bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular weight characterization of polyacrylamide‐CO‐sodium acrylate. II. Light scattering
Authors: Hunkeler D. , Wu X. Y. , Hamielec A. E. 
Published: April 2003

AbstractThe first large‐scale fractionation method for polyacrylamides is reported. This has been optimized to prepare a series of narrowly distributed polymer standards with molecular weights between 10,000 and 1,000,000. These were subsequently hydrolyzed to between 5 and 35% sodium acrylate content through a saponification reaction. It has been found that the classical light‐scattering theory, derived for nonionic scattering bodies, can be applied to polyelectrolytes provided the specific refractive index increment (∂n/∂c) is evaluated at constant electrochemical potential (μ). This is obtained by dialyzing the polymer solution against the dialysate (0.2MNa2SO4 for polyacrylamide‐co‐sodium acrylate) for a predetermined equilibrium period, specific to the pore size of the membrane used. From such measurements at various copolymer compositions (F), the following empirical relationship is established:

where a was found to be −0.076. The validity of the specific refractive index increment at constant chemical potential is established through light‐scattering measurements of the weight‐average chain length of the hydrolyzed polyacrylamides. These were then compared with the chain lengths of the parent nonionic polymers from which they were derived. Excellent agreement is observed, implying the polyelectrolyte characterization method developed, and specifically the (∂n/∂c)μ's, are accurate and reliable.
Factors affecting the coefficient of friction of paper
Authors: Gurnagul N. , Ouchi M. D. , Dunlop‐Jones N. , Sparkes D. G. , Wearing J. T. 
Published: April 2003

AbstractElectron spectroscopy for chemical analysis (ESCA) studies on a variety of paper samples show that for samples of similar surface roughness the coefficient of friction is a function of the amount of extractives that are present on the sheet surface. Corona discharge treatment in air is found to produce a marked increase in the coefficient of friction of newsprint due to surface oxidation effects. © 1992 John Wiley & Sons, Inc.
Linear copolymer analysis with dual‐detection size exclusion chromatography: Correction for instrumental broadening
Authors: Bielsa R. O. , Meira G. R. 
Published: April 2003

AbstractThis article deals with data treatment problems associated with the estimation of the combined distribution of molecular weights and chemical composition in linear copolymers by size exclusion chromatography, when correction for instrumental broadening is considered. Standard dual detection is assumed, i.e., the chromatograph is fitted with a “universal” detector (a differential refractometer) and a specific sensor to one comonomer only (a UV spectrophotometer). A real and a “synthetic” example (involving the analysis of a diblock styrene–butadiene rubber) are presented. Also, a propagation of errors study associated with the deconvolution operations is developed. It is concluded that the best calculation procedure is to first compute the combined distributions from the raw chromatograms and then correct such distributions for instrumental broadening. © 1992 John Wiley & Sons, Inc.
Alkaline hydrolysis of homopolymers and copolymers of 2‐hydroxypropyl methacrylate
Authors: Daly Joseph , Lenz Robert W. 
Published: April 2003

AbstractHomopolymers of 2‐hydroxypropyl methacrylate (HPMA) and copolymers with acrylic acid (AA) were prepared in 1,4‐dioxane. The reactivity ratios were determined to be rAA = 0.27 ± 0.04 and rHPMA = 2.2 ± 0.2. The alkaline hydrolysis by sodium hydroxide of the HPMA monomer and polymers showed that while the HPMA monomer hydrolyzed readily as expected for a low‐molecular‐weight carboxylic ester the HPMA homopolymer and water‐soluble sodium acrylate (NaA) copolymers were extremely resistant to alkaline hydrolysis. The saponification reaction followed a second‐order rate equation, being first order with respect to both HPMA and hydroxide ion concentration. The Arrhenius parameters, activation energy E and frequency factor A, for the alkaline hydrolysis of HPMA monomer in water were found to be E = 10.3 Kcal/mol and A = 1.5 × 108 L/mol min, and those for the NaA–HPMA copolymers in water were found to be E = 24 kcal/mol and A = 4 × 1012 L/mol min. The NaA–HPMA copolymers had a limiting extent of hydrolysis, ranging from 9–90% ester conversion. A sharp rate decrease at low conversion was noted during the HPMA homopolymer hydrolysis in 58/42 dimethyl sulfoxide/water, allowing the calculation of two distinct reaction rates. © 1992 John Wiley & Sons, Inc.
Synthesis and characterization of iminodiacetate cellulosic sorbent and its application in metal ion extraction
Authors: Chan W. H. , Lam‐Leung S. Y. , Fong W. S. , Kwan F. W. 
Published: April 2003

