bluuebunny/crossref_metadata_2025_split huggingface dataset:
Graft copolymerization of acrylonitrile and methyl methacrylate monomer mixtures on crumb natural rubber
Authors: Okieimen F. E. , Urhoghide I. N. 
Published: August 2002

AbstractGraft copolymerization of mixtures of acrylonitrile and methyl methacylate on crumb natural rubber was carried out in toluene at 60°C. The nitrogen content of the grafted copolymer was determined by elemental analysis and used to estimate the composition of the copolymer samples. It was found that the amount of acrylonitrile monomeric units incorporated into the polymer was disproportionately lower than the acylonitrile content of the feed and explanations in terms of the e‐value of the monomers and the inherent heterogenous nature of the polymerization mixture were offered. The miscibility of the natural rubber‐g‐polyacrylonitrile‐co‐poly(methyl methacrylate) with poly(vinyl chloride) was studied by viscometry, differential scanning calorimetry, and phase contrast microscopy. It was found that the natural rubber‐g‐polyacrylonitrile‐co‐poly(methyl methacrylate) formed semimiscible blends with poly(vinyl chloride). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1872–1877, 2002; DOI 10.1002/app.10474
The study of rapid curing crease‐resistant processing on cotton fabrics. II. Effect of poly(ethylene glycol) on physical properties of processed fabrics
Authors: Shih Chung‐Yang , Huang Kuo‐Shien 
Published: August 2002

AbstractThis study aimed to examine the effects of the addition of poly(ethylene glycol) (PEG) on the physical properties of processed cotton fabrics in a rapid heat‐curing crease‐resistant process. Our results show that this addition influences the moisture absorbency, crease resistance in both dry and wet conditions, and tensile strength preservation rate of the processed fabrics. Moreover, with such addition, the use of higher temperature in the process would enhance the moisture absorbency and dry–wet crease resistance but reduce the tensile strength preservation rate. The optimum condition for processing cotton fabric is to use PEG with a molecular weight of 1000 at a concentration of 10%, heated at 200°C for 30 s. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1008–1012, 2002
Effect of PVP in dispersion and seeded dispersion polymerizations
Authors: Wang Danni , Dimonie Victoria L. , Sudol E. David , El‐Aasser Mohamed S. 
Published: August 2002

AbstractThe outcome of seeded dispersion polymerizations of n‐butyl acrylate (BA) and styrene (St) in terms of the success of growing the seed particles without nucleating new particles or generating coagulum was found to be dependent on the seed type (poly[n‐butyl acrylate] [ PBA] or polystyrene [PSt]), the second‐stage monomer (BA or St), and the type of polyvinylpyrrolidone (PVP) stabilizer (PVP K30 or PVP K90). All seeds were first cleaned of excess stabilizer by medium replacement before the seeded polymerizations. In general, successful particle growth was achieved when the second‐stage polymerization employed PVP K30 (1 wt%) as the stabilizer. In contrast, nearly all reactions employing PVP K90 (1 wt%) as the second‐stage stabilizer resulted in the nucleation of a second crop of particles. These phenomena were further investigated by carrying out dispersion polymerizations using the supernatant obtained by separating the seeds from the second‐stage media (containing monomer). The results paralleled those in the seeding studies and were explained by the presence of small amounts of grafted PVP created in situ during the preparation of the seeds. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2721–2732, 2002
Effect of surface modification of glass wool on the mechanical and electrical properties of polypropylene/modified glass‐wool composites
Authors: Turky G. M. , Abd El‐Reheim M. H. , Badran A. S. 
Published: August 2002

