bluuebunny/crossref_metadata_2025_split huggingface dataset:
Graft copolymerization of poly(butyl methacrylate) onto wool in the presence of air and nitrogen atmosphere. I
Authors: Shukla J. S. , Tiwari S. C. , Dixit Subodh K. 
Published: April 2003

AbstractPoly(butyl methacrylate) (PBMA) was grafted onto wool in the presence of air and nitrogen atmosphere using potassium persulphate (KPS) and thioacetic acid (TAA) as redox pair under different reaction conditions. The percentage grafting and efficiency were compared. The graft copolymer was characterized by scanning electron micrograph, thermogravimetry, and molecular weight.
The second‐generation polysulfone gas‐separation membrane. II. The relationship between sol properties, gel macrovoids, and fiber selectivity
Authors: Kesting R. E. , Fritzsche A. K. , Cruse C. A. , Moore M. D. 
Published: April 2003

AbstractAll integrally skinned asymmetric membranes contain some defects which are attributable to the incomplete coalescence of the nodule aggregates of which the skin layer is composed. When such defects are small in size and few in number, they can be effectively sealed by coating with a highly permeable polymer. The resulting composite then exhibits the selectivity to gas permeation which is characteristic of the base polymer. Prior to their sealing, therefore, such membranes can be said to exhibit the potential for intrinsic selectivity. However, not all gas separation membranes can be effectively sealed. In the present study the relationship between sol properties, the presence of macrovoids in the substructure of the gel, and the subsequent failure of the fibers to achieve the potential for intrinsic selectivity are considered. Macrovoid‐free fibers with the potential for intrinsic selectivity can be prepared by the utilization of high viscosity, high total solids sols with low nonsolvent tolerance whose solvent vehicles consist of appropriate Lewis acid: base complexes.
Morphology of polymer films and single molecules
Authors: Howell Barbara , Reneker Darrell H. 
Published: April 2003

AbstractSeven polymeric substances were examined by high‐resolution transmission electron microscopy. Features on the scale of the diameter of single molecular chains were observed. Polymers examined include (1) linear polyethylene (Mw = 52,000), (2) linear polyethylene (Mw approximately 5,000,000), (3) poly(cis‐1,4‐butadiene), (4) poly‐γ‐benzyl‐L‐glutamate, (5) poly(etheretherketone) (PEEK), (6) deuterated polystyrene‐poly(methylmethacrylate) (PMMA) block copolymer, and (7) a polydiacetylene, poly(1,12‐di(butoxy‐carbonylmethylurethanyl)‐5,8‐dodecadiyne), also called poly‐4BCMU. A variety of methods were used to prepare dispersed single molecules and very thin films, some of which had regions with strands containing only a few molecules. Staining with RuO4 revealed structures near the surface of the films that were reproducible and characteristic of each polymer.
Prediction of dynamic properties of plastic foams from constant–strain rate measurements
Authors: Ramon Ori , Miltz Joseph 
Published: April 2003

AbstractThis study demonstrated how cushioning curves can be predicted from constant‐strain rate measurements and a limited number of stress‐relaxation or drop experiments. For rate‐independent foams, only one stress‐strain curve and the proposed dynamic model are required. For rate‐dependent foams, however, a computer and appropriate software are also needed to predict accurately cushioning curves.
Investigation of surface morphology of emeraldine hydrochloride by scanning tunneling microscopy
Authors: Mantovani J. G. , Warmack R. J. , Annis B. K. , Macdiarmid A. G. , Scherr E. 
Published: April 2003

AbstractAn STM investigation of the surfaces of emeraldine hydrochloride films indicates that the surfaces are characterized by features that are generally fiberlike in appearance. The widths of these structures ranged from 10 to 140 nm, and the apparent heights varied from 0.5 to 70 nm. Fiber lengths of up to 1 μm were observed. In some regions, the fibers appeared to be highly interconnected in a random fashion while in others there was nearly parallel alignment.
Melt rheology of poly(ethylene terephthalate), polyarylate, and their blends
Authors: Kim Byung Kyu , Jeong Han Mo , Lee Yong Ho 
Published: April 2003

