bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toughening epoxy resins with polyepichlorohydrin
Authors: Jackson Mervyn B. , Edmond Lex N. , Varley Russell J. , Warden Peter G. 
Published: April 2003

AbstractPolyepichlorohydrin (PECH) rubbers were found to toughen epoxy resins based on the diglycidyl ether of bisphenol A (DGEBA) and cured with piperidine. The degree of toughening depends on the molecular weight of the PECH and on the curing temperature. Best toughening was achieved with PECH of the highest nominal molecular weight of 3400 (Hydrin 10 × 2). Hydrin 10 × 1 (nominal molecular weight 1700) did not toughen the epoxy resin unless bisphenol A was also added, whereas Hydrin 10 × 2 toughened it in the absence of bisphenol A. Curing resins containing bisphenol A and Hydrin 10 × 1 at 160°C resulted in a slightly more brittle resin than when cured at 120°C. The effect of PECH rubbers on the Tg, modulus, and hot/wet properties is similar to that of carboxy‐terminated butadiene‐acrylonitrile rubbers (CTBN). Dynamic mechanical thermal analysis (DMTA) and scanning electron micrographs (SEM) of fractured surfaces show that the PECH separates as a discrete phase during curing. © 1993 John Wiley & Sons, Inc.
Polymerization of 3,9‐dimethyl‐1,5,7,11‐tetraoxaspiro [5,5] undecane with dithiols
Authors: Luo Yanming , Bailey William J. 
Published: April 2003

AbstractNew polymers containing spiroorthocarbonate units on the main chain were synthesized and characterized. The polymers were prepared by using redox or free‐radical catalysts in solution polymerization of 3,9‐dimethylene‐1,5,7,11‐tetraoxaspiro [5,5] undecane [or simply called bimethylenespiroorthocarbonate (BMSOC)] and dithiols at lower temperatures. Their spiroorthocarbonate units could undergo hydrolysis in acidic conditions at room temperature. The structure of polymers was investigated by nuclear magnetic resonance (1H‐ and 13C‐NMR) and Fourier transform infrared (FTIR) spectroscopy. The kind of dithiols had a remarkable effect on properties of the polymers. Block polymers obtained from BMSOC and dithiols could result in a better combination of properties. © 1993 John Wiley & Sons, Inc.
Physical studies of ionically terminated polytetrahydrofuran polymers. IV. Solid‐state studies
Authors: Ali S. A. M. , Hourston D. J. 
Published: April 2003

AbstractThe object of this work was to investigate the effect of the introduction of pyridinium chain‐ends in polytetrahydrofuran (PTHF) polymers on certain solid‐state properties. A comparison of solid‐state properties of methoxy‐terminated (PTHF‐OMe) with pyridinium bromide‐terminated (PTHF‐Py) polytetrahydrofuran polymers of virtually identical molecular weights was made. Crystallization studies and dynamic mechanical and stress‐strain analyses have been undertaken. It was concluded that the introduction of the ionic pyridinium bromide groups to the PTHF polymers influenced the degree of crystallinity and this, in turn, affected other physical properties. © 1993 John Wiley & Sons, Inc.
Radiation degradation of fluoropolymers: Carboxylated fluoropolymers from radiation degradation in presence of air
Authors: Bürger W. , Lunkwitz K. , Pompe G. , Petr A. , Jehnichen D. 
Published: April 2003

AbstractIrradiation of PTFE by accelerated electrons in the presence of air gives rise to a carboxylated structures at doses above 50 kGy. The surface of the irradiated suspension polymerizate TF 1750 is more carboxylated than is the bulk. The influence of oxygen content and radicals is much higher than it is with the emulsion polymerizate TF 2025. The melting point of irradiated PTFE increases at low doses. Electron‐beam irradiation of the fluorinated copolymers perfluoroalkoxy (PFA) and tetrafluoroethylene‐hexafluoropropylene (FEP) leads to loss of fluorine. In all cases, the oxygen uptake was higher near the surface than in the bulk. PFA was better carboxylated than was FEP. The fact that cross‐linking was not found to a measurable extent up to 800 kGy suggested that double‐bound formation was important. The main effects of electron‐beam irradiation are chain scission, oxidation, and unsaturation depending on dose rate, oxygen content, and particle size. © 1993 John Wiley & Sons, Inc.
Influence of the antimony catalyst remnants on the melt crystallization of PET
Authors: Di Fiore C. , Leone B. , De Rosa C. , Guerra G. , Petraccone V. , Di Dino G. , Bianchi R. , Vosa R. 
Published: April 2003

