bluuebunny/crossref_metadata_2025_split huggingface dataset:
Separation of phenol–water mixture by membrane pervaporation using polyimide membranes
Authors: Pradhan Narayan C. , Sarkar Chandra Sekhar , Niyogi Sobhan , Adhikari Basudam 
Published: August 2002

AbstractSeparation of components of aqueous waste streams containing organic pollutants is not only industrially very important but also is a challenging process. In this study, separation of a phenol–water mixture was carried out by using a membrane pervaporation technique with indigenously developed polyimide membranes. The membranes were found to permeate water selectively. The total flux as well as that of the individual components were measured. The effect of lithium chloride modification of polyimide film on total flux was investigated. The total flux obtained with 2% lithium chloride modification was about 3.6 times higher than that obtained with virgin membrane. The effects of different parameters such as feed composition and temperature on flux, and separation factor were determined. With modified membrane, a separation factor as high as 18.0 was obtained for water at 27°C and with 8.0 wt % phenol solution. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 822–829, 2002
Sugarcane bagasse reinforced phenolic and lignophenolic composites
Authors: Paiva Jane M. F. , Frollini E. 
Published: August 2002

AbstractLignin, extracted from sugarcane bagasse by the organosolv process, was used as a partial substitute of phenol (40 w/w) in resole phenolic matrices. Short sugarcane fibers were used as reinforcement in these polymeric matrices to obtain fiber‐reinforced composites. Thermoset polymers (phenolic and lignophenolic) and related composites were obtained by compression molding and characterized by mechanical tests such as impact, differential mechanical thermoanalysis (DMTA), and hardness tests. The impact test showed an improvement in the impact strength when sugarcane bagasse was used. The inner part of the fractured samples was analyzed by scanning electron microscopy (SEM), and the results indicated adhesion between fibers and matrix, because the fibers are not set free, suggesting they suffered a break during the impact test. The modification of fiber surface (mercerization and esterification) did not lead to an improvement in impact strength. The results as a whole showed that it is feasible to replace part of phenol by lignin in phenolic matrices without loss of properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 880–888, 2002
Biodegradation studies of LDPE filled with biodegradable additives: Morphological changes. I
Authors: Contat‐Rodrigo L. , Ribes Greus A. 
Published: August 2002

AbstractLow‐density polyethylene (LDPE) samples filled with three commercial biodegradable additives (Mater‐Bi, Cornplast, and Bioefect) have been subjected to an accelerated soil burial test in a culture oven for 1 year. By means of Differential Scanning Calorimetry (DSC), the effect of the degradation in soil in the samples morphology has been analyzed, in terms of their melting temperature, their crystalline content, and their lamellar thickness distribution. These morphological parameters evolve in different stages, depending on the additive used. It has been found that the LDPE–Mater‐Bi samples are the ones exhibiting faster changes in their crystalline content. However, the LDPE blends with Cornplast and Bioefect display more significant changes in their lamellar thickness distribution. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1683–1691, 2002
Preparation and properties of polyimide films codoped with barium and titanium oxides
Authors: Tong Yuejin , Li Yuesheng , Liu Jieping , Ding Mengxian 
Published: August 2002

AbstractPolyimide hybrid films containing bimetalic compounds were obtained by codoping poly(amic acid) with a barium and titanium precursor prepared from BaCO3, Ti(OBu)4, and lactic acid followed by casting and thermal curing. FTIR, WAXD, and XPS measurements showed that barium and titanium precursor could be transformed to BaTiO3 at a temperature above 650°C, while the mixed oxides were only found in hybrid films. The measurements of TEM and AFM indicated a homogeneous distribution of inorganic phase with particle sizes less than 50 nm. The hybrid films exhibited fairly high thermal stability, good optical transparency, and promising mechanical properties. The incorporation of 10 wt % barium and titanium oxide lowered surface and volume electrical resistivity by 2 and 5 orders, respectively, increasing dielectric constant from 3.5 to 4.2 and piezoelectric constant from 3.8 to 5.2 × 10−12 c/N, relative to the nondoped polyimide film. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1810–1816, 2002
Red phosphorus–controlled decomposition for fire retardant PA 66
Authors: Schartel B. , Kunze R. , Neubert D. 
Published: August 2002

