bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of cationic starch containing quaternary ammonium substituents by reactive twin‐screw extrusion processing
Authors: Carr M. E. 
Published: April 2003

AbstractCationic starch, an important additive for papermaking and other uses, was prepared from native cornstarch and 3‐chloro‐2‐hydroxypropyltrimethylammonium chloride in aqueous sodium hydroxide using a twin‐screw extruder as the reactor. The effects of physical and chemical reaction variables on reaction efficiency (RE) and degree of substitution (DS) of up to 0.05 were studied. RE was based on nitrogen content contributed by cationization of the starch after the products were exhaustively washed to remove unreacted monomer. Under certain reaction conditions, exceptionally high RE (90%+) was achieved, exceeding maximum values previously reported using laboratory‐batch reaction procedures. The combined effects of high reaction temperature (90°C), intense mixing, high‐starch solids (65%), and appropriate levels of catalyst contributed to the unusually high RE values achieved by the reactive extrusion process. © 1994 John Wiley & Sons, Inc.†
Thermal analysis of controlled‐release formulations based on entrapment of a larvicide in cross‐linked carboxymethylcellulose
Authors: Prasad M. P. , Kalyanasundaram M. 
Published: April 2003

AbstractThermal analysis of controlled‐release formulations of fenthion, prepared by its entrapment in cross‐linked carboxymethylcellulose and carboxymethylcellulose–gelatin matrices was carried out by thermogravimetric analysis and under accelerated storage conditions. Thermograms of samples of sodium carboxymethylcellulose, cross‐linked polymer samples, and the formulations were studied. The thermogravimetric analysis showed improved heat resistance and retention of fenthion or its decomposition products in the formulated samples. The decomposition maximum of technical‐grade fenthion was 260°C and the corresponding weight loss was about 90%, whereas fenthion or its decomposition products appear to be retained up to temperatures ranging from 400 to 500°C in the formulations. The half‐life of fenthion in the mechanical mixture with the carrier polymer was found to range from 19.92 to 29.98 days, whereas in the formulated samples, it was found to range between 41.54 and 113.35 days. © 1994 John Wiley & Sons, Inc.
Addition‐cured silicone adhesive technology: Vinyl silicone crosslinker
Authors: Lin Shaow B. 
Published: April 2003

AbstractSilicone pressure‐sensitive adhesives prepared from a platinum‐catalyzed, high solids silicone composition are described. The adhesive compositions consist of an MQ siloxane resin, vinyl‐and hydride‐terminated silicone fluids, and a multifunctional vinyl silicone crosslinker. In this study, multifunctional vinyl silicone crosslinkers of various structures, including linear polymers, T, TQ, and Q resins, were prepared and evaluated for their effect on the adhesive properties of cured silicone pressure‐sensitive adhesives. Additionally, the activity of these multifunctional vinyl silicones in hydrosilylation reaction was investigated. © 1994 John Wiley & Sons, Inc.
Simple 13C‐NMR methods for quantitative determinations of polyflavonoid tannin characteristics
Authors: Thompson D. , Pizzi A. 
Published: April 2003

AbstractA simple 13C‐NMR method for the quantitative determination of polyflavonoid tannin characteristics was developed. The system is effective for use on concentrated (25–50%) solutions of natural and modified tannins. It allows the determination of the average degree of polymerization (DPn) of the polyflavonoid, resorcinol vs. phloroglucinol proportion of the A‐ring and catechol vs. pyrogallol proportion of the B‐ring. The results obtained are consistent with existing data determined by other techniques. The method was also tried with tannin extract that was modified to form thermosetting adhesive intermediates, and with tannin modified by sulfonation, a common commercial modification for these materials. The results were again consistent with what was expected. The method affords the possibility to follow by a simple technique the variations in DPn and MM̄n (number‐average molecular weight) induced by chemical modifications of polyflavonoid tannin extracts and thus to correlate them with relevant structural modifications affecting these parameters. The method is not capable of distinguishing the relative proportions of the four important flavonoid units present in commercial polymeric tannin extract. It can only distinguish the relative proportions of (i) (procyanidins + prodelphinidins) vs. (profisetinidins + prorobinetinidins) and (ii) (prorobinetinidins + prodelphinidins) vs. (profisetinidins + procyanidins). © 1995 John Wiley & Sons, Inc.
Low loss second‐order nonlinear optical polymers based on all organic sol‐gel materials
Authors: Jeng R. J. , Hsiue G. H. , Chen J. I. , Marturunkakul S. , Li L. , Jiang X. L. , Moody R. A. , Masse C. E. , Kumar J. , Tripathy S. K. 
Published: April 2003

