bluuebunny/crossref_metadata_2025_split huggingface dataset:
Durability of radiation‐sterilized polymers, XI. The effect of irradiation on rubber gloves
Authors: Kadir Zahrah Abdul , Yoshii F. , Hosoi F. , Makuuchi K. , Ishigaki I. 
Published: April 2003

AbstractThe effect of both gamma ray and electron beam irradiations on three rubber gloves are compared in relation to sterilization. Two of these gloves are sulfur vulcanized and the other is radiation vulcanized. It was found that the radiation‐vulcanized rubber gloves could be used, even at 25 kGy, the sterilization dose used. For all three gloves, it was found that the tensile strength and elongation at break are not significantly affected after irradiation in either gamma rays or electron beam or during storage. The tear strengths, however, decrease with increasing dose and storage, and it was found that degradation was higher in gamma rays than electron beam. The chemiluminescence data show that the rate of degradation is the highest in latex film followed by radiation‐vulcanized and sulfur‐vulcanized gloves.
CP–MAS NMR spectra of polyurethane–lignin blends
Authors: Natansohn A. , Lacasse M. , Banu D. , Feldman D. 
Published: April 2003

AbstractSolid‐state high‐resolution C‐13 NMR spectra of lignin, a polyurethane, and their blend give information about phase structure and interactions in the blend. As the Tg values indicate, this is an incompatible blend, and values of the spin–lattice relaxation times in the rotating frame confirm tthat there are two separate phases in the blend. However, buildup of magnetization wiitthin the two phases clearly indicates some interactions between the phases, which allow transfer of magnetiization from lignin to the polyurethane.
Thermal conductivity of a polymer filled with particles in the wide range from low to super‐high volume content
Authors: Agari Y. , Ueda A. , Tanaka M. , Nagai S. 
Published: April 2003

AbstractPolyethylene and polystyrene composites filled with high‐volume content of filler particles (quartz or Al2O3) were prepared by ordinary melt‐casting method to effectively increase the thermal conductivity. The result, however, suggested that fractional void volume cssentially occupied by filler particles is left unfilled when high or super‐high content of filler is used. After investigating the relation between the mixing ratio of different sized filler particles and the fractional voidage under various compression intensities, a mixture of filler was found to give minimum fractional voidage. Polymers filled with such an optimum mixture of fillers for minimum fractional voidage were then prepared under compression. Thus, expected monotonous increases in thermal conductivity in the wide range from low to super‐high filler content were obtained. Further, it was confirmed that a predictive model proposed by us agreed quite satisfactorily with the experimental data in comparison with many other models.
Solubility and diffusivity of sulfur dioxide in latex paint films
Authors: Hendricks B. J. , Balik C. M. 
Published: April 2003

AbstractSorption of SO2 in latex paint films is measured as a function of time. This data is used to extract the solubility (S) and the diffusion coefficient (D) for SO2 in these films. The solubility of SO2 in each of the samples follows Henry's law behavior. Sorption occurs only in the polymer, with the inorganic pigment particles acting as impenetrable fillers. The diffusion of SO2 is Fickin with an exponential dependence upon the concentration of SO2. This data is used to calculate the permeabilities of the paint samples to SO2, at levels typically found in the atmosphere.
Studies on the role of organophosphites in polyester blends: II. The inhibition of ester‐exchange reactions
Authors: Cheung M.‐F. , Carduner Keith R. , Golovoy A. , Van Oene H. 
Published: April 2003

AbstractEster‐exchange reactions during melt extrusion of polyarylate, polycarbonate, and polyethylene terephthalate ternary blends result in a decrease of the melting point and the heat of fusion of the poly(ethylene terephthalate). When an organophosphite is used to suppress the ester‐exchange reactions, it was found that whenever the phosphite is converted into a phosphonate, there is little change in both the melting point and the heat of fusion of the polyethylene terephthalate during prolonged exposure to high temperature in the blends. 31P nuclear magnetic resonance is employed to investigate the chemical changes and differential scanning calorimetry to evaluate the thermal stability of the blends. The organophosphite appears to be transformed through side‐chain hydrolysis into other phosphorous species, such as diphosphonate in order to be an effective suppressant of the ester‐exchange reactions.
Determination of the entanglement molecular weight of thermoplastic elastomers by tensile retraction measurements
Authors: Hergenrother William L. , Doshak John M. 
Published: April 2003

