bluuebunny/crossref_metadata_2025_split huggingface dataset:
The absorption of direct dyes by crosslinked cellulose. II. Rate of dyeing and diffusivity
Authors: Ibe E. Chianakwalam , Valko Emery I. 
Published: April 2003

AbstractThe effect of crosslinking in the dry state on the rate of dyeing of cellophane with two direct dyes, Chrysophenine G and Chlorazol Sky Blue FF, has been studied. Dimethylolethyleneurea and bis(hydroxyethyl) sulfone were the crosslinking agents. It was found that the rate of dyeing was reduced at high degree of crosslinking by more than 90%, whereas the amount of dye absorbed at equilibrium was reduced by only 40%. It was concluded that the major factor in the practical undyeability of the crosslinked cellulose fibers in commerce is the reduction of the rate of dyeing rather than that of the absorption at final equilibrium. The average diffusivities of the dyes in the cellulose film were calculated from the rate data. The diffusion coefficients as functions of the dye concentration in the films were estimated from the diffusivity values. The two models of swollen cellulose, the pore model and the gel model, were applied to explain the effect of crosslinking on the diffusion coefficients. The pore model offers a satisfactory explanation by assuming that crosslinking reduces the average pore diameter and therefore increases the drag and also the tortuosity. The gel model offers an equally satisfactory explanation by assuming that crosslinking reduces the free volume by increasing the rigidity and concentration of the cellulose chains in the cellulose gel.
Acetylene–butadiene copolymer for polymer coatings
Authors: Furukawa Junji , Kobayashi Eiichi , Kawagoe Takahiro 
Published: April 2003

AbstractLow molecular weight,M̄n1800–2400, and soluble copolymers of acetylene and butadiene were prepared by nickel naphthenate–diethylaluminum chloride catalyst. These copolymers possess high cure tendency to give insoluble and highly crosslinked films. The curing ability can be controlled by the amount of acetylene content in the copolymer and is in the following order: acetylene–butadiene copolymer > tung oil >cis‐1,4‐polybutadiene ≫ linseed oil, 1,2‐polybutadiene, butadiene–isobutylene copolymer. Chemical modifications of the copolymer such as maleic reaction, metallation by lithium or sodium, graft polymerization by methyl methacrylate, 4‐vinylpyridine or vinyl acetate, and epoxidation were also examined. The divinyl methylene in the copolymer gives a high cure tendency and high chemical reactivity.
Iodine‐initiated, solid‐state copolymerization of tetraoxane with 1,3‐dioxolane in the presence of methylal. II. Properties of copolymer obtained by beaker‐scale copolymerization
Authors: Morita Yosuke , Ishigaki Isao , Watanabe Yuhei , Okubo Hiroshi , Ito Akihiko 
Published: April 2003

AbstractIn order to elucidate the copolymerization mechanism, the properties of the copolymer obtained by the iodine‐initiated copolymerization of the tetraoxane–1,3‐dioxolane–methylal system have been studied using gas chromatography, microscopy, scanning electron microscopy, differential scanning calorimetry, and gel permeation chromatography. From the behavior of the thermal stability and gas chromatography of the reaction mixture, it was found that reactivity of 1,3‐dioxolane with active center is larger than that of tetraoxane, i.e., more than 90% 1,3‐dioxolane is consumed at an early stage of the polymerization. The results obtained by microscopy, DSC, and GPC of the copolymer suggested that the copolymerization proceeds from the surface to the center of the tetraoxane crystal as if it were a core model. It was also suggested that the heterogeniety in copolymer properties can be explained not only by heterogeneous dispersion of 1,3‐dioxolane in tetraoxane crystal, but also by the difference of reactivity of 1,3‐dioxolane with the active center.
Iodine‐initiated, solid‐state copolymerization of tetraoxane with 1,3‐dioxolane in the presence of methylal. III. Study on larger‐scale copolymerization
Authors: Ishigaki Isao , Morita Yosuke , Nishimura Koichi , Yokooji Makoto , Ito Akihiko 
Published: April 2003