AbstractA new class of all organic sol‐gel second‐order nonlinear optical (NLO) materials based on hexa(methoxymethyl) melamine (HMM) was developed. Two NLO active chromophores, 4 (4′‐nitrophenylazo) aniline (DO3) and 4‐amino‐4′‐nitrobiphenyl (ANB), were incorporated into the melamine matrices. The samples exhibited second‐order optical nonlinearity after poling and curing at 220°C for 30 min. DO3/HMM and ANB/HMM samples showed a second harmonic coefficient, d33 of 10.7 and 1.8 pm/V at 1064 nm, respectively. The temporal stability of both systems was studied at room temperature as well as at 100°C. Waveguide optical losses of samples at 633 and 830 nm were found. © 1995 John Wiley & Sons, Inc.
Effect of process parameters on residual stress distribution in poly(ethylene terephthalate) fibers and films as revealed by chemical etching
Authors: Gupta V. B. , Radhakrishnan J. , Sett S. K. 
Published: April 2003

AbstractPoly(ethylene terephthalate) fibers and films produced by varying process parameters, such as production speed and medium, temperature and rate of drawing, were annealed at temperatures between 100 and 250°C in the free‐to‐shrink and constant‐length conditions. The as‐spun, as‐drawn, and drawn and annealed samples were etched in 40% aqueous methylamine at room temperature for 4 h. The etch patterns were examined on a scanning electron microscope and were found to be related mainly to residual stress and its distribution in the samples and thereby to sample morphology. The studies clearly bring about the important role played by the processing history. © 1995 John Wiley & Sons, Inc.
Effects of added metal ions on the interaction of chitin and partially deacetylated chitin with an azo dye carrying hydroxyl groups
Authors: Shimizu Y. , Kono K. , Kim I. S. , Takagishi T. 
Published: April 2003

AbstractThe binding of chrome violet, which is a monoazo dye and involves two hydroxyl groups in the o and o′ positions to an azo group, to chintin and partially decetylated chitin, was examined in the presence of metal ions. Zn2+ and Cu2+ ions do not perceptively influence the binding affinity of chrome voilet to chitin. In contrast, Co2+ ion enhances the binding and Ni2+ ion suppresses it. In the lower free dye concentrations the dye uptake by partially deceteylated chitin was tremendously enhanced by adding. Co2+ ion in the buffer solution of pH 5. The dye uptake by the polymer was considerably increased by the addition of Cu2+ ion at pH 5 and became much larger at pH 6. The amount corresponded to that in the presence of Co2+ ion. To investigate further the action of added metal ions, a cobalt‐ or a chrome–complex dye was prepared, and the binding properties for the polymers were compared with those of chrome violet in the presence of Co2+ and Cu2+ ions. Some possible mechanisms for the enhancement of chrome violet binding by the addition of Co2+ and Cu2+ ions are described. © 1995 John Wiley & Sons, Inc.
Mechanism of proton doping in polyaniline
Authors: Wan Meixiang , Yang Jiping 
Published: April 2003

AbstractThe protonation processes of polyaniline (PANI) were examined by means of both UV‐visible and fluorescence spectra and in situ UV‐visible and in situ electron spin resonance (ESR) spectra in order to understand he mechanism of proton doping in PANI. Results obtained from UV‐visible and fluorescence spectra of PANI films indicate that the protonation processes take place on the imine segment of the polyemerldine chain consistent with MacDiarmid's suggestions. It is noted that the protonation processes consist of chemical and diffusion processes. The doping processes at the initial stage are controlled by a chemical reaction, whereas the doping processes at the middle period are dominated by a diffusion process. In situ ESR spectra of PANI films have demonstrated that a polaron is formed after protonation processes, but a splitting process of bipolaron into polaron at the measured time region was not observed. For partial protonated PANI, moreover, the fact that variation of absorption value of the peak at 630 nm with doping time supported suggestions in which a parameter of the protonation state for the molecular structure of doped PANI should be considered. © 1995 John Wiley & Sons, Inc.
Sorption of aromatic compounds on macroporous anion exchangers based on polyacrylamide: Relation between structure and sorption behavior
Authors: Drăgan Stela , Cristea Mariana , Airinei A. , Poinescu Ig. , Luca Cornelia 
Published: April 2003