AbstractRheological properties of two polyesters; poly(ethylene terephthalate) (PET) and bisphenol A‐50/50 isophthalic/terephthalic acid based polyarylate (PAR), and their 85/15, 50/50, and 30/70 (PET/PAR) blends were investigated using a RDS rheometer, 290–310°C. Measurements included complex viscosity and modulus. Activation energy for flow and relaxation spectrum were subsequently calculated. Results indicated that PET/PAR blends are rheologically incompatible, i.e., zero‐shear viscosities of the blends showed a negative deviation from the averages of the two homopolymers with a sharp minimum at 85/15 composition. The relaxation spectrum for 85/15 blend also showed a relaxation plateau, a characteristic of rigid particle suspension. The morphology of the polymer blends was examined from cryogenically fractured and etched surface using a scanning electron microscopy (SEM). Morphological observation indicated that PAR‐rich phases, order of 0.1μm, were finely dispersed in PET phase for 85/15 blend, whereas the dispersion of PET phase in PAR‐rich phase was in spherical form, order of 0.5μm in diameter, for the 50/50 blend.
On the thickening mechanism of unsaturated polyesters by alkaline earth oxides and hydroxides
Authors: Rodriguez Ernesto L. 
Published: April 2003

AbstractThe mechanism that describes the thickening process of unsaturated polyester resins with inorganic oxides and hydroxides is presented. This mechanism includes the formation of water, the formation of the ion cluster, the network expansion and the equilibrium, where the viscosity reaches a constant value.
A dynamic‐mechanical study of polycarbonate‐polystyrene blends
Authors: Li Yuan , Williams H. Leverne 
Published: April 2003

AbstractBisphenol‐A polycarbonate (PC) and polystyrene (PS) were melt‐blended and molded for dynamic mechanical tests on a Dynastat. Corresponding powders were submitted to thermal analysis using the differential scanning calorimeter. The deduced glass transition temperatures of the blends and those of the pure polymers were compared to estimate the miscibility of the two polymers.
Crosslinking of an epoxy with a mixed amine as a function of stoichiometry. I. Cure kinetics via dynamic mechanical spectroscopy
Authors: Wingard Charles D. , Beatty Charles L. 
Published: April 2003

AbstractVariation of the epoxy/curing agent ratio by as much as ±10 wt% from the stoichiometric ratio for a system containing a diglycidyl ether of bisphenol‐A (DGEBA) and a mixed aromatic amine was found to have a significant effect on the cure kinetics as determined by dynamic mechanical measurements. A sample preparation technique was developed for monitoring the cure of glass reinforced epoxy in flexure. Shear measurements were also made on the neat resin. From gel time flexural data, the activation energy of cure passed through a maximum at the stoichiometric ratio of epoxy/amine for a glass cloth composite. In shear for the neat resin, a minimum was observed. By considering the curing of the mixed system to follow third‐order kinetics, overall reaction rate constants were estimated after the gel point.
Solubility behavior of an organic soluble polyimide
Authors: Lee Hurng‐Rern , Lee Yu‐Der 
Published: April 2003

AbstractThe solubility behavior of an organic soluble polyimide synthesized from 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride and 2,3,5,6‐tetramethyl‐p‐phenylene diamine in about 60 liquids was investigated via solubility experiments. These results were put into a computer program to obtain a three‐dimensional representation of the polymer solubility region in the hansen space; the values of dispersion, hydrogen bonding, and polar components of the total solubility parameter were 10.6, 5.3, and 5.3 cal 1/2/cm3/2, respectively, and the total solubility parameter was 12.96 cal1/2/cm3/2 after calculation. The total solubility parameter determined from an equilibrium swelling method was between 12.9 cal1/2/cm3/2and 13.1 cal1/2/cm3/2. Both experimental results were in very good agreement. The calculated dispersion solubility parameter obtained from its correlation with the refractive index of the polymer was 10.56 cal1/2/cm3/2 and was in accordance with the result obtained from the polymer solubility region in the Hansen space. However, the total solubility parameter of the organic soluble polyimide calculated from the Fedors method was 12.1 cal1/2/cm3/2 and was low in comparison to the experimental results.
Synthesis and charaterization of new arowmatic polymers containing long alkyl side chains and 1,3,5‐triazine rings
Authors: Lin Jui‐Kun , Yuki Yasuo , Kunisada Hideo , Kondo Shuji 
Published: April 2003

