bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rubber elasticity of poly(n‐butyl acrylate) networks formed with multifunctional crosslinkers
Authors: Yeo J. K. , Sperling L. H. , Thomas D. A. 
Published: April 2003

AbstractThe rubber elasticity characteristics of poly(n‐butyl acrylate) networks crosslinked with tetrafunctional (EGDM and TEGDM), hexafunctional (TMPTM), and octafunctional (PETMA) vinyl crosslinkers were investigated. Both gel—sol analyses and crosslinking efficiency theories were used to evaluate the chemical crosslink contribution vc and the entanglement contribution vp to the elastically effective network chains ve, and the effect of the crosslink junction functionality f on the front factor g. The front factors obtained were in the range of 0.50–0.92, depending upon the network system and the counting method for vc. The relationship of g = [(f − 2)/f]/〈r2〉/〈r2〉o seems reasonable in the case of the tetrafunctional and hexafunctional networks, but deviates in the case of the octafunctional network. It is also evident that the functionality scheme for the front factor could only be valid under the postulate of a high vp, which increases with increasing vc, especially in the high vc region near the Gaussian limit. The average energetic contribution to the retractive force of the present systems, expressed as Fe/F, is −0.30 ± 0.1.
Novel oxidatively drying urea resin. I. Drying properties of urea resins prepared from N,N′‐bis(methoxymethyl) urea and alcohols containing allyl ether groups
Authors: Toivonen Hannu 
Published: April 2003

AbstractA new type of urea resin prepared by copolycondensating N,N′‐bis(methoxymethyl) urea with an alcohol containing allyl ether groups have been studied and found to have adequate drying properties when used for surface coating purposes. The drying behavior of the resins can be controlled by conventional drier metals, cobalt being an efficient catalyst. Calcium was found to have a synergetic effect with cobalt on drying, zinc and lead had no synergetic effect, and manganese and sodium hydroxide acted as drying inhibitors. Increasing the amount of allylic alcohol in the monomer mixture and higher molecular weight led to the formation of a faster drying resin. The molecular weight distribution of the resins was found to have an effect on the surface coating properties. It was found that for resins having an equal drying rate those with a broader molecular weight distribution had higher solution viscosities. Resins with a narrow molecular weight distribution were also found to be advantageous when formulating coating compositions containing a minimum concentration of solvents.
Semicontinuous emulsion copolymerization of ethyl acrylate and butyl acrylate at high conversions
Authors: Šňupárek Jaromír , Kašpar Karel 
Published: April 2003

AbstractSemicontinuous emulsion copolymerization of ethyl acrylate and butyl acrylate was studied at conversions higher than 0.9. It was found that, in the cases in which the mole fraction of ethyl acrylate in the reaction mixture was over 0.65, the copolymerization diagram differs from the one given by the reactivity ratios. It was suggested that this deviation was caused by the diffusion control of the process. This suggestion was also supported by the differences in the free‐monomer composition of the systems with and without seed latex, respectively, at the beginning of the copolymerization.
Study of the thermal degradation of acrylic copolymers
Authors: Tomescu Margareta , Demetrescu Ioana , Segal E. 
Published: April 2003

AbstractThe thermal degradation of the following copolymers prepared by radical polymerization: acrylonitrile–butyl acrylate–vinylidene chloride, acrylonitrile–butyl acrylate–vinylidene chloride–styrene, and acrylonitrile–methacrylic acid–vinylidene chloride–styrene was investigated. The techniques of thermogravimetry and differential thermal analysis were used. The IR spectra of degradated copolymers are discussed.
Transport from an aqueous phase through cellulosic gels and membranes
Authors: Brown Wyn , Johnsen Robert M. 
Published: April 2003

AbstractDiffusion of some homologous series of solutes [polyhydric alcohols, oligosaccharides, poly(ethylene oxide) polymers] has been studied in cellulose gels (<20% w/w) and membranes (<60% w/w) and the same materials when acetylated. It was found that (1) The molecular weight dependence of D approximates that for the solutes in water alone; the activation energies are also identical to the value for diffusion in pure solvent. (2) The presence of the cellulose chains reduces the rate of diffusion to a degree which is approximately given by the Mackie—Meares equation. (3) Exclusion is pronounced, particularly with the acetylated membranes, and gives a high degree of molecular size discrimination by a sieving mechanism. The membranes have a very narrow range of “pore” sizes, whereas the gels have a contrastingly broad distribution.
Anodic synthesis of polyaniline coatings onto fe sheets
Authors: Mengoli Giuliano , Munari Maria Teresa , Bianco Paolo , Musiani Marco M. 
Published: April 2003