AbstractThe sorption of phenol, p‐toluenesulfonic acid (p‐TSA), Na‐p‐toluenesulfonate (Na‐p‐TS), 1,2‐dihydroxy‐3,5‐benzene disulfonic acid disodium salt (Tiron), and 3‐hydroxy‐4(sulfonaphthyazo)‐5,7‐naphthalenedisulfonic acid trisodium salt (Poceau 4R) on the macroporus anion exchangers with acrylamide structural units (weak and strong basic anion exchangers) and on the ion exchangers with amidoxime groups were studied. The maximum specific sorption of p‐TSA was almost identical with the total exchange capacity for both the weak and strong basic anion exchangers. The sorption of Na‐p‐TS is strongly related to the functional group structure of the anion exchangers, being significant on the strong basic anion excahngers. The maximum specific sorption of Tiron was higher tan the total exchange capacity of the strong basic anion exchangers because it is mainly dependent on the ionic exchange properties. The morphological characteristics influenced only the establishement rate of the sorption equilibrium. The sorption of Ponceau 4R, which has the highest molecular weight, is important on the strong basic anion exchangers with high permanent porosity. The sorption of the organic anions is also dependent on the number of the sulfonic groups. © 1995 John Wiley & Sons, Inc.
Morphology and rheology of polysulfone/Vectra‐A950 blends
Authors: Magagnini P. L. , Paci M. , La Mantia F. P. , Surkova I. N. , Vasnev V. A. 
Published: April 2003

AbstractBlends of polysulfone (PSu) with a liquid crystalline copolyester (Vectra‐A950; VA) have been prepared by melt mixing. Their morphology has been studied by scanning electron microscopy (SEM). Either blend specimens as obtained from the melt mixing or fibers drawn from the melt were used for the SEM analysis. Further information on the morphology of the blends was gained by extraction of the PSu phase with methylene chloride. Preliminary rheological characterization of the blends was made by measuring the viscosity curves at 290 and 300°C, with a capillary viscometer having a die of 1 mm diameter and L/D = 40. Finally, an attempt at improving the phase compatibility was made by synthesizing a copolyester, having the same structure of commercial VA, in the presence of preformed PSu and using the product as a possible compatibilizer.It was demonstrated that the blends are composed of two immiscible phase showing poor adhesion. The LCP droplets could, nevertheless, be deformed into oriented fibrils under elongational flow conditions. The LCP particles were shown to coalesce into large domains, and to migrate toward the outer layer of, e.g., extruded rods, under the influence of appropriate flow conditions, thus showing that there is a strong mutual influence between morphology and rheology of these materials. © 1995 John Wiley & Sons, Inc.
Creep/recovery behavior of open‐cell foams
Authors: Phillips J. C. 
Published: April 2003

AbstractStatic measurements have been used to predict the dynamic response of ldquo;unboundedrdquo; open‐cell noninked (dry) and inked foam materials. Creep, ec(t), and recovery, er(t), were determined in compression from static and dynamic modes. Force measurements, f(t), and strain decay, e(t), were used to determine the change in creep, δec(t). The change in creep represents the plastic strain, ep1(t=th), and is uniquely defined by the recovery function, er(t=th), where th is the hold time. Creep and recovery results of various classes of foam materials and nonfoam materials were found to fit a master curve of the form Fr(t) =exp[–k′r(th)t] = [er(t) ‐ e00( th)]/[e0 (t = 0) ‐ e00(th)] at a reduced time of k′r(th) t [k′r(th)] C0/(th)a (where Co depends on the material's “dry” or “wet” state), a is a function of the type of material, and em is the permanent set]. These empirical results are applicable to printing ink transfer and print quality. Other important factors of concern are diffusion processes within the polymer matrix and the nature of the polymer (e. g., chemical constitution, porosity, molecular weight, and solubility). © 1995 John Wiley & Sons, Inc.
The effect of teflon™ coatings in polyethylene capillary extrusion
Authors: Hatzikiriakos Savvas G. , Hong Peter , Ho Wally , Stewart Charles W. 
Published: April 2003

