bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photolysis of poly(3‐buten‐2‐one), poly(4,4‐dimethyl‐1‐penten‐3‐one), and poly(3‐methyl‐3‐buten‐2‐one) in the presence of oxygen
Authors: Naito Ikuo , Teshima Kazuhiro , Sato Noboru , Sekito Hirofumi , Kinoshita Akihiro 
Published: April 2003

AbstractPhotolysis of poly(3‐buten‐2‐one) (PMVK), poly(4,4‐dimethyl‐1‐penten‐3‐one) (PBVK), and poly(3‐methyl‐3‐buten‐2‐one) (PMIK) were carried out in dioxane under oxygen or nitrogen bubbling. The main chain degradations of PBVK and PMIK were quenched and polymeric peroxides were produced. The heat treatment of the polymer irradiated in the presence of oxygen promoted the degradation. The photodegradation of PMVK was enhanced in the presence of oxygen.
Relationship between electron sensitivity and chemical structures of polymers as EB resists. III. Electron sensitivity of various polyamides using 3‐amino perhydroazepine
Authors: Oguchi Kiyoshi , Sanui Kohei , Ogata Naoya , Takahashi Yoichi , Nakada Tomihiro 
Published: April 2003

AbstractHomopolyamides and copolyamides containing a variety of reactive and/or stabilizing groups, such as double bonds, epoxy groups, or naphthalene moieties, were synthesized using 3‐amino perhydroazepine (APA) as a diamine monomer. These polymers were evaluated as electron beam (EB) resists, in order to investigate the relationship between EB sensitivity and chemical structure of the polyamides. It was found that polyamides containing double bonds were easily crosslinked by the EB exposure and that the sensitivity of a polyamide containing double bonds in the side chain was higher than that of a polyamide containing double bonds in the main chain. The sensitivity of a polyamide containing epoxy groups was lower than that of the above. Copolymer from APA, 77 mol % of trans‐3‐hexenedioyl chloride (HC) and 23 mol % of 2,6‐naphthalenedioyl chloride (NC) had the same EB sensitivity as that of the homopolymer from APA and HC. The polyamides had excellent dry etching durability and were adaptable to EB lithography.
Thermal and structural properties of tri‐O‐substituted cellulose ethers
Authors: Isogai Akira , Ishizu Atsushi , Nakano Junzo 
Published: April 2003

AbstractTri‐O‐substituted cellulose ethers prepared by the use of SO2–diethylamine (DEA)–dimethylsulfoxide (DMSO) and powdered sodium hydroxide were characterized by measurement of melting points and degradation points and by differential scanning calorimetric (DSC) and X‐ray analyses. Their thermal and structural characteristics were ascertained to be dependent on the kinds of substituents. Among the ethers examined, four kinds of arylmethylcelluloses showed the characteristics of thermotropic liquid crystals (smectic). Tri‐O‐α‐naphthylmethyl‐cellulose showed the three transformations due to a solid–smectic phase, a smectic–nematic phase, and a nematic–isotropic phase transformation. This thermotropic liquid crystal was enantiotropic below 200°C.
Polymeric reaction of acrylic polymer–monomer system irradiated by low energy electron beam. I. Effects of molecular weight of polymer and polymer‐to‐monomer ratio
Authors: Takiguchi Ryohei , Uryu Toshiyuki 
Published: April 2003

AbstractPolymeric reaction of the poly(n‐butyl acrylate) (PBA)–benzyl acrylate (BzA) system induced by a low‐energy electron beam was investigated. In order to elucidate the reaction behavior of the PBA–BzA system, the gel fraction, molecular weight of soluble part, and molecular weight distributions were examined by means of gel permeation chromatography (GPC) equipped with both ultraviolet (UV) and refractive index (RI) detectors. RI‐detected GPC curves represented the molecular weights and their distributions of the total polymers, graft polymer, homopolymer, and unreacted PBA, while UV‐detected curves only corresponded to the benzyl groups of graft polymer and homopolymer. Thus, the reaction behavior of the system was able to be followed by GPC. The molecular weight of the added PBA and the mole ratio of PBA/BzA were varied. The crosslinking, the graft reaction and the homopolymerization of BzA proceeded competitively during the polymeric reaction. The proportions of BzA unit incorporated into the crosslinked, graft and homo polymers were estimated by combining of measurement of gel fraction, UV‐detected GPC curves, and infrared (IR) spectrum of gel. It was revealed that in the system containing PBA with high molecular weight, the grafting, and the crosslinking reactions predominated. The main reaction was the grafting in the system with a high mole ratio of PBA/BzA, while it was the homopolymerization in the systems with the low mole ratio of PBA/BzA. The reaction mechanism is discussed on the basis of reactivity and mobility of polymer radicals.
Crystalline‐state extrusion of low density polyethylenes
Authors: Benelhadjsaid Chadli , Porter Roger S. 
Published: April 2003