AbstractA series of new aromatic polyamides, polyimides, and polyureas containing 1,3,5‐triazine rings in the main chain and two flexible long side chains for each unit, were prepared by the reaction of 2‐(N‐phenyl‐N‐octadecylamino)‐4‐(N‐aminophenyl‐N‐octadecylamino)‐6‐aminophenyl‐1,3,5‐triazines with aromatic diacid chlorides, pyromellitic dianhydride, and diisocyanates, respectively. These polymers were soluble in tetrahydrofuran, chloroform, and benzene, but had poor solubility in polar aprotic solvents such as dimethyl sulfoxide and N,N‐dimethylformamide. These polymers were stable up to 410°C for polyamides, 430°C for polyimides, and 290°C for polyureas in air. The differntial scanning calorimetric studies of the polymers indicated that the degree of side‐chain crystallinity based side chain was 6‐10%.
Studies on mechanical properties of polymer composites by X‐ray diffraction. I. Residual stress in epoxy resin by X‐ray diffraction
Authors: Nakamae Katsuhiko , Nishino Takashi , Airu Xu , Matsumoto Takeshi , Miyamoto Tomoharu 
Published: April 2003

AbstractResidual stress in epoxy resin cured on Al plate was investigated by X‐ray diffraction. Microdeformation of Al crystal can be detected as a shift of X‐ray diffraction peak induced by the stress resided. Results show that Al plate is subjected to a uniaxial compressive stress of 29 MPa parallel to the adherend surface. In contrast to this, epoxy resin side (embedded particles) was found to be subjected to a uniaxial tensile stress. Experimental data have been compared with the calculated data and that obtained by the bimetallic method. On the basis of results, it is reasonable to conclude that Tg is a key factor determining the residual stress, and the difference of thermal expansion coefficients between Al plate and the cured epoxy resin from Tg to room temperature causes the residual stress. It has been shown that the X‐ray diffraction method is useful to detect the stress at the interface between resin and adherend in situ and nondestructively.
Kraft lignin in polyurethanes. III. Effects of the molecular weight of PEG on the properties of polyurethanes from a kraft lignin–PEG–MDI system
Authors: Reimann Anders , Mörck Roland , Yoshida Hirohisa , Hatakeyama Hyoe , Kringstad Knut P. 
Published: April 2003

AbstractPolyurethane (PU) films were prepared by solution casting using a three‐component system consisting of a low molecular weight fraction of softwood kraft lignin (KL), polyethylene glycol (PEG) of various molecular weights, and crude diphenylmethane diisocyanate (MDI) as starting materials. All films were prepared using a constant NCO/OH ratio. The effects of KL content, PEG content, and molecular weight of PEG on the tensile, thermal, and swelling properties of the PUs were studied. The results showed that the crosslink density Tg and tensile properties were essentially unaffected by variations in the sequence length of the soft segment at a given PEG content. The properties of the PUs were found to depend mainly on the soft/hard segment ratio. The behavior of the glass transition temperature upon changes in the PU composition indicated that the soft and hard segments were extensively mixed.
Synthesis and characterization of poly(imide‐sulfonamide)s
Authors: Adduci Jerry M. , Kuckoff Eric J. 
Published: April 2003

AbstractEight novel poly(imide‐sulfonamide)s have been prepared by reacting pyromellitic dianhydride and benzophenone tetracarboxylic acid dianhydride with variously substituted dianilines containing preformed sulfonamide linkages. Inherent viscosities of the prepared polymers ranged from 0.13 to 0.53 dL/g. Four of the polymers formed tough, transparent yellow, flexible films. Glass transition temperatures, determined by differential scanning calorimetry, ranged from 103 to 249°C. Thermogravimetric analyses of the polymers showed that they have moderate thermal stability with weight losses ranging from 6.8 to 42% at 400°C.
Atomic‐oxygen induced structural changes in polyphosphazene films and coatings
Authors: Fewell Larry L. 
Published: April 2003

AbstractVarious polymers were exposed to atomic oxygen O(3P) and comparisons made of their stability. The rates of reaction and mass removal for polyphosphazenes exposed to atomic oxygen were found to be significantly lower than for other polymers evaluated in this study. Surface analysis of poly‐phosphazene films indicated that O(3P) induces rearrangements in the phosphorus‐nitrogen backbone of the polymer resulting in crosslinking and cleavage of some pendant groups that are then replaced by oxygen.
Coextrusion of it‐polypropylene film
Authors: Kunugi Toshio , Yoneyama Yuko , Porter Roger S. 
Published: April 2003

