containing polypyrrolone for gas‐separation application
Authors: Zhou Wenle , Gao Xuesong , Lu Fengcai
Published: April 2003

The permeability to H2, O2, and N2 of silicon‐containing polypyrrolone (SiDA–OTA) and three silicon‐containing polypyrrolone random copolymers was determined at 30°C and 1 atm. The SiDA–OTA shows simultaneously increased permeability and permselectivity over the analogous polyimide (SiDA–ODA). The substitution of SiDA for the BPDA moiety in a polypyrrolone appears to result in a significant increase in gas permeability. The random copolymers contain different amounts of SiDA and DODA, which show lower permeability and higher permeselectivity than does SiDA–OTA. Wide‐angle X‐ray diffraction measurements of the mean intersegmental distance of the materials characterized the packing of different polymer types. © 1994 John Wiley & Sons, Inc.
Continuous UV cure monitoring and dielectric properties of photocross‐linked epoxy–acrylate resins
Authors: Radhakrishnan S. , Pethrick R. A.
Published: April 2003

The changes in viscosity of epoxy–acrylate resins during the photocross‐linking process have been monitored continuously. The curing show change of shape and a distinct peak especially at high intensities. The intensity dependence of gel time follows a superlinear power law of the type tpαI−1.6 rather than the ½ power law. The dielectric relaxation studies on these photocross‐linked films having different compositions of epoxy and n‐butyl methacrylate reveal a particular composition range in which various dielectric parameters pass through critical values. These various findings have been explained on the basis of phase separation taking place during the UV curing process but at a submicron level leading to a very small domain size. © 1994 John Wiley & Sons, Inc.
NG‐migration into double‐base inhibitors. II. Diffusion
Authors: Potgieter H. F. , Sanderson R. D.
Published: April 2003

The maximum sorption of nitroglycerine (NG) in polymeric material was measured in Part 1. The results of the sorption is used to determine the average diffusion coefficient for each polymer, utilizing Fick's second law. These values are compared to the chlorine content in the polymer backbone to ascertain whether the chlorine has any influence in lowering the diffusion coefficient. © 1994 John Wiley & Sons, Inc.
In situ compatibilized polymer blends of phenoxy and ABS
Authors: Chen Sue‐Hua , Chang Feng‐Chih
Published: April 2003

The combination of styrene‐acrylonitrile‐glycidyl methacrylate (SAG) reactive copolymer and sodium lauryl sulfonate catalyst is able to function as an effective in situ compatibilizer for the otherwise immiscible and incompatible polymer blends of phenoxy and acrylonitrile‐butadiene‐styrene (ABS). The copolymer formed from the reaction between phenoxy and SAG under melt blending conditions tends to reduce interfacial tension in the melt and results in finer morphological domains of the blends. The presence of this in situ formed compatibilizer also raises the interphase adhesion of the blends and results in significant improvements in mechanical properties. © 1994 John Wiley & Sons, Inc.
Particle control of Ziegler–Natta catalysts based on TiCl3 for propylene polymerization. Effect of prepolymerization
Authors: Coutinho Fernanda M. B. , Costa Marcos A. S. , Maria Luiz C. Santa , Bruno José C.
Published: April 2003

Prepolymerizations employing an extremely high stereospecific and high active catalyst based on TiCl3 modified by di‐n‐butyl ether (DBE) were carried out with different monomers (styrene, propylene, hexene‐1, cyclopentadiene). The influence of prepolymerization on the morphology of polypropylene obtained with TiCl3 catalyst was investigated. The catalyst was synthesized by TiCl4 reduction in toluene solution with A1Et3·DBE complex. The polymer morphology was evaluated through optical and scanning electron microscopies and polymer bulk density and particle size distribution. © 1994 John Wiley & Sons, Inc.
Spontaneous hydrolytic degradability of copolyesters having tetrahydropyran rings in their backbones
Authors: Okada Masahiko , Ito Shinji , Aoi Keigo , Atsumi Miharu
Published: April 2003

Homo‐ and copolyesters, containing 2,5‐linked tetrahydropyran rings in their backbones, were prepared by cationic ring‐opening polymerization of bicyclic lactones, 2,6‐dioxabicyclo [2.2.2] octan‐3‐one (1), and its 4‐methoxy‐carbonyl and 4‐methoxy‐carbonyl and 4‐benzyloxycarbonyl derivatives (3 and 4). Copolyesters, having pendant carboxyl groups, were derived from the copolymers containing 4 as one of the comonomers by the catalytic hydrogenolysis of the pendant benzyloxy–carbonyl groups. Copolyesters, containing both 2,5‐linked and 2,6‐linked tetrahydropyran rings in the main chains, were obtained by the copolymerization of 1 with 6,8‐dioxabicyclo [3.2.1] octan‐7‐one (13), which is a structural isomer of 1. Spontaneous hydrolytic degradability of these polyesters was investigated in a phosphate buffer solution (pH 7.5) at 27°C. The degradability of the polyesters markedly depended on the molecular structure: hydrophobic pendant groups retarded the hydrolytic degradation, whereas hydrophilic pendant groups accelerated it. In particular, a small amount of pendant carboxyl groups significantly enhanced the hydrolytic degradability of the copolyesters from 1. Polyesters, containing 2,6‐linked tetrahydropyran rings in their backbones, underwent hydrolytic degradation more readily than those entirely consisting of 2,5‐linked tetrahydropyran rings. © 1994 John Wiley & Sons, Inc.
Biodegradability of polyesters having tetrahydropyran rings in their backbones
Authors: Okada Masahiko , Ito Shinji , Aoi Keigo , Atsumi Miharu
Published: April 2003