AbstractAniline Black coatings were obtained on Fe anodes by electrolyzing a basic solution of aniline in a water—methanol medium. Allylamine (an inhibitor of Fe corrosion), although not essential to the process, imparts better efficiency to it. The deposited polymers contain 15–20% azobenzene and exhibit semiconductor properties. The three nitroaniline isomers need a more efficient corrosion‐inhibition system. They may be polymerized to adherent films in the presence of both allylamine and K2CrO4.
Effects of polydispersity on critical concentration of polymer solutions
Authors: Chee K. K. 
Published: April 2003

AbstractA semiempirical equation is developed to compute the unperturbed parameter from the critical concentration of polymer solutions derived from the viscometric and kinetic data. This equation gives satisfactory results for various vinyl polymers including poly(vinyl chloride), polystyrene and poly(methyl methacrylate) among others that follow the Schulz molecular weight distribution function. It is found that the segments of a Gaussian polymer chain are associated with an equal number of foreign segments near its center of mass, when the polymer solution has attained a uniform segment density at the critical concentration. The effect of molecular weight distribution on the present studies is significantly large that it merits an empirical treatment. Defects of the model is also discussed.
Chain extension of partially neutralized carboxyl‐terminated liquid polybutadiene with bisepoxide
Authors: Matsuda Hideaki 
Published: April 2003

AbstractChain extension of partially neutralized carboxyl‐terminated liquid polybutadiene (PB) with bisepoxide was investigated by the carboxyl–epoxide reaction. The partially neutralized liquid PB were prepared, by the partial neutralization with MgO and CaO, from a carboxyl‐terminated liquid PB (Hycar CTB 2000X162). As the bisepoxide, hydroquinone diglycidyl ether was used. The metal carboxylate groups in the system catalyzed the reaction and, further, the Mg carboxylate group showed higher catalytic activity than the Ca carboxylate group. The chain‐extended metal‐containing PB obtained by the reaction were found to be elastic when subjected to a rapid impact, but plastic under slowly applied stress and their solution behavior in pyridine was examined. The viscosities were very low at very low concentrations but increased markedly as the concentration increased. This solution behavior is attributed to ionic associations of carboxylate anions and metal cations to longer chains. Further, thermal and other properties were evaluated.
Vapor phase dyeing of synthetic fibers with disperse dyes
Authors: Bendak A. , Abdou L. A. , El‐Kashouti M. 
Published: April 2003

AbstractDyeing of synthetic fibers by the heat transfer process of disperse dye vapors is performed by contacting white receptor polyester or polyamide fabric with other dyed polyester fabrics (donor) under the influence of heat. The dye vapours flowing away will diffuse across the very slight air gap enclosed between the inner donor and receptor surfaces under the applied pressure. It is found that the dye uptake by the receptor fabric is dependent on the original dye content of the donor fabric, transfer temperature and dwell time. The released dye from the donor fabric under the influence of heating is found to be dependent on the original dye content of the donor fabric as well as the transfer temperature. The efficiency of the dye transfer is also attributed to the original shading of the donor fabric. Evaluation of the imparted colors on the receptor fabric (polyester, polyamide) obtained by heat contact with the same donor fabric showed visually the same colour level up to the 13th run. Thermodynamic interpretation of the standard affinity (Δu0) and heat of dyeing (ΔH0) as well as the partition coefficient of the dye show that the dyeing process has an exothermic character. The rate controlling step in this dyeing process is found to be dependent on the diffusion of the dye vapors into the fiber phase.
Graft polymerization of acrylic acid onto polyethylene film by preirradiation method. I. Effects of preirradiation dose, monomer concentration, reaction temperature, and film thickness
Authors: Ishigaki Isao , Sugo Takanobu , Senoo Keiji , Okada Toshio , Okamoto Jiro , Machi Sueo 
Published: April 2003

