bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystallinity, particle size, and mechanical properties of fibers in some egyptian and american cotton cultivars
Authors: Abdel‐Rehim Salwa A. , Ahmed Naeima A. , Hammad S. M. , Askalany Zeinab M. 
Published: April 2003

AbstractThe main objective of this study was to measure the crystallinity, particle size, and mechanical properties of fibers and to assess their relationship in 18 Egyptian and American cotton cultivars. Remarkable variations in crystallinity were found, ranging between 49 and 90%, whereas the range of differences in particle size was somewhat narrow, and so its effect on mechanical properties was not detectable. The cotton cultivars that have higher values of crystallinity are characterized by higher values of tenacity at either \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{1}{8} $\end{document} in. or zero gauge and stiffness and by reduced elongation. © 1993 John Wiley & Sons, Inc.
The interfacial polycondensation of tetrabromobisphenol‐A polycarbonate. II. Reactivities and phase distribution of catalysts
Authors: Gu Jen‐Tau , Wang Chun‐Shan 
Published: April 2003

AbstractTetrabromobisphenol‐A (TBBPA), a sterically hindered bisphenol, is known to give only low molecular weight polymers using the interfacial process. The low reactivity is attributed to the bulkiness and electron‐withdrawing bromine substituents at the ortho positions. The optimum reaction conditions for the interfacial polymerization of TBBPA using pyridine derivatives as a catalyst have been developed. From the two‐phase concentration distribution constant (Ke) and pK's values of triethylamine, 4‐dimethylaminopyridine (DMAP), and TBBPA, the critical process parameters were obtained. Because of its high nucleophilicity and facile leaving character, the DMAP catalyst system produces a high molecular weight TBBPA–polycarbonate (PC) successfully. The profile of the process was followed to obtain a better understanding of the reaction mechanism. © 1993 John Wiley & Sons, Inc.
Plasma treatment of polypropylene surfaces: Characterization by contact‐angle measurements
Authors: Wittenbeck P. , Wokaun A. 
Published: April 2003

AbstractAir plasma treatment has been used to introduce polar functional groups onto polypropylene surfaces to enhance the adhesion of coatings and paints. Plasma exposure times as well as the reaction medium (ambient, technical, and moistured technical air) have been varied. Time‐dependent changes subsequent to the plasma treatment are monitored by contact‐angle measurements. After short plasma exposures, the polar component of the surface energy is observed to decrease, to reach a minimum after ≈ 40 min. This behavior is interpreted in terms of a rotation of the introduced surface hydroperoxide groups into the interior of the polymer. This undesired loss in surface functionalization can be avoided by (a) increasing the treatment time in dry air, (b) use of moistured air as the reaction medium, or (c) posttreatment of the plasma‐treated parts by water immersion. A plasma exposure of 120 s in dry air, followed by posttreatment in an aqueous medium at room temperature for 2–5 min, results in reproducible values of the surface energy σ, with polarities (σpolar/σtotal) close to the desired value of ≈ 50%. © 1993 John Wiley & Sons, Inc.
Bound rubber theory and experiment
Authors: Meissner B. 
Published: April 2003

AbstractAdsorption of polymer on filler from bulk is known to result in a partial loss of polymer solubility (“bound rubber”). The existing theories of this phenomenon were critically examined, and the random adsorption model suggested by the author was found to provide the most complete explanation of available experimental data. Theory based on this model and containing one adjustable parameter (filler surface area per adsorption site) correctly predicts the change of molar mass distribution with adsorption on filler and satisfactorily describes the experimental dependence of fraction B of the filler‐bound polymer on filler concentration and surface area and on Mw of the polymer, in both narrow and very broad molar mass distributions. No distinct effect on B of a moderate degree of branching of EPM, EPDM chains could be detected. It is concluded that the modification of the random adsorption model suggested by Shiga is not warranted, neither theoretically nor experimentally. © 1993 John Wiley & Sons, Inc.
Synthesis of N‐(aminoalkyl) chitosan for microcapsules
Authors: Dunn E. J. , Zhang X. , Sun D. , Goosen M. F. A. 
Published: April 2003