AbstractThe iodine‐initiated, solid‐state copolymerization of tetraoxane with 1,3‐dioxolane in the presence of methylal has been studied using 15 l kneader‐type reactor. Effects of the addition method of the 1,3‐dioxolane–methylal solution on the copolymerization has been mainly discussed. The copolymerization rate, intrinsic viscosity, and thermal stability of the copolymer were found to be largely dependent on the addition method of the 1,3‐dioxolane‐methylal solution, i.e., if the solution is added all at once, properties of the copolymer are different at the early stage then at the later stage of the copolymerization, while on successive addition of the solution, the copolymer properties become almost constant irrespective of the polymerization time. Therefore, it was suggested that 1,3‐dioxolane and methylal can easily diffuse through the copolymer layer formed on the surface of the tetraoxane particle and reacts with an active center as copolymerization proceeds.
On the crystal structure of nylon 6
Authors: Parker James P. , Lindenmeyer Paul H. 
Published: April 2003

AbstractNylon 6 can exist in either of two stable crystal structures, the α crystal with hydrogen bonds between antiparallel chains or the γ crystal with hydrogen bonds between parallel chains. Both structures have been observed in the same highly annealed fiber, suggesting that the polymer should not be regarded as a pure compound but a multicomponent mixture. Nylon 6 can also exist in a series of metastable crystal structures which vary continuously in size, perfection, and structural parameters from a pseudohexagonal structure to either of the two stable forms. A single equatorial reflection in the wide‐angle x‐ray pattern (i.e., pseudohexagonal structure) will not distinguish which of the two stable forms will result upon annealing. Measurement of the 0,14,0 reflection in oriented fibers will distinguish the major trend, but it is still uncertain to what extent annealing conditions can favor one stable form over the other. The variation in the unit cell parameters as a function of annealing has been accurately measured, and the observed phenomena can be qualitatively described by postulating various balances between the basic forces which hold the crystal together (i.e., hydrogen bonding, dipole–dipole interaction, van der Waals attraction, and covalent bonding).
On the relationship between K and a and between Kθ and the molecular weight per chain atom
Authors: Aharoni Shaul M. 
Published: April 2003

AbstractIt is shown that in [η] = KMa there exists a relationship between K and a of the form log K = C − Ba. The parameters C and B are typical of each polymer and, under θ conditions, define a characteristic Kθ for the polymer. When plotted against m0/z, the molecular weight per backbone atom, the values of log Kθ cluster along three distinct lines. In a fashion similar to the observed dependence of number of atoms between chain entanglements on m0/z, the lines are associated with highly flexible polymers, intermediate flexibility polymers, and stiff chain polymers. Deviations from the intermediate flexibility line are explained on the basis of changes in the distribution of mass in the plane perpendicular to the overall direction of the backbone chain.
Melt spinning of nylon 6: Structure development and mechanical properties of as‐spun filaments
Authors: Bankar Vilas G. , Spruiell Joseph E. , White James L. 
Published: April 2003

AbstractThe structure of melt‐spun nylon 6 filaments was studied using on‐line x‐ray diffraction and birefringence measurements. Measurements were also made on as‐spun and treated filaments. On‐line wide‐angle x‐ray scattering measurements indicated that crystallization did not occur on the nylon 6 spinline at spinning rates up to 1000 m/min when spinning was done into either ambient air of 60% relative humidity or into wet saturated air. The filaments did crystalline gradually on the bobbin to a paracrystalline pseudohexagonal (γ) form. The rate of crystallization was dependent on the molecular orientation developed in the spun filaments. Crystalline orientation factors based on hexagonal symmetry were computed as a function of take‐up velocity for fibers which were conditioned 24 hr in air at 65% relative humidity. Annealing in air or treatment in water or 20% formic acid solution causes a transformation from the pseudohexagonal form to the α monoclinic form. The tangent modulus of elasticity and tensile strength of spun and conditioned filaments increase with increasing take‐up velocity and spinline stress, while elongation to break decreases with these variables.
Physical properties and structure of silk. III. The glass transition and conformational changes of tussah silk fibroin
Authors: Magoshi Jun , Magoshi Yoshiko , Nakamura Shigeo 
Published: April 2003

AbstractThe glass transition, crystallization, and α–β transition of the Tussah silk fibroin were studied by means of DSC (differential scanning calorimetry) and infrared spectroscopy. The endothermic shift due to the glass transition was observed at 162°C. The endothermic peak at 220°C was attributed to the α–β conformational transition from the infrared spectra. The exothermic peak due to the crystallization occurred at 230°C.
Melting of hydrogels containing ammonium nitrate
Authors: Ahad Elie 
Published: April 2003