AbstractThree low density polyethylenes, one long branched (A) and two linear (B and C), have been solid‐state‐extruded at several constant temperatures from ambient to 80°C and to draw ratios ⩽ 8. The initial densities and melt indices of A, B, and C are 0.920, 0.920, and 0.935 g/cm3, and 1.9, 0.8, and 1.2, respectively. Melt‐crystallized cylindrical billets were extruded through conical dies in an Instron Capillary Rheometer. The linear polymers were found to draw by extrusion more readily than the branched; all three strain‐harden. Density, birefringence, tensile, and thermal properties have been evaluated as functions of extrusion temperature and draw ratio. Despite a measured loss via die swell, substantial orientation takes place during solid‐state extrusion as evidenced by increases in transparency, birefringence, and tensile modulus (up to 4.5 times that of the original isotropic polymer). Depending on the polymer and the draw temperature, density does go through a minimum or shows a monotonic increase with draw by extrusion. A minimum in modulus is also observed at low draw and at all draw temperatures for all three polymers. The highest tensile moduli achieved are 0.73, 0.46, and 1.5 GPa for A, B, and C, respectively, at their highest draw ratio. The melting point for polymer B decreases with extrusion draw ratio, whereas it remains constant after a small initial drop, for the two others. For all three low density polyethylenes, birefringence increases rapidly with extrusion draw and then levels off at high draw. The birefringence limit is similar for A and B, i.e., 0.046 ± 0.004, but higher for C, i.e., 0.068 ± 0.009. This work extends beyond others in that it studies the effect of short as well as long branches in solid‐state extrusion by comparing the linear and long branched LDPE polymers and LDPE with prior evaluations of HDPE.
Porous bead aliphatic–aromatic methacrylate copolymers III. The effect of diluent on porous structure formation of MMA–DMN copolymers
Authors: Wójcik Anna B. 
Published: April 2003

AbstractPorous bead copolymers of di(methacryloyloxymethyl)naphthalene and methyl methacrylate have been synthesized using a mixture of isooctane and toluene as a diluent of the monomer system. The copolymers obtained exhibit similar specific surface areas and enhanced specific pore volume as compared to those prepared in the presence of dodecane and toluene. Their submicroscopic structure is visualized as first‐order organization of microglobules similarly to PPS‐type styrene–divinylbenzene copolymers.
Electrically conducting polymers from conjugated bis‐phthalonitrile monomers
Authors: Walton Theodore R. , Griffith James R. , Reardon Joseph P. 
Published: April 2003

AbstractElelectrically conducting polymers have been synthesized from completely conjugated bisphthalonitrile monomers. The monomers melt and are thermally polymerized at 260–300°C in air and then are converted into conductive materials by further processing at elevated temperatures in an inert atmosphere. Because the monomers remain in a liquid stage for 1–2 h, depending on the cure conditions, moldings, castings, and pre‐pregs can be fabricated using conventional processing techniques. The conductivity can be varied from that of an insulator to approximately 10+2(Ωh cm)−1. For example, after a 600°C treatment, the conductivity is approximately 1(Ω cm)−1. Since reactive dopants are not used, the material and conductivity are stable in ambient as well as more aggressive environments, allowing them to function at 300°C and above. The monomers are well characterized, but the structure of the cured and postcured polymers are not yet well defined because of their high stability and intractability in the cured state.
On the effects of very low levels of long chain branching on rheological behavior in polyethylene
Authors: Bersted B. H. 
Published: April 2003