AbstractChitosan was chemically modified by alkylation with N‐(2‐bromoethyl) phthalimide, N‐(3‐bromopropyl) phthalimide, and N‐(4‐bromobutyl) phthalimide. The resulting N‐(phthalidimidoalkyl) chitosans were treated with hydrazine to remove the phthalidimido group resulting in the final N‐(aminoalkyl) chitosan products. For comparison purposes, poly(vinyl alcohol) (PVA) was alkylated with N‐(3‐bromopropyl) phthalimide, then treated with hydrazine to give the N‐(3‐aminopropyl) PVA product. All alkylation products were characterized by solution 1H‐ and 13C‐NMR and by solid‐state CP‐MAS 13C‐NMR. The above synthetic polymer derivatives, as well as chitosan, polyallyl amine, and polyethylen‐imine, were used to form membrane coatings around calcium alginate beads in which blue dextran of molecular weight 7.08×104 or 26.6×104 was entrapped. These microcapsules were prepared by extrusion of a solution of blue dextran in sodium alginate into a solution containing calcium chloride and the membrane polymer. Membrane integrity and permeability were assessed by measuring the elution of the blue dextran from the capsules, spectrophotometrically. © 1993 John Wiley & Sons, Inc.
Synthesis of water‐soluble polyamidoamines for biomedical applications. II. Polymers possessing intrachain‐type secondary amino groups suitable for side‐chain attachment
Authors: Caldwell Gregg , Neuse Eberhard W. , Stephanou Andreas 
Published: April 2003

AbstractAs part of a program to synthesize water‐soluble polymeric carriers suitable for drug binding, the polyaddition reaction of methylenebisacrylamide with comonomers containing two pri‐mary amino groups is investigated. The copolymerization of the bisacrylamide with equi‐molar quantities of primary diamines under properly controlled experimental conditions is found to proceed in a linear propagation, giving rise to the formation of polyamides comprising two or more secondary amino groups in the recurring unit. Selected diamine monomers include ethylenediamine, diethylenetriamine, triethylenetetramine, 1,2‐bis (3‐aminopropylamino) ethane, and three 0,0´‐bis‐(2‐aminopropyl) derivatives of poly(ethylene glycol) of different chain length, the last three monomers being chosen because of their outstanding hydrosolubilizing properties. Use of two different diamines in the proper stoi‐chiometry leads to corresponding copolymers. The reactions are conducted in aqueous phase over periods of 1–3 days at 65°C, and the polymeric products, possessing the linear polyamidoamine structures 1 and 2, are fractionated by dialysis in membrane tubing with 12000–14000 molecular‐mass cutoff and are isolated by freeze‐drying as solid or resinous materials possessing complete solubility in water. Inherent viscosities are in the range of 8– 40mLg‐1. Microanalytical and spectroscopic data confirm the proposed structures. The suitability of the intrachain secondary amine functions for side chain attachment and drug coupling is demonstrated in model reactions involving N‐substitution. © 1993 John Wiley & Sons, Inc.
Gas‐phase polymerization of ethylene using MgCl2/ethyl benzoate/TiCl4 + triethylaluminum catalyst: Effects of triethylaluminum and temperature
Authors: Dusseault John J. A. , Hsu Cheng C. 
Published: April 2003

AbstractA gas‐phase reactor system was developed to polymerize ethylene using the MgCl2/ethyl benzoate (EB)/TiCl4+ triethylaluminum (TEA) catalyst. The reproducibility of the reactor was tested and found to be adequate for kinetic study. The effects of TEA and temperature were studied with the multisite model that assumes a multiplicity of active sites. It was found that the productivity increased with Al/Ti molar ratio while initial activity leveled off. The deactivation rate, after an initial increase, Al/Ti molar that assumes a multiplicity of active sites. It was found that the productivity increase, decreased with Al/Ti. This corresponded with a transition in deactivation order: below Al/Ti = 70, first‐order deactivation was predominant; above Al/Ti = 70, second‐order deactivation was predominant. The second‐order deactivation reactions were made less disperse at higher Al/Ti. Molecular weight of the polyethylene was very high (> 1,000,000) indicating negligible transfer reactions. For Al/Ti > 130 a monomer sorption limitation for polymerization was found. The effect of temperature was also studied with a maximum in productivity at 55°C for Al/Ti = 98.0 and no maximum when Al/Ti = 53.0. Apparent activation energies (Ea) for activity were found to be 19.5 ±3.3 kJ/mol at Al/Ti = 98.0 and 9.3±1.1 kJ/mol at Al/Ti = 53.0. for deactivation Ea was found to be 36.6±5.0 kJ/mol at Al/Ti = 98.0 and–15.5± 4.4 kJ/ mol at Al/Ti = 53.0. Temperature increased the dispersity of second‐order deactivation reactions. © 1993 John Wiley & Sons, Inc.
Pervaporation separation of binary organic‐aqueous liquid mixtures using crosslinked PVA membranes. I. Characterization of the reaction between PVA and PAA
Authors: Rhim Ji‐Won , Sohn Min‐Young , Joo Hyeok‐Jong , Lee Kew‐Ho 
Published: April 2003