AbstractThe nucleating activity of antimony catalyst remnants on the melt crystallization of poly(ethylene terephthalate) (PET) is proved through comparisons, for samples with Sb concentrations in the range 180‐1850 ppm, of the crystallization behaviors before and after a complete extraction of the catalyst remnants. These comparisons are performed by analysis of the crystallization peaks of differential scanning calorimetry (DSC), by the study of the isothermal crystallization kinetics from X‐ray diffraction experiments, and by optical microscopy observations of the size of the spherulites. The dependence of the crystallization temperature (Tc, as evaluated by the position of the DSC peak) on the Sb concentration, reported in the literature, is shown to be largely overestimated. In particular, it is found that the Tc of commercial samples are essentially unaffected by the presence of the standard concentrations of Sb catalyst remnants. © 1993 John Wiley & Sons, Inc.
Viscous properties of polymer‐thickened water‐in‐oil emulsions
Authors: Pal Rajinder 
Published: April 2003

AbstractThe viscous flow properties of polymer‐thickened water‐in‐oil emulsions were measured using a coaxial cylinder viscometer. The emulsions were prepared using deionized water and polyisobutylene in oil solutions. Three different molecular weight polyisobutylenes (Vistanex MML‐140, Vistanex MML‐100, and Vistanex MML‐80) were studied. The effects of polymer concentration and water (droplet) concentration on the flow properties were determined. The polymer concentration varied from 0 to 3.96% by weight based on the oil phase whereas the water concentration varied from 0 to 80% by volume (based on total emulsion volume). The polymer solutions behaved like non‐Newtonian Ellis model fluids. At low water concentrations, the flow curves for emulsions were similar to their suspending medium (polymer solution). At high values of water concentration, emulsions clearly exhibited a yield stress. The yield stress increased with both water and polymer concentrations. The shear stress/shear rate data for the emulsions possessing a yield stress were described adequately by a modified Herschel‐Bulkley model. A comparison was also made of the relative viscosities of emulsions having different polymer concentrations. The relative vis‐cosities for polymer‐thickened emulsions were found to be significantly lower than the corresponding values for emulsions without polymer. The correlation of relative viscosity/ concentration data is discussed. © 1993 John Wiley & Sons, Inc.
Fast determination of polymer melt viscosity by optical falling needle viscometer
Authors: Chu Benjamin , Wang Jian , Tuminello William H. 
Published: April 2003

AbstractAn optical falling needle rheometer was employed to measure the melt viscosity of high density polyethylene (HDPE) and low molecular weight poly (tetrafluoroethylene) (PTFE). The temperature dependence of the melt viscosity of these two polymers was obtained and described by an empirical Arrhenius relation. At the present time, this method has been confirmed to be a simple and fast (within several tens of seconds for each measurement) approach to determine polymer melt viscosities of up to at least 1×105 Pa s. The sample cell containing ∼ 2.5 cm3 materials can be vacuum sealed and disposed of without the need of subsequent cleaning each time, which could be a useful feature. In comparison with HDPE, the PTEF sample melt was found to show a much higher melt viscosity with about the same degree of polymerization. © 1993 John Wiley & Sons, Inc.
Transport properties of dichloromethane in glassy polymers. II. Amorphous syndiotactic polystyrene films
Authors: Vittoria V. , Filho A. Ruvolo 
Published: April 2003

AbstractSorption and diffusion of dichloromethane vapor were measured in amorphous syndiotactic polystyrene films, obtained with different cooling conditions and after controlled aging times at different temperatures. The diffusional behavior, at the temperature of 25°C, was characterized by three stages, depending on penetrant activity. In the first stage, at low activity, the diffusion coefficient was independent of vapor concentration; the second stage was characterized by concentration‐dependent diffusion, whereas in the third stage, at high activity, the strong interaction solvent–polymer increased the mobility, allowing the polymer crystallization. The different cooling conditions neither have an effect on the diffusional behavior nor on the sorption curve. The aging, both at room temperature and at 70°C, did not change the diffusion parameters, but led to the appearance of more and more anomalous sorption behavior. The sorption curve, as a function of vapor activity, did not show any difference for the fresh and the aged‐at‐room temperature samples, whereas the samples aged at 70°C presented a lower sorption at low activity. The presence of ordered domains, impermeable to the penetrant at low activity, was suggested on the basis of sorption results. The solvent‐induced crystallization was investigated for all the samples. Crystallization was induced at an activity of 0.45 for the fresh and the aged‐at‐room temperature samples; at variance, the samples aged at 70°C crystallize at a slightly higher activity, reaching, nevertheless, a higher level of crystallinity. © 1993 John Wiley & Sons, Inc.
Rate of electropolymerization of N,N'dimethyl acrylamide in aqueous sulfuric acid solution
Authors: Iroh Jude O. , Bell J. P. , Scola D. A. 
Published: April 2003