AbstractThe fusion of hydrogels containing ammonium nitrate (AN) has been investigated by differential scanning calorimetry (DSC). The polymers used were guar and xanthan gums as well as synthetic polyacrylamide polymers. Water in hydrogels could be classified into three types labeled as ordinary water (hump of the melting peak), intermediate water (broad component of the peak), and bound nonfreezing water (without any phase transition). The temperature of fusion of intermediate water was about 10° to 35°C lower than that of ordinary water. Intermediate and bound water was found in all the gels studied, whereas ordinary water existed mainly in mixtures with total water content higher than 62%. The presence, type, and concentration of a crosslinker had no effect on the amount of bound water in hydrogels containing AN. In such mixtures the amount of nonfreezing water increased with the polymer concentration as well with the AN proportion relative to water and represented in some cases up to 27% of the gel. Cold‐crystallization was observed in all cases (except xanthan) and was probably initiated by AN or the crosslinking agent.
Wood fiber–synthetic polymer composites. II. Laminates of treated fibers and polyolefins
Authors: Michell Anthony J. , Vaughan Janet E. , Willis Donald 
Published: April 2003

AbstractFlexural properties of laminates prepared by hot pressing commercial papers and laboratory handsheets with films of polyolefins were measured following exposure to different levels of moisture. Prior to their incorporation in the laminates, the fibers, either individually or as preformed paper, were acetylated or crosslinked with formaldehyde to reduce their sensitivity to moisture. The results are compared with earlier measurements which showed that the properties of laminates based on paper precoated with polyethylene declined sharply at high relative humidities. For laminates comprising laboratory handsheets made from acetylated fibers, the decline in properties is less but the initial values under dry conditions are lower also. However, acetvlation or crosslinking of preformed paper improves up to threefold the retention of flexural modulus by the laminates under the wettest conditions with no concurrent loss in this property under dry conditions, although some embrittlement of the component paper sheets is observed. Enhanced fiber alignment or the addition of 5% glass fibers to the paper does not arrest the decline in flexural properties of the laminates with increasing relative humidity. This decline differs little when other polyolefins are used but is accentuated when ethylene–vinyl acetate copolymer is the binder.
Studies on heating and cooling of synthetic fibers, yarns, and fabrics. I. Properties of nylon and polyester filament yarns on heat setting in silicone oil
Authors: Venkatesh G. M. , Bose P. J. , Shah Rekha V. , Dweltz N. E. 
Published: April 2003

AbstractNylon 6, nylon 66, and polyester [poly(ethylene terephthalate)] filament yarns were heat set at different temperatures in oil under a variety of experimental conditions. The effect of time of heat setting, tension on the yarn during heat setting, as well as the effect of the initial tenacity and extension on subsequent changes in the mechanical properties of the heat‐set yarns have been studied. The breaking strength, elongation at break, and work of rupture have been found to be different for samples heat set while slack and at constant length. The breaking strength remains more or less constant over a wide range of heat setting temperatures up to 240°C in the case of nylon 66 and polyester, and up to 200°C in the case of nylon 6, contrary to the observations of Dumbleton et al. When treated in the slack condition, the breaking extension increases by about 1–2.5 times the control value, while heat setting at constant length produces a decrease in the case of nylon 66 and a marginal increase in the case of nylon 6 and polyester. The initial modulus decreases irrespective of the conditions under which the filaments are heat set. From measurements of the shrinkage and the residual shrinkage in boiling water it appears that dimensional stability can be achieved by heat setting even at constant length. Heat setting produces significant improvement in the crease recovery and resiliency of the fibers. Heat setting has also been found to significantly increase the overall crystallinity of the fibers as determined by critical dissolution time and parallel and perpendicular refractive indices. The overall orientation of the polymer chains, as determined from sonic velocity measurements, decreases on heat setting in the slack condition. Heat setting at constant length produces a marginal improvement in the overall orientation only in the case of nylon 66 yarns. Shrinkage occurs instantaneously. Crystallinity, on the other hand, improves with increasing time of heat setting.
Rheology of high solid coatings. I. Analysis of sagging and slumping
Authors: Wu Souheng 
Published: April 2003