AbstractFor the purposes of the water‐selective membrane material development for pervaporation separation, poly(vinyl alcohol) (PVA) was crosslinked with a low molecular weight of poly(acrylic acid) (PAA). The crosslinking reactions between PVA and PAA were characterized through IR spectroscopy, differential scanning calorimetry (DSC), and tensile tests when varying the reactions conditions, that is, time, temperature, amounts of cross‐linking agents, PAA. It was found that the crosslinking reaction was fast: in other words, that the reaction mainly occurred at the initial step of each reaction condition. The best reaction conditions for preparing the crosslinked PVA membranes were found to be: reaction time not over 1 h, reaction temperature in the range of 150–180°C. PAA contents of 15–20 wt % were found satisfactory with respect to the application areas. © 1993 John Wiley & Sons, Inc.
The molecular orientation and mechanical properties of poly(ethylene terephthalate) under uniaxial extension
Authors: Chang C. L. , Chiu W. Y. , Hsieh K. H. , Ma C.‐C. M. 
Published: April 2003

AbstractThe molecular orientation, induced crystallization, and mechanical properties of amorphous poly(ethylene terephthalate) (PET), stretched at different temperatures and strain rates, were studied. The results indicate that the orientation parameter [P2(cosθ)] of oriented PET varies strongly with both temperature and strain rate, but the strain‐induced crystallinity seems dependent on temperature only. It was also found that as draw ratio increased, the Young's modulus, yield stress, and necking ratio were greatly improved in the stretching direction, but slightly declined in the transverse direction. A rubber network model was used to make a quantitative description of the orientation development with draw ratio. © 1993 John Wiley & Sons, Inc.
Measurement of adhesion between fibers and fast curing elastomer resin
Authors: Epstein M. , Shishoo R. L. 
Published: April 2003

AbstractA method was developed to measure the adhesion between fibers and fast curing elastomer, in droplet form, using the microbond pull‐out method. Samples were fabricated by arranging the fibers as a grid on which elastomer droplets were formed for testing. A droplet sliding test method was developed to investigate the nature of the sites of the droplets on the fiber after displacement of the droplets. Fibers of polyester, aramid, and HMW‐polyethylene were tested with resins of polyurethane and natural rubber latex. The fibers had been surface‐treated by corona, gamma radiation, or methanol extraction. The shape of the droplets was determined by microscopic measurement. The shear strength of the fiber/matrix bond was tested using a microvise grip in a tensile strength tester. © 1993 John Wiley & Sons, Inc.
Flexural strength, toughness, and fracture properties of polyester composites
Authors: Vipulanandan C. , Mebarkia S. 
Published: April 2003

AbstractFlexural behavior of particle‐filled fiber‐reinforced polyester composite was investigated by varying the polymer and fiber contents. The polymer content was varied between 10% and 18% of the total weight of the polyester composite (PC) and the glass fiber content was varied up to 6% (by weight of PC). The chopped glass fibers were 13 mm long. The fine aggregates were well graded, with particle size varying from 0.1 to 5 mm, and were mainly composed of quartz. The fine aggregates and glass fibers were also pretreated with a coupling agent (γ‐methacryloxypropyltrimethoxysilane, γ‐MPS) to improve the mechanical and fracture properties of the polyester composites. In general, the addition of fibers increased the flexural strength, toughness, fracture properties, and failure strain (strain at peak stress), but the flexural modulus of polyester composites remained almost unchanged. The addition of 6% fiber content and silane treatment increased flexural strength of 18% PC by 95% to 41.6 MPa (6,040 psi). Crack resistance curves, based on the stress intensity factor (KR‐curve), have been developed for the fiber‐reinforced PC systems. A two‐parameter relationship was used to predict the complete flexural stress‐strain data. There is good agreement between the predicted and measured stress‐strain relationships. © 1993 John Wiley & Sons, Inc.
Development of a new advanced process for manufacturing polyacetal resins. Part II. Vapor‐liquid equilibrium of formaldehyde‐water system
Authors: Masamoto J. , Matsuzaki K. , Morishita H. 
Published: April 2003