AbstractThe surface of glass wool (GW) was modified by two different methods, either by grafting methyl acrylate (MA) onto GW in the presence of potassium persulfate (PPS) as initiator, or by adsorbing stearic acid (AS) as surface active agent onto the GW surface. It was found that conversion and grafting yield of poly(methyl acrylate) (PMA) onto the GW surface increased with increasing initiator concentration, whereas by modifying the GW surface by adsorption of SA, the adsorption of SA was found to be high at small values of equilibrium concentrations and two distinct plateau regions were observed. Mechanical and electrical properties of polypropylene (PP) sheets loaded with modified GW were measured. The obtained data showed that the presence of PMA as grafted polymer onto the GW surface has a plasticizing effect on the prepared PP composites. On the other hand, SA, as a surface modifier for GW, acts as a reinforcing agent for the formed PP composites, which have very good dielectric properties. From the obtained results, one can deduce that the prepared PP/GW composites have promising dielectric properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1061–1069, 2002
Polymerization kinetics of styrene using coordination catalysts containing rare earth compounds
Authors: Kothandaraman H. , Sangeetha D. , A. A. Sriramulu  , Nayagam M. P. M. , Aminabhavi T. M. 
Published: August 2002

AbstractPolymerization reactions of styrene in toluene at 60°C have been carried out using Ziegler–Natta catalysts containing praseodymium trichloroacetate‐triethyl aluminum [Pr(OCOCCl3)3‐Et3Al] (system I) and praseodymium trichloroacetate‐diethyl aluminum bromide [Pr(OCOCCl3)3‐Et2AlBr] (system II). The reaction was of first order with respect to both monomer and catalyst concentrations. At a stoichiometric ratio of Al/Pr = 8, an optimum catalytic activity was observed. The activation energies for systems I and II ranged between 21.06 kJ/mol and 13.79 kJ/mol, respectively. System I was white in color and system II is waxy. Molar masses of systems I and II were 9.1 × 105 and 2.2 × 104, respectively. The polymers were characterized by viscometry and 1H NMR methods. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 995–1002, 2001
The effects of atacticity, comonomer content, and configurational defects on the equilibrium melting temperature of monoclinic isotactic polypropylene
Authors: Bond Eric Bryan , Spruiell Joseph E. 
Published: August 2002

AbstractA series of isotactic polypropylenes were investigated to account for total defect content using xylene fractionation and carbon‐13 NMR experimental methods. The defects of interest were percent atactic content, copolymer content, and configurational defects. Experimental equilibrium melting temperatures were obtained for each material using the Gibbs‐Thomson equation and extrapolation to infinite crystal thickness or the Hoffman‐Weeks analysis. The experimental equilibrium melting temperature was then compared with the theoretical equilibrium melting temperature predicted by Flory's melting point depression model. Flory's model was found to fit the experimental data using an equilibrium melting temperature of 186°C when configurational defects are ignored. However, to account for all defects, the equilibrium melting temperature for 100% isotactic polypropylene must be increased from 186 to 192°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 229–236, 2001
Action of hydrocarbon and ester plasticizer in urethane elastomer for sealing purposes
Authors: Jeczalik Jerzy 
Published: August 2002

AbstractA comparison of the effects of two types of modifiers, anthracene oil (hydrocarbon) and dioctyl phthalate (ester), on physical and mechanical properties of urethane elastomers prepared from polyetherols (propylene oxide derivatives of various functionalities and MW) and TDI was performed. The aim of the study was to assess their suitability as binders in permanently elastic urethane sealants for use in construction. The urethane elastomers under investigation were synthesized by a prepolymer method. The modifiers, added to the reactive mixture before curing, were found to be fully compatible with the urethane elastomers and did not interfere with the curing process. The usable range of application for both modifiers was found to be up to 40 phr. Over this range the modified urethane elastomers are viscoelastic liquids. The hydrocarbon modifier does enhance the hydrophobic properties of urethane elastomer, at a lower degree of crosslinking. It was found that modified urethane elastomers may be good binders for sealants, although their long‐term sealing properties must be confirmed under field conditions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 523–529, 2001
Characterization of structural heterogeneity of polyurethane coatings
Authors: Paolpi M. , Lacabanne C. 
Published: August 2002