AbstractThe rheology of sagging and slumping of high solid coatings on vertical surfaces is analyzed in terms of a non‐Newtonian power‐law model. The results indicate that, in order to have good sag control and good sprayability at the same time, high solid coatings should be pseudoplastics with a power constant of about 0.6 and a viscosity at 1 sec‐1 of about 25 poise at the temperature of interest. This theoretical prediction is confirmed experimentally.
Plasma‐deposited polymer films. II. Transmission and scanning electron microscopy
Authors: Havens M. R. , Mayhan K. G. , James W. J. 
Published: April 2003

AbstractA transmission electron microscopy (TEM) and scanning electron microscopy (SEM) study of plasma‐formed polyethylene and polystyrene is reported. A two‐phase structure of spheres embedded in a polymer binder is evident, supporting the predictions of earlier low‐angle x‐ray scattering data taken of these two plasma‐deposited polymers.
Bromostyrene crosslinked polyesters. IV. The effects of the CBr bond strength and of synergists on fire retardancy
Authors: Alsheh D. , Marom G. 
Published: April 2003

AbstractThe present study compares the effect of ortho‐bromostyrene to that of para‐bromostyrene on fire retardancy of polyesters at low and high flame temperatures. It is shown that the first isomer is more effective at the lower temperature and vice versa at the higher temperature. Thermoanalysis results partly explain this difference as well as the effect of additives such as Sb2O3 and bis(2‐chloroethyl) vinylphosphate.
2,2′,6,6′‐Tetrabromo‐3,3′,5,5′‐tetramethyl‐4,4′‐biphenol (TTB)–flame retardant copolycarbonates and copolyesters
Authors: Kinson P. L. , Orlando C. M. 
Published: April 2003

Abstract2,2′,6,6′‐Tetrabromo‐3,3′,5,5′‐tetramethyl‐4,4′‐biphenol (TTB) is a new flame retardant monomer possessing a high degree of chemical and thermal stability. This brominated biphenol can be directly incorporated as a comonomer in condensation polymerizations. An example is the preparation of copolycarbonates of TTB and 2,2‐(4‐hydroxyphenyl)propane (BPA) via the aqueous caustic phosgenation method. The reaction of TTB with either ethylene oxide or ethylene chlorohydrin affords 4,4′‐bis(2‐hydroxyethoxy)‐2,2′,6,6′‐tetrabromo‐3,3′,5,5′‐tetramethylbiphenyl (TTB‐Diol). This diol is melt polymerized into a series of terephthalate copolymers with 1,4 butanediol. The above copolymers possess flame retardancy, thermal stability, and good mechanical properties. These high‐bromine‐content copolymers are blended with nonhalogen‐containing polymers to afford blends with specific degrees of flame resistance.
Phase equilibra of polystyrene/polybutadiene/tetrahydrofuran using gel permeation chromatography
Authors: Narasimhan Venkataraman , Lloyd Douglas R. , Burns Charles M. 
Published: April 2003

AbstractGel permeation chromatography using sequential differential refractive index and ultraviolet detectors has been successfully used to give the compositional analysis of conjugate phases in the incompatible system of polystyrene and polybutadiene with tetrahydrofuran as solvent. Application of this method to equilibrated samples yields tie lines, binodal curves, and plait points. The effects of molecular weights and molecular weight ratios on the slopes of the tie lines, the location of the binodal curve, and the depletion of second polymers from phases are discussed.
Formation of peroxide on aldehyde cellulose and its ability to initiate graft copolymerization
Authors: Ogiwara Yoshitaka , Umasaka Tatsuo , Kubota Hitoshi 
Published: April 2003

AbstractCellulose peroxide formed by the treatment of aldehyde cellulose with hydrogen peroxide (H2O2) was investigated with respect to formation and decomposition conditions and with respect to graft initiation. Periodic acid‐oxidized cellulose was proved to produce the peroxide group on the substrate by subsequent treatment with H2O2, whereas no peroxide was produced with unoxidized cellulose. Since the peroxide content of oxidized cellulose increased with increasing carbonyl content of the sample, the peroxide was presumed to be introduced at the site of the aldehyde group of the sample. The peroxide groups formed were proved to revert to aldehyde groups by decomposition upon heating with water to nearly the same level as the original. The structure of the peroxide group was believed therefore to be an α‐hydroxy hydroperoxide type. The cellulose peroxide was found to initiate graft copolymerization of methyl methacrylate very easily in thermal initiation and photoinitiation systems.
Copolymerization of styrene–m‐divinylbenzene in the presence of poly(vinyl chloride)
Authors: Kagiyama Yasuhiro , Shikata Kazuo , Mizutani Yukio 
Published: April 2003