AbstractTo develop a new technology for the purification of formaldehyde from formalin by a distillation method, the vapor‐liquid equilibrium of formaldehyde—water binary systems was investigated. Based on the studies of Thompson et al. and Iliceto et al., the vaporliquid equilibrium of formaldehyde and water are calculated and these calculations are in good agreement with the reported data. It was found that the vapor pressure of formaldehyde is determined by the free formaldehyde concentration (mol/L), whereas the vapor pressure of water is determined by the molar ratio of free water. The vapor‐liquid equilibrium of formaldehyde‐water in the presence of a diluent was also investigated. It was shown by calculation that in some cases, when the concentration of the diluent is high, the volatility of formaldehyde is always higher than that of water and these calculations are in good agreement with experimental data. Based on this principle, the purification of formaldehyde by an extraction distillation method was established. © 1993 John Wiley & Sons, Inc.
Chain extension of recycled poly(ethylene terephthalate) with 2,2′‐Bis(2‐oxazoline)
Authors: Cardi Nicoletta , Po Riccardo , Giannotta Giorgio , Occhiello Ernesto , Garbassi Fabio , Messina Giuseppe 
Published: April 2003

Abstract2,2′‐Bis(2‐oxazoline) was used as a chain extender during processing in a twin‐screw extruder with the aim of counteracting degradation phenomena in recycled poly(ethylene terephthalate) (PET). The same experiments were performed on fiber‐grade PET for comparison purposes. Rheological characterization showed that while the melt viscosity of fiber‐grade PET at constant temperature and shear rate is quite constant with time, that of recycled PET decreases dramatically. By addition of oxazoline, an increase of melt viscosity occurs for fiber‐grade PET, whereas for recycled PET, thermal and hydrolitic degradation effects are partially compensated. Characterization was performed by solution viscosity measurements, gel permeation chromatography, and COOH end‐group titration on samples obtained at variable residence times at 280°C. Lower molecular weights accompanied by a higher amount of COOH were observed; the use of oxazoline resulted in higher molecular weights and lower COOH concentrations at equal residence times, while polydispersity did not vary. © 1993 John Wiley & Sons, Inc.
Removal and recovery of gallium ion from solution by insoluble amphoteric starches
Authors: Chan Wu‐Chung 
Published: April 2003

AbstractThe removal and recovery of gallium ion (Ga+3) from a solution with the high cross‐linked amphoteric starches containing the phosphate anionic group and the quaternary ammonium or tertiary amine cationic group was investigated. The adsorption capacity of tertiary amine phosphate starch (TAP) and quaternary ammonium phosphate starch (QAP) is 0.54 and 0.48 meq/g, respectively. The adsorption process has been found to be concentration dependent and endothermic, and follows the Langmuir isothermal adsorption. The heat of adsorption (ΔH) is equal to 7.65 kcal/mol for the QAP and equal to 7.65 kcal/mol for the TAP. The percentage of adsorbed Ga+3 ion decreases when HCl, H2SO4, NaCl, or Na2SO4 is added to the solution. The Ga+3 ion adsorbed on the adsorbents can be recovered by treating with an NaOH or HCl solution (1M and 3M); the maximum percentage of recovery is about 70% when 1M NaOH solution is used. © 1993 John Wiley & Sons, Inc.
Effect of irradiation on crystallinity and mechanical properties of ultrahigh molecular weight polyethylene
Authors: Zhao Yong , Luo Yunxia , Jiang Bingzheng 
Published: April 2003

AbstractUltrahigh molecular weight polyethylene (UHMWPE) has been irradiated (0–40 Mrad) with a Co60 source at room temperature under vacuum. The crystallinity has been investigated by differential scanning calorimetry (DSC) and small‐angle X‐ray scattering (SAXS). The mechanical properties have been determined at room temperature. A significant increase of heat of fusion can be seen at low irradiation doses, which is attributed to crystallization, caused by chain scission during the process of irradiation. It is also observed that the thickness of the lamellae changes with irradiation dose. The Young's modulus has been improved significantly after irradiation at low doses. © 1993 John Wiley & Sons, Inc.
On the poly(vinyl alcohol)–iodine complexes
Authors: Takamiya Hiroyuki , Tanahashi Yumi , Matsuyama Tosiki , Tanigami Tetsuya , Yamaura Kazuo , Matsuzawa Shuji 
Published: April 2003