Biodegradability of several homo‐ and copolyesters, containing tetrahydropyran rings in their backbones with or without pendant groups, was investigated by degradation tests, both in soil and in an activated sludge. These polyesters were hydrolytically degraded to lower molecular weight compounds, and eventually to hydroxytetrahydropyran carboxylic acids, at different rates, depending on their molecular structure. Quantitative determination of carbon dioxide, generated during the treatment with the activated sludge, showed that the hydrolysates from polyesters 2 and 10, without pendant alkoxycarbonyl groups, were catabolized by microorganisms. It was concluded from these results that at least the polyesters without pendant groups were biodegradable, and that polyester 10, consisting of 2,6‐linked tetrahydropyran rings, underwent biodegradation more readily than polyester 2, consisting of 2,5‐linked tetrahydropyran rings. © 1994 John Wiley & Sons, Inc.
Phase equilibria in SBR/polybutadiene elastomer blends: Application of Flory–Huggins theory
Authors: Maier T. R. , Jamieson A. M. , Simha R.
Published: April 2003

Blends of anionically‐polymerized polybutadiene (BR) and styrene–butadiene copolymer (SBR) must be treated as mixtures of terpolymers and tetrapolymers, due to the presence of three different BR isomers: cis‐1,4, trans‐1,4, and vinyl‐1,2. Moreover, in the absence of specific interactions or chemical reactions that strongly influence miscibility, structural characteristics of the component polymers, such as BR isomer content, SBR styrene content, monomer sequence distribution, molecular weight, and molecular weight distribution, are expected to have an increased role in determining the blend miscibility characteristics. Small angle neutron scattering (SANS) studies of SBR/BR blends have resulted in the computation of the monomer–monomer segmental interaction energetics via a Flory–Huggins treatment. This allows quantitative prediction of miscibility behavior as a function of polymer structure. We have used the Flory–Huggins chi parameters, describing the styrene/cis‐1,4, styrene/trans‐1,4, and cis‐1,4/trans‐1,4 segmental interactions, to identify certain blend combinations expected to exhibit phase transitions in an experimentally accessible temperature range. The appropriate polymers were synthesized, solution blended, and the blends analyzed via optical microscopy and thermal analysis. Our results show that the blend behavior, observed experimentally, is consistent with the calculated cloud point curves. © 1994 John Wiley & Sons, Inc.
Surface reactive acetal functional waterborne microparticles
Authors: Kjellqvist Kerstin , Rassing Jörgen , Wesslén Bengt
Published: April 2003

Small particles have been prepared by means of emulsion polymerization from styrene and ethyl acrylate, using different concentrations of emulsifier. The particle size can be controlled in the range of 45–85 nm. The particle surface was modified by introducing an acetal functionality, suitable for acid catalyzed processes. Surface functionalization was performed in two principally different ways. First, by using an acrylic monomer with acetal functionalities in the polymerization step and, second, by means of a surface grafting technique, using nonacrylic monomers. © 1994 John Wiley & Sons, Inc.
Desorption of residual monomer from PVC resins in a fluidized bed drier
Authors: Bouaffar H. , Yilmazer U. , Elbirli B.
Published: April 2003

The present study deals with the investigation of the desorption of vinyl chloride from various commercial and experimental suspension PVC resins in a laboratory fluidized bed drier simulating an industrial drier. The results show that PVC resins may differ widely in the rate at which the monomer is desorbed. The rate of diffusion of the monomer is a function of the drying time, the fluidization air temperature, the porosity, and the amount of glassy particles in the PVC. The residual monomer content decreases with increasing air temperature, drying time, and resin porosity. After 105 min of drying with hot air at 80°C, the residual monomer content in the grade with the highest porosity is reduced from 3400 to 2 ppm, whereas for the grade with the lowest porosity, it is reduced from 4300 to 172 ppm on a dry basis. It appears that the resins of the high molecular weight grades are more porous and the low molecular weight grades contain a high proportion of nonporous or glassy particles and, hence, the desorption rate is smaller in these grades. The proportion of glassy particles and the size of glassy domains are estimated in this study by applying the experimental desorption data at long times to a desorption model. The model is useful in differentiating the interior structure of various PVC grades. © 1994 John Wiley & Sons, Inc.
Magnetic field processing of polymers. I. Hydroxypropyl cellulose
Authors: Liepins Raimond , Jahn Randy K. , Elliott Norman E. , Hubbard Kevin M.
Published: April 2003

Hydroxypropyl cellulose (HPC) of degree of substitution three and average molecular weight of 100,000 was processed in a magnetic field of 1.2T. Films of HPC were cast from water, methanol, ethyl methyl ketone, and 1,1,2,2‐tetrachloroethane solutions in a magnetic field using static and dynamic casting techniques. The processed films were evaluated for tensile strength, elastic modulus, microhardness, and molecular chain alignment by wide angle x‐ray diffraction and polarized infrared. The best alignment and hence the greatest improvement in properties was obtained using a combined magnetic field and flow alignment procedure. These samples showed no increase in the elastic modulus, a 106% increase in the tensile strength, a 21% increase in the microhardness, and were dichroic. © 1994 John Wiley & Sons, Inc.

