bluuebunny/crossref_metadata_2025_split huggingface dataset:
Absorption of water in polyimide resins and composites
Authors: Paplham W. P. , Brown R. A. , Salin I. M. , Seferis J. C. 
Published: April 2003

AbstractThe effect of temperature, postcure, and fiber orientation on water absorption were examined for Kerimid® 723 bismaleimide resin. The effect of fiber orientation was also examined for Avimid® N and BASF X‐5260. Water absorption in Kerimid® 723 was found to have an Arrhenius temperature dependence, depend on degree of postcure, and be independent of fiber orientation. BASF X‐5260 water absorption was also found to be independent of fiber orientation. Avimid® N water absorption exhibited a strong dependence on fiber orientation. © 1995 John Wiley & Sons, Inc.
Preparation and viscosity behavior of hydrophobically modified poly(vinyl alcohol) (PVA)
Authors: Yahya G. O. , Ali Sk. Asrof , Al‐Naafa M. A. , Hamad E. Z. 
Published: April 2003

AbstractIn this study, a novel series of water‐soluble hydrophobically modified poly(vinyl alcohol) (PVA) is prepared by chemical modification of PVA, with the objective of investigating the polymer's rheological behavior for enhanced oil recovery applications. The solution viscosity of the polymer obtained is studied with respect to the polymer concentration, temperature, salinity, polymer modification, aging, shear rate, and polymer molecular weight. The solution viscosity of the PVA is greatly enhanced by the modification. The modified PVA exhibits a relatively high salt tolerance, typical of nonionic polymers, in the range of 0–7.0 wt % NaCl concentrations, and the viscosity of the polymer solution is relatively invariant with NaCl above 3.0 wt % NaCl concentration. Below 3 wt %, the viscosity shows a maximum then a minimum, an unusual behavior. Generally, the polymer exhibits an almost constant viscosity at high shear rates and a typical shear thinning behavior at low shear rates. In addition, increasing polymer concentration and molecular weight leads to an increase in the polymer solution viscosity. Moreover, the polymer exhibits smaller solution viscosity at a high temperatre, and a slight decrease in viscosity is also exhibited by the modified polymer with aging. Comparison of the viscosities of 18 polymer modifications indicates that the larger the numbers of hydrophobic groups (side chains) in the polymer structure, the smaller the viscosity. Moreover, the longer the hydrophobic groups (side chains) in the polymer structure, the greater the viscosity, if their number is small. © 1995 John Wiley & Sons, Inc.
Surface properties of EPDM, silicone rubber, and their blend during aging
Authors: Bhowmick Anil K. , Konar J. , Kole S. , Narayanan S. 
Published: April 2003

AbstractSurface energy of EPDM, silicone rubber, and their 50 : 50 (by weight) blend during aging was determined by contact angle measurement using water and formamide as the probe liquids. The surface energy increases initially with aging time. The results are explained on the basis of the polar component of the surface energy. Blending offers a good degree of protection toward aging of EPDM rubber. The generation of polar groups during aging is confirmed by IR and ESCA investigations. © 1995 John Wiley & Sons, Inc.
Gas transport properties of soluble aromatic polyimides with sulfone diamine moieties
Authors: Kawakami H. , Anzai J. , Nagaoka S. 
Published: April 2003

AbstractAromatic polyimides derived from 2,2′‐bis(3,4‐dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 3,3′‐ or 4,4′‐diaminodiphenylsulfone (m‐DDS or p‐DDS) have been synthesized with a chemical imidization. The disappearance of amic acid groups and the appearance of imide groups are determined by IR and 1H‐NMR spectroscopies. The obtained polyimides are amorphous and soluble in organic solvents. The gas transport properties of the polyimide membranes to CO2, O2, N2, and CH4 have been determined at 35°C and at a pressure up to 10 atm. The (PCO2/PCH4) and (PO2/PN2) selectivities of the membranes are augmented due to their large gas diffusivity selectivities. This is considered to be due primarily to the high packing density of polymer chain. © 1995 John Wiley & Sons, Inc.
Free radical grafting of glycidyl methacrylate onto polypropylene in a co‐rotating twin screw extruder
Authors: Sun Yi‐Jun , Hu Guo‐Hua , Lambla Morand 
Published: April 2003