AbstractIminodiacetate cellulosic chelating sorbent, derived from cotton fabric, was synthesized in a two‐step reaction sequence. The pH dependence of the metal ion extraction for Cd (II), Co(II), Cu(II), Pb(II), and Ni(II) was studied. Under optimum conditions, the average sorptive capacity of the sorbent was found to be 0.38 mmol metal ion/sorbent. The viability of using this sorbent for recycling, preconcentration of metal ion, and selective metal ion extraction was demonstrated.
Two‐stage drawing of poly(ethylene 2,6‐naphthalate)
Authors: Ito Masayoshi , Honda Katsumi , Kanamoto Tetsuo 
Published: April 2003

AbstractInitially amorphous and semicrystalline films of poly(ethylene 2,6‐naphthalate) with different molecular weights were drawn by two‐stage drawing, that is, coextrusion at low temperatures (25–160°C) followed by tensile drawing at high temperatures (200–245°C). Both films could be drawn up to a draw ratio of 8–10 by this method under controlled conditions. The tensile modulus and strength of drawn samples were greatly affected by the draw temperature for the first stage, predrawn morphology, and molecular weight. The remarkable effects of these variables on the tensile properties are closely related to the difference in the resultant amorphous chain orientation of the samples, reflecting the disentanglements and chain slippage during drawing, and the dissipation of chain orientation after processing.
An equilibrial process zone in polymeric materials
Authors: Stojimirovic A. , Kadota K. , Chudnovsky A. 
Published: April 2003

AbstractA process zone at the tip of a fatigue crack grown in polymeric materials has been widely reported. A new method that treats the process zone as an allotropically transformed material is employed for the prediction of the process‐zone size. A specific energy of material transformation as well as transformation stress and draw ratio are determined from an independent test on polymer drawing. The prediction of the model with no adjustable parameters appears to be in a good agreement with the experimentally observed process zone for various polyethylenes and polycarbonate.
Analysis of the curing behavior of bismaleimide resins
Authors: Tungare A. V. , Martin G. C. 
Published: April 2003

AbstractThe curing behavior of bismaleimide resins was investigated using formulations containing different stoichiometric ratios of 1,1′‐(methylenedi‐4,1‐phenylene) bismaleimide (BMI) and 4,4′‐methylenedianiline (MDA). The resin cure involved a low temperature primary amine addition to the maleimide double bounds and a high temperature homopolymerization of the maleimide double bonds. The kinetics of the amine addition and the homopolymerization reactions were determined using Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry. The nucleophilic addition of the primary amines to the maleimide double bonds occurred by a second‐order reaction, and was at least two orders of magnitude faster than the homopolymerization reaction, which occurred by a multistep mechanism involving thermal initiation of chain growth, followed by chain propagation. A kinetic model for the curing behavior was developed and used to predict the extents of the amine addition and the homopolymerization reactions in networks cured under isothermal or dynamic conditions.
Gas‐permeation properties of asymmetric polycarbonate, polyestercarbonate, and fluorinated polyimide membranes prepared by the generalized dry–wet phase inversion process
Authors: Pinnau Ingo , Koros William J. 
Published: April 2003

AbstractEssentially defect‐free, ultrathin asymmetric polycarbonate, polyestercarbonate, and 6FDA–IPDA polyimide membranes were prepared by a dry/wet phase inversion process using forced‐convective evaporation. The pure gas permeation properties of these membranes were determined for N2, O2, He, CO2, and CH4. The average apparent skin‐layer thicknesses of the membrane samples varied between 330 and 580 Å, which is substantially thinner than for previous defect‐free membranes formed by the conventional wet phase inversion process. This study indicates that the dry/wet phase inversion process appears to be universally applicable to form ultrathin, defect‐free asymmetric membranes from hydrophobic, glassy polymers. © 1992 John Wiley & Sons, Inc.
Investigations of the crystallinity of polyamide‐6 fibers by two x‐ray diffraction methods
Authors: Rabiej Stanisław , Włochowicz Andrzej 
Published: April 2003

AbstractThe methods of Hindeleh and Johnson and of Ruland and Vonk were employed for determination of the crystallinity in polamide‐6 fibers. The values given by the methods were found to be relatively close to one another. However, using the method of Hindeleh and Johnson, the manner of the amorphous background approximation must be changed. © 1992 John Wiley & Sons, Inc.
Interaction of polystyryl radical with Cu(DMF)2Br2
Authors: Baruah Shashi D. 
Published: April 2003