AbstractThe thermal degradation and the combustion behavior of glass fiber–reinforced PA 66 materials containing red phosphorus were investigated. Thermogravimetry (TG), TG coupled with FTIR, and TG coupled with mass spectroscopy were used to investigate the thermal decomposition. The flame retardant red phosphorus was investigated with respect to the decomposition kinetics and the release of volatile products. The combustion behavior was characterized using a cone calorimeter. Fire risks and fire hazards were monitored versus external heat fluxes between 30 and 75 kW/m2. Red phosphorus acts in the solid phase and its efficiency depends on the external heat flux. The use of red phosphorus results in an increased amount of residue and in a corresponding decrease in total heat release. The decrease of the mass loss rate peak results in a corresponding decrease of the peak heat release. With increasing external heat flux applied the first effect on the total heat release decreases linearly, whereas the second effect on the peak heat release expands linearly. The investigation provides insight into the mechanisms of how the fire retardant PA 66 is achieved by red phosphorus controlling the degradation kinetics. Taking into account that a decrease of the volatile products also leads to a decrease of heat production in the flame zone and that the char acts as heat transfer barrier, a reduced pyrolysis temperature is suggested as a further feedback effect. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2060–2071, 2002
Preparation and characterization of microporous polyethylene hollow fiber membranes
Authors: Shen Li‐Qiang , Xu Zhi‐Kang , Xu You‐Yi 
Published: August 2002

AbstractMicroporous polyethylene (PE) hollow fiber membrane with a porosity of 43% and N2 permeation of 4.96 cm3 (STP)/cm2 s cmHg was prepared by melt‐spinning and cold‐stretching method. It was found that PE with a density higher than 0.96 g/cm3 should be used for the preparation of microporous PE hollow fiber membranes. By increasing the spin–draw ratio, both the porosity and the N2 permeation of the hollow fiber membranes increased. Annealing the nascent hollow fiber at 115°C for 2 h was suitable for attaining membranes with good performance. By straining the hollow fiber to higher extensions, the amount and size of the micropores in the hollow fiber wall increased, and the N2 permeation of the membranes increased accordingly. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 203–210, 2002; DOI 10.1002/app.10305
Multiple‐beam Fizeau fringe‐pattern analysis using Fourier transform method for accurate measurement of fiber refractive index profile of polymer fiber
Authors: El‐Morsy M. A. , Yatagai T. , Hamza A. , Mabrouk M. A. , Sokkar T. Z. N. 
Published: August 2002

AbstractIn this article the Fourier transform method is applied to analyze multiple‐beam interference Fizeau fringes. The real part of the inverse Fourier transform is used to estimate a theoretical pattern. This pattern coincides with the experimental one. A derivative‐sign binary image of the interference pattern is also used in automated determination of the contour line of the fringe pattern, regardless of the quality of this pattern. A correlation between the pixel size and the accuracy of the measured fiber refractive index is presented. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 475–484, 2002
Epoxy‐toughened, unsaturated polyester interpenetrating networks
Authors: Shaker Z. G. , Browne R. M. , Stretz H. A. , Cassidy P. E. , Blanda M. T. 
Published: August 2002