AbstractLow‐and high‐density polyethylenes were irradiated by electron beams with dose of 2–50 Mrad and then immersed in aqueous solution of acrylic acid (monomer concentration from 30 to 100 wt %) for 10 min−5 h at a temperature of 25–40°C. The degree of grafting increases with time and levels off. High density polyethylene shows lower grafting rate and higher final % grafting in compared with low‐density polyethylene. Both grafting rate and final % grafting increase with total dose of preirradiation, but show some saturation at high doses. The highest grafting rate was observed at 60 wt % of monomer concentration where the grafted polyethylene swells to the largest extent in the monomer mixture. Apparent activation energies for the grafting are 19.6 and 27.3 kcal/mol for low‐ and high‐density polyethylenes, respectively, reflecting the proces of monomer diffusion in the film. Grafting rate decreases with increasing film thickness. Graft polymerization starts on the surface of the film and proceeds to the inner part with monomer diffusion through the grafted layer.
Effects of foaming variables on density and morphology of expanded ethylene–propylene terpolymers
Authors: Wang C. S. 
Published: April 2003

AbstractAn experimental study of the relationships between foaming variables and foamed structures of expanded ethylene–propylene terpolymer (EPDM) is reported. The study was carried out using EPDM composition containing azobisformamide blowing agent. The compositions were expanded and cured in hot air into a foamed structure consisting of dense skin and foamed core. The results showed that the foam density, skin thickness, average cell size, and number of cells of the expanded rubbers can be controlled closely by the foaming variables such as residence time, foaming temperature, and blowing agent concentration.
Rheological properties of liquid crystalline copolyesters
Authors: Prasadarao M. , Pearce E. M. , Han C. D. 
Published: April 2003

AbstractCopolyesters were synthesized by modifying poly(ethylene terephthalate) (PET) withp‐acetoxybenzoic acid (PAB) and hydroquinone diacetate/tetrasubstituted (tetramethyl, tetrachloro, and tetabromo) terephthalic acid (HQTS). It was found that the copolyesters containing 33 mol% or higher concentrations of (PAB+HQTS) from mesomorphic liquid crystalline structures. Rheological properties of copolyesters formed of PET, modified with PAB and hydroquinone diacetate/tetramethyl terephthalic acid (HQTM), were measured using a cone‐and‐plate rheometer. It was found that the copolyesters in the mesomorphic state exhibit yield values at a low shear rate (or at a low shear stress), and negative values of first normal stress difference were observed for certain compositions of (PAB+HQTM), over the range of shear rates (or shear stresses) tested.
Resistance of a polyetherimide to environmental stress crazing and cracking
Authors: White S. A. , Weissman S. R. , Kambour R. P. 
Published: April 2003

AbstractThe environmental stress crazing and cracking (ESC) behavior of an aromatic polyetherimide (PEI) has been characterized in a wide spectrum of organic liquids and compared to the behavior of several other glassy thermoplastics. PEI's response is qualitatively similar to that of the other resins for each of which ESC resistance reaches a minimum in solvents having solubility parameters close to that of the resin. Taken as a whole, the ESC resistance of PEI is found to be quantitatively superior to that of any other glassy resin for which similar data are available for comparison.
Water‐soluble copolymers. V. Compositional determination of random copolymers of acrylamide with sulfonated comonomers by infrared spectroscopy and C13 nuclear magnetic resonance
Authors: McCormick Charles L. , Chen Gow‐Sheng , Hutchinson Brewer H. 
Published: April 2003