AbstractThe kinetics of 2,2′‐azobisisobutyronitrile (AIBN) initiated polymerization of styrene in N,N‐dimethylformamide (DMF) at 60°C were investigated in the presence of dibromo(N,N‐dimethylformamide)copper(II) complex. The complex was prepared in situ by mixing tetrakis (N,N‐dimethylformamide)copper(II) perchlorate with LiBr in the molar ratio of 1 : 2. The equilibrium constant for [Cu(DMF)4]2+ + 2Br− ⇌ Cu(DMF)2Br2 + 2DMF was calculated by the limiting logarithmic method as 1.80 × 103 L2 mol−2. The velocity constant at 60°C for the interaction of polystyryl radical with Cu(DMF)2Br2 is 7.46 × 104 L mol−1 s−1.
Modification of styrene–divinylbenzene copolymer by anchoring ferric–dipyridylamine complex
Authors: Mukherjee Amit , Biswas Mukul 
Published: April 2003

AbstractPolystyrene–divinylbenzene (PS–DVB) copolymer was modified by anchoring dipyridylamine (DPA) on it followed by complexation with Fe(III). Under the experimental conditions followed, 9% incorporation of Fe(III) was achieved. PS–DVB–DPA and PS–DVB–DPA–Fe(III) were characterized by IR spectra. Diffuse reflectance spectra for PS–DVB–DPA–Fe(III) and DPA–Fe(III) revealed λmax at ∼ 360 and ∼ 310, respectively. This difference could be due to a difference in the nature of the coordinating moieties complexing with Fe(III) in these two systems. Scanning electron micrographs of PS–DVB, PS–DVB–DPA–Fe(III), and heat‐treated PS–DVB–DPA–Fe(III) revealed some typical surface features. Thermal stability varied in the order PS–DVB–DPA–Fe(III) > PS–DVB–DPA ≅PS–DVB, and DTA showed characteristic exotherms. © 1992 John Wiley & Sons, Inc.
Epoxy composites based on glass beads. II. Mechanical properties
Authors: Amdouni N. , Sautereau H. , Gerard J. F. 
Published: April 2003

AbstractA DGEBA/DDA network was used to study the toughening effect due to the introduction of glass beads with different volume fractions. The influence of surface treatment was also studied by comparing untreated, silane‐treated glass beads, and beads coated with different thicknesses of an elastomeric adduct. The effect of the volume fraction of glass and the surface treatment were discussed in terms of elastic and plastic properties. The results were compared with the usual theoretical models. Linear elastic fracture mechanics and impact tests were performed to study the crack propagation process. The various parameters influenced the deformation mechanism, especially for the coated glass bead composites, for which an optimum thickness was displayed. A large improvement in GIc value was obtained with a slight decrease for the stiffness. © 1992 John Wiley & Sons, Inc.
Comparison of two distinct phenolic antioxidants in γ‐sterilized NR compounds used as rubber pistons in syringes for single use
Authors: Martakis Nick , Niaounakis Michael 
Published: April 2003

AbstractThe effects of γ‐irradiation and aging on pharmaceutical NR compounds have been studied mainly by DSC. The extent of aging was measured quantitatively by enthalpy changes and peak temperature shifts of the primary oxidation exotherm. Quantitative thermal evaluations were supplemented by extraction tests and mechanical testing. The NR compound formula has been kept constant and only the type and concentration of antioxidant was varied. Two distinct phenolic antioxidants, BHT and Wingstay‐L at four different concentration levels, have been employed for this purpose. The most effective antioxidant package for a given elastomeric compound, subjected to γ‐irradiation and aging, giving the lowest changes in physical properties, is evaluated. © 1992 John Wiley & Sons, Inc.
Preparation and characterization of two HEMA/PVA copolymers: Poly[HEMA‐co‐(PVA‐AA)] and poly[HEMA‐co‐(PVA‐MA)]
Authors: Liou F. J. , Niu G. C. C. , Wang Y. J. 
Published: April 2003

AbstractThe copolymers of poly[HEMA‐co‐(PVA‐AA)] and poly[HEMA‐co‐(PVA‐MA)] were synthesized and characterized. The presence of PVA‐AA in the copolymer increased the mechanical strength but decreased the water content of the material. The presence of PVA‐MA, on the other hand, caused a decrease of mechanical strength and an increase of water content. The ionization of acidic group in poly[HEMA‐co‐(PVA‐MA)] resulted in the swelling of the copolymer, and the swelling extent was controlled by the change of pH. Both copolymers have great potential in biomedical application. © 1992 John Wiley & Sons, Inc.
Polymer bead preparation from bulk polymers
Authors: Davy K. W. M. , Causton B. E. 
Published: April 2003