AbstractA comparison is made of the effects of very low levels of long chain branching (less than 0.1 branch per 1000 CH2) on the rheological behavior of polyethylene for samples, in which the branching has been introduced by means of peroxide decomposition or thermal‐mechanical degradation. Both the activation energy and viscosity at low rates are shown to increase considerably more rapidly with branching level for samples containing branching formed from peroxide decomposition than for samples containing branching formed as a result of thermal or mechanical degradation. A model, which is based on parameters obtained for highly branched low density polyethylene and experimental molecular structure measurements, is shown to adequately account for the flow curves of samples containing branching introduced by thermal or mechanical degradation. Poor agreement of the model with experimental flow curves for peroxide branched samples is obtained, presumably because of the inability of the low density polyethylene parameters to adequately describe the flow properties of these samples, which are thought to contain tetrafunctional branch points. The good agreement between theoretical models, predicting relationships between activation energy and branching level, and experimental data is taken as lending further credence to the idea that the large variations seen in the rheological behavior with branching concentration at low branching levels are due to changes in the relative proportion of discrete branched and linear species with branching level. In accord with experimental results, a maximum in low rate viscosity with branching level is predicted. The maximum is predicted at approximately 0.25 branches/1000 CH2.
Effect of stirring on cellulose graft copolymerization. V. Influence of reaction parameters
Authors: Graczyk Tomasz , Hornof Vladimir 
Published: April 2003

AbstractStyrene was grafted onto dissolving pulp by the cellulose xanthate–Fe2+–H2O2 system. Reaction parameters were found to have strong influence on conversion to both copolymer and total polymer, as well as on the dependence of polymerization on stirring. The formation of polymer was almost completely inhibited by pure oxygen, while air only slowed down the reaction. Under inert atmosphere, the effect of agitator speed was found to be strongly dependent on monomer and substrate concentration as well as on the concentration of emulsifier. The location of the maximum on the conversion vs. agitator speed curve was strongly affected by the shape of the stirrer. The presence of emulsifier had a relatively small effect on copolymer formation in the case of acrylamide, a water‐soluble monomer. Also the effect of stirring was less marked in the case of acrylamide. In all the systems investigated, the conversion to copolymer and total polymer was found to drop rapidly above a certain limiting agitator speed. The latter was different and characteristic for each system. No polymer formation was observed beyond 1000 rpm regardless of all other reaction conditions.
A rheological study of laminar–turbulent transition in drag reducing polymeric solutions
Authors: Tandon P. N. , Kulshreshtha A. K. 
Published: April 2003

AbstractPresented herein are the studies of laminar–turbulent transition in micropolar and power law fluids flowing in a circular pipe. For some parametric values of micropolar and power law fluids, both depict the drag reducing properties. The parametric values of these representations have been obtained from the experimental results of Mc‐Comb. It has been observed that, in both the cases, as the drag‐reducing property in the solution increases, the first transition point moves towards the walls of the pipe. It is also observed that the onset of early turbulence phenomenon occurs for the drag‐reducing polymeric solutions.
Characterization of acidic groups in oxycelluloses III. Effect of cation freeing and blocking on estimation of carboxyl groups and lactones by the idometric method
Authors: Achwal W. B. , Murali Radha 
Published: April 2003

AbstractA differentiation between free carboxyl and various lactone groups in different types of oxycelluloses was carried out based on the variation in their reaction rate with KI/KIO3 solution. For oxycelluloses prepared under acidic conditions, a large proportion of carboxyl groups are present in free form. Each oxycellulose was also studied after cation freeing as well as after blocking the free carboxyl groups by treatment with sodium chloride.Cation freeing was found to cause considerable lactonization of carboxyl groups; sodium chloride treatment blocked them only partially.
Pyrolyzed, conducting kapton polyimide: An electrically conducting material
Authors: Hu C. Z. , Andrade J. D. 
Published: April 2003

AbstractPolyimide was pyrolyzed in an argon atmosphere at 900°C for 1h. The room temperature conductivity of the polyimide gradually increased from 15 to 100 S/cm with increased pyrolysis time. Further increase in the pyrolysis time did not increase the conductivity. X‐ray photo‐electron spectroscopy (XPS) showed that the polyimide changed from pure insulator to conductor; detailed XPS spectra of carbon, nitrogen, and oxygen 1s bands showed no further elemental decomposition of the polyimide at 900°C. The high temperature treatment results in internal rearrangement to form a large, dense heterocyclic network. The film probably consists of tiny conductive particles dispersed in an amorphous carbon matrix. The polyimide is placed between two quartz plates during pyrolysis; the resulting film is flat, has uniform conductivity, is nonbrittle, has high chemical resistance, and shows better mechanical strength than films pyrolyzed in free‐standing conditions.
Miscibility of polyethyloxazoline with thermoplastic polymers
Authors: Keskkula H. , Paul D. R. 
Published: April 2003