AbstractCompositional analyses of random copolymers of acrylamide with sodium‐2‐sulfoethyl methacrylate and with sodium‐2‐acrylamido‐2‐methylpropane sulfonate have been performed utilizing elemental analysis, infrared spectroscopy, and C13 NMR. A mathematical method involving nitrogen to sulfur ratios has been developed to eliminate errors which often arise from associated water in hydrophilic copolymers. The ratios of infrared absorbances at 1043 cm−1 and 1664 cm−1 were used to determine the composition of AM—NaAMPS copolymers; likewise, absorbance ratios at 1040 cm−1 and 3200 cm−1 were utilized for determination of the AM—NaSEM copolymer composition. Carbon‐13 NMR spectra of the copolymers were also obtained, and characteristic peaks were utilized to quantitate copolyer composition. The results obtained by elemental analyses, infrared spectroscopic studies, and NMR were in excellent agreement. These techniques are of great value for determining composition of hygroscopic copolymers which can crosslink or form strong intramolecular hydrogen bonds, often precluding further characterization.
Polymorphism and orientation development in melt spinning, drawing, and annealing of nylon‐6 filaments
Authors: Gianchandani J. , Spruiell J. E. , Clark E. S. 
Published: April 2003

AbstractA new method has been developed for determining the total crystallinity and relative amounts of α‐ and γ‐phases in nylon‐6 samples. The procedure is based on a combination of X‐ray and density data and does not require complicated analytical procedures to separate overlapping reflections. The technique has been applied to study the structural changes accompanying the melt spinning, annealing, and drawing of nylon‐6 filaments. Higher spin draw ratios result in higher crystallinity, greater relative amounts of γ‐phase, and higher orientation. Annealing up to 2 h in boiling water or a 20% aqueous formic acid solution decreases the γ‐phase content, increases the α‐phase content and total crystallinity, but does not eliminate all of the γ‐phase in samples spun with high spin draw ratios. Annealing in vacuum also increases the α‐phase content when annealing is carried out at temperatures above 120°C, but there is little effect below this temperature. Drawing of as‐spun and conditioned filaments at 90°C also increases the α‐phase content and decreases the γ‐phase content. The total crystalline content increases with draw ratio for samples with low spin draw ratios, but drawing has little effect on the total crystalline content of samples spun with higher spin draw ratios. Drawing also results in substantial increases in orientation, especially for samples spun with low spin draw ratios. The effects of these changes in structure on the mechanical properties are also described.
A comparative study of stress‐induced crystallization of guayule, hevea, and synthetic polyisoprenes
Authors: Shimomura Yasushi , White James L. , Spruiell Joseph E. 
Published: April 2003

AbstractA comparative study of the stress induced crystallization of natural (Hevea, Guayule) and synthetic high cis‐1,4‐polyisoprenes at room temperature is presented. Hevea and Guayule are both found using WAXS to crystallize into the unit cell of Morss and Bunn previously described for Hevea. DSC studies of polyisoprenes held at −25°C indicate that Hevea and Guayule crystallize more rapidly than synthetics. Studies of relative birefringence and stress decay following uniaxial extension confirm this. Under conditions of comparison at the same stress, raw Hevea crystallizes more rapidly than extracted Hevea, Guayule, and the other polyisoprenes.
Vinyl graft polymerization‐induced modification of some properties of poly(ethylene terephthalate) fabric
Authors: Hebeish A. , Shalaby S. E. , Bayazeed A. M. 
Published: April 2003

AbstractPolymerization of glycidyl methacrylate (GMA), methyl methacrylate (MMA), and acrylic acid (AA)/styrene (St) mixtures with poly(ethylene terephthalate) (PET) fabric to different polymer add‐ons was performed. Moisture regain, dyeability, and soiling properties of the modified PET were examined. It was found that introduction of poly(GMA) in PET structure brings about (a) improved moisture regain, (b) enhanced dyeing with disperse dyes, (c) affinity and possible dyeing with acid, direct, and reactive dyes, (d) improved aqueous and nonaqueous oily soil resistance, and (e) decreased ease of soil removal. The magnitude of moisture regain, dyeability, and soiling properties are dependent upon the percent of polymer add‐on. Polymerization of MMA with PET improved the dyeability of the latter with the disperse dye as well as its resistance to nonaqueous oily soil while decreasing the resistance to aqueous soiling and ease of both aqueous and nonaqueous soil removal. In the case of PET polymerized with poly(AA/St), there was a considerable enhancement in moisture regain, dyeing with the disperse dye, and resistance to aqueous and non‐aqueous oily soiling. On the other hand, both aqueous and nonaqueous soil characteristics of PET were imparted by polymerization of the latter with AA/St mixtures.
Craze initiation and growth in high‐impact polystyrene
Authors: Donald Athene M. , Kramer Edward J. 
Published: April 2003

