bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma polymerized protective films for plated magnetic disks
Authors: Harada Katsuhiro 
Published: April 2003

AbstractPlasma polymerized protective films (PPP films) for magnetic disks have been investigated in order to improve weak durability of plated disk media to head friction and clash. The thickness heterogeneity of PPP films within 5% was realized around the all surface of 140 mmϕ model substrates, determining the best discharge condition and apparatus geometry, which did not exert and aggravating influence upon head floating. The friction coefficients of PPP films to a ferrite slider of 0.3 ∼ 0.4 were obtained in the thickness of above near 1500 Å, although PPP films are composed of hydrocarbon or fluorocarbon. As the results of contact start/stop cycle tests by a floating head, plasma polymerized toluene‐2,4‐diisocyanate films show good abrasive durability because of its superior adhesiveness to metal substrates, and PPP films in small thickness near 1000 Å give good protective films. The result of read/write tests indicated that the magnetic deterioration and instability of plated disk media did not occur by the process of plasma polymerization.
Stochastic modeling of polymerization in a continuous flow reactor
Authors: Nassar R. , Too J. R. , Fan L. T. 
Published: April 2003

AbstractA stochastic approach, namely, a continuous time Markov chain (Markov process), is employed to analyze and model, in a unified fashion, both polymerization and dispersive mixing in a continuous flow reactor. Results include the distribution of numbers of active and dead polymers with chain length j both inside the reactor and at the exit. This approach can be extended to the determination of the degree of polymerization of a copolymer. Expressions are derived for the mean and variance of the number of monomers of a given type in a copolymer chain. The model can be applied to both the time homogeneous and heterogeneous processes.
Effect of fillers on the viscoelastic behavior of rubbers
Authors: Stenberg B. , Jansson J. F. 
Published: April 2003

AbstractThe different reinforcing effects of carbon blacks are determined by measurements of the linear and nonlinear viscoelastic behavior of natural rubber samples subjected to prestrains at different levels. The transition from linear to nonlinear viscoelastic behavior occurs at lower strains as the carbon black content is increased. At a given filler concentration, the limiting strain is highest for the most reinforcing carbon black. Prestraining increases the limiting strain. The reinforcing effect of carbon black can be estimated by determining the extent to which prestraining influences the linear viscoelastic properties of vulcanizates.
Grafting onto wool. XI. Graft copolymerization of poly(vinyl acetate) and poly(methyl acrylate) onto reduced wool in presence of potassium persulfate–ferrous ammonium sulfate (KPS—FAS) system as redox initiator
Authors: Misra B. N. , Dogra R. , Mehta I. K. , Gill Kiran Dip 
Published: April 2003

AbstractIn an attempt to ascertain the role of—SH groups of Himachali wool during graft copolymerization, poly(viny acetate) (PVAc) and poly(methyl acrylate) (PMA) were graft copolymerized onto reduced wool by using potassium persulfate—ferrous ammonium sulfate (KPS—FAS) redox pair in aqueous medium. Reduction of wool was carried out by sodium bisulfite solution of varying concentrations for different reaction periods. Concentration of reducing agent and the extent of reduction were found to influence grafting of vinyl monomers. Maximum grafting of methyl acrylate (MA) and vinyl acetate (VAc) occurred when wool was reduced by 1% and 0.5% NaHSO3 solution, respectively, for 24 h. Increase in percent grafting of MA onto reduced wool compared to that of unreduced wool has been ascribed to the production of more—SH groups by reduction of—SS—groups of wool fiber.
Trimethylsilyl cellulose as precursor to regenerated cellulose fiber
Authors: Cooper Geoffrey K. , Sandberg Karen R. , Hinck John F. 
Published: April 2003

AbstractTrimethylsilyl cellulose (TMSC) has been found to melt at 320–340°C in the absence of oxygen. When TMSC is prepared from chemical cellulose, using hexamethyldisilazane and a catalytic amount of chlorotrimethylsilane/pyridine in dimethylformamide, a thermoplastic material is obtained which may be melt spun into a fiber. This fiber, when treated with mild aqueous acid, yields regenerated cellulose plus hexamethyldisiloxane. The hexamethyldisiloxane can be converted back to hexamethyldisilazane by known chemistry. The fiber properties of the regenerated cellulose were found to be comparable to commercially available rayons. X‐Ray diffraction analyses of the cellulose suggest formation of an unusual polymorphic form.
Fluoroalkylene ether silicate/Viton GLT blends: An approach toward improved low temperature flexibility
Authors: Shaffer A. A. , Cochoy R. E. 
Published: April 2003