AbstractPolyethyloxazoline (PEOx) blends with several other thermoplastic polymers were examined by differential scanning calorimetry (DSC) for miscibility. Styrene/acrylonitrile (SAN) copolymers having compositions in the range of about 20–40% acrylonitrile (AN) by weight were found to be miscible with PEOx whereas SANs outside this range were not. The polyhydroxyl ether of bisphenol A (Phenoxy) was also found to be miscible with PEOx. A vinylidene chloride copolymer (Saran) was found to be partially miscible with PEOx, whereas poly(methyl methacrylate) and polycarbonate were not miscible at all.
Thermodynamics of the process of adsorption of aliphatic amidpolyamine on cellulose
Authors: Nedelcheva Margarita , Mladenova Stefka , Valcheva Eva 
Published: April 2003

AbstractThe subject of this research is the thermodynamics of the adsorption equilibrium of three types of bleached pulp in water solutions of aliphatic amidpolyamine—Lamid‐1, (L‐1) in concentrations from 0.03 to 0.50 g/L in a temperature interval of 0–60°C and the influence of pH of the environment on the adsorption process. It was established that with the increase of temperature the quantity of adsorbed L‐1 decreases. The values of the heat of adsorption are negative, do not depend on the quantity of adsorbed L‐1, and are of the order 111.7–14.7 kJ/mol. The values of the entropy of the entropy of adsorption are also negative and are of the order of 76.8 ÷ 84.5 J/mol•K. Adsorption equilibrium is described by ther adsorption isotherm of Langmuir. Optimum pH for lower concentrations of the solution is from 5 to 7. When the concentrations of the solution are higher (C ≧ 0.15 g/L) the process can also take place very satisfactorily in an alkaline environment.
Analysis of mass transfer effects in ethyl cellulose manufacture
Authors: Chakrabarti A. , Jaganathan R. , Chaudhari R. V. 
Published: April 2003

AbstractA theoretical analysis of mass transfer effects in ethyl cellulose manufacture has been reported. This is the first model to describe a complex fluid–solid reaction in the presence of two immiscible liquids. The model derived here can be used to evaluate the dependency of the overall rate on different parameters incorporating the multiphase mass transfer effects.
A study on the polycondensation of bis‐hydroxyethyl terephthalate
Authors: Lin Chen‐Chong , Baliga Satish 
Published: April 2003

AbstractPoly(ethylene terephthalate) (PET) was synthesized from its monomer bis‐hydroxyethyl terephthalate (BHET), in the presence of Sb2O3 catalyst. A second order irreversible reaction model was developed, and the apparent rate constant was evaluated by observing the course of intrinsic viscosity change. At 278°C, the apparent rate constant in the presence of 0.025% (by weight) of Sb2O3 was found to be 0.945 L/mol h.
Influence of chalk and its surface treatment on crystallization of filled polypropylene
Authors: Kowalewski T. , Galeski A. 
Published: April 2003

AbstractIsotactic polypropylene has been shown to crystallize from the melt spherulitically at intermediate undercoolings (100–130°C) in the presence of a high amount (40 wt %) of chalk (calcium carbonate). Linear growth rate is not remarkably affected by the presence of a filler. Both nonisothermal and isothermal crystallization DSC experiments indicate that chalk acts as a weak nucleant. Introduction of liquid [oligomer of ethylene oxide (OEO), Mw = 300] at polymer–filler interface lowers the nucleating activity of chalk. Analysis of crystallization kinetics in Avrami coordinates, followed by dimensional‐analysis correction for the case of nonintegral values of exponents, indicates that the amount of extra “chalk nuclei” is approximately constant in the range of 100–130°C while the amount of OEO‐modified “chalk nuclei” decreases with the increase of the crystallization temperature. Comparison of the melting endotherms indicates that filled melt‐crystallized material contains higher fraction of lower melting crystallites than unfilled polypropylene. This fraction is also higher in the case of polypropylene filled with unmodified chalk. Nucleating activity of chalk has been shown to depend upon its crystal structure (calcite or aragonite), surface topography, and aggregation.
Synthesis and characterization of some aromatic polyphosphonates
Authors: Natansohn Almeria 
Published: April 2003