This article is a US Government work and, as such, is in the public domain in the United States of America.
XPS study of dimethylolurea polymers and hollow fibers modified by these polymers. II. XPS study of hollow fibers modified by dimethylolurea polymers
Authors: Rouzies P. , Lebugle A.
Published: April 2003

Polysulfone ultrafiltration hollow fibres are modified on the surface with polymers obtained by polycondensation of dimethylolurea (DMU). Depending upon the reaction conditions, polymers on the surface present a gel or a film form. In the first case the membranes are called “gel‐supported” and in the second case “coated”. Modified and unmodified polysulfone membranes were analysed by XPS spectroscopy. The modifications observed on a modified membrane were studied by reference to the previous article dealing with XPS analysis of gel and film DMU polymers. The study showed that gel‐supported membranes are modified by a polymer of a gel‐type chemical structure whereas coated membranes are modified by a polymer of film‐type chemical structure. The nature of the support, polysulfone, does not affect the final form of the polymer. © 1994 John Wiley & Sons, Inc.
Effect of chemical doping on the electrical conductivity of poly(2,6‐dimethyl‐1,4‐phenylene oxide)
Authors: Kalkar A. K. , Kundagol Shankar , Chand Suresh , Chandra Subhas
Published: April 2003

The electrical conductivity of solution‐grown poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) films doped with TCNQ, TCNE, TNF, and I2 has been studied as a function of dopant concentration, temperature (298–353 K), and field (50–2000 V). PPO forms a conductive complex on doping with these strong electron‐acceptor organic molecules. As with PPO, two distinct ohmic and nonohmic conduction regions at low and higher fields, respectively, are observed. The conduction properties of doped PPo films result from the formation of an isotropic continuous charge‐transfer complex. The existence of such a complex is confirmed by UV‐visible absorption spectra measurements. A possible mechanism for the electrical conduction process is discussed. © 1994 John Wiley & Sons, Inc.
Synthesis of NAD polystyrene microspheres and application as a carrier of glucoamyrase immobilization
Authors: Omi Shinzo , Kaneko Kazuyoshi , Takesue Mariko , Tsujimura Hamana , Satoh Atsunori , Iso Mamoru
Published: April 2003

Polystyrene microspheres with a small amount of acrylic acid (200 : 1) incorporated were synthesized by nonaqueous phase dispersion (NAD) polymerization to investigate the feasibility of use as a carrier for immobilized enzyme. Seeded emulsion polymerization was then carried out to obtain larger cross‐linked polystyrene spheres, the structure of which was expected to yield a favorable environment to keep the original activity of the immobilized enzyme. Glucoamylase, a particular enzyme catalyzing the hydrolysis of oligosaccharides to glucose, was immobilized through peptide bonding using a carbodiimide activating agent. Thirty percent of the enzyme activity at maximum was retained relative to free glucoamylase. The immobilized enzyme remained active after 4 months, although its poor resistance to heat was not improved. © 1994 John Wiley & Sons, Inc.
Dissolution of perfluoroalkyl oligomers in lubricating oil for enhancing wear resistance and fuel economy
Authors: Derosa Thomas F. , Kaufman Benjamin J. , Sung Rodney L.‐D. , Russo Joseph M.
Published: April 2003

Perfluorobutyl‐1,1,2‐tri‐H‐1‐hexene and perfluoroalkyl methacrylate have been solubilized in lubricating oil by single‐step free radically grafting onto poly(ethylene‐co‐propylene). Perfluoroalkyl‐1,1,2,2‐tetra‐H‐ethanol and perfluoropolyether carboxylic acid were solubilized by condensing with poly[(ethylene‐co‐propylene)‐g‐glycidyl methacrylate], generating the corresponding perfluoroalkyl ether or ester, respectively. Solubilization of 1,1,2,2‐tetra‐H‐ethanol was also achieved by condensing with poly[(ethylene‐co‐propylene)‐g‐2‐isocyanoethyl methacrylate] to the corresponding perfluoroalkyl urethane. Scar diameter reductions ranged from 9.4 to 58% using perfluoro‐modified graft copolymers as determined using the Four Ball Wear Test, although optimum reductions were obtained using perfluoroalkyl urethane‐modified graft copolymers. Moreover, a semiquantitative correlation of scar reductions and thermal instability was determined. Sequence VI engine testing of perfluoroalkyl urethane graft copolymers containing pendant perfluoroalkyl chain lengths of 8.2 and 7.2 had an Equivalent Fuel Economy Index of 4.33 and 4.27, respectively. © 1994 John Wiley & Sons, Inc.
Separability behavior in viscoelastic properties of EPDM gum vulcanizate
Authors: Namboodiri C. S. S. , Tripathy D. K.
Published: April 2003

Dynamic mechanical properties of EPDM gum vulcanizates were studied using the dynamic viscoelastometer, Rheovibron. A small sinusoidal strain was superimposed on a static strain and its effect on dynamic mechanical properties were analyzed. The results are discussed in terms of total strain which takes the static strain into account. Separability of time and strain effects for loss modulus and the nonseparability for storage modulus are discussed. A critical strain was identified after which the stress dissipation mechanism changes. © 1994 John Wiley & Sons, Inc.
Polysulfide sealant compositions. II. Interactions between elemental sulfur and organosulfur compounds
Authors: Hanhela Peter J. , Hook Robert J. , Paul D. Brenton
Published: April 2003

Added sulfur in polysulfide aircraft sealants can become chemically bound to the polymer backbone. The chemical processes involved, and their effect on thermal performance of the resulting sealants, have been examined. Reactions of aliphatic thiols with sulfur and amine catalysts have been reinterpreted to include possible involvement of hydropolysulfide intermediates. When the procedure was applied to polysulfide liquid polymers, products with substantial levels of tri‐ and tetra‐sulfide links were formed. 13C–NMR spectroscopy of model compounds enabled the assignment of chemical shifts associated with S3 to S5 links in the sulfur enriched polymers. Spectroscopic examination afforded no evidence for the presence of such species in commercial polysulfide liquid polymers.