Abstractit‐Polypropylene films were coextruded by using dies of varying extrusion draw ratio (EDR) from 2–10. Among the resulting films, the film coextruded at EDR 9 possesses the most attractive superstructure and the highest modulus. The dynamic modulus at room temperature was 7 GPa and an αc dispersion peak occurred at 100°C in E″‐temperature curves, which is higher by about 20°C than that of the multistep zone‐drawn and zone‐annealed fibers previously reported. Further, to prepare films with higher draw ratio and higher modulus, repetition of the coextrusion was attempted. Consequently, the draw ratio and the E′ at room temperature reached 12 and 13 GPa, respectively. The present paper discusses changes in molecular orientation, crystallinity, uniformity of the superstructure, and dynamic viscoelasticity, with increasing of the used EDR and repeating the coextrusion with some combinations of EDR.
Rubber‐modified epoxies. I. Influence of carboxyl‐terminated butadiene‐acrylonitrile random copolymers (CTBN) on the polymerization and phase separation processes
Authors: Verchere D. , Sautereau H. , Pascault J. P. , Moschiar S. M. , Riccardi C. C. , Williams R. J. J. 
Published: April 2003

AbstractA bisphenol‐A diglycidylether (DGEBA) based epoxy was cured with a cycloaliphatic diamine (4,4′‐diamino‐3,3′‐dimethyldicyclohexylmethane, 3DCM), in the presence of an epoxy terminated butadiene‐acrylonitrile random copolymer (ETBN). Results showed that vitrification is slightly delayed with the rubber addition. With ETBN the auto‐catalytic mechanism by [OH]0 is predominant at the beginning of the reaction, and on the contrary dilution is the dominant factor after x = 0.15. Phase separation takes place completely, well before gelation and vitrification; the conversion at the onset of phase separation decreases with the rubber amount but does not depend significantly on the temperature. The maximum Tg of the rubber‐modified matrix does not depend on the cure temperature but decreases with the initial rubber concentration. This implies that a significant amount of rubber remains in solution in the continuous phase. This explains the delay in vitrification.
Influence of polycaprolactam morphology on thermal cis–trans isomerization and photofading of azo dyes differently dispersed in it: A kinetic study
Authors: Dubini‐Paglia Ernestina , Beltrame Pier Luigi , Marcandalli Bruno , Seves Alberto 
Published: April 2003

AbstractTwo polycaprolactam films were prepared characterized by different crystallinity degrees, the free volume model being prevalent in the former and the pore model in the latter. They were colored with azo dyes XC6H4NNC6H4N(C2H5)2 (where X is H and COOH), the latter of which gives specific interactions with the polymer. The kinetics of the thermal cis–trans isomerization of these dyes has been studied below and above the glass transition temperature of the polymer (Tg) in the range 20–80°C. In every case, the isomerization process was found to be the result of a multiplicity of first‐order reactions and the dependence on temperature exhibited a break at the Tg value. Lightfastness of the dyes in the polymer matrices has been also investigated. The isomerization and fading kinetics are discussed in terms of polymer structural features as well as of the nature of the dye.
Swelling of PVC particles during gelation and fusion of plastisols as observed with small‐angle light scattering
Authors: Nakajima N. , Sadeghi M. R. , Kyu T. 
Published: April 2003

AbstractSmall‐angle light scattering was employed as a nondestructive technique for the in situ observation of swelling of PVC particles during gelation and fusion. One typical plastisol grade of PVC and three different plasticizers were used. The results demonstrate that quantitative measurements of average PVC particle size appear possible while they are in the process of swelling with plasticizers. From the degree of swelling the solvent power of plasticizers may be evaluated. The ranking of plasticizers made in this manner was in good agreement with the previous studies involving viscoelastic measurements.
A study of toluene diisocyanate‐based polyurethanes of various isomer ratios
Authors: Nierzwicki W. , Walczynski B. 
Published: April 2003

AbstractSeveral urethane elastomers based on poly(oxytetramethylene glycol), butanediol 1,4 and various mixtures of 2,4 and 2,6 toluene diisocyanates were prepared. The tensile strength, moduli, glass transition temperatures, flow temperatures and relaxation properties were measured. These properties are discussed with reference to changes in microphase separation.
Transport properties of filled elastomeric networks
Authors: De Candia F. , Gargani L. , Renzulli A. 
Published: April 2003