AbstractLow molecular weight fluoroalkylene ether silicate (FES) polymers demonstrating glass transition temperatures of −82°C to −91°C were obtained from the condensation polymerization of fluoroether bisdimethyl carbinols and bis(dimethylamino)methyl vinyl and dimethyl silane derivatives. Peroxide cure reactivity through the pendant vinyl moieties was demonstrated. In an effort to improve the low temperature flexibility of a peroxide curable fluorocarbon elastomer (Viton GLT from Du‐Pont), blends were prepared using the FES material as an additive cocuring plasticizer. Temperature retraction tests demonstrated an optimum 5°C (9°F) improvement in low temperature flexibility. The optimum blend formulation employed FES polymers with vinyl cure site concentrations ranging from 2.35 to 2.70 mol %. The optimum blend formulation maintained the strength and low compression set properties of the Viton GLT standard. These properties reflect sufficient cocuring between the FES and Viton GLT components to provide physical properties adequate for o‐ring seal application. o‐Ring seal evaluations in Freon E6.5 fluid (rod and piston seal tests) demonstrated some seal enhancement and comparable durability to standard Viton GLT o‐rings.
Structure‐property relations of carboxylated nitrile rubber
Authors: Chakraborty S. K. , Bhowmick A. K. , De S. K. 
Published: April 2003

AbstractThe technical properties and the network structure of carboxylated nitrile rubber (XNBR) having a mixed crosslink system of sulfur and metal carboxylate have been studied. XNBR of different carboxyl contents (Krynac 221, Krynac 110C), yielding different concentrations of ionic crosslinks, have been used for this purpose. The amount of ionic crosslinks was also varied by varying the amount of crosslinking agent (zinc peroxide). It has been observed that ionic crosslinks impart high tensile strength, permanent set, and hardness, while sulfur crosslinks introduce high flex crack resistance, elongation at break, and tear strength in the vulcanizate. Heat buildup and resilience could be explained with the help of stress relaxation experiments. Stress decay is more when the amount of ionic crosslinks is higher. Higher stress relaxation gives higher hysteresis. The kinetics of the crosslinking of a mixed crosslink system has also been studied. At overcure times the amount of ionic crosslinks is greater than that of sulfur crosslinks which desulfurizes in this region. The technical properties could be explained on this basis.
Viscoelastic breakup in a high velocity airstream
Authors: Matta J. E. , Tytus R. P. 
Published: April 2003

AbstractViscoelastic fluids were injected into a high velocity airstream (200 m/s) to investigate how the addition of small polymer quantities to fluids significantly increase the resultant disseminated drop size. For each liquid tested several hundred resultant drops were sampled and measured using an automated image analyzer. The resultant mass median diameter (MMD) for a viscoelastic fluid was an order of magnitude larger than a comparable viscous Newtonian fluid. A relaxation time measured from a die swell experiment correlates the dissemination results suggesting, an elongational rather than shear breakup mechanism.
Photoinduced acrylamide graft polymerization onto extended hard elastic polypropylene
Authors: Nito Keiichi , Suzuki Shin‐Ichi , Miyasaka Keizo , Ishikawa Kinzo 
Published: April 2003

AbstractHard elastic PP films were graft polymerized with PAAm, using a photoinduction method derived by Tazuke. The graft yield (GY) was measured as a function of extension applied to the PP film during the polymerization. The GY increased stepwise when the extension increased above the yield point. This remarkable increase in GY is due to the fact that the surface of voids created by extension are involved in the graft polymerization. The GY obtained under extensions larger than the yield point was much larger than that ever achieved for the usual PP films. The residual strain after the graft polymerization increased with increase in GY, and the relationship between them changed at about 40% GY, suggesting that some change occurred in the location of grafted PAAm in PP films. The graft ratio, determined after complete extraction of PP and PAAm homopolymers, remained nearly constant with polymerization time, except at the early stage of the polymerization. The effect of extension on the graft ratio implied that the size of the voids may affect the degree of polymerization of graft PAAm when the size is comparatively small.
Further studies on cellulose III polymorphs. Transformations to cellulose IV lattices and subsequent reactions
Authors: Chidambareswaran P. K. , Sreenivasan S. , Patil N. B. , Lokhande H. T. 
Published: April 2003