No obvious detrimental effects on elevated temperature performance of polysulfide sealants resulted from the incorporation of up to 1% sulfur into the polymer backbone. A higher degree of cure is achieved and this is associated with increased hardness and modulus, together with reduced extension as compared with untreated sealants. © 1994 John Wiley & Sons, Inc.
Thermal and crystallization behavior of engineering polyblends. II. Unfilled polyphenylene sulfide with poly(ethylene terephthalate)
Authors: Shingankuli V. L. , Jog J. P. , Nadkarni V. M.
Published: April 2003

The melting and crystallization behavior of blends of poly(phenylene sulfide) (PPS) with poly(ethylene terephthalate) (PET) has been investigated. The component polymers in the blend exhibited separate crystallization peaks and overlapping melting peaks. The nonisothermal DSC scans indicated that the crystallization parameters for PET become modified to a greater extent than do those for PPS in the blends. The PET crystallization peak became narrower with a higher heat of crystallization, suggesting a faster rate of crystallization as a result of blending with PPS. The isothermal crystallization studies revealed that the nucleation of PPS is facilitated by the presence of PET. This contention has been substantiated by polarized light microscopic observations. The spherulites of PPS were found to be smaller in the blends as compared to those in neat PPS. This enhancement in the nucleation of PPS has been attributed to the possibilities of chemical interactions between the component polymers. On the other hand, the increase in the rate of crystallization of PET has been attributed to the heterogeneous nucleation provided by the alreadycrystallized PPS. The melt crystallized blends exhibited slightly higher heats of fusion compared to the values computed from the rule of proportional additivity. © 1994 John Wiley & Sons, Inc.
Photoinduced graft copolymerization of 2‐hydroxyethyl methacrylate on cotton cellulose in the presence of triethyleneglycol dimethacrylate
Authors: Shukla S. R. , Athalye A. R.
Published: April 2003

The addition of a bifunctional monomer, triethylene glycol dimethacrylate (TEGDMA), to a grafting system containing 2‐hydroxyethyl methacrylate (HEMA) and benzoin ethyl ether photoinitiator substantially increased the graft add‐on of the unswollen and sodium hydroxide–swollen cotton cellulose. Grafting caused changes in the properties of the substrate such as moisture regain, the water of imbibition, and the dyeability with a direct and a reactive dye in accordance with the graft level. The observations have been explained in relation to structural changes in the grafted cotton. © 1994 John Wiley & Sons, Inc.
Deformation and fracture of PMMA at high rates of loading
Authors: Sahraoui S. , Lataillade J. L.
Published: April 2003

The scope of this article is to study the influence of loading rates on the deformation and the fracture of PMMA. The dynamic loading was achieved by means of an impact three point bend device for intermediate strain rates and by using a split Hopkinson's tensile bar apparatus for higher rates of loading. Tensile properties (Young modulus, yield stress) and fracture toughness are determined in a wide range of loading rates and compared to the literature results. Scanning electron micrographs of the tensile fracture surfaces are presented to illustrate the dynamic effect on the crack propagation. © 1994 John Wiley & Sons, Inc.
Sequence analysis of fluorine‐containing polyarylethersulfone copolymers by 13C–NMR
Authors: Wang Zhonggang , Chen Tianlu , Xu Jiping
Published: April 2003

HexafluorobisA polyethersulfone‐cardo polyethersulfone, random and block copolymers with different segment lengths were synthesized by a reaction of 4,4′‐(hexafluoroisopropylidene) diphenol and 3,3′‐bis(4‐hydroxyphenyl)‐1‐isobenzopyrrolidone with bis (4‐chlorophenyl) sulfone. Their NOE‐suppressed quantitative 13C–NMR spectra were recorded on a 400 MHz NMR spectrometer. The 13C–NMR signals of tertiary carbon atom and quaternary carbon atom, on the benzene ring adjacent to sulfone group, appeared to be sensitive to sequence variation. Degrees of randomness of the copolyarylethersulfone synthesized were 0.96, closing to 1, and 0.39, as well as 0.55, far smaller than 1, indicating random distribution and regular distribution of the comonomers, respectively. The number average sequence length, calculated by 13C–NMR spectra, were shorter than expected, due to the transetherification reaction. © 1994 John Wiley & Sons, Inc.
Coemulsion and electrodeposition properties of mixtures of cationic epoxy resin and cationic acrylic resin containing blocked‐isocyanate groups
Authors: Chen Yahn‐Haur , Yang Chin‐Ping
Published: April 2003