AbstractThe molecular weight between crosslinks was measured as a function of the maximum extension to which samples of solution cast films of ABA triblocks were tested. These measurements were done by applying the kinetic theory of rubber elasticity to the retraction portion of a tensile hysteresis curve. The molecular weight between chain restrictions, as determined by extrapolation to 0% elongation, was found to be identical to the entanglement molecular weight normally associated with the polybutadiene or polyisoprene that was used for the center block. The disentanglement of the small amount of AB diblock present could also be followed by fitting the data collected to what could be pictured kinetically as a simultaneous first‐and second‐order loss of crosslink density.
Ultrahigh molecular‐weight polyethylene–chalk composites resulting from in situ polymerization
Authors: Gorelik V. M. , Fushman E. A. , Topolkaraev V. A. , Dyachkovsky F. S. , Shestenina L. A. , Borisova L. F. , Sergeev V. I. 
Published: April 2003

AbstractEthylene polymerization on chalk surface under the action of TiCl4–organoaluminium compound systems yields filled composites possessing high stress–strain properties and preserving their ductility up to the chalk content of 60–70 wt %. The kinetics of the process and the properties of the composites have been investigated, as well as the interrelation between catalyst fixation technique, polymerization rate, and the ductile properties of composites containing 50 wt % of chalk. The conditions leading to the formation of “homogeneous” composites with a high ductility are examined. The possible causes of the formation of composites with a low value of elongation at break are analyzed. The principal regularities of the mechanical behavior of composites are considered for the case when the process is taking place on the filler surface and leads to “homogeneous” composites.
The effect of surface treatments on wear of polytetrafluoroethylene
Authors: Deli Gong , Qunji Xue , Hongli Wang 
Published: April 2003

AbstractThis paper reports the effect of surface chlorination, oxidation, and phosphatization of carbon steel, copper, and aluminum, and surface treatment with sodium naphthalenide of PTFE on wear of PTFE. It was found that the wear behavior of untreated PTFE is not affected by surface treatments of metals but treatment of PTFE can reduce its wear by a factor of at least 100. The wear mechanism of PTFE is discussed.
Emulsion copolymers of α‐methylstyrene and styrene
Authors: Branston Randolph E. , Plaumann Heinz P. , Sendorek Jerzy J. 
Published: April 2003

AbstractThe preparation of copolymers of α‐methylstyrene and styrene in an emulsion system is described. At both 40 and 60°C, there was no evidence of deviation from simple kinetics. Polymers of high molecular weight and high and high α‐methylstyrene content showed good thermal properties such as Tg and softening point. However, these polymers proved to be awkward to process due to a strong proclivity to degrade under shearing conditions.
Differential scanning calorimetry cure studies on the effect of addition of epoxy diluents of tetrafunctional epoxy resins
Authors: Jagadeesh K. S. , Siddaramaiah  , Kalpagam V. 
Published: April 2003

AbstractThe effect of the addition of p‐aminophenol and aniline‐based epoxy diluents on the curing behavior of highly viscous tetraglycidyl diamino diphenyl methane resin with diamino diphenyl sulfone hardener have been investigated kinetically by differential scanning calorimetry. Dynamic scans were carried out over a temperature range 30–300°C for different resin formulations. Isothermal scans at four differnt temperatures have also been carried out for the evaluation of kinetic parameters. Heat flow measurements at different heating rates have indicated the evidence of autocatalytic behavior of curing reaction following a simple nth‐order kinetics.
Multiple endotherm melting behavior in relation to the morphology of poly[3,3‐ bis(ethoxymethyl) oxetane]
Authors: Fay J. J. , Murphy C. J. , Sperling L. H. 
Published: April 2003