AbstractThe crosslinking copolymerization of styrene (St)‐m‐divinylbenzene (m‐DVB) in the presence of poly(vinyl chloride) (PVC) was studied. The rate of the copolymerization decreased with the addition of PVC powder, because of the depressing of the diffusion of the monomers to the polymerizing center and the difficulty in the transfer of the polymer radicals in the swelled PVC powder. The exponential value of the benzoyl peroxide concentration and the activation energy of the copolymerization were obtained as 0.67 and 17.4 kcal/mol, respectively. The monomer reactivity ratios of St and m‐DVB were determined as r1 = 0.25 and r2 = 1.42 (M1: St, M2: m‐DVB). From the extraction of the resultant polymer composite with THF, both the grafting of the St‐m‐DVB copolymer onto PVC and the entanglement of PVC with St‐m‐DVB copolymer seems to occur in the St‐m‐DVB‐PVC system.
Novel binary chlorides containing TiCl3 as components of coordination catalysts for ethylene polymerization. I. Synthesis and characterization of the solid solutions obtained
Authors: Greco A. , Perego G. , Cesari M. , Cesca S. 
Published: April 2003

AbstractNew binary chlorides have been obtained by reacting TiCl4 with V(CO)6, Cr(CO)6, Mn2(CO)10, Mn(CO)5Cl, Ni(CO)4, Co2(CO)8, Fe(CO)5, or Mo(CO)6. The reactions yield quantitatively mixed chlorides having the general formula MCln·n TiCl3, where n = 2 or 3 and M is a divalent or trivalent transition metal cation. MCln is generally isomorphous with the α‐ or γ‐modification of TiCl3. X‐Ray and spectroscopic investigations indicate that the mixed chlorides obtained are solid solutions. High surface area values are associated with the adducts displaying lower crystallinity. Catalyst efficiencies two or three times higher than that of AlCl3·3TiCl3 were observed in the low‐pressure polymerization of ethylene (HDPE) when some binary chloride was associated with Al(i‐C4H9)3. These results allow treating the obtained solid solutions as reference systems of high‐yield catalysts for HDPE synthesis.
Composite hollow fiber membranes
Authors: Cabasso Israel , Tamvakis Anthony P. 
Published: April 2003

AbstractComposite polysulfone hollow fibers consisting of a polysulfone porous substrate coated with crosslinked polyethyleneimine (PEI) or furan resin are reported. These composite hollow fibers are analogous to the flat‐sheet composite membranes known as NS‐100 and NS‐200. The surface structure of the porous substrate was rigorously studied before and after coating. Scanning electron microscope observations and reverse osmosis transport studies showed that the support fiber must have surface pore diameters of less than 0.2 μm to obtain a durable composite hollow fiber membrane. The curing process would normally follow in situ condensation of the PEI or the cationic polymerization of the furfuryl alcohol. However, since both the dense layer and surface of the porous substrate contract when exposed to the curing temperature (110–150°C), it was found to be profitable to cure the hollow fiber before applying the coating. When tested in a reverse osmosis rig, PEI/TDI‐coated polysulfone hollow fiber bundles displayed 98% salt rejection and a flux of 5–7 gfd for a feed solution of 10,000 ppm NaCl at a hydraulic pressure of 400 psi. A new method of depositing furan resin on the polysulfone hollow fiber is described. The furfuryl alcohol is instantaneously polymerized by exposing the alcohol‐soaked fiber to a 60% solution of concentrated sulfuric acid. It has been demonstrated that in such a polymerization procedure a dense, semipermeable layer is formed on top of the porous substrate; the resulting composite hollow fiber membrane yields salt rejections higher than 98% when tested under the above reverse osmosis conditions.
Aspects of the thermal and dynamic mechanical behavior of EPDM rubbers
Authors: Byrne L. F. , Hourston D. J. 
Published: April 2003

AbstractThe influence of both ethylene content and the degree of crystallinity on the thermal and dynamic mechanical properties of certain commercial EPDM rubbers were investigated using the TMA, DSC, and Rheovibron techniques. The six materials chosen for this study were Nordel 1560, Intolan 260, Royalene 1812, Vistolan 3708, Intolan 255, and Keltan 778.