AbstractThe thermal analysis techniques—Differential Scanning Calorimetry and ThermoStimulated Current—have been used to characterize a polyurethane high solid coating. The glass transition temperature, as determined by DSC, is 60°C. Below this glass transition temperature, an αsub dielectric relaxation mode has been observed; it corresponds to cooperative movements precursor of the glass transition. The αss dielectric relaxation mode, located at ≈ Tg has been attributed to movements of soft sequences of the amorphous phase liberated at the glass transition temperature. The analysis of the fine structure shows that they are constituted of elementary processes characterized by relaxation times following a compensation law. Above Tg, the αhs dielectric relaxation of hard sequences has been shown. It corresponds to hard sequences hydrogen bonded in polyurethane. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2786–2790, 2001
Ultrasonic disassociation of EVA random copolymer in dilute solutions
Authors: Qian J. W. , Zhou G. H. , An Y. L. 
Published: August 2002

AbstractUltrasonic disassociation of the ethylene–vinyl acetate (EVA) random copolymer in 1,2‐dichloroethane (DCE), cyclohexane (CYH), and their solvent mixtures was investigated using viscometry and dynamic laser light scattering (DLLS). It was found that the disassociation of the EVA aggregates in solutions increases with increasing the time and intensity of ultrasonic shearing and approaches invariant finally. This phenomenon is especially marked for the EVA copolymer with low vinyl acetate (VA) content in the polar solvent of DCE at higher concentration and lower temperature. This is attributed to disassociation of the ethylene segment of the EVA random copolymer in dilute solutions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2798–2802, 2001
Studies on the dipping characteristics of RVNRL and NR latex compounds
Authors: Sasidharan K. K. , Joseph Rani , Rajammal G. , Pillai P. Viswanatha , Gopalakrishnan K. S. 
Published: August 2002

AbstractThe dipping characteristics of radiation‐vulcanized natural rubber latex and natural rubber latex compounds were investigated with a lab‐model semiautomatic dipping machine. The effect of the variation of the speed of immersion and withdrawal, dwell time, compound viscosity, and concentration of coagulant on the thickness of the latex deposit was investigated. The results of the study show that the deposit thickness depends on the withdrawal speed of the former, the concentration of the coagulant, dwell times, and the viscosity of the latex compounds. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3141–3148, 2001
Study of ethylene polymerization catalyzed by nBu‐Cp2ZrCl2/MAO catalytic system and their polymerization kinetics
Authors: Wang L. , Zhang P. Y. , Jiang S. , Feng L. X. 
Published: August 2002

AbstractPolyethylene was prepared by using a nBu‐Cp2ZrCl2/MAO catalytic system. Considering the reactivation of Zr species, a novel and reasonable mathematical model of kinetics has been developed and the kinetic profiles of ethylene polymerization have been fitted satisfactorily. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3186–3189, 2001
Thermal behavior of elastomer–resin mixtures used as friction materials
Authors: Camino G. , Alba E. , Buonfico P. , Vikoulov K. 
Published: August 2002

AbstractThis study looks at the thermal behavior of mixtures of nitrile‐butadiene rubber (NBR) with a resol or a novolac resin. When heated in the 200–300°C range, NBR became hard and insoluble because of exothermic curing and cyclizing chain reactions involving the double bonds of its butadiene units and the nitrile groups of its acrylonitrile units. The NBR proved to be compatible with the novolac but not the resol. Heating increased the modulus of elasticity of the mixtures, which was due to crosslinking of the resin and the rubber. Preliminary linking of the resin resulted in phase separation in the novolac and prevented curing of the rubber when the mixture was heated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1346–1351, 2001
Unsteady stirring method staged used in suspension polymerization of styrene
Authors: Yang Bin , Takahashi Koji , Takeishi Makoto 
Published: August 2002

AbstractThe results of an unsteady stirring method staged, used in the suspension polymerization of styrene in a lab‐scale batch reactor, are presented. Variation of droplet size during the whole polymerization process under the unsteady stirring condition, compared with that under a steady stirring condition, was found to be small. According to the variable droplet size character, two methods were used to divide the polymerization process into four stages and the unsteady stirring method was used in only one stage of each experimental run. By these operations, the optimum operation of obtaining large particle product with uniform particle size distribution was achieved. The results suggest that controlling the droplet coalescence process is more important than controlling the initial droplet size distribution to obtain uniform final particle products. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1873–1881, 2001
Enhanced dynamic mechanical and shape‐memory properties of a poly(ethylene terephthalate)–poly(ethylene glycol) copolymer crosslinked by maleic anhydride
Authors: Chun Byoung Chul , Cha Sang Hyuk , Chung Yong‐Chan , Cho Jae Whan 
Published: August 2002