AbstractTwo LLDPE resins were used in this work to determine the critical conditions for the occurrence of wall slip and melt fracture in capillary extrusion. It was found that the polymer‐metal interface fails at a critical value of the wall shear stress of about 0.1 MPa and, as a result, slip occurs. At values of wall shear strees of about 0.18 MPa the extrudate surface appears to be matte, while small amplitude periodic distortions (sharkskin) appear on the surface of extrudates at wall shear stresses above 0.25 MPa. Using a special slit die, the polymer–wall interface was coated with Teflon™ in order to examine the effect of this coating on the processability of polyethylenes. It was found that use of Teflon™ promotes slip, thus reducing the power requirement in extrusion and, most importantly, eliminates sharkskin at high extrusion rates. © 1995 John Wiley & Sons, Inc.
Mixed esters of chitin
Authors: Van Luyen Dang , Rossbach Volker 
Published: April 2003

AbstractOne of the main obstacles to the wider application of chitin in polymeric materials is its poor tractability due to unfavorable solubility properties. The solubility can be enhanced by introducing bulky acyl residues into the polymer (as in butyrylchitin and valeroylchitin). However, if modification is carried out with shorter‐chain carboxylic acids (as in acetylchitin), the solubility remains poor. By substituting the acetyl residues partially by butyryl residues (mixed ester formation), exclusive use of the bulky carboxylic acids can be avoided and yet good solubility is achieved. These relationships were shown by using high molecular weight mixed chitin esters, prepared with methanesulfonic acid as the solvent and catalyst. The mixed chitin esters, varying both in the overall degree of substitution (1.5‐1.9) and the molar ratios of butyryl‐to‐acetyl residues (1: 0.62 to 1:0.72), were characterized by IR spectroscopy, DSC, elemental analysis, and 1H‐NMR spectroscopy (in trifluoromethanesulfonic acid); the latter allowed the degree of substitution to be determined as well as the moral ratios of butyryl‐to‐acetyl residues © 1995 John Wiley & Sons, Inc.
Injection molding of semicrystalline polymers. II. Modeling and experiments
Authors: Isayev A. I. , Chan T. W. , Gmerek M. , Shimojo K. 
Published: April 2003

AbstractThe injection molding of an isotactic polypropylene was computer‐simulated with both quiescent and shear‐induced crystallization taken into account. A one‐dimensional finite difference model was used to simulate the filling, packing, and cooling stages of the injection‐molding cycle. The Spencer‐Gilmore equation was used to relate the density variations to the pressure and temperature traces in the packing simulation. The quiescent crystallization kinetics was modeled by the differential form of the Nakamura equation. The theory developed by Janeschitz‐Kriegl and co‐workers was used to model the shear‐induced crystallization kinetics. The pressure traces during the filling and packing stages of the molding cycle, the thickness of the shear‐induced crystallization layer, and the crystallinity profile throughout the thickness of the part were measured and compared with predicted values. © 1995 John Wiley & Sons, Inc.
Influence of gamma‐irradiation on structural and mechanical properties of polypropylene yarn
Authors: Sen Kushal , Kumar Praveen 
Published: April 2003

AbstractPolypropylene multifilament yarn samples were irradiated by gamma rays in air. The effect of radiation dose on thermal, structural, and mechanical properties was studied. Melting endotherms and crystallization exotherms gave useful information regarding the structural changes. X‐ray diffraction, infrared spectroscopy, density, and viscosity data of the irradiated samples were analyzed. Although viscosity and mechanical properties decreased with irradiation, the density marginally increased. Breaking elongation has been found be a sensitive parameter for assessing deterioration. © 1995 John Wiley & Sons, Inc.
Induced accelerated autocondensation of polyflavonoid tannins for phenolic polycondensates. II. Cellulose effect and application
Authors: Pizzi A. , Meikleham N. , Stephanou A. 
Published: April 2003

AbstractPolyflavonoid tannin autocondensation was found to be facilitated by the reaction occurring on cellulose and lignocellulosic substrates. Although the mechanism of polyflavonoid autocondensation induced by cellulose differs from that induced by the action of Lewis acids, the subsequent reaction of autocondensation appears to be similar. The determining step of tannin rearrangement pathways under alkaline conditions in cellulose‐induced highertemperature autocondensation is the favoring of the heterocycle pyran ring opening over the normal interflavonoid bond cleavage and catechinic acid rearrangement. This is caused by relevant bond weakening and easier cleavage induced by strong attractive forces between flavonoid and cellulosic substrate. Applied bonding of cellulosic substrates by polyflavonoid tannin autocondensation reaction appear to be feasible and to occur as predicted from theoretical predictions. © 1995 John Wiley & Sons, Inc.
Grafting of methacrylic acid to loomastate viscose fabric using KMnO4/NaClO2 system
Authors: Hafiz S. A. Abdel , El‐Rafie M. H. , Hassan S. M. , Hebeish A. 
Published: April 2003