AbstractProduction of cellulose IV polymorphs, their characterization using X‐ray diffraction and infrared spectroscopy, as well as the effect of chemical treatments on these polymorphs have been investigated. Cellulose IIII and IIIII polymorphs, produced from celluloses I and II using EDA—MeOH treatments, were of particular interest as starting materials in the study. Celluloses IVI and IVII gave identical equatorial X‐ray patterns in the absence of other crystal lattices in the samples. Crystallinity as well as conformation were indicated to influence production and further reactions of the samples. The latter included boiling in water, acid hydrolysis, and treatments with EDA—water, EDA—MeOH, and NaOH solutions. Cellulose IVI → I, IVI → I → II, and cellulose IVII → II lattice conversions were demonstrated to occur with EDA—water treatments, thereby providing a new technique for observing these transformations. Conformational differences were apparent among celluloses I, II, IIII, and IIIII, each produced using different experimental procedures.
The effects of orientation and crystallinity on the solvent‐induced crystallization of poly(ethylene terephthalate). II. Physical structure and morphology
Authors: Jameel Hasan , Noether Herman D. , Rebenfeld Ludwig 
Published: April 2003

AbstractThis series of papers summarizes the results of an experimental research program designed to establish the effects of preexisting orientation and crystallinity on the solvent‐induced crystallization of poly(ethylene terephthalate) films. Dimethylformamide was used as a model for a strongly interacting solvent. This paper deals with the morphological and structural modifications induced by the solvent crystallization process. The effects on the structure and morphology of the solvent crystallization were dominated by surface cavitation, creation of voids, and by changes in the degree of crystallinity. The surface structure varied from a spherulitic cavitated structure for films of low orientations (low draw ratios) to a smooth surface at the higher draw ratios. In addition to the change in the surface morphology, an internal void structure was formed due to crystallization taking place in a swollen state. The formation of voids is dependent on the treatment temperature, draw ratio, and the method of solvent removal. The voids collapse upon annealing at high temperatures. Increases in the degree of crystallinity and changes in orientation were dependent on the treatment temperature. The crystallite size goes through a maximum at an intermediate degree of orientation. The crystalline orientation decreases with increasing treatment temperature. The structures formed during solvent treatments did not show any characteristic premelting endotherms at the low draw ratios. In the case of higher draw ratios, a small premelting endotherm was noticeable at a temperature 70°C greater than that of the solvent treatment.
Miscible binary blends containing the polyhydroxy ether of bisphenol‐a and various aliphatic polyesters
Authors: Harris J. E. , Goh S. H. , Paul D. R. , Barlow J. W. 
Published: April 2003

AbstractBlends of the polyhydroxy ether of bisphenol‐A, Phenoxy, with the polyesters poly(1,4‐butylene adipate), poly(ethylene adipate), poly(2,2‐dimethyl‐1,3‐propylene succinate), poly(2,2‐dimethyl‐1, 3‐propylene adipate), poly(1,4‐cyclohexane‐dimethanol succinate), and poly(ϵ‐caprolactone), are found to exhibit the single, composition‐dependent glass transition temperatures characteristic of miscible systems. Phenoxy blends containing poly(ethylene succinate), poly(hexamethylene succinate), or poly(pivaloactone) were found to be immiscible. Blend interaction parameters, obtained from analysis of the melting‐point depressions observed for miscible blends containing crystallizable polyester components, are found to vary with polyester chemical structure so as to suggest an optimum density of ester groups in the polyester chain for achieving maximum interaction with Phenoxy. Too many or too few ester groups lead to immiscible polyester–Phenoxy blends.
Plastic zones at the tips of inclined cracks in glassy polymers under small scale yielding
Authors: Gdoutos E. E. 
Published: April 2003

AbstractA thorough study of the shape and size of plastic zones developed around cracks subjected to combined opening‐mode and sliding‐mode loading conditions in glassy polymers under small scale yielding was undertaken. Two pressure‐modified von Mises yield criteria which take into account the characteristic behavior of glassy polymers expressed by the dependence of their yield locus on the hydrostatic stress component and the difference in their tensile and compressive yield stresses were used. The case of an infinite plate subjected to a uniaxial uniform stress at an arbitrary inclination with respect to the axis of the crack was considered. From the whole study useful results concerning the dependence of the shape and size of plastic zones on the crack inclination angle, the Poisson's ratio, and the ratio of the compressive to tensile yield stress of the plate were derived.
A study of poly(p‐xylylene)‐coated AsF5‐doped polyacetylene
Authors: Osterholm J. E. , Yasuda H. K. , Levenson L. L. 
Published: April 2003