AbstractA series of translucent interpenetrating polymer networks (IPNs) made of a reactive elastomer [linear (D) and branched (T) with varying molecular weights] (Jeffamine™), a commercially available epoxy (D.E.R. 331), and an unsaturated polyester (15:85 wt %) were prepared. DSC data indicated complete cure after 8 h at 90°C. DMTA data showed a single glass‐transition temperature (Tg) for all elastomer‐containing IPNs, an indication of homogeneity. As expected, all IPNs showed a decrease in Tg with incorporation of elastomer, from 16 to 114°C or lower, the largest decrease being with T‐5000. Izod impact strengths were increased by 28–44%, but with no apparent pattern among structure and molecular weight variations. In several cases the standard deviation of impact data increased significantly. Flexural data were measured using a three‐point bend test. The highest flexural modulus obtained was that which incorporated linear D‐2000 with a decrease of only 22% upon incorporation of the elastomer, whereas other compositions dropped up to 55% in flexural modulus. The strongest material obtained was that using D‐2000 with a flexural strength increase of 65% upon incorporation of the elastomer. Two of the three branched elastomer components showed flexural strength increases of about 53%, but one was only equal to the base polyester resin. TGA data were recorded for all IPNs and values compared well to that of the pure polyester resin, with the exception of T‐403, which showed a 20°C decrease, and D‐2000 with a 10°C decrease. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2283–2286, 2002
Structural investigations of poly(ethylene terephthalate)‐graft‐polystyrene copolymer films
Authors: Nasef Mohamed Mahmoud 
Published: August 2002

AbstractStructural investigations of poly(ethylene terephthalate)‐graft‐polystyrene (PET‐g‐PS) films prepared by radiation‐induced grafting of styrene onto commercial poly(ethylene terephthalate) (PET) films were carried out by FTIR, X‐ray diffraction (XRD), and differential scanning calorimetry (DSC). The variation in the degree of crystallinity and the thermal characteristics of PET films was correlated with the amount of polystyrene grafted therein (i.e., the degree of grafting). The heat of melting was found to be a function of PET crystalline fraction in the grafted films. The grafting is found to take place by incorporation of amorphous polystyrene grafts in the entire noncrystalline (amorphous) region of the PET films and at the surface of the crystallites. This results in a decrease in the degree of crystallinity with the increase in the degree of grafting, attributed to the dilution of PET crystalline structure with the amorphous polystyrene, without almost any disruption in the inherent crystallinity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1949–1955, 2002; DOI 10.1002/app.10515
Core–shell latex containing fluorinated polymer rich in shell
Authors: Cheng Shiyuan , Chen Yanjun , Chen Zhengguo 
Published: August 2002

AbstractCore–shell latex with polyacrylate rich in core and fluoropolymer rich in shell was prepared by semicontinuous emulsion polymerization in the presence of mixed emulsifiers. The solids content of the latex was about 25 wt %. The polymerization conditions for the latex were discussed. The morphology of latex particles was characterized by transmission electron microscopy and the surface properties were determined by the Wilhelmy method. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1147–1153, 2002
Ion‐exchange membranes prepared by blending sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide) with polybenzimidazole
Authors: Kosmala Barbara , Schauer Jan 
Published: August 2002

AbstractNew ion‐exchange acid/base‐blend (SPPO/PBI) membranes were prepared by mixing N,N‐dimethylacetamide (DMA) solutions of sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide) (SPPO) in the ammonium form and of polybenzimidazole (PBI), casting the solution as a thin film, evaporating the solvent, and treating the membrane with aqueous hydrochloric acid. The resulting membranes were found insoluble in DMA. The preliminary tests of the membranes were carried out in an H2/O2 fuel cell at room temperature. Their performance in the fuel cell increased with the increase in the concentration of SPPO sulfonic acid groups in the blend, but the membranes formed with the highly sulfonated SPPO alone or predominanting, which swelled excessively in water, did not give reproducible results, and their performance was usually inferior to that of the membranes having an optimum ratio of both components. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1118–1127, 2002
Weathering characteristics of modified rubberwood (Hevea brasiliensis)
Authors: Pandey K. K. , Pitman A. J. 
Published: August 2002