AbstractTwo crystalline melting peaks have been observed by differential scanning calorimetry for low molecular weight poly[3,3‐bis(ethoxymethyl) oxetane] (polyBEMO) samples, Mn < 1 × 104 g/mol, whereas only one melting peak has been observed for samples of higher molecular weight, Mn < 1 × 104 g/mol. Crystallization of low molecular weight samples at large supercoolings produces the lower melting form while low supercooling or annealing favors the higher melting species. Enthalpy of fusion values obtained by DSC for a multiple melting endotherm sample range from 28 to 39 J/g for crystallization temperatures from 58 to 35°C, respectively. Optical microscopy studies indicate that the lower melting peak corresponds to a spherulitic type morphology and the higher melting peak correlates to a fine grained crystal structure. Wide angle X‐ray powder diffraction studies do not detect differences in the crystal structures of samples exhibiting either one or two melting peaks, which suggests that the multiple melting phenomenon is due to differences in morphology rather than the presence of different crystal forms.
Modeling of polymerization of urea and formaldehyde using functional group approach
Authors: Kumar A. , Sood A. 
Published: April 2003

AbstractThe urea formaldehyde polymerization has been modeled using the functional group approach, which accounts for the formation of higher oligomers. The kinetic model involves four molecular species and three rate constants, as opposed to six as proposed in earlier studies. The experimental data of Price et al. have been curve fitted using our model, which is found to describe them very well in the entire range of temperature and urea formaldehyde ratio. Based on the activation energies, it has been argued that the reverse reaction step must involve the condensation product, water.
Fractionation and characterization of polyacetal copolymers by column elution method
Authors: Ogawa Toshio 
Published: April 2003

AbstractSufficient fractionation was attained for polyacetal copolymers by the column elution method. The characteristics of molecular weight, composition, and sequence length of the original copolymers were evaluated through the analyses of fractions by 1H‐NMR, GPC, and DSC. Comonomer content in polymer fractions decreased with the increase of molecular weight in any samples, and the copolymer prepared by gas‐phase polymerization showed broad compositional distribution as compared with that by solution polymerization.
Rubber‐modified polystyrene from multistage latexes: Rheological and physical properties
Authors: Silverstein M. S. , Narkis M. 
Published: April 2003

AbstractThe combination of rubbery and rigid polymers in a multiphase structure using staged emulsion polymerization has yielded materials with properties ranging from reinforced elastomers to high impact plastics. The many different particle morphologies that result from multistage latexes include core/shell, domain, interpenetrating polymer networks, and various combinations thereof. The present work focuses on rubber modified polystyrene (polyacrylates (PA) and polystyrene (PS) in a 1:3 ratio). The nature of the rubber‐modified polystyrene from multistage latexes has been determined through a combination of microscopy and mechanical property analyses. The uncrosslinked PS shells that form around the crosslinked PA seed particles with grafted PS microdomains coalesce upon molding to form a continous thermoplastic PS matrix that may absorb impact energy through mechanisms of crazing and shear yielding. The crosslinking of the acrylate seed with butadiene enhances PS grafting through residual unsaturation and thus affects the effective particle volume fraction and particle‐matrix interaction in these rubber‐modified PS materials. The substitution of some of the uncrosslinked PS of the second stage with crosslinked PS in a separate intermediate stage, resulting in a three‐stage latex, also affects the effective volume fraction and the particle‐matrix interaction through enhanced PS grafting and the formation of interpenetrating networks. In flow the rubber modified PS exhibits a Newtonian plateau at low shear, unlike crosslinked particles which flow through a particle slippage mechanism, and an unexpected deviation from power law behavior at high shear with a viscosity plateau, or even a slight increase in viscosity. These materials may essentially flow through molecular deformation, depending upon the temperature, molecular weight, particle‐matrix interaction, and level of shear. The rubber‐modified PS from the multistage latexes are a potential high impact material whose unique structure and chemistry distinguish it from commercial high impact PS (HIPS), although its mechanical and impact properties are, at the very least, similar to those of HIPS.
Preparation and characterization of hydroxamic acid derivative and its metal complexes derived from cellulose
Authors: Maekawa Eiichi , Koshijima Tetsuo 
Published: April 2003

AbstractCellulose‐hydroxamic acid derivatives, which were reported as a novel cellulose derivative were prepared from dialdehyde celluloses obtained by periodate oxidation of cellulose, and certain properties of unusual cellulose derivative containing hydroxamic acid groups and of various metal complexes formed with heavy metal ions were characterized in this investigation.
Surface modification by continuous graft copolymerization. I. Photoinitiated graft copolymerization onto polyethylene tape film surface
Authors: Yao Zhang Pei , RÅNby Bengt 
Published: April 2003