AbstractElectrical conductivity measurements and scanning electron microscopy have been used to study uncoated and poly(p‐xylylene)‐coated samples of polyacetylene doped with AsF5. These initial results indicate a considerable reduction in the decay rate of conductivity in the presence of oxygen as well as a decreased rate of thermal decomposition of the dopant when heated between 50°C and 115°C in vacuum by the coating.
Crosslinking cotton cellulose with aldehydes
Authors: Frick J. G. , Harper Robert J. 
Published: April 2003

AbstractThe relative effectiveness of several aldehydes in crosslinking cellulose of cotton fabric was determined using a pad‐dry‐cure treatment and a treatment by immersion in a solution at room temperature. Aldehydes ranked in the same order of ability to crosslink in both treatments. Factors related to crosslinking ability are discussed. The aldehydes crosslinking to the greater extent hydrated readily in water because the aldehyde group was activated or because cyclic hydrates could be formed.
Grafting of polymeric side chains to gelatin
Authors: Joseph Anne , Radhakrishnan Ganga , Joseph K. T. , Santappa M. 
Published: April 2003

AbstractKinetics of grafting of poly(butyl acrylate) onto gelatin was studied with H2O2—ascorbic acid redox systm. Percent grafting, grafting efficiency, Rg, and Rh were determined as a function of time, temperature, initiator, monomer, and backbone concentration. It was found that Rg depends on first power of monomer concentration and 0.5 power to the initiator concentrations. A detailed kinetic scheme is proposed to explain these results.
The evolution of thermosetting polymers in a conversion–temperature phase diagram
Authors: Adabbo Humberto E. , Williams Roberto J. J. 
Published: April 2003

AbstractA conversion–temperature phase diagram for thermosetting polymers is analyzed. The curing under different external conditions—isothermal, at a constant heating rate, adiabatic, and in a mold at constant wall temperature—is represented by definite trajectories in the phase diagram. Conditions related to incomplete curing or falsification of kinetic parameters are stated.
Effect of heat treatment on the structure and mechanical properties of polyacrylonitrile fibers
Authors: Gupta A. K. , Maiti A. K. 
Published: April 2003

AbstractStrucure and mechanical properties of untreated and thermally treated (at 110°C and 150°C) drawn polyacrylonitrile (PAN) fiber have been studied through IR spectroscopy, wide angle X‐ray diffraction, and tensile and dynamic mechanical properties measurements. The results are interpreted in terms of the change in the degree of bound nitrile group pairs on heat treatment. The heat treatment at both the temperatures resulted in higher degree of bound nitrile groups (through their dipolar interactions) in the heat‐treated PAN than that of the untreated PAN, as evidenced by IR spectroscopy, X‐ray diffraction, and the mechancal properties. The difference between the results for the two heat‐treatment temperatures are not sufficiently large, although the changes produced by heat treatment at 110°C seems somewhat more prominent than those produced by heat treatment at 150°C.
Investigation of the cellulose/LiCl/dimethylacetamide and cellulose/LiCl/N‐methyl‐2‐pyrrolidinone solutions by 13C NMR spectroscopy
Authors: El‐Kafrawy Adel 
Published: April 2003

AbstractThe cellulose/lithium chloride/dimethylacetamide (DMAc) and cellulose/lithium chloride/N‐methyl‐2‐pyrroilidinone (NMP) solutions were investigated by 13C NMR spectroscopy. Well‐resolved spectra were obtained for both solutions and indicated that cellulose was present in these systems in the form of underivatized cellulose. The change in 13C chemical shifts of DMAc and NMP in the presence of LiCl and LiBr was compared with that of several salt/aprotic solvents, and the results point to the existence of a cellulose–LiCl–DMAc (or NMP) complex in which the lithium cation is strongly bound to the amide carbonyl oxygen and the chloride anion involved in the dissociation of the cellulose hydrogen bonds. Spin–lattice relaxation times (T1 of the 13C carbons of the solvent molecules, DMAc and NMP, show a large decrease in T1 for all solvent carbons upon addition of LiCl. Further decrease in T1 is observed when cellulose is introduced to the LiCl/NMP but not to the LiCl/DMAc systems. These observations are attributed to slower molecular motions of DMAc and NMP in the presence of LiCl, and, in the case of NMP, in the presence of cellulose.
The effect of ultraviolet light on the mechanical properties of polyethylene and polypropylene films
Authors: Raab M. , Kotulák L. , Kolařík J. , Pospíšil J. 
Published: April 2003