AbstractSurfaces of rubberwood treated with dilute aqueous solutions of chromium trioxide, chromic nitrate, ferric chloride, and ferric nitrate and modified with acetic anhydride were weathered outdoors for periods from 1 day to 1 year. Fourier transform infrared (FTIR) spectroscopy, fluorescence spectroscopy, light microscopy (LM), and scanning electron microscopy (SEM) were used to analyze chemical and microscopic changes in treated and untreated weathered wood surfaces. Severe delignification and hemicellulose degradation occurred in untreated samples, evident from rapid decreases in IR band intensities at 1505 and 1740 cm−1, respectively. Surface delignification occurred after 1 day's exposure, with severe lignin loss within 2–3 days and almost complete surface delignification after 1 week of exposure. Fluorescence spectra of weathered wood surfaces showed a rapid decrease in intensity and a large red shift in emission maxima. Scanning electron microscopy of untreated wood surfaces exposed for 125 and 360 days showed them to have ridges in the S3 cell‐wall layer adjacent to the lumen, together with wall checking and pit degradation. Fungal spores and hyphae were observed in wood cell lumens. Pretreatment of wood surfaces with chromium trioxide (chromium VI compound) significantly restricted weathering deterioration and microbial colonization, whereas ferric chloride was most effective in preventing microbial colonization. Acetylation also partially prevented delignification and fungal staining. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 622–631, 2002
Rheological behavior of controlled‐rheology polypropylenes obtained by peroxide‐promoted degradation during extrusion: Comparison between homopolymer and copolymer
Authors: Berzin F. , Vergnes B. , Delamare L. 
Published: August 2002

AbstractIn the present work, experimental studies of the free‐radical‐initiated molecular weight degradation of polypropylene in a modular self‐wiping corotating twin‐screw extruder are investigated. The control of the molecular weight distribution of polypropylene resins by peroxide degradation is widely used in the polymer industry. It allows one to adjust the viscosity of these resins to the level required for processing applications. The purpose of this work was to characterize the influence of peroxide degradation on the rheological behavior of a polypropylene homopolymer and a block polypropylene/polyethylene copolymer, which includes an addition of a low percentage of polyethylene (around 7%). The homopolymer exhibits a classical behavior: When the peroxide amount is increased, we observe a decrease in the viscosity corresponding to a decreasing molecular weight and a pronounced shift toward more Newtonian behavior. The rheological behavior of the copolymer is influenced by the presence of the polyethylene phase which greatly modifies the viscoelastic properties and increases the viscosity when the polypropylene matrix is highly degraded. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1243–1252, 2001
Studies on high‐speed melt spinning of noncircular cross‐ section fibers. I. Structural analysis of as‐spun fibers
Authors: Takarada Wataru , Ito Hiroshi , Kikutani Takeshi , Okui Norimasa 
Published: August 2002

AbstractFlat fibers and hollow fibers were prepared through the high‐speed melt spinning of poly(ethylene terephthalate) (PET), and the structures of these fibers were compared with those of circular fibers. The cross‐sectional shape of each fiber changed to a dull shape in comparison with that of the respective spinning nozzle. The change in the cross‐sectional shape was slightly suppressed with an increase in the take‐up velocity. There was a significant development of structural variation in the cross section of flat fibers in that the molecular orientation and crystallization were enhanced at the edge. Despite the difference in the cross‐sectional shape, the structural development of flat, hollow, and circular fibers with increasing take‐up velocity showed almost similar behavior. Considering that the tensile stress at the solidification point of the spin line is known to govern the structure development of high‐speed spun PET fibers, it was speculated that the effects of the enhancement of cooling and air friction on the tensile stress at the solidification point cancel each other. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1575–1581, 2001
Ionic conductivity of a novel solid polymer electrolyte
Authors: Xie Wenming , Xu Peixin , Liu Qing , Xie Yi 
Published: August 2002

AbstractA novel kind of solid polymer electrolyte, the solvation unit of which is OCNHR, has been studied. The effects of host polymer structure, ion species, salt concentration, and plasticizers on ionic conductivity are discussed in detail. The solvability of host polymers is a very important factor that affects the ionic conductivity of electrolytes and is fully decided by the structure of solvation units and their density in polymer chain. The latter two rest with monomers structure and copolymerization ratio. Effects of alkali metal salts and divalent metal salts on ionic conductivity are different because of their different leading factor of cation radius. Salt concentration dependence of ionic conductivity appears as a double‐peak shape when alkali metal salts are added because of the total contribution of two kinds of ionic conductance modes, and appears as similar shapes when divalent metal salts are added. Different influences of plasticizers on ionic conductivity result from their different action ways. Ethylene glycol acts well because of its effective action from three different modes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2176–2184, 2001
Bismaleimide resin modified with diallyl bisphenol A and diallyl p‐phenyl diamine for resin transfer molding
Authors: Li Zhongming , Yang Mingbo , Huang Rui , Zhang Meidong , Feng Jianmin 
Published: August 2002