AbstractFree radical grafting of glycidyl methacrylate (GMA) onto molten polypropylene (PP) was studied in a co‐rotating twin screw extruder. Grafting yields of GMA obtained under various experimental conditions along the screw length allowed for a good appreciation of the effects of chemical parameters (the presence of styrene and the concentrations of peroxide and monomers) and those of processing parameters (feed rate, screw speed, and specific throughput). Similar to the results obtained in a batch mixer,1 free radical grafting of GMA carried out in the extruder in the presence or absence of styrene proceeded rapidly, as it was virtually completed half‐way down stream of the extruder. Additionally, the presence of styrene as a second monomer increased the GMA grafting yield reatly with reduced PP chain degradation. The ultimate GMA grafting yield increased with increasing concentration of peroxide, 1,3‐bis(tert‐butylperoxyisopropyl)benzene. This similarity between the batch mixer and the extruder is related to the fact that in both cases it is the concentration of the peroxide and its half lifetime that determine the grafting rate and the ultimate grafting yield. On the othe hand, the GMA grafting yield decreased with increasing screw speed or feed rate. For a particular specific throughput (the ratio of throughput to screw speed), an increase in throughput with a concomitant increase in screw speed brought about a decrease in GMA grafting yield. It was concluded that the GMA grafting yield is affected primarily by the residence time in the zone in which free radicals are not depleted. The effects of screw speed, feed rate, and specific throughput manifest mainly through this local residence time distribution. Specific energy is not a good measure of the performance of the extruder with respect to the free radical rafting of GMA onto PP. © 1995 John Wiley & Sons, Inc.
The application of statistical process control to rheological measurements
Authors: Bafna Sudhir S. 
Published: April 2003

AbstractThis article presents data on and discusses the application of statistical process control (SPC) to rheological measurements. With the help of case studies on capillary rheometry and dynamic oscillation, it is shown how SPC, coupled with careful calibration and maintenane of rheometers, can demonstrate significant improvement in the accuracy and precision of rheological measurements. This improvement is evident on examination of the various control charts discussed and the narrowing of their control limits. Specifically, individual and moving range control charts for the apparent viscosity measured at an apparent shear rate of 100 s−1 using capillary rheometers are discussed. For the dynamic oscillatory rheometer, the charts presented are for the magnitude of the complex viscosity measured at a frequency of 1 Hz. This article shows how SPC provides quality assurance by assuring that erroneous data will not be inadvertently reported. The issues discussed are of universal interest and relevance, not only to rheologists, but to all scientists and engineers who make and/or use measurements. © 1995 John Wiley & Sons, Inc.
Recycling of sheet‐molding compounds by chemical routes
Authors: Winter H. , Mostert H. A. M. , Smeets P. J. H. M. , Paas G. 
Published: April 2003

AbstractThis article describes a number of chemical routes for the recycling of sheet‐molding compounds (SMC) consisting of glass fibers, filler (calcium carbonate), and an unsaturated polyester–styrene thermoset resin. Treatment of milled SMC with ethanol/potassium hydroxide at 85°C for 48 h ultimately affords a soluble polymeric fraction, consisting of styrene–fumaric acid copolymers. The excess of potassium hydroxide as well as the filler are removed via a neutralization step, which results in a large stream of waste chemicals. Treatment of SMC chips with ethanolamine at 180°C for 48 h gives a reaction mass that can be split into three fractions, viz., the glass fibers, the filler, and a methanol‐soluble polymeric residue. The excess of ethanolamine is recovered by distillation at 220°C and reduced pressure. The polymeric fraction consists of terpolymers of styrene, N,N′‐di(2‐hydroxyethyl)fumaramide and N‐2‐hydroxyethylmaleimide monomer units, the latter two bearing two and one hydroxyl groups, respectively. The terpolymer shows little solubility in unsaturated polyester, epoxy, or isocyanate resins. The glass fibers and the filler coated with the polymeric fraction can be used as constituents of bulk‐molding compounds (BMC). Replacing half of the original amount of glass fibers or filler of a standard BMC formulation by recycled materials does not significantly alter the mechanical properties. Increasing the amount of recyclate results in processing difficulties in the case of the glass fibers or a serious decline of the mechanical properties in the case of the filler/polymer. © 1995 John Wiley & Sons, Inc.
Alcell® lignin solubility in ethanol–water mixtures
Authors: Ni Y. , Hu Q. 
Published: April 2003