AbstractThe color development due to the complex formation of poly(vinyl alcohol) (PVA) with iodine increased with increasing syndiotacticity of PVA. Isotactic PVA showed no color development. The color development of syndiotacticity‐rich PVA film decreased with increasing annealing temperature for films before complexization, whereas that of atactic (commercial) PVA increased with it. Lower temperatures, the elongation of complex film, and the presence of boric acid enhanced the absorbance at 600 nm due to I−5. The complexes are assumed to be made by incorporation of polyiodines into aggregates of syndiotactic sequences in PVA. The polarizability and electric conductivity of complex films are investigated. © 1993 John Wiley & Sons, Inc.
Rheological behaviors of bisphenol series thermotropic liquid crystalline wholly aromatic copolyesters
Authors: Zhao Zhouming , Wu Xuqin , Lin Yongwei 
Published: April 2003

AbstractRheological experiments were performed on a series of thermotropic liquid crystalline aromatic copolyesters based on terephthalic acid (TPA), isophthalic acid (IPA), p‐hydroxybenzoic acid (HBA), and a family of bisphenols. The anisotropic melts behaved as non‐Newtonian fluids in a shear elongation flow. The non‐Newtonian exponents of the melts decreased with increasing the linearity of the bisphenol bridge group, and decreased with increasing the optical anisotropy in the liquid crystalline phase. The cross‐section morphologies along the longitudinal direction of the extrudates were surveyed by scanning electronic microscopy (SEM) and discussed with melt‐flow rate distributions. The extrudates exhibited skin–core microstructures and oriented fibril structures. The die swells of the extrudates decreased sharply to negligible levels when shear stress was above 1000 Pa. © 1993 John Wiley & Sons, Inc.
Injection molding of polypropylene: X‐ray investigation of the skin–core morphology
Authors: Wenig W. , Herzog F. 
Published: April 2003

AbstractThe skin–core morphology of injection‐molded polypropylene bars has been investigated employing X‐ray small‐and wide‐angle scattering. The small‐angle scattering has been evaluated by means of interface distribution functions. It is found that skin and core exhibit different morphologies. In the skin, the crystal lamellae are oriented primarily around the c axis, but a (small) fraction of a*‐axis‐oriented lamellae also exists. The lamellar thickness in the skin layer measured from the meridional small‐angle X‐ray scattering shows higher values than in the core. The composition of the monoclinic α1, α2 crystal modifications show dependencies that are typical for the cooling conditions in the mold during injection. © 1993 John Wiley & Sons, Inc.
Synthesis of polymeric microspheres employing SPG emulsification technique
Authors: Omi Shinzo , Katami Ken'ichi , Yamamoto Arihiro , Iso Mamoru 
Published: April 2003

AbstractRelatively uniform polymeric microspheres, the coefficients of variation being close to 10%, were obtained by the BPO‐initiated suspension polymerization of styrenic monomers. Unlike the conventional stirred‐tank system, a particular microporous glass membrane (SPG) provided uniform monomer droplets continuously when monomer was allowed to permeate through the micropores. The monomer droplets were suspended in an aqueous solution containing the stabilizing agents, transferred to a stirred vessel, and polymerized. Up to 10μm spheres, of a far narrower size distribution than those obtained by conventional microsuspension polymerization spheres, were obtained. The initial droplet size and distribution were retained with the successful suppression of secondary particle nucleation by the addition of hydroquinone in the aueous phase. Crosslinked polystyrene spheres were also synthesized in the presence of various low‐molecular‐weight diluents. While a good solvent, toluene, was not so effective; poor solvents, n‐heptane and n‐heptane, easily yielded the microporous structure, the specific surface area being as high as 160 m2/g. © 1994 John Wiley & Sons, Inc.
Crystallization characteristics of polypropylene and low ethylene content polypropylene copolymer with and without nucleating agents
Authors: Zhang Ruiyun , Zheng Haifeng , Lou Xiaolie , Ma Dezhu 
Published: April 2003

AbstractIn this paper, the crystallization characteristics of polypropylene and low ethylene content polypropylene copolymers with and without nucleating agents were studied by differential scanning calorimetry (DSC) and polarized light microscopy (PLM). In order to determine the nonisothermal crystallization rate of these materials, a new estimation method was introduced. Comparing with the crystallization rate coefficient (CRC), which was proposed by Khanna, we found the new approach is more reasonable. From the analysis of results of DSC and PLM, it can be concluded that nucleating agent is more efficient than it is in PP homopolymer. © 1994 John Wiley & Sons, Inc.