2‐Ethylhexanol–half‐blocked‐toluene diisocyanate (2EH‐half‐blocked TDI) was first reacted with 2‐hydroxyethyl methacrylate (HEMA) to prepare HEMA–TDI–2EH monomer containing blocked‐isocyanate groups. This monomer was reacted with butyl acrylate, styrene, and N,N‐dimethylaminoethyl methacrylate to prepare an acrylic copolymer III′ containing blocked‐isocyanate groups and tertiary amine groups. The acrylic copolymer III′ can be mixed with an epoxy–amine adduct IV′, acetic acid, and deionized (D.I.) water to from an electrodepositable coemulsion. The electrophoretic codeposition of the coemulsion and physical and chemical properties of the codeposited film were investigated. The resin composition of film deposited from coemulsion was determined by Fourier transform infrared (FTIR) quantitative analysis to study the coemulsion and electrophoretic codeposition behavior. The applicability of this two‐component coemulsion in primer–surface (pricer) electrodepositable paint was also discussed. The results indicate that the deposition yield of cationic acrylic copolymer III is greater than that of cationic epoxy resin IV, i.e., the deposition velocity of III is faster than that of IV. However, resins III and IV can be well codispersed in D.I. water to form stable coemulsion; thus, the resin composition of deposited is almost equal to the resin composition. Moreover, the throwing power of coemulsion is almost equal to that of IV emulsion but greater than that of III emulsion. The optimum resin compositions of coemulsions for obtaining better gel content of deposited films are between 0.65 and 0.8 (III/III+IV, by weight). © 1994 John Wiley & Sons, Inc.
Identification of fluorescent products produced by the thermal treatment of bisphenol‐A‐based polycarbonate
Authors: Rufus I. B. , Shah H. , Hoyle C. E.
Published: April 2003

Polycarbonate is routinely subjected to heat treatment, and the thermal degradation products formed during this thermal treatment give rise to a distinct structured fluorescence spectrum. The structured fluorescence emission is observed when polycarbonate is subjected to thermal treatment in air as well as in nitrogen. A mixture of thermal rearrangement products of polycarbonate including dibenzofuran and phenyl‐2‐phenoxybenzoate are mainly responsible for the structured fluorescence emission. Most of the thermal degradation products of polycarbonate undergo photolysis, leading to the formation of photoproducts, which subsequently undergo a photoinduced bleaching process, with the noted exception of phenyl‐2‐phenoxybenzoate. The exposure of polycarbonate to high temperature for only short time periods, simulating mild industrial processing conditions, results in the formation of a relatively small amount of thermal degradation products, which, accordingly, has only a minor effect on the photodegradation of polycarbonate. © 1994 John Wiley & Sons, Inc.
Thermal, stability, morphological, and conductivity characteristics of polypyrrole prepared in aqueous medium
Authors: Biswas Mukul , Roy Anindita
Published: April 2003

The aqueous polymerization of pyrrole with varying FeCl3/Py mol ratio produces black insoluble powders. IR characterization reveals the shifting of the NH stretching band to higher frequency with increasing FeCl3 amount in the feed composition due to lowering of intermolecular H‐bonding. SEM shows a spongy texture of the polymer. TGA indicates the initial decomposition temperatures (180°–237°C) to be somewhat dependent on the FeCl3/Py feed ratio. DSC suggests the glass‐transition temperature to be in the range 160–170°C for the polymers prepared with various feed compositions. The conductivity is also dependent on the FeCl3/Py feed composition and levels off at a value of ∼3 ohm−1cm−1. © 1994 John Wiley & Sons, Inc.
The electrodeposition properties of coemulsion‐contained quaternary ammonium/tertiary amine salt epoxy–amine adducts and the composition analysis of its electrodeposited film
Authors: Yang Chin‐Ping , Ting Chih‐Yang
Published: April 2003

Two‐component electrodepositable coemulsion‐contained quaternary ammonium resin Q, as a pigment grinding vehicle, and DGEBA–N‐methylethanolamine (MEA) tertiary amine salt resin T, as the principal resin, were obtained and then deposited to form a resinous film on the cathode during electrodeposition. The resin composition of this deposited film was determined by the quantitative analysis of FTIR and it was found different from the resin composition of the original coemulsion. The electrodeposition behaviors of the coemulsion were deeply affected by the quaternary ammonium resin. In addition, the electrodeposition properties of emulsions dispersed by quaternary ammonium resin and tertiary amine salt resin were also studied for comparison. © 1994 John Wiley & Sons, Inc.
Heat pulse monitoring of curing and polymer–gas systems
Authors: Skripov Pavel V. , Puchinskis Stanislavs E. , Begishev Valerij P. , Lipchak Alexander I. , Pavlov Pavel A.
Published: April 2003

An implantable thermal probe is used to study the reaction of molten polymers and curing systems to pulse heat release. At the heating rates T˙≥5·105K/s, a polymer system shows the response to pulse heating that is confined in time and reproducible with respect to temperature. This response is related to the abrupt change in the conditions of the contact between the probe and a substance. The temperature of the response T* is determined by the polymer properties and depends on the pressure and T˙. The pulse thermal probe method, which includes two measuring procedures, complementing each other, has been used to monitor a number of processes in polymeric systems. The variation of the values of T* and the thermal activity of a polymer is compared with the variation of its molecular weight (M̄n∼ 102–106), the molecular weight distribution, and the concentration of a low molecular weight component. The method allows one to trace the kinetics of polymerization and curing and the kinetics of dissolution of volatile impurity and polymer devolatilization, and to determine the limit of supersaturation of gas solutions in molten polymers. The pulse repetition frequency is changed from 0.1 to 1 Hz. The heated volume of a substance is 10−4 mm3. © 1994 John Wiley & Sons, Inc.
A study of electrostatically stabilized poly(methyl methacrylate) latex
Authors: Chu Hou‐Hsein , Hsu Xue‐Chaun
Published: April 2003