AbstractThe transport properties of networks filled with carbon black have been studied in order to obtain information on the rubber–filler interactions. The obtained results show that the filling particles can be completely or partially excluded from the transport phenomena which occur mainly in the rubberlike matrix. The transport properties of the pure components, compared with the filled system, allow to obtain a possible evaluation of the interphase phenomena.
Kinetic study of random chain scission by viscometry
Authors: Chee K. K. 
Published: April 2003

AbstractBased on the Saito's model for random chain scission, a novel procedure is developed to determine the activation energy of polymer degradation process. Basically, this is a simple viscometric technique which yields reliable results. In fact, it is superior to the existing viscometry which has been widely used to study the kinetics of random scission. The present method is successfully applied to the thermal degradation of natural rubber, polycarbonate, and poly(tetramethylene oxide) in bulk.
Photodegradation of poly(methyl methacrylate) by monochromatic light: Quantum yield, effect of wavelengths, and light intensity
Authors: Torikai Ayako , Ohno Masakuni , Fueki Kenji 
Published: April 2003

AbstractPoly(methyl methacrylate) (PMMA) was photolyzed with monochromatic light of wavelengths 260, 280, and 300 nm by the use of the Okazaki large spectrograph. The quantum yield of mainchain scission (ϕcs), effects of wavelength, and incident photon intensity on the photodegradation were investigated. It turned out that photodegradation of PMMA took place by the irradiation of 260–300 nm light, but did not by the irradiation at λ ⩾ 320 nm. The number of main‐chain scission (Ncs) has a maximum value in the case of the irradiation with 280 nm light. Under the same conditions of wavelength and total photon intensity, a longer‐term irradiation with a weaker incident photon intensity tends to yield a greater amount of main‐chain scission. A linear relationship was found between the number of main‐chain scission and the incident photon intensity. The average values of ϕcs obtained in this work were 2.1 × 10−4, 2.4 × 10−4, and 4.1 × 10−4, respectively, for the irradiations at 260, 280, and 300 nm. It was found that the photoinduced side‐chain scission initiates the main‐chain scission of PMMA.
Physical properties of wool keratin yarn modified with dibasic acid anhydrides
Authors: Tsukada Masuhiro , Shiozaki Hideki , Konda Atsuo 
Published: April 2003

AbstractThe structure and physical properties of wool keratin yarns modified with dibasic acid anhydrides, namely, succinic and glutaric anhydride are analysed by thermomechanical analysis (TMA), differential scanning calorimetry (DSC), thermogravimetry (TG), and on the basis of measurements of the tensile properties. The optimum temperature for the reaction with dibasic acid anhydride can be achieved at 65°C. The weight gain of wool yarn treated with glutaric anhydride was 3% larger compared with that of the sample treated with succinic anhydride for the reaction time of 4 h. However, the acyl contents of the wool yarn treated with succinic and glutaric anhydride was the same. The moisture regain values of the wool yarn treated with glutaric anhydride were much lower by about 2% compared with those for the wool yarn treated with succinic anhydride. The original properties in mechanic of the wool yarn are not damaged even after the modification with dibasic acid anhydride. Taking into account the dyeability and thermal properties of the chemically modified wool keratin yarns, it would seem that the ester crosslinks are easily formed in keratin much more by the glutarylation than by succinylation.
Structure and surface properties of plasma polymerized acrylic acid layers
Authors: Cho Dong L. , Claesson Per M. , Gölander Carl‐Gustaf , Johansson Kenth 
Published: April 2003

AbstractThin plasma polymerized layers of acrylic acid (PPAA) were deposited onto polyethylene and muscovite mica surfaces. Structure and surface properties of the deposited layer depend on the polymerization conditions. The content of carboxylic groups in the layer decreases, whereas the degree of crosslinking or branching increases, with increasing discharge power. A soft, sticky layer with a low contact angle against water is obtained when a low discharge power (5 W) is used. In contrast, a hard film with a rather high water contact angle is obtained when the discharge power is high (50 W). A surface force apparatus was employed to study some film properties including adhesion force, crack formation, and capillary condensation. The adhesion force between plasma polymerized acrylic acid layers prepared at a low discharge power is high in dry air. It decreases remarkably in humid air and no adhesion is observed in water. In dry air, the adhesion force between PPAA layers decreases as the discharge power increases.