AbstractGraft polymerization of methacrylic acid (MAA) to loomstate viscose fabric (greige fabric) using KMnO4/NaClO2 system was studied. Residual thiocarbonate and/or sizing materials on the fabric as well as presence of NaClO2 act in favor of primary radical formation which, in turn, accelerate formation of cellulose macroradicals capable of initiating grafting. The polymerization reaction was studied with respect to polymer yield, graft yield, homopolymer, total conversion, and graft efficiency. The magnitude of each of these characteristics was found to depend upon parameters such as concentrations of KMnO4, NaClO2, and MAA as well as liquor ratio, reaction time, and temperature of polymerization. By and large all these parameters enhance the polymerization process with the exception of the liquor ratio. A reaction mechanism for the polymerization reaction is also reported. © 1995 John Wiley & Sons, Inc.
Choice of monomer partition model in mathematical modeling of emulsion copolymerization systems
Authors: Gugliotta Luis M. , Arzamendi Gurutze , Asua José M. 
Published: April 2003

AbstractA criterion for the choice for the monomer partition model in mathematical modeling of emulsion copolymerization systems is presented. In order to develop this criterion, seeded emulsion copolymerizations of several monomer systems with a wide variety of reactivity ratios and water solubilities were simulated using monomer partition models of different complexity. The simulations included different processes, solids contents and amounts of seed. The criterion for the choice of the monomer partition model was made on the basis of using the simplest but sufficiently accurate model. © 1995 John Wiley & Sons, Inc.
HTPB‐based polyurethanes for inhibition of composite propellants
Authors: Gupta D. C. , Deo S. S. , Wast D. V. , Raomore S. S. , Gholap D. H. 
Published: April 2003

AbstractPolyurethanes were synthesized by the reaction of hydroxyterminated polybutadiene (HTPB) and diisocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HMDI), and isophoron diisocyanate (IPDI). A number of fillers such as carbon black, kaolin, and antimony trioxide (Sb2O3) were used in these formulations. Mechanical and thermal stability of these polyurethanes were studied. Based on its properties, HTPB‐MDI derived filled polyurethane was selected and evaluated as an inhibitor for a composite propellant. © 1995 John Wiley & Sons, Inc.
Studies on graft copolymerization of glycidyl methacrylate onto poly(vinyl chloride) and curing behavior of its grafted copolymer
Authors: Lee Wen‐Fu , Lai Cherng‐Ching 
Published: April 2003

AbstractPoly(vinyl chloride) was dehydrochlorinated in an alkali solution and then grafted with glycidyl methacrylate (GMA) using benzol peroxide as the free‐radical initator under a nitrogen atmosphere. The efficiency of grafting GMA under the influence of an alkali, GMA concentration, and duration of the grafting reaction, the viscosity properties, and the curing behavior with diamine were investigated. Maximum grafting to the extent of 46.4% was obtained. The optimum curing reaction condition were investigated. © 1995 John Wiley & Sons, Inc.
Emulsion polymerization of methyl methacrylate in concentration of emulsifiers below their CMCs—polymerization rate, particle size, and particle‐size distribution
Authors: Yu Zai‐Zhang , Li Bo‐Geng , Cai Ming‐Jian , Li Bao‐Fang , Cao Kun 
Published: April 2003

AbstractThe emulsion polymerization of methyl methacrylate (MMA) in concentration of emulsifiers below their critical micelle concentrations (CMCs) initiated by K2S2O8 (KPS) was studied. It was observed that the initiator concentration has little effect on both polymerization rate and particle size. However, the polymerization rate is faster and particle size is smaller obviously when decreasing the ratio of the water/monomer or increasing the temperature of polymerization or the amount of the emulsifier. In the range of a 200–400 rpm stirring speed, the polymerization rate is almost unchanged although the particle size become larger with increase in the stirring speed. The monodisperse particle (size about 100–200 nm) can be obtained using this process. The mechanism of emulsion polymerization of MMA in the emulsifier concentration below its CMC is discussed. © 1995 John Wiley & Sons, Inc.