AbstractThe lignin solubility in aqueous solutions of different ethanol concentrations was studied. The concept of the solubility parameter was applied to account for the effect of ethanol concentration on the lignin solubility. Experimental results showed that the lignin solubility increased strongly as the ethanol concentration increased from 9.5 to 47.5% then, it increased much more slowly until a maximum was reached at an ethanol concentration of about 70%. Further increase in the ethanol concentration resulted in a slight decrease in the lignin solubility. Based on the lignin molecular formula, the solubility parameter (δ‐value) of the ALCELL® lignin was 13.7 (cal/cm3)1/2. The δ‐value of aqueous ethanol solutions of increased ethanol concentration was calculated and was found to decrease continuously from 22.31 (cal/cm3)1/2 for pure water to 12.08 (cal/cm3)1/2 for pure ethanol. The effect of ethanol concentration on the solubility of the ALCELL lignin was then explained based on the theory that lignin exhibited the maximum solubility when the δ‐value of the solvent was close to that of the ALCELL lignin and the H‐bonding capacity of the solutions with different ethanol concentrations was similar. © 1995 John Wiley & Sons, Inc.
Phase separation, crystallization, and structure formation in immiscible polymer solutions
Authors: Zryd J. L. , Burghardt W. R. 
Published: April 2003

AbstractMorphological and calorimetric studies of phase separation have been carried out in solutions of a crystallizable polymer in poor solvents. Hydrogenated polybutadiene with low branch content was investigated in solutions with diphenyl ether and diphenyl methane, in which the equilibrium phase diagram exhibits both liquid–liquid phase separation and crystallization of the polymer. Emphasis is placed on sample preparation protocols using thermal treatments at low concentrations where it is anticipated that both phase separation mechanisms may influence the resulting morphology. Samples prepared using either ramp cooling or isothermal crystallization exhibit porous structures such as those seen in membrane materials, that predominantly reflect liquid phase separation. However, the interplay between the different kinetics of liquid demixing and crystallization provides a mechanism to control, for instance, pore size. DSC studies during ramp cooling showed evidence of two discrete crystallization processes associated with the two liquid phases expected to be present under these circumstances. Finally, high concentration samples showed morphological evidence of liquid phase separation induced at the growth front of spherulites in otherwise single‐phase polymer solutions. © 1995 John Wiley & Sons, Inc.
Competition between micellization and adsorption of diblock copolymers in a colloidal system
Authors: Dewalt L. E. , Ou‐Yang H. D. , Dimonie V. L. 
Published: April 2003

AbstractSignificant adsorption of polystyrene‐poly(ethylene oxide) (PS‐PEO) diblock copolymers onto PS latex particles in an aqueous dispersion is accomplished through suppression of micelle formation by adding tetrahydrofuran (THF) as a cosolvent. We add THF, a good solvent for the micelle core, to weaken the micelle and allow free chains for adsorption to the colloidal particles. Choosing a PS colloidal particle as the adsorption substrate (thus the adsorbed PS block can fully wet the subsurface), we eliminate the complications which arise from micelle formation on the colloidal surface. Since the PS particles swell in the mixed solvent, the adsorbed PS block may penetrate into the swollen latex core, which is favored for entropic reasons. A subsequent water quench of the system to a low THF solution shrinks the PS particle to its original size while retaining most of the adsorbed polymers. The adsorbed chains cannot be removed by adding surfactants or raising temperature to 90°C, indicating that the adsorbed layer is tightly attached to the surface due to kinetic hinderance of the chains in a confined environment. Neutron scattering experiments is being carried out to settle whether the PS penetrates the PS particle. © 1995 John Wiley & Sons, Inc.
Blending of natural rubber with linear low‐density polyethylene
Authors: Abdullah Ibrahim , Ahmad Sahrim , Sulaiman Che Som 
Published: April 2003

AbstractBlends of natural rubber (NR) with linear low‐density polyethylene (LLDPE) were prepared by melt blending of the materials in a plasticorder mixer at various temperatures around the melting point of LLDPE and at various mixing rates. The optimum processing conditions were a temperature of about 135°C and a mixing rate of 55 rpm. The tensile properties, stress and strain, of the blend had improved significantly with the addition of liquid natural rubber (LNR) into the blend. For blends with compositions around 50% NR, about 10–15% LNR produced the most significant improvement in the physical properties. Welldispersed plastic particles in a rubber matrix were strongly indicated in these samples. Scanning electron micrographs (SEM) of the samples also indicated an increase in the homogeneity of the mixes with the addition of LNR. A single glass transition temperature of about−55°C for the blend was observed via dynamic mechanical analysis (DMA). Interfacial linking between the NR and LLDPE phases was attributed to the presence of active groups on the polyisoprene chain of LNR, which induced the interphase reaction between the NR and LLDPE phases. © 1995 John Wiley & Sons, Inc.
Aromatic polyamide–imides as materials for membranes. I. Synthesis and characterization
Authors: Reddy A. V. Rami , Reddy P. Sreenivasulu 
Published: April 2003