AbstractQuantitative transmission electron microscopy and optical microscopy is used to study craze initiation and growth in thin films of high‐impact polystyrene (HIPS). Dilution of the HIPS with unmodified polystyrene reduces the craze–craze interactions, permitting equilibrium growth and craze micromechanics to be studied. It is found that the equilibrium craze length depends on the size of the nucleating rubber particle, but not the internal structure; no short crazes less than a particle diameter are observed. The long crazes can be adequately modelled by the Dugdale model for crazes grown from crack tips. The effects of particle size and particle internal occlusion structure on craze nucleation have been separated. Craze nucleation is only slightly enhanced at highly occluded particles relative to craze nucleation at solid rubber particles of the same size. There is a strong size effect, however, which is independent of particle internal structure. Crazes are rarely nucleated from particles smaller than ∼1 μm in diameter, even though these make up about half the total number. These craze nucleation and growth effects may be understood in terms of two hypotheses for craze nucleation: (1) the initial elastic stress enhancement at the rubber particle must exceed the stress concentration at a static craze tip and (2) the region of this enhanced stress must extend at least three fibril spacings from the particle into the glassy matrix. Since the spatial extent of the stress enhancement scales with the particle diameter, the second hypothesis accounts in a natural way for the inability of small rubber particles to nucleate crazes.
Light scattering from polyethylene solutions
Authors: Stejskal Jaroslav , Horska Jitka , Kratochvíl Pavel 
Published: April 2003

AbstractThe technique of measurement of light scattering from dilute polyethylene (PE) solutions is reviewed. Conditions are discussed under which various PE samples can be characterized. The choice of the solvent affects the accuracy of molecular weight determination. It appears that measurement with thermodynamically poorer solvents yields results subjected to a smaller error. The interpretation of light scattering data is often disturbed by the presence of supermolecular structures in PE solutions. The effect of reprecipitation on the behavior of PE samples is described. The measurements were mostly performed on PE standards and on the Czechoslovak sample Liten Macro.
Melting and crystallization behavior of miscible copolyester–polycarbonate blends
Authors: Barnum R. S. , Barlow J. W. , Paul D. R. 
Published: April 2003

AbstractThe melting and crystallization behavior of Kodar, a copolyester formed from 1,4‐cyclohexanedimethanol and a mixture of terephthalic and isophthalic acids, and its miscible blends with polycarbonate was examined. The results of the melting behavior are discussed in terms of crystallization‐induced chemical rearrangements and the copolymeric character of Kodar and interchange reactions between components when polycarbonate is present in the blend. For various reasons, the melting behavior cannot be extrapolated to infinite crystal size using the Hoffman–Weeks approach. Crystallization kinetics follows the Avrami equation, with rates being higher when the crystallization temperatuare is approached from the glass rather than from the melt. The kinetic data are discussed in terms of modern theories. An approximate melting point depression analysis is used to estimate the interaction parameter for the blend, and the result obtained is compared to a value from another technique.
Effects of water on starch‐g‐polystyrene and starch‐g‐poly(methyl acrylate) extrudates
Authors: Henderson Alex M. , Rudin Alfred 
Published: April 2003

AbstractPolystyrene and poly(methyl acrylate) were grafted onto wheat starch by gamma radiation and chemical initiation, respectively. The respective percent add‐on values were 46 and 45;68% of the polystyrene formed was grafted to starch, and the corresponding proportion of poly(methyl acrylate) was 41%. The molecular weight distributions of the homopolymer and graft portions were characterized, and extrusion conditions were established for production of ribbon samples of starch‐g‐PS and starch‐g‐PMA. Both copolymer types were considerably weakened by soaking in water, and this effect was more immediate and drastic for starch‐g‐poly(methyl acrylate). Both graft copolymers regained their original tensile strengths on drying, but the poly(methyl acrylate) specimens did not recover their original unswollen dimensions and retained high breaking elongations characteristic of soaked specimens. Tensile and dynamic mechanical properties of extruded and molded samples of both graft polymers are reported, and the plasticizing effects of water are summarized.