AbstractDimethyl terephthalate (DMT) and ethylene glycol (EG) were used for the preparation of poly(ethylene terephthalate) (PET), and poly(ethylene glycol) (PEG) was added as a soft segment to prepare a PET–PEG copolymer with a shape‐memory function. MWs of the PEG used were 200, 400, 600, and 1000 g/mol, and various molar ratios of EG and PEG were tried. Their tensile and shape‐memory properties were compared at various points. The glass‐transition and melting temperatures of PET–PEG copolymers decreased with increasing PEG molecular weight and content. A tensile test showed that the most ideal mechanical properties were obtained when the molar ratio of EG and PEG was set to 80:20 with 200 g/mol of PEG. The shape memory of the copolymer with maleic anhydride (MAH) as a crosslinking agent was also tested in terms of shape retention and shape recovery rate. The amount of MAH added was between 0.5 and 2.5 mol % with respect to DMT, and tensile properties and shape retention and recovery rate generally improved with increasing MAH. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 27–37, 2002
Effect of chlorine substitution in 4,4′‐diaminodiphenylmethane hardener on shelf life and mechanical properties of epoxies
Authors: Jagadeesh K. S. , Gururajarao J. , Shashikiran K. , Ambekar Sarvottam Y. 
Published: August 2002

AbstractCuring of N,N,N′,N′‐tetraglycidyldiaminodiphenylmethane with new curing agents like 3,3′‐dichloro‐4,4′‐diaminodiphenylmethane and 2,2′‐dichloro‐4,4′‐diaminodiphenylmethane in comparison with diaminodiphenylmethane and 4,4′‐diaminodiphenylsulphone (DDS) was carried out using dynamic differential scanning calorimetry. The shelf life of various epoxy formulations was evaluated by the residual cure exotherm method. The glass‐transition temperatures of cured epoxy formulations were determined using dynamic mechanical analysis. The mechanical properties such as the tensile strength, tensile modulus, flexural strength, and Izod impact strength were also evaluated and compared. The activation energy, frequency factor, and shelf life of chloro‐substituted hardener formulations were high as compared to those of unsubstituted hardener formulations. The marginal differences in the glass‐transition temperature, tensile strength, tensile modulus, and flexural strength and the small decrement in the Izod impact strength values were interpreted in terms of chlorine substitution. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3082–3088, 2002; DOI 10.1002/app.2337
Developments in the application of photography to ecological monitoring, with reference to algal beds
Authors: Ducrotoy Jean‐Paul A. , Simpson Stephen D. 
Published: August 2002

Abstract1. The potential for using photographic methods in ecological monitoring of intertidal rocky shores was investigated at two scales: the scale of a bay, and at sampling quadrat level.2. The macroalgal beds at Selwicks Bay, Flamborough Head (north Humberside Coast, England) were used as a case study.3. At each station on three 90 m transects, a photograph was taken of a 50 cm2 quadrat. These images were analysed using SigmaScan™ to measure the cover of algal species. These data were highly correlated with field data collected using a grid quadrat.4. Ground techniques were developed for drawing a scaled overhead map of the bay. The potential for a quantitative survey of the extent of the algal beds using cliff top photographs was investigated. The photographs were merged, and rectified using Arc/Info™ (a Geographical Information System package) to produce scaled overhead images of the bay.5. The two complementary methods developed are suitable for involving amateur naturalists into field‐data collection. They were also designed to meet long‐term statutory monitoring requirements. They are quick, so are well suited to intertidal areas where field sampling windows are limited. In long‐term monitoring strategies, the use of photography produces interactive permanent records of the sample area for back reference. Reporting on the conservation status of sites of European interest could be greatly facilitated by such techniques.6. There are obvious applications for overseas monitoring and base‐line surveys, which demand large data sets to be collected in limited periods of time. Copyright © 2001 John Wiley & Sons, Ltd.
A method for estimating the extent of standing fresh waters of different trophic states in Great Britain
Authors: Palmer M.A. , Roy D.B. 
Published: August 2002