Poly(methy methacrylate) latex with various solid contents, stabilized electrostatically, was studied. The hydrodynamic layer (H.L.) extends rapidly at volume fraction larger than 0.35. The agglomeration of particles was found. When the reduced thickness (δ/r) of H. L. exceeds 3.0, particle agglomeration becomes more serious and the gel‐like product forms. In comparison, the value of (δ/r) is much smaller than 3.0 when the H. L. begins to contact each other. Using a higher amount of emulsifier, the thickness of H. L. decreases. This is attributed to the fact that more free emulsifier presenting in the aqueous phase leads to more depletion stabilization. Meanwhile, in the presence of unreacted monomer, the use of the monomer‐swollen volume fraction is suggested to replace the unswollen volume fraction. © 1994 John Wiley & Sons, Inc.
Dimethylacetamide sorption kinetics in a urethane/urea/ether block copolymer
Authors: Gou M. M. , Koros W. J. , Goldman G.
Published: April 2003

Polymer solvent interactions in a block polyurethane/urea/ether polymer belonging to the spandex family are considered in this article. Independent analysis of the sorption isotherms for dimethylacetamide (DMAc) in the spandex spandex polymer as a function of vapor activity and temperature were presented in a previous article. A second aspect in understanding solvent/polymer interactions is the kinetics of desorption. Characterization of the solvent devolatilization is an important aspect of the drying procedure to guide processing protocols to eliminate residual solvent in the final spandex products, especially for medical applications [E. Hicks, A. Ultee, and J. Drougas, Science, 147, 373 (1965); J. W. Boretos and W. S. Pierce, J. Biomed. Mater. Res., 2, 121 (1968); P. M. Knight and D. J. Lyman, J. Membr. Sci., 17, 245 (1984)]. This article reports data for desorption kinetics under nominally isothermal conditions to provide diffusion coefficients as a function of polymer phase concentration and temperature. Desorption curves were found to be Fickian at least up to the half‐time of desorption. Diffusion coefficients were therefore calculated using a half‐time method. Temperature effects upon sorption or desorption were measured to obtain corrected diffusion coefficients and found to be singificantly different than the apparent diffusion coefficient measured from a conventional McBain sorption cell. © 1994 John Wiley & Sons, Inc.
Microphase separation and crystallization of crystalline–amorphous type block copolymer. VI. Crystalline part in crystalline domain
Authors: Ishikawa Satoshi
Published: April 2003

The crystalline and amorphous areas in poly(tetrahydrofuran) (PTHF) domains in a poly(tetrahydrofuran‐b‐isoprene) (crystalline–amorphous, PTHF = 52 wt %) film were distinguished by transmission electron microscopy and the relation between the crystallization and domain shape was clarified. The ratio of PTHF domain containing amorphous area was low in the case of the fewer interfaces of the small curvature formed by poly(isoprene) domain. The PTHF crystallization was closely related to the interface shape. © 1994 John Wiley & Sons, Inc.
Recognition of substrates by membrane potential of immobilized glucose oxidase membranes
Authors: Higuchi Akon , Hara Mariko , Yun Kyu‐Sik , Tak Tae‐Moon
Published: April 2003

The shifts in membrane potential, caused by the injection of glucose into a permeation cell, were measured using immobilized (entrapped) glucose oxidase membranes. No, pH change in the permeation cell was observed upon injection of glucose, but the shift in membrane potential was definitely detected. The shift in membrane potential was observed under nitrogen bubbling (in the absence of oxygen) using initially used enzyme membranes. It was, therefore, suggested that the shifts in membrane potential were not caused by an enzyme‐substrate reaction, but by binding of the substrate to the enzyme, which indues a conformational change in the enzyme and leads to a change in charge density in the enzyme membrane. This mechanism is also supported by the fact that the shifts in membrane potential were observed upon injection of not only D‐glucose but also L‐glucose as reported in our previous study [J. Chem. Soc. Faraday Trans., 87, 695 (1991)]. © 1994 John Wiley & Sons, Inc.
Electron beam chemistry of polyvinylpyridinium salts
Authors: Lee Kang I.
Published: April 2003

Various polyvinylpyridinium salts have been studied under electron beam. The relationship between electron beam sensitivities and chemical structural variables of polyvinylpyridinium salts has been studied by conventional scanning electron microscopy. Several possible mechanisms of radiation‐induced solubility change in the polyvinylpyridine system have been discussed. © 1994 John Wiley & Sons, Inc.
Evaluation of a sorption equation for polymer–solvent systems
Authors: Vrentas J. S. , Vrentas C. M.
Published: April 2003

The predictive capabilities of a proposed sorption equation for describing the sorption behavior of glassy polymer–penetrant systems is evaluated. Factors determining the shapes of isotherms for glassy polymer–penetrant systems are considered. Data–theory comparisons are presented for three glassy polymer–penetrant systems. © 1994 John Wiley & Sons, Inc.
Determination of infinite dilution diffusion and activity coefficients of solvents in polystyrene by inverse gas chromatography on a capillary column
Authors: Bonifaci Luisa , Carnelli Lino , Cori Laura
Published: April 2003

Infinite dilution activity and diffusion coefficients of several solvents in polystyrene have been measured by inverse gas chromatographic on a capillary column for temperatures between 110 and 170°C. Chromatographic data have been treated according to Khan's model, evaluating the contribution to the peak broadening due to radial and axial molecular diffusion in the mobile phase, radial diffusion in the stationary phase, and interfacial mass transfer resistance. Four capillary columns have been prepared with coating thickness ranging from 0.5 to 3.3 microns in order to determine the minimum thickness necessary to obtain reliable measurements of the diffusion coefficient of the solvent in the polymer in every possible experimental condition. Our experimental data are in considerable agreement with the data already available in the literature, obtained by static and chromatographic methods. © 1994 John Wiley & Sons, Inc.
Synthesis of graft polyethers by ring‐opening copolymerization of epoxy‐terminated poly(ethylene glycol) with epoxides
Authors: Ikeda Isao , Horie Naofumi , Suzuki Kimihiro
Published: April 2003