AbstractA process has been developed for continuous photoinitiated graft copolymerization of acrylamide (AM) and acrylic acid (AA) onto the surface of high‐density polyethylene (HDPE) tape film, presoaked in a solution containing monomer and initiator under nitrogen atmosphere. As photoinitiator we have used benzophenone, which is efficient for photografting of polyolefins with acrylic monomers. The presoaking procedure of the tape film is very important for efficient photografting within short irradiation times. In ESCA spectra of the grafted tape film the relative intensity of the nitrogen over carbon peaks of film grafted with acrylamide is about 5–10% after 6 s irradiation time. The relative intensity of oxygen over carbon peaks in ESCA spectra of film grafted with acrylic acid is about 10–20% after 8 s irradiation time. The effects of varying the monomer concentration in presoaking solution and the different irradiation conditions on the grafting yield have been investigated. This technique has the advantages of being a continuous process with short irradiation times without requirements of vacuum conditions and appears to be promising for practical applications.
A preliminary correlation between macroscopic and microscopic polymer properties: Dynamic storage modulus vs. CPMAS NMR cross polarization rates
Authors: Parker A. A. , Marcinko J. J. , Shieh Y. T. , Hedrick D. P. , Ritchey W. M. 
Published: April 2003

AbstractA correlation has been established between the dynamic storage modulus (E') and the mean cross polarization time constants 〈TCH〉 for a set of five morphologically diverse polymers, including one at two temperatures and one at two plasticizer concentrations. The correlation is only possible when the TCH values for all of the motional environments within the polymers are considered. An inversion recovery cross polarization (IRCP) NMR technique is used to obtain motional and morphological information from the main chain carbons of each polymer. After comparing simplified correlation functions for the two parameters, an experimental relationship between them is established that suggests that TCH and E' are both modulated by a similar distribution of molecular motions.
Mechanical and dielectric properties of cyanoethylated wood
Authors: Yamawaki Yukio , Morita Mitsuhiro , Sakata Isao 
Published: April 2003

AbstractThe mechanical properties and dielectric properties of film specimens from cyanoethylated wood (CE‐wood) which is a mixture of CE‐(cellulose, hemicellulose, and lignin) were investigated and compared with those of cyanoethylated cellulose (CEC). From the dynamic mechanical measurement for CE‐wood, it was observed distinctively that the segmental motions of the main chains were restrained by lignin. But these restraints were released with chlorination of CE‐wood. The dynamic behavior for chlorinated CE‐wood was similar to that for CEC. It was found that the CE‐wood was plasticized effectively by blending with cyanoethylated poly(vinyl alcohol) (CE‐PVA). The dynamic and static modulus of CE‐wood decreased with increasing the CE‐PVA fraction in the blended film, and the change of tensile strength at break for the CE‐wood polyblends showed a maximum value at the CE‐PVA fraction of ca. 40%. It was found that CE‐wood which contained lignin showed very high values of dielectric constant comparable to those of CEC which was well known to be a high‐performance dielectric materials. These dielectric properties were attributed to the segmental motion of the side chains, and it was tough that the behavior of the side chain was not so much influenced by the lignin as that of the main chain. CE‐wood film specimens could be drawn to threefold the initial length in acetone aqueous solution. The degree of orientation measured by optical method increased rapidly at the early stage of drawing. The Young's modulus and the tensile strength at break of the high‐drawn specimen increased to as much as three or four times those of the undrawn one, and the elongation at break changed little.
In situ polymerization of nylon–polyurea block copolymers. I. Synthesis and characterization
Authors: Gardlund Zack G. , Bator Mary Ann 
Published: April 2003

AbstractThe synthesis of a carbamyl caprolactam terminated polyurea and a series of nylon–polyurea block copolymers has been accomplished. In addition to reaction profiles and thermal properties, proof of block copolymer formation is described.
Polyamic acid interactions at metal surfaces
Authors: Linde H. G. 
Published: April 2003