AbstractElectropolymerization of N,N‐dimethylacrylamide has been performed in aqueous sulfuric acid solution, using unsized AS‐4 graphite fibers as the working electrode. The electro‐polymerized poly (N,N‐dimethylacrylamide) deposited on the surface of the graphite fiber working electrode. The formation of poly (N,N'dimethyl acrylamide) was inhibited by hydroquinone. The addition of about 0.05 moles of hydroquinone to the reaction solution resulted in about a 90% decrease in the weight gain of fibers, in agreement with the proposed free radical mechanism of aqueous electropolymerization. The rate of electropolymerization varied with the initial monomer concentration, current density, and sulfuric acid concerntration, raised to the power of 1.3, 0.42, and 0.07, respectively, that is, Rp ∝ [M]1.3‐Cd0.42 [H2SO4]0.07. A mathematical model, based upon free radical polymerization kinetics, is discussed. © 1993 John Wiley & Sons, Inc.
Experimental measurement of internal stresses in polypropylene‐injected disks
Authors: Delbarre P. , Jasse B. , Pabiot J. , Rietsch F. 
Published: April 2003

AbstractDisks in polypropylene were injected in a mold with an unbalanced cooling pattern to induce warpage. The internal stresses were determined using IR dichroism for molecular orientation measurement and an original method for thermal stress assessment, on the basis of the analysis of the dilatometrical behavior of microtomed cuts removed from the part. From both experimental results and structural observations with an optical microscope, a simple model is proposed to describe the warpage due to the effect of unbalanced cooling. A constant deformation was observed and cannot be described by our model, but calculated relative deformations of the part geometry are in good agreement with experimental results. © 1993 John Wiley & Sons, Inc.
The slip‐reducing mechanism in polypropylene‐laminated films studied by FTIR and XPS
Authors: Nishioka T. , Tanaka Y. , Kume K. , Satoh K. , Teramae N. , Gohshi Y. 
Published: April 2003

AbstractFTIR spectroscopy and X‐ray photoelectron spectroscopy (XPS) were applied to examine the slip‐reducing mechanism of polypropylene‐laminated films. The relationship between the slip and the amount of lubricants was established on the basis of quantitative analysis of lubricants on the cast and laminated polypropylene film surfaces. The results suggested that erucic amide used as a lubricant for the cast film migrated from the film surface into the adhesive layer, probably due to intermolecular interactions (hydrogen bonds) with an isocyanurate‐ether‐polyol used as an adhesive for laminating the films. This enabled us to understand the slip‐reducing mechanism in the laminated films. © 1993 John Wiley & Sons, Inc.
In situ compatibilization of PET/PS blends through reactive copolymers
Authors: Maa Chyn‐Tein , Chang Feng‐Chih 
Published: April 2003

AbstractPolymer blends of poly(ethylene terephthalate) (PET) and polystyrene (PS) are immiscible and incompatible, which has been well recognized. Styrene–glycidyl methacrylate (SG) copolymer has been synthesized by suspension polymerization and employed in this study as an in situ compatibilizer for the polyblends of PET and PS. This copolymer contains reactive epoxy functional groups that are able to react with PET end groups OH and COOH) under melt conditions to from SG‐graft‐PET copolymer. The presence of a small amount of phosphonium catalyst (200 ppm) accelerated the graft reaction and results in a better compatibilized blend. The compatibilized PET/PS blend has a smaller phase domain and higher viscosity than does the corresponding noncompatibilized blend. Mechanical properties of the compatibilized blends have also been improved significantly over the corresponding noncompatibilized blends. © 1993 John Wiley & Sons, Inc.
Effect of polymerization initiator on early colour of poly(vinyl chloride)
Authors: Rogestedt Mikael , Jonsson Torbjörn , Hjertberg Thomas 
Published: April 2003