AbstractO,O′‐diallyl bisphenol A (DBA) and N,N′‐diallyl p‐phenyl diamine (DPD) were used for the reactive diluents of 4,4′‐bismaleimidodiphenol methane (BDM). The objective was to obtain a modified BDM resin system suitable for resin transfer molding (RTM) process to prepare the advanced composites. The processing behavior was determined by time–temperature–viscosity curves, gel characteristics, and differential scanning calorimetry (DSC). The injection temperature of the resin system in RTM could be 80°C, at which its apparent viscosity was only 0.31 Pa/s, and the apparent viscosity was still less than 1.00 Pa/s after the resin was held at 80°C for 16 h. The gel time test result indicated that at low temperatures, the reactivity of the resin system is low, whereas at high temperatures, the resin could cure very fast, which was beneficial to RTM. The postcure of the cured resin at a given temperature was necessary because the resin had a wide and flat cure exothermic peak, observed by DSC curve. The cured resin displayed both high heat and hot/wet resistance and high mechanical properties, especially tensile strength, tensile modulus, and flexural strength at room temperature, which reached 96.2 MPa, 4.8 GPa, and 121.4 MPa, respectively. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2245–2250, 2001
Preparation and characterization of chitosan/poly(vinyl alcohol) blend fibers
Authors: Zheng Hua , Du Yumin , Yu Jiahui , Huang Ronghua , Zhang Lina 
Published: August 2002

AbstractChitosan and poly(vinyl alcohol) blend fibers were prepared by spinning their solution through a viscose‐type spinneret at 25°C into a coagulating bath containing aqueous NaOH and ethanol. The influence of coagulation solution composition on the spinning performance was discussed, and the intermolecular interactions of blend fibers were studied by infrared analysis (IR), X‐ray diffraction (XRD), and scanning electron micrograph (SEM) and by measurements of mechanical properties and water‐retention properties. The results demonstrated that the water‐retention properties and mechanical properties of the blend fibers increase due to the presence of PVA in the chitosan substract, and the mechanical strength of the blends is also related to PVA content and the degree of deacetylation of chitosan. The best mechanical strength values of the blend fibers, 1.82 cN/d (dry state) and 0.81 cN/d (wet state), were obtained when PVA content was 20 wt % and the degree of deacetylation of chitosan was 90.2%. The strength of the blend fibers, especially wet tenacity could be improved further by crosslinking with glutaraldehyde. The water‐retention values (WRV) of the blend fibers were between 170 and 241%, obviously higher than pure chitosan fiber (120%). The structure analysis indicated that there are strong interaction and good miscibility between chitosan and poly(vinyl alcohol) molecular resulted from intermolecular hydrogen bonds. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2558–2565, 2001
The use of metal‐containing monomer in the preparation of molecularly imprinted polymer to increase the adsorption capacity
Authors: Sreenivasan K. 
Published: August 2002

AbstractMolecular imprinting is an elegant approach to induce antibody like recognition ability in synthetic polymers. The technique of molecular imprinting has been used extensively in the preparation of tailor‐made stationary phases in chromatography, sorbents in solid phase extraction, sensor elements, etc. Though several of the reported molecularly imprinted polymers (MIPs) possess substrate selectivity comparable to antibodies, they are poor in adsorption capacity. The adsorption capacity could be improved presumably through enhanced interaction between the functionalities of the monomers and the print molecule. A simple approach to improve the interaction is perhaps the use of chemically modified monomers in the synthesis of the MIPs. This article explores this possibility by using a metal‐containing monomer in the synthesis of MIP. The data obtained using a copper acrylate based MIP and cholesterol as substrate indicates the adsorption capacity can be improved considerably through the simple chemical modification of the functional monomer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2795–2799, 2001