AbstractPyromellitic dianhydride‐oxydianiline (PMDA‐ODA)‐derived polyamic acid‐metal interactions were delineated by grazing incidence infrared spectroscopy on mirror surfaces. Vast differences were observed between unreactive gold, titanium, chromium, and aliminum, and reactive copper and silver, where copper and silver form amic acid salts. Other polymer‐metal interactions were observed with unreactive metals where aromatic ether rings appear to align on the metal surface. Further, reactive meta and para diacid carboxylates appear to assume different surface conformations. Heating the surface‐bound metal salts destroys the polymer interface, but nonsalt film, formed from amic acid or amic ester, appears to establish near planar aromatic ether conformations on the metal surfaces, with resultant orthogonal imide links.
Fractionation and characterization of a 1‐butene linear low density polyethylene
Authors: Springer H. , Hengse A. , Hinrichsen G. 
Published: April 2003

AbstractA commercial 1‐butene LLDPE, Stamylex 1048, is cross fractionated by dynamic direct extraction and subsequent solution crystallization. The fractions are characterized by determining molecular masses Mn, Mn, and Mw and the comonomer content. DTA measurements are performed on unannealed and annealed samples of the fractions. The temperatures and specific heats of crystallization and fusion can be interpreted by reflecting the influence of molecular weight and comonomer content. The presented results are compared to data of 1‐butene LLDPE published in the recent literature.
Synthesis of polymeric chiral oxazoline and its applications on the asymmetric induction
Authors: Liu Jui‐Hsiang , Kuo Jue‐Cheng 
Published: April 2003

AbstractA series of diastereoisomeric amino bicyclo [2,2,1] heptane derivatives was synthesized from (+)‐camphor. Further treatment of aminobornanols with triethyl orthopropionate afforded chiral oxazolines, which were found to be efficient for the asymmetric induction of carboxylic acids. Synthesis and polymerization of the new chiral oxazolinebornyl methacrylate derived from aminobornanols was carried out. Effects of temperature, solvents, and molar ratio of the reagent on the polymerization of the linear chiral polymers and the synthesis of the insoluble chiral crosslinked polymers were also discussed. Aminobornanols and chiral polymers with pendant aminobornanol moieties were found to be efficient for the asymmetric induction of chiral methylalkanoic acids. Recovery of the chiral reagents, the stereoselectivity of chiral oxazolines, and the parameters governing its successful implementation and the mechanistic aspects of the processes were also investigated.
Dielectric and dynamic mechanical behaviors of 1,2‐polybutadienes
Authors: Ni Shaoru , Yu Fusheng , Shen Lianfang , Qian Baogong 
Published: April 2003

AbstractThe dielectric relaxation behavior of 1,2‐polybutadienes is analyzed in terms of the experimental data and master curves. The dielectric measurement data were fitted to the empirical relaxation time distribution model of Havriliak and Negami over a frequency range from 100 to 1012 Hz. The constants of the WLF equation, C1 and C2, were evaluated with Tg at 100 kHz as a reference temperature for some samples, and the master curve of a sample was constructed. The dynamic mechanical measurements for a series of 1,2‐polybutadienes with different chain structure were performed over a temperature range from −150 to 50°C. A qualitative comparison of the dielectric and dynamic mechanical behaviors of 1,2‐polybutadienes has been made.
Polymerization of olefins through heterogeneous catalysis. VIII. Monomer sorption effects
Authors: Hutchinson R. A. , Ray W. H. 
Published: April 2003

AbstractIn solid catalyzed olefin polymerization, equilibrium sorption plays a key role in determining the local monomer concentration (s) in the semicrystalline polymer shell which surrounds the active sites of the catalyst surface. Modelling based on polymer solution thermodynamics indicates that crystallinity and reactor environment have a major effect on this local monomer concentration. The model is used to explain well known experimental trends seen in the literature, such as observed differences in gas phase and diluent slurry polymerization rates, and enhanced α‐olefin incorporation in gas phase copolymerization.
Thermodynamic models for swelling of heterogeneous networks
Authors: Harland Ronald S. , Klier John , Peppas Nikolaos A. 
Published: April 2003

AbstractThe equilibrium swelling behavior of heterogeneous systems consisting of a consisting of a continuous network phase and a dispersed lamellar, spherical, or cylindrical phase is described using a thermodynamic model. The case of swelling of both phases but to different extents is described. The equilibrium volume fractions of each phase as well as the stresses at equilibrium are predicted as functions of the polymer interaction parameter, X, the modulus, G, and the geometric character of the networks.