AbstractDiamine amic acids were synthesized by reacting aromatic diamines with pyromellitic dianhydride in dimethylacetamide/dioxane. High molecular weight polyamide‐amic acids were prepared by low‐temperature solution polymerization of diamine amic acids with isophthaloyl chloride in dimethylacetamide. The cyclodehydration of polyamide‐amic acids to the corresponding polyamide–imides was accomplished by heating the cast films at 175°C for 3 h. The polyamide–imides were soluble in polar aprotic solvents like dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N‐methyl‐2‐pyrrolidone and could be cast into tough and flexible films. They were characterized by elemental analyses, inherent viscosities, IR, and 1H‐NMR spectra. The glass transition temperatures of polyamide–imides were determined by differential scanning calorimetry. The thermal stabilities of the polymers were measured by thermogravimetric analyses in air. © 1995 John Wiley & Sons, Inc.
Screening of mycelial fungi for nitrocellulose degradation
Authors: Sundaram S. T. , Zhang Y. Z. , Sharma A. , Ng Koonwing , Brodman B. W. 
Published: April 2003

AbstractSeveral mycelial fungi were screened in liquid medium for their ability to degrade nitrocellulose. Nitrocellulose was tested as the sole source of nitrogen while starch was provided as an additional carbon source. More than 20% nitrocellulose degradation was accomplished with Acremonium persicinum ATCC 60921, Bjerkandera adusta ESF 620, Fusarium solani, IFO 31093, and Sclerotium rolfsii ATCC 24459 in a 3‐day growth period utilizing submerged cultivation. Cyathus stercoreus NRRL 6473 degraded only 8% of the nitrocellulose, while Irpex lacteus Z 212 degraded 24% of the nitrocellulose in a 7‐day growth period. © 1995 John Wiley & Sons, Inc.
Effect on the elastic modulus of high‐density polyethylene of differing thermal treatments
Authors: Daver F. , Cherry B. W. 
Published: April 2003

AbstractThe effect of different thermal treatments on the elastic modulus of high‐density polyethylene has been studied in order to determine which of the parameters defining the polymer morphology has the major effect on the modulus. After examination of the effects of crystallinity, spherulite size, and lamellar thickness, it is concluded that it is the spherulite size which plays the dominant role in controlling the magnitude of the modulus. © 1995 John Wiley & Sons, Inc.
Mesenchymal stem cells from rat visceral fat exhibit multipotential differentiation in vitro
Authors: Tholpady S.S. , Katz A.J. , Ogle R.C. 
Published: April 2003

AbstractHuman subcutaneous fat‐derived stem cells were recently shown to have the potential to differentiate in vitro into a variety of cell types, including adipocytes, osteoblasts, chondrocytes, and myoblasts (Zuk et al., Tissue Eng. 2001;7:211–228). Subcutaneous adipose tissue may therefore prove to be an easily acquired and abundant source of stem cells. Presently it is unclear whether mammals such as rats (which possess small or nonexistent subcutaneous fat pads) contain mesenchymal stem cells within the visceral fat of the abdominal cavity, or whether the visceral fat of any species contains stem cells. In this study we isolated and expanded a pool of mesenchymal cells from visceral fat of adult Sprague‐Dawley rats and induced their differentiation in vitro into adipocytes, osteoblasts, neural cells, and chondrocytes. The differentiated phenotypes were verified by morphology as well as detection and expression of tissue‐specific protein and mRNA. We conclude that despite well‐documented differences in the metabolic and biochemical properties among anatomically distinct depots of fat, the visceral fat of rats contains adult mesenchymal stem cells with developmental potential similar to those isolated from subcutaneous fat in humans. Therefore, animals such as rats provide both a source of fat‐derived stem cells and an immunocompetent, autologous host animal in which to investigate the capacity of the fat‐derived cells to differentiate and form tissues in vivo. Anat Rec Part A 272A:398–402, 2003. © 2003 Wiley‐Liss, Inc.
Effective PSA contamination in the Rotterdam section of the European Randomized Study of Screening for Prostate Cancer
Authors: Otto Suzie J. , van der Cruijsen Ingrid W. , Liem Michael K. , Korfage Ida J. , Lous Jan J. , Schröder Fritz H. , de Koning Harry J. 
Published: April 2003