Abstract1. The total area of standing fresh water in Great Britain has been estimated at approximately 2400 km2. The aim of the work described in this paper was to estimate the extent of the dystrophic, oligotrophic, mesotrophic and eutrophic habitat types making up this total.2. Botanical survey data collected by the statutory nature conservation agencies provided habitat type and surface area for 3500 water bodies, mostly in Scotland. Because survey in England and Wales had been less thorough than in Scotland, it was not possible to estimate the areas of habitat types simply by direct extrapolation from the survey sample to the total resource of standing water in Great Britain.3. A system of Trophic Ranking Scores (TRS) has been developed for aquatic plant species. Using plant records from the Biological Records Centre, a mean TRS for each 10×10 km square was produced, and Great Britain was divided into TRS bands. For each of these bands, the percentage by surveyed area of each freshwater habitat type was calculated. These percentages were applied to the total area of standing water in each TRS band, obtained from Ordnance Survey summary statistics, in order to predict the proportions of the different habitat types likely to occur in each band. The extent of these habitats in Great Britain as a whole could then be calculated.4. Estimates produced by this method of the extent of the four standing freshwater habitat types in Great Britain are: dystrophic — 11 km2 (0.5%); oligotrophic — 1445 km2 (60%); mesotrophic — 267 km2 (11%); eutrophic — 679 km2 (28%).5. The application of this work to nature conservation is discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Histochemical and biochemical analysis of phospholipase C isoforms in normal human gastric mucosa cells
Authors: Di Baldassarre Angela , Marchisio Marco , Felaco Mario , Antonucci Adriano , Centurione Lucia , Grilli Alfredo , Di Valerio Valentina , Cutroneo Giuseppina , Schiavone Cosima , Miscia Sebastiano , Ianetti Giovanni 
Published: August 2002

AbstractThe expression and activity of PIP2‐specific phospholipase C (PLC) in healthy human gastric mucosa cells were investigated by means of Western blotting, immunohistochemistry and in vitro activity assays. The results provide direct evidence for an almost exclusive expression of the PLC beta family and at the same time supply a cellular cartography of each represented isoform of this family. In this context, the putative roles of each isoform in the signaling events regulating the gastric mucosa metabolic machinery are discussed. These data provide a unique map of the specific expression and cellular distribution of the most represented PLC isoforms in healthy human gastric mucosa cells, which may constitute a reference point in future studies aimed at highlighting possible cytochemical and biochemical hallmarks of metaplastic or malignant transformation. Anat Rec 262:440–444, 2001. © 2001 Wiley‐Liss, Inc.
Use of hair pores to determine the orientation of collagen fibers in skin
Authors: Osaki Shigeyoshi 
Published: August 2002

AbstractMost people are interested in recovery of skin defects caused by burn, scald or trauma from the aesthetic and functional point of view. It will occupy an important role for successful skin graft for patients with such skin defects that the orientation of collagen fibers in the grafted skin matches to the fiber orientation in surrounding skin. There have been, to my best knowledge, no methods for determining the orientation of collagen fibers in the skin from the clinical point of view. Recently, the author has found a new method for directly determining the collagen‐fiber orientation without cutting samples from a calf leather by analyzing the anisotropic shape of hair pore. Its principle is based on the quantitative evaluation of collagen‐fiber orientation by approximating a hair pore to an ellipse. The results obtained by the new method using hair pores were supported by the microwave method, mechanical measurements and scanning electron microscopy. Such a method will be applicable for determining the orientational distribution of collagen fibers in skins of animals and humans and give a valuable probe for performing skin grafting based on the scientific data of hair pores. Anat Rec 263:161–166, 2001. © 2001 Wiley‐Liss, Inc.