AbstractMeasurements were made of dynamic mechanical response spectra and stress–strain properties at room temperature on films of isotactic polypropylene and low‐density polyethylene prior and after ultraviolet irradiation in a Xenotest 450 apparatus. The period of irradiation that caused a deep deterioration of ultimate mechanical properties influenced the dynamic mechanical properties only insignificantly. This is attributed to the heterogeneous nature of the photo‐oxidative degradation process which is concentrated in a finite number of sites, thus forming crack precursors rather than changing the material properties in bulk. For a biaxially oriented tubular film of low‐density polyethylene, anisotropic embrittlement after exposure in Xenotest 450 was observed. This even reversed the order of strain‐at‐break values in the two main directions of the film. This is remarkably similar to the effect of artificial incisions introduced into the specimens.
Nylon 6 polymerization in the solid state
Authors: Gaymans Reinoud J. , Amirtharaj John , Kamp Henk 
Published: April 2003

AbstractThe postcondensation of nylon 6 in the solid state was studied. The reactions were carried out on fine powder in a fluidized bed reactor in a stream of dry nitrogen in the temperature range 110–205°C and during 1–24 h. The solid‐state polymerization (SSP) did not follow melt kinetics, but was found to be limited by the diffusion of the autocatalyzing acid chain end group. Factors thought to influence SSP were studied, e.g., heat treatment, starting molecular weight, and remelting. Surprisningly, heat treatment had little effect, but the starting molecular weight had a strong effect on the reaction rate. The higher the starting molecular weight, the faster the reaction. This could be explained as a changing concentration distribution of the reactive groups in the solid state on SSP. The kinetics of the SSP had more than one region, and the rate of reaction for conversions of over 30% could be expressed as − dc/dt = k(c/t), where k is a dimensionless constant independent of temperature with a value of 0.28. The integrated form has the form − In(c/co) = k In(t/τ), where co is the acid end‐group concentration at the start, t is the reaction time, and τ is the induction time. The value of τ is both dependent on the starting concentration co and the reaction temperature and has an activation energy of 105 kJ/mol.
Kinetic aspects of dyeing processes
Authors: Sada Eizo , Kumazawa Hidehiro , Ando Testuo 
Published: April 2003

AbstractThe dyeing of textiles was classified into two main categories: reactive and adsorptive dyeing. A mathematical model for each case was developed on the basis of a pore model concept. The validity of the proposed models was confirmed by comparison with existing experimental data on dyeing of reactive dyes in cellulose and acid dyes in nylon. It was further desired that the proposed models be checked by experimental results in high fixation regimes. The overdyeing phenomenon may be simulated by intrafiber diffusion with simultaneous multimodal adsorption.
Tensile and impact behavior of drawn polystyrene and high‐impact polystyrene
Authors: Yokouchi Mitsuru , Yokota Akitoshi , Kobayashi Yasuji 
Published: April 2003

AbstractThe tensile behaviors of drawn polystyrene (PS) and high‐impact polystyrene (HIPS) were examined systematically in the wide range of strain rate, 1.7 × 10−4–13.1 m/s, without changing the mode of deformation and the shape of the test pieces. It was found for both PS and HIPS that the flexion points of birefringence with increase of draw ratio are intimately correlated with the tensile properties. Especially, the breaking strain and energy of undrawn and drawn HIPS were assigned to the contributions of the following three toughening mechanisms: (a) the generation of large numbers of microcrazes from the equatorial zone of the dispersed rubber particles; (b) the extension of interfacial rubber phase around the circumpolar zone of the dispersed rubber particles and its disintegration from the matrix component; and (c) the shear band formation of the matrix component followed by cold drawing. These mechanisms were discussed in connection with the factors of stress concentration to the rubber particles, hydrostatic pressure effect arising from the difference in Poisson's ratio of rubber and matrix components, and heat generation due to the adiabatic deformation.