AbstractA method of preparing polymer beads from chloroform solutions of bulk polymer was developed. The technique involved solvent removal while the polymer solution was stirred in an aqueous dispersing medium. Bead size could be varied by adjusting the concentration of the suspending medium and the method was found to be applicable to chloroformsoluble, water‐insoluble polymers. Copolymers, low‐tack rubbers, and polyblends were also converted to bead form and, in the latter case, phase separation occurred. Furthermore, it was possible to encapsulate finely divided inorganic fillers within the polymer beads. © 1992 John Wiley & Sons, Inc.
PVC filled with vacuum pyrolysis scrap tires‐derived carbon blacks: An investigation on rheological, mechanical, and electrical properties
Authors: Dufeu J. B. , Roy C. , Ajji A. , Choplin L. 
Published: April 2003

AbstractPyrolysis of scrap tires produces oil and carbon black (CB). The purpose of this work is to compare pyrolytic CBs with commercial grades as fillers for poly(vinyl chloride) (PVC). Blending of PVC with CB was performed in the melt at 180°C. The compositions prepared were 1,5,10,20, and 30 wt % of CB. The dynamic rheological, mechanical, and electrical properties of the PVC–CB composites were investigated. The results obtained for the storage modulus and complex viscosity of the composites of PVC with the pyrolytic CBs were between those of a high‐grade (Monarch 1100) and a low‐grade (Sterling R) commercial CBs. Intermediate tensile modulus, elongation at break, and electrical conductivity were also obtained. The specific surface area of the CB was shown to influence the composite properties. Reduction of the volatile matter and ash contents of the pyrolytic CB led to better properties of the PVC composites. © 1992 John Wiley & Sons, Inc.
Preparation of polymeric initiators of the anionic polymerization of lactams from polyetherdiols
Authors: Stehlíĉek J. , Chauhan Ghanshyam S. , Znáŝiková M. 
Published: April 2003

AbstractThe kinetics of alcoholysis of bis(N‐acyl‐6‐hexanelactams) and bis(N‐carbamoyl‐6‐hexanelactams) was studied for the purpose of the preparation of bifunctional polymeric initiators of the anionic polymerization of 6‐hexanelactam used in the production of polyamide block copolymers by reactive processing. The reaction was carried out with 1‐octanol as a model alcohol and with poly(propylene oxide)diol, without catalysis or using anionic and polyesterification catalysts, and in 6‐hexanelactam as a solvent. Applicability of this functionalization method is discussed with respect to a broad spectrum of formed products, competition of lactam oligomerization in the presence of basic catalysts, preparation of the initiator component for two‐component polymerization systems, and in situ functionalization during polymerization. © 1992 John Wiley & Sons, Inc.
Mechanical properties of complexed α,ω‐diamino polybutadiene
Authors: Tant M. R. , Song J. H. , Wilkes G. L. , Charlier P. , Jerome R. 
Published: April 2003

Abstractα,ω‐Dipiperazino polybutadiene (PBD) was complexed with the hydrated forms of copper chloride, iron chloride, and nickel chloride in methanol. The polymers were recovered and compression molded into films and properties investigated. In particular, the tensile stress‐strain behavior as well as stress relaxation behavior were monitored with time at ambient conditions. It was observed that the polybutadiene material showed a strong association with copper providing a pseudo network behavior. The association for the iron and nickel components were considerably weaker than that of copper. Comparisons of the data obtained from these systems were also made with earlier data obtained from the same laboratory on carboxylated or sulfonated telechelic ionomers based on polyisoprene and polyisobutylene. It was concluded that the copper complex with the α,ω‐dipiperazino polybutadiene has comparable or better behavior than some of the carboxylate systems. © 1992 John Wiley & Sons, Inc.
Preparation and characterization of 2‐cyanoacrylate copolymers
Authors: Stein Michael 
Published: April 2003

AbstractButyl and ethoxyethyl 2‐cyanoacrylate and mixtures thereof in different molar ratios were subjected to polymerization at pH 2.0, 3.0, 4.0, 5.5, and 6.9 and characterized by X‐ray diffraction, hot‐stage microscopy, and NMR analysis. The polymers were in an X‐ray amorphous state. Their softening temperatures increased with ascending pH during polymerization. In all cases, the temperatures of the ethoxyethyl polymers were below those of the butyl polymers. Softening temperatures between those of the pure polymers could by achieved by copolymerization. The molar composition of the polymers was checked by NMR analysis. © 1992 John Wiley & Sons, Inc.
Thermal conductivities of blends of polyethylene/SEBS block copolymer and polystyrene/SEBS block copolymer
Authors: Agari Y. , Ueda A. , Nagai S. 
Published: April 2003