AbstractThe development of early colour and the dehydrochlorination rate were compared for poly(vinyl chloride) samples obtained by suspension polymerization using two different initiators, dicetylperoxydicarbonate and butylperoxyneodecanoate. The degree of discolouration was measured on pressed plates and expressed as yellowness index (YI), the polyene sequence distribution was monitored by UV/Vis‐spectroscopy, and the degradation rate was determined by measuring evolved HCI conductometrically. The PVC sample initiated by dicetylperoxydicarbonate exhibited more extensive early colour and a higher dehydrochlorination rate as compared to the sample obtained with butylperoxyneodecanoate as initiator. The UV/Vis‐spectra showed that the early colour originates from polyene sequences. After extraction of the PVC resins with heptane: acetone (85 : 15) the early colour turned out to be almost the same for the two samples. From 13C‐NMR measurements it was found that the extract of the sample polymerized with dicetylperoxydicarbonate contains unreacted initiator. We suggest that the radicals formed when the remaining initiator decomposes initiate dehydrochlorination. Our results also indicate that radicals from dicetylperoxydicarbonate may cause long‐chain branches during polymerization. The radicals formed from butylperoxyneodecanoate, on the other hand, do not seem to react with the polymer molecules. © 1993 John Wiley & Sons, Inc.
Effect of mode of filler addition on the dynamic mechanical properties of epoxidized natural rubber‐cis‐1,4‐polybutadiene rubber blend
Authors: Varughese Susy , Tripathy D. K. 
Published: April 2003

AbstractThe effect of different modes of filler addition on dynamic mechanical properties of 50/50 blends of epoxidized natural rubber (ENR) and cis‐1,4‐polybutadiene rubber (BR) has been studied. The present study is confined to the systems that have fillers alone to reduce complexities due to the presence of other compounding ingredients and vulcanization. The effects of both carbon black and silica filler have been investigated. The mode of filler addition was found to have a profound influence on the loss tangent (tan δ) peak height, its spread, and the storage modulus, E′ value. The tendency of the filler to adhere predominantly to one of the phases depends on the mode of filler addition and the processing history rather than the individual component polarity or viscosity. © 1993 John Wiley & Sons, Inc.
Melting and recrystallization of PA‐6/PA‐66 blends
Authors: Rybnikár̆ Frantis̆ek , Geil P. H. 
Published: April 2003

AbstractThe morphology of a number of polyamides (PA)—namely, PA‐66, PA‐6/PA‐66 blends, and PA‐6/PA‐66 copolymers—prepared from HCOOH solution and from the melt has been examined as well as the effect of annealing. In the blends, the PA‐6 crystallizes within the PA‐66 spherulites. When prepared from HCOOH solution at 25°C, the PA‐66‐containing samples show a large exothermic peak before the sample melting peak is observed by DSC. This exothermic peak, which cannot be fully explained by previously known observations, PA recrystallization, and/or the morphology changes we describe here, is not seen for PA‐6 or for PA‐66 prepared from HCOOH solution at 100°C. © 1993 John Wiley & Sons, Inc.
Effect of graft chain length of the stabilizer on dispersion polymerization of methyl methacrylate in petrol
Authors: Kargupta Kajari , Rai Purnendu , Kumar Anil 
Published: April 2003

AbstractTo carry out dispersion polymerization of methyl methacrylate (MMA) in petrol, we have used a poly(MMA) grafted‐poly(12‐hydroxystearic acid) copolymer as the stabilizer. This special copolymer was prepared as a solution in a mixture of ethyl acetate and butyl acetate solvents. We investigated the effect of graft chain length of the stabilizer on the dispersion polymerization in petrol. We synthesized the stabilizer copolymer with n = 1–4 and determined the rate and the molecular weight of the PMMA formed. There is no dispersion polymerization for n = 1. However, for any other n, for a given stabilizer concentration, as the chain length of the graft is increased, the molecular weight as well as the rate of PMMA formation increases. As opposed to this for a given graft length as the concentration of the stabilizer increases, the molecular weight of PMMA first rises, but for a larger concentration, it begins to fall after undergoing a maximum. In this work, we modeled the heterogeneity of the reaction mass and proposed a mathematical model for dispersion polymerization of MMA in petrol. The computer results are found to conform to the experimentally observed molecular weight of the PMMA. © 1993 John Wiley & Sons, Inc.
Evaluation of light‐scattering detectors for size exclusion chromatography. I. Instrument precision and accuracy
Authors: Jeng L. , Balke S. T. , Mourey T. H. , Wheeler L. , Romeo P. 
Published: April 2003