The copolymerization of epoxy‐terminated poly(ethylene glycol methyl ether) (CH3PEG–epoxide) with low molecular weight epoxides such as phenyl ether (PGE) was carried out to prepare the PEG graft polyethers. Potassium tert‐butoxide was the most favorable catalyst used to obtain the graft polyethers. The apparent number‐average molecular weight (Mn) of the graft polyethers decreased with increase in PGE concentration because PGE acted as both solvent and comonomer. The composition of the graft polyethers (PGE/CH3PGE), however, increased with increase in PGE concentration and was almost consistent with the feed ratio of the two monomers. The graft polyethers whose composition was over 10 were insoluble in water. The Mn of the graft polyethers was little affected by the reaction temperature, but more affected by the presence of solvent. Besides PGE, n‐butyl glycidyl ether and styrene oxide were effective as comonomers. CH3PEG–epoxide hardly polymerized in tert‐butyl alcohol. © 1994 John Wiley & Sons, Inc.
Soldering deterioration of epoxy‐molded IC packages after moisture absorption
Authors: Asai Shin'ichiro , Saruta Uki , Tobita Masanori
Published: April 2003

Molding compounds for surface‐mount devices were studied by using various kinds of epoxy resins in a practical model compound with phenol resins as curing agents. The physical properties of the cured compounds were studied at 215°C to simulate the condition that they encounter during the soldering process that can relate to package cracks. The compounds that have low modulus at soldering temperature, low equilibrium water concentration, and good adhesion toward the die pad developed few cracks after soldering. The compounds from difunctional epoxy resins showed good durability, resisting this phenomenon. © 1994 John Wiley & Sons, Inc.
ESCA characterization of polyacrylonitrile‐based carbon fiber precursors during its stabilization process
Authors: Bhardwaj Ashish , Bhardwaj Ishwar Singh
Published: April 2003

Oxidation process control plays a key role in influencing the development of carbon fiber properties. The characterization of oxidized fibers is difficult because of their poor solubility in organic solvents and strong absorbance. X‐ray photoelectron spectroscopy (XPS) has been used in the surface characterization of carbon fiber precursors during the oxidation or stabilization process. The changes in surface elemental composition and functionalities of carbon and oxygen have been identified. Quantitative changes have been noticed in surface functional groups as the oxidation process proceeds. © 1994 John Wiley & Sons, Inc.
Synthesis and properties of polyamides and copolyamides based on 2,6‐naphthalene dicarboxylic acid
Authors: Yang Chin‐Ping , Hsiao Sheng‐Huei , Lin Yie‐Shin
Published: April 2003

A number of polyamides based on 2,6‐naphthalene dicarboxylic acid (NDA) and various aromatic diamines were synthesized in N‐methyl pyrrolidone (NMP) containing lithium chloride (LiCl) or calcium chloride (CaCl2) by direct polycondensation using triphenyl phosphite and pyridine. The best reaction conditions for polycondensation were determined in terms of factors such as the amount of the solvency‐promoting reagent such as LiCl or CaCl2 and the initial reactant concentration. Thus, almost all polyamides were obtained with inherent viscosities above 1.0 and up to 3.28 dL/g. Similarly, high molecular weight copolyamides with inherent viscosities of 1.76–3.61 dL/g were prepared from 4,4′‐oxydianiline (ODA) and mixed dicarboxylic acids of NDA/terephthalic acid (TPA) or NDA/isophthalic acid (IPA). The solubility of NDA homopolyamides depended on the diamine components. The polyamides derived from meta‐, sulfone‐, or alkylene‐linked diamine showed increased solubility. Copolymerization of ODA with NDA/IPA led to a significant increase in solubility, whereas with NDA/TPA, it gave a limited improvement. All the homopolyamides and copolyamides showed an amorphous X‐ray diffraction pattern. Almost all the polymers soluble in aprotic solvents can be solution‐cast into strong and tough films. Glass transition shifts of some NDA polyamides can be observed in the differential scanning calorimetry (DSC) curves ranging from 243 to 345°C. Most NDA/IPA–ODA copolyamides also showed clear transitions in the range of 255–268°C. In nitrogen, all the polymers showed no significant weight loss up to 400°C, and their 10% weight loss temperatures were recorded in the range of 434–541°C. © 1994 John Wiley & Sons, Inc.
Monomer‐to‐water ratios as a tool in controlling emulsion copolymer composition: The methyl acrylate–indene system
Authors: Noël Lilian F. J. , Van Zon Jan M. A. M. , German Anton L.
Published: April 2003

A drifting copolymer composition as a function of conversion is an aspect typical of copolymerization. Reducing this so‐called composition drift in batch copolymerizations will lead to a decrease in chemical heterogeneity of the copolymers formed. For monomer systems in which the more water‐soluble monomer is also the more reactive one, theory predicts that composition drift in emulsion copolymerization can be reduced or even minimized by optimizing the monomer‐to‐water ratio. The monomer combination methyl acrylate–indene (MA–Ind) meets the requirements needed to minimize composition drift in batch emulsion copolymerization. Therefore, this monomer combination is chosen as a model monomer system in order to verify this theoretical prediction. Reactivity ratios needed for model predictions have been determined by low conversion bulk polymerization, resulting in rMA = 0.92 ± 0.16 and rInd = 0.086 ± 0.025. Furthermore, emulsion copolymerization reactions at the same monomer mole fraction are performed at different monomer to water ratios. From the good agreement between experiments and theoretical predictions for MA–Ind, it was concluded that control and even minimization of composition drift in batch emulsion copolymerization for monomer systems in which the more water‐soluble monomer is also the more reactive one is indeed possible by changing the initial monomer‐to‐water ratio of the reaction mixture provided that the reactivity ratios of both monomers are not too far from unity. © 1994 John Wiley & Sons, Inc.
Number‐average molecular weight by size exclusion chromatography
Authors: Balke S. T. , Mourey T. H. , Harrison C. A.
Published: April 2003