AbstractThermal conductivities of two series of blends of polystyrene and styrene–ethylene/butyrene–styrene block copolymer (PS/SEBS), and polyethylene and styrene‐ethylene/butylene‐styrene block copolymer (PE/SEBS) were measured. Here the PS part and hydrogenated polybutadiene (EB; ethylene‐butene‐1 copolymer) part of SEBS were confirmed to be miscible in PS and PE homopolymers, respectively, by the differential scanning calorimetry. The thermal conductivity of PS/SEBS increased, while that of PE/SEBS blends decreased monotonically, with increasing SEBS content. No significant changes in the range where microphases usually occur were noted. The thermal conductivities of PS/SEBS and PE/SEBS were explained by modifications of our equation for composites. Thermal conductivity of EB in SEBS was estimated from that of PS/SEBS blend as 4.9 × 10−4 cal/s cm °C. Further, the thermal conductivity of PE/SEBS could be predicted by substituting the obtained value of EB into the modified equation. Therefore, the modified equations were confirmed to be applicable to thermal conductivities of PE/SEBS and PE/SEBS blends. © 1993 John Wiley & Sons, Inc.
IR spectroscopy approach for the study of interactions between an oxidized aluminium surface and a poly(propylene‐g‐acrylic acid) film
Authors: Romero M. A. , Chabert B. , Domard A. 
Published: April 2003

AbstractIn this paper, we report the study of the interactions between a poly(propylene‐g‐acrylic acid) and an oxidized aluminium surface by IR spectroscopy. A deposit of a pure poly(acrylic acid) on the same surface is used as a model. Under free acid form (COOH) we demonstrate the formation of hydrogen bondings between the acrylic carboxyl groups and OH functions located at the surface of alumina. This is characterized by an IR absorption [v(co)] at 1733 or 1743 cm−1 when we observe the metal surface either after peeling of a PPg(OH) film initially pressed on it or after a deposit of PAA(OH). Under the carboxylate form (COO−), we observe two modes of interaction, the one purely ionic between COO− and Al3+ with an absorption located near 1550 cm−1 and the other of complex form between COO− and Al3+ giving a band near 1610 cm−1. The water molecules can play a major part, in particular in the first case (COOH) where they destroy hydrogen bondings in favor of the formation of COO− groups, interacting with the metal surface according to ionic or complex modes as above. © 1993 John Wiley & Sons, Inc.
Determination of polymer‐solvent interaction parameters using piezoelectric crystals, with reference to the sorption of chemical warfare agents
Authors: Charlesworth John M. , Riddell Stuart Z. , Mathews Robert J. 
Published: April 2003

AbstractPolymeric materials which show sensitivity to certain classes of organic vapors and give minimal responses from interferents are being sought for use as coatings on piezoelectric mass detection devices. The present work illustrates some simple methods for the determination of fundamental properties such as polymer‐solvent interaction parameters and diffusion constants, and relates these to the sensitivity and response time of the sensor. Polymers with a controlled variation in crosslink density were exposed to a variety of common solvents and vapors covering a range of solubility parameters. Seven non‐crosslinked amorphous polymeric materials were also assessed for their suitability as selective coatings for the detection of a range of chemical warfare vapors. Gross differences in the response characteristics of coated crystals immersed in liquids can be predicted, and an approximate guide to the relative rates of solvent penetration can also be obtained. More accurate predictions are hampered by the lack of knowledge of the specific interactions which occur within polymer–solvent pairs. Crosslinking the polymer film to enable operation in strongly solvating liquids has the effect of reducing the extent of swelling to a larger degree than expected on the basis of existing theories. The operation of coated crystals in the gas phase at very high vapor concentrations leads to a dual site adsorption process which can be described by the BET equation. At much lower vapor concentrations Henry's law appears to determine the response, and a simple solution model developed from partition theory for stationary phases in gas–liquid chromatography can be used to interpret the sensitivity of three non‐crosslinked amorphous polymeric films to DMMP, GA, GB, and GD. While adequately describing the responses of the organophosphorus esters, the model is not as satisfactory in predicting the interactions with HD. © 1993 John Wiley & Sons, Inc.