AbstractNovel aromatic polyphosphonates are synthesized by polycondensation of chloromethyl (methyl, phenyl) phosphonic dichloride with bisphenols using three procedures: melt, solution, and phase transfer catalysis. The molecular weights and spectral characteristics are presented. Mixtures of the polyphosphonates with polyacrylonitrile and nylon 66 are compatible only when the chloromethyl group is present. Eight percent of polyphosphonate in the mixture confers flame resistance to the polymers.
High‐speed reverse‐phase liquid chromatography with 3 μm packing for analysis of fiber‐reinforced epoxy composite formulations
Authors: Noël D. , Cole K. C. , Hechler J.‐J. , Chouliotis A. , Overbury K. C. 
Published: April 2003

AbstractA high‐speed reverse‐phase liquid chromatography column packed with 3 μm particles has been used to separate different epoxy resin formulations used in manufacturing fiber‐reinforced composites. The mass transfer of the solute between the stationary phase and the mobile phase is improved with the decrease of the particle diameter, and the height equivalent to a theoretical plate remains low even at higher flow rates of eluent. The separation of a typical epoxy resin was achieved with good resolution in less than 6 min on a short column 4 cm long packed with 3 μm particles, as compared to about 30 min on a 30 cm long column packed with 5 μm particles. Moreover, the regeneration time with gradient elution is considerably reduced with a short column. Separations of different formulations are shown and the advantages and disadvantages of these 3 μm packings for a quality control laboratory are discussed. In addition, the ageing of Narmco Rigidite 5208/WC3000 prepreg at room temperature in a controlled atmosphere has been quantified using these high‐speed columns.
Crosslinking of amidated polybutadiene with resole. I
Authors: Hara Hajime , Araki Yoshihiko , Orii Shingo 
Published: April 2003

AbstractVarious liquid polybutadiene derivatives were examined as modifiers to improve the brittleness of phenolic resins. Amidated polybutadienes obtained from a maleinated polybutadiene and ammonia had the highest curing tendency when they were reacted with resole under mild conditions. The cured resins were homogeneous and the brittleness of the phenolic resins was remarkably improved. Crosslinking efficiency was closely related to the succinamic acid group of the amidated polybutadiene. Thermal behavior of the succinamic acid group was also related to the effects of curing temperature and curing time on crosslinking. From these observations, cross‐condensation between the succinamic acid group of an amidated polybutadiene and resole seemed to have occurred to a great extent than the self‐condensation of resole itself and oxidative crosslinking of the amidated polybutadiene.
Kinetics of transesterification of dimethyl terephthalate with 1,4‐butanediol catalyzed by tetrabutyl titanate
Authors: Hsu J. , Choi K. Y. 
Published: April 2003

AbstractThe kinetics of tetrabutyl titanate catalyzed transesterification of dimethyl terephthalate (DMT) with 1,4‐butanediol (BD) is investigated. Detailed analysis of experimental data indicates that equal reactivity hypothesis for functional groups is valid for [BD]/[DMT] molar ratios greater than 2 up to 75% conversion. Effects of reaction temperature and catalyst concentration are also discussed.
Cinnamylidene‐amine‐sensitized photodegradation of polyethylene
Authors: Czekaj Tadeusz 
Published: April 2003

AbstractThe activity of Schiff's bases of cinnamic aldehyde and aromatic amines in the controlled photodegradation of polyethylene (PE) was studied. N‐cinnamylidene anilines containing different substituents in the amine ring (methyl group, halogen, or amine group) and N‐cinnamylidene α‐naphthyl amine were synthesized and introduced into the polyethylene films by compression molding or extrusion, and they were exposed to the filtered ultraviolet light produced by mercury lamp. The changes in molecular weight, tensile strength, and characteristic IR absorptions were followed during irradiation to control the processes undergoing in the polymer films. It was discovered that N‐cinnamylidene anilines containing methyl or halogen substituents and N‐cinnamylidene α‐naphthyl amine accelerated the photodegradation of polyethylene. Their sensitizing activity increased when the mixtures of Schiff's bases and stannous laurate were introduced into the polymer. PE films containing these additives became brittle after 600 h exposure to the artificial UV light which was the equivalent of 1.5–2 years exposure to the natural sunlight in the medium geographic latitudes. The mechanism of the initial step of photodegradation is discussed.