It is now theoretically possible to obtain absolute accurate values of number‐average molecular weight of complex polymers (e.g., branched polymers or copolymers) using size exclusion chromatography (SEC) with only a detector that measures the difference between the eluting polymer solution viscosity and the viscosity of the pure mobile phase (a differential viscometer [DV] detector). However, both precision and accuracy of these “DV M̄n” values are of concern. In this work, the precision of NBS 706 polystyrene was found to be two to three times worse for the DV M̄n than for the conventionally calculated M̄n. Also, regarding accuracy, the DV M̄n values were affected by the location of the universal calibration curve along the retention volume axis (a problem intimately associated with the problem of specifying the correct interdetector volume), the sensitivity of the DV detector to low molecular weights present in the sample, and axial dispersion. Each of these sources of error are examined in turn and two methods of calculating M̄n values are proposed. © 1994 John Wiley & Sons, Inc.
A polymerizable photoredox initiation system for vinyl photopolymerization
Authors: Du Fu‐Sheng , Zhang Peng , Li Fu‐Mian
Published: April 2003

A polymerizable photoredox system consisting of 4‐methacryl oxbenzophenone (MABP) and N,N‐dimethlaminoethyl methacrylate (DMAEMA) used for the photopolymerization of acrylonitrile (AN) was studied. It was found that the polymerization rate is proportional to the 0.93th power for the AN concentration, the 0.28th power for the MABP concentration, and the 0.25th power for the DMAEMA concentration. The overall activation energy of the polymerization obtained is 30.43 kJ/mol. The recorded ESR spectrum indicates that the excited‐state MABP abstraets hydrogen mainly from the methyl group of the dimethylamino moiety. The comparison of the initiation ability of polymeric MABP or polymeric DMAEMA with their monomeric forms has also been done and the results indicate that in good solvents P (MABP) has a much higher initiation ability than that of monomeric MABP, but monomeric DMAEMA and P (DMAEMA) display almost the same initiation ability. In poor solvent, the initiation ability of P (MABP) is not so obviously higher than that in good solvents. The result of UV analysis of P (AN) initiated by the MABP–DMAEMA system indicates that both MABP and DMAEMA not only initiate the photopolymerization of AN, but also enter into P (AN) polymer chains. © 1994 John Wiley & Sons, Inc.
Iron (III) chelating resins. V. Cross‐linked copolymers of 1‐(β‐acrylamidoethyl)‐3‐hydroxy‐2‐methyl‐4(1H)pyridinone (AHMP) and N,N‐dimethylacrylamide (DMAA) for iron (III) chelation studies
Authors: Feng Minhua , Van Der Does Leen , Bantjes Adriaan
Published: April 2003

Iron (III) chelating resins containing 3‐hydroxy‐2‐methyl‐4(1H)pyridinone (HMP) groups were prepared from 1‐(β‐acrylamidoethyl)‐3‐hydroxy‐2‐methyl‐4(1H)pyridinone (AHMP) and N,N‐dimethylacrylamide (DMAA), using N,N′‐ethylene‐bis‐acrylamide (EBAA) as a cross‐linking agent. The cross‐linked AHMP–DMAA copolymer resins were very stable and exhibited a high hydrophilicity with water contents of the swollen resins of 85–90%. The iron (III) chelating capacity of the resins was determined at physiological pH, and the chelating efficiency was, in general, higher than 90%. The iron (III) chelation was about 80% after 2 h and almost complete in 8 h. The distribution ratio of iron (III) between the resin and iron (III) solutions was quite high (3700–25,000 mL/g) and depended on the initial iron (III) concentration. It was possible to remove iron completely from aqueous solutions by using excess amounts of the resin. The resin also showed a very high selectivity for iron (III), and selectivity coefficients for iron (III) in the range of 9.6 × 108−1.4 × 1012 were determined at pH 5.6 in binary solutions of Fe3+ with Mg2+, Cu2+, Ca2+, Mn2+, and Zn2+. The iron (III) chelating resins could be easily regenerated and used again without any considerable loss of their iron (III) chelating capacities. © 1994 John Wiley & Sons, Inc.
Titration of aldehydes present in poly(ethylene terephthalate)
Authors: Villain Franck , Coudane Jean , Vert Michel
Published: April 2003

Aldehydes are known to be present in PET performs and PET bottles. However, the analysis of these aldehydes is difficult because of the high crystallinity of PET and because of its insolubility in common solvents. Titration of acetaldehyde was investigated comparatively by four different methods: by the solid/gas headspace technique (s/g HG), accepted industrially as the standard method, by colorimetry, based on complexation with pararosaniline dye, by colorimetry, based on derivatization as 2,4‐dinitrophenyhydrazones, and by headspace liquid/gas chromatography (1/g HS). Similar results were achieved by the last three methods. In contrast, the standard solid/gas headspace chromatography yielded data that was one order of magnitude smaller. The presence of formaldehyde in PET performs was detected by liquid/gas headspace Chromatography only. © 1994 John Wiley & Sons, Inc.