AbstractA systematic evaluation of two types of light‐scattering detectors for size exclusion chromatography (SEC) was completed. The two detectors were the low‐angle laser light scattering photometer (LALLS) and the multiangle laser light‐scattering photometer (MALLS). Instrument evaluations were performed at both room (30–40°C) and high (135–145°C) temperatures using the polystyrene standard, NBS 706, at room temperature and the polyethylene standard, SRM 1476, at high temperature. Results of the evaluation showed that when experimental uncertainties were taken into account LALLS and MALLS demonstrated equivalent precision and accuracy for molecular weight determination. The main source of inaccuracy found (particularly for SRM 1476) was the sensitivity difference between the light‐scattering and the concentration (DRI) detectors; i.e., the DRI detector was unable to measure very low concentrations of very high molecular weight material present in SRM 1476, whereas the light‐scattering detectors respond strongly. It was shown that for LALLS the overall weight‐average molecular weight (M̄w) for the whole polymer calculated using an equation that did not require the DRI detector output circumvented this sensitivity problem while assuming that the low angle used was sufficiently close to zero. Use of this equation for MALLS is possible by extrapolating data from all angles used to obtain a light‐scattering chromatogram at zero angle. However, this possibility was not examined here. A particular advantage of MALLS over LALLS is that MALLS can provide the z‐average root mean square radius (commonly referred to here and in other light‐scattering literature as the “radius of gyration”) values from the same data as those used to obtain molecular weight values. Although the radius of gyration values at each retention volume were not as precise as the corresponding weight‐average molecular weights, at room temperature, precision was better than 2% for a significant portion of the chromatogram. © 1993 John Wiley & Sons, Inc.
Study on the polymer latex agglomeration by another polymer latex
Authors: Zhang Liucheng , Liu Yanqiu , Liu Zhiqing 
Published: April 2003

AbstractIn this paper, the agglomeration of polymer latex that was caused by another latex was studied. The basic pattern and the factors affecting the agglomeration have been ascertained. Two agglomerating peaks appeared as the amount of added agglomeration latex increased. The agglomerating mechanism corresponding these two peaks has been proposed. © 1993 John Wiley & Sons, Inc.
New equation for fitting rheological data of bingham materials
Authors: Philippov G. G. , Gorbunov A. I. , Kestelman V. N. 
Published: April 2003

AbstractIn this article we propose a new equation that combines behaviors of Bingham and Williamson pseudoplastic materials. We compare this equation with other ones, and in the Appendix, we consider its theoretical foundation. © 1993 John Wiley & Sons, Inc.
The effect of a diazide as adhesion agent on composite materials consisting of an elastomeric matrix and short polyester fiber
Authors: Ibarra L. 
Published: April 2003

AbstractThis research reports on the effect of a diazide, i.e., 1.4‐carboxybenzenesulfonyl diazide, which had been incorporated onto fiber by a chemical reaction, on the formation of an interphase between the elastomeric SBR matrix and polyester fiber. The existence of the interphase becomes manifest not only in the variation of the mechanical properties, but especially through swelling measurements and dynamic properties. The effect of the new system based on diazide is similar to that obtained from a conventional adhesive system, but presents certain benefits, such as a shorter curing time due to absence of resin, enhanced tensile strength, and the formation of a more flexible interphase, which entails lesser heat generation due to mechanical energy loss. © 1993 John Wiley & Sons, Inc.
Extraction of gold from Au(III) ion containing solution by a reactive fiber
Authors: Lin Weiping , Lu Yun , Zeng Hanmin 
Published: April 2003

AbstractMetallic gold was extracted directly from a solution containing Au(III) ion by a reactive fiber with the amidoxime group. It is concluded that in the solution containing Au(III), Cu(II), Zn(II), and Cr(III) the reactive fiber presents high selectivity to Au(III). During the adsorption process, the adsorbed Au(III) is partially reduced into spongy metallic gold and the amidoxime group is finally oxidized into the carboxyl group. © 1993 John Wiley & Sons, Inc.
Growth mechanism of transparent and conducting composite films of polyaniline
Authors: Wan Meixiang , Yang Jing 
Published: April 2003

AbstractComposites of polyaniline (PANI) with various polymeric matrices as substrates were synthesized by means of diffusion–oxidation of aniline swollen polymeric matrices with FeCl3 as oxidizer. The conductivity at room temperature, transmittance at 400–800 nm, stability in air, and morphology of PANI composite films depend on the polymerization time, concentration of FeCl3, and substrate used. A maximum conductivity at room temperature and the highest transmittance at 500–800 nm can be achieved of 10−1 S/cm and 70–80%, respectively. The growth mechanism of PANI composite films has been discussed. © 1993 John Wiley & Sons, Inc.