AbstractThe extent of effective prostate‐specific antigen (PSA) contamination in the Rotterdam section of the ongoing European Randomized Study of Screening for Prostate Cancer (ERSPC) trial was evaluated and defined as when opportunistic PSA testing of ≥ 3.0 ng/ml was followed by biopsy, similar to the regular procedure within the trial. Records of participants aged 55–74 years at entry were linked to the regional database of the general practitioner (GP) laboratory to obtain PSA tests requested by GPs in the period 1 July 1997 to 31 May 2000 (2.9 years), and to the national pathology database to quantify the number of biopsies. All men randomized were included, only those with prostate cancer screen‐detected or clinically diagnosed before July 1997 were omitted from the analyses. 2,895 out of the 14,349 men (20.2%) in the control arm and 1,981 out of the 14,052 men (14.1%) in the screening arm were PSA‐tested, at an average annual rate of 73 and 52 per 1,000 person‐years, respectively. These rates were higher than those recorded at the national and regional levels, 33 and 38 per 1,000 person‐years, respectively. Opportunistic PSA testing in the control arm reached a peak within the first months of randomization, after which it decreased to around 70 per 1,000 person‐years. An opposite pattern was observed in the screening arm, where participants already had received the scheduled screening within the trial. The proportion of men in the control arm with PSA ≥ 3.0 ng/ml followed by biopsy and prostate cancer was 7–8% and 3%, respectively (3% and 0.4–0.6% in the screening arm), over the whole study period. Over a 4‐year rescreening interval, the average PSA and effective contamination amount were approximately 28% and 10%, respectively. PSA testing in the control arm in the Rotterdam ERSPC section is high, but was not followed by a substantial increase in prostate biopsies. Although the reasons for ordering PSA test or indicating biopsy are unknown, effective PSA contamination in the Rotterdam ERSPC section is low and not likely to jeopardize the power of the trial. © 2003 Wiley‐Liss, Inc.
Plasma DNA microsatellite panel as sensitive and tumor‐specific marker in lung cancer patients
Authors: Beau‐Faller Michèle , Gaub Marie Pierre , Schneider Anne , Ducrocq Xavier , Massard Gilbert , Gasser Bernard , Chenard Marie Pierre , Kessler Romain , Anker Philippe , Stroun Maurice , Weitzenblum Emmanuel , Pauli Gabrielle , Wihlm Jean Marie , Quoix Elisabeth , Oudet Pierre 
Published: April 2003

AbstractThe majority of lung cancer patients have tumor‐derived genetic alterations in circulating plasma DNA that could be exploited as a diagnostic tool. We used fluorescent microsatellite analysis to detect alterations in plasma and tumor DNA in 34 patients who underwent bronchoscopy for lung cancer, including 11 small cell lung cancer (SCLC) and 23 nonsmall cell lung cancer (NSCLC) (12 adenocarcinomas, 11 squamous cell carcinomas) and 20 controls. Allelotyping was performed with a selected panel of 12 microsatellites from 9 chromosomal regions 3p21, 3p24, 5q, 9p, 9q, 13q, 17p, 17q and 20q. Plasma DNA allelic imbalance (AI) was found in 88% (30 of 34 patients), with a similar sensitivity in SCLC and NSCLC. In the 24 paired available tumor tissues, 83% (20 of 24) presented at least 1 AI. Among these patients, 85% (17 of 20) presented also at least 1 AI in paired plasma DNA, but the location of the allelic alterations in paired plasma and tumor DNA could differ, suggesting the presence of heterogeneous tumor clones. None of the 20 controls displayed plasma or bronchial DNA alteration. A reduced panel of six markers (at 3p, 5q, 9p, 9q) showed a sensitivity of 85%. Moreover, a different panel of microsatellites at 3p and 17p13 in SCLC and at 5q, 9p, 9q and 20q in NSCLC patients could be specifically used. Analysis of plasma DNA using this targeted panel could be a valuable noninvasive test and a useful tool to monitor disease progression without assessing the tumor. © 2003 Wiley‐Liss, Inc.