bluuebunny/crossref_metadata_2025 huggingface dataset:
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

An 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

Rheological 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

The 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

Bisphenol‐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

Variation 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

The 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

A 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

Residual 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

Polyurethane (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

Eight 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

Various 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

it‐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

A 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

Two 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

Small‐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

Several 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

The 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

Based 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

Poly(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

The 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

Thin 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.
Morphology development of polymeric microparticles in aqueous dispersions. I. Thermodynamic considerations
Authors: Sundberg Donald C. , Casassa Anthony P. , Pantazopoulos John , Muscato Mark R. , Kronberg Bengt , Berg Johan
Published: April 2003

A thermodynamic analysis of polymer particle morphology highlights the role of interfacial tensions in controlling particle structure. The influence of the surfactant and the nature of the incompatible polymers is seen through their individual and collective effects upon these interfacial tensions. It has been found that by simply changing the type of surfactant used in the emulsion the particle morphology can change from core‐shell to hemispherical, in agreement with thermodynamic predictions. Several apparently different morphologies (hemispherical, sandwich, multiple lobes) have been found to coexist at the same time within a single emulsion, suggesting that they may be simply different states of phase separation and not thermodynamically stable, unique morphologies. The thermodynamic analyses are independent of particle size and method of emulsion processing. Experimental evidence shows that the morphology of particles formed via in situ polymerization (as in a synthetic latex) is controlled by interfacial tensions in the same manner as those particles formed via solvent evaporation from a solution of an incompatible polymer pair (as in an artificial latex or microencapsulation).
Effects of surface cleaning and X‐ray irradiation in XPS study of polymers
Authors: Takahagi T. , Nakayama Y. , Soeda F. , Ishitani A.
Published: April 2003

We have examined effects of surface cleaning and X‐ray irradiation in XPS study of polymers. Contamination‐free surfaces of polymer samples for XPS study were successfully prepared by ultrasonic washing in organic solvents. Polymers were revealed to have lower surface chemical activity than metal and semiconductor crystals. The degradation behavior of polymers induced by X‐ray irradiation was found to be different from thermal degradation processes. Polymers like PET, polyimide, and PAN have high stability against X‐ray irradiation in XPS measurement. On the other hand, we must take degradation into consideration in XPS measurement for polymers such as PTFE and nylon because of their low stability against X‐ray irradiation. For an extremely X‐ray‐sensitive polymer like nitrocellulose, a quantitative XPS study cannot be carried out.
Effect of moisture sorption on ac properties of glass–epoxy composites
Authors: Doukkali K. , Segui Y.
Published: April 2003

Alternating current responses of fiberglass‐reinforced epoxy composites have been studied as a function of frequency (10 Hz to 100 kHz) and temperature (−30 to 100°C). At higher water content, permanent defects are created presumably at the fiber—matrix interfaces as the temperature goes down to 0°C. These defects increase significantly the dielectric losses. A recovery of the initial state is possible under thermal annealing above the glass transition temperature of the epoxy resin.
The diffusion of oxygen through uniaxially and biaxially drawn polypropylene
Authors: Taraiya A. K. , Orchard G. A. J. , Ward I. M.
Published: April 2003

The oxygen permeability of uniaxially and biaxially drawn polypropylene has been studied for both film and tube samples. With few exceptions the permeability coefficient decreases on drawing, but effects are small, particularly for biaxially drawn material where the coefficient does not fall below about 60% of the isotropic value. Molecular orientation as indicated by refractive index measurements appears as a major cause of the reduction in permeability.
Numerical examination of the dual‐mode sorption model for sorption rate experiments with an extension for a mobile langmuir component
Authors: Riedl Carl M. , Spencer H. Garth
Published: April 2003

Numerical methods were applied to the dual‐mode sorption model for sorption rate experiments with an immobilized Langmuir component over broad ranges of polymer characteristics and experimental conditions. The variation of the diffusion coefficient evaluated using a single scaling procedure was examined. The numerical procedure was also applied to the model for infinite volume sorption and to sorption allowing for mobility of the Langmuir component of the penetrant.
Synthesis and physical properties of poly(fluoroalkylether)urethanes
Authors: Yu X‐H. , Okkema A. Z. , Cooper S. L.
Published: April 2003

Polyurethane block copolymers were synthesized containing between 33 and 50 wt % hard segments based on 4,4'‐diphenylmethane diissocyanate (MDI) and either 1,4‐butanediol (BD), or N‐methyldiethanolamine (MDEA) as the chain extender. The soft segments were composed of poly(tetramethylene oxide) (PTMO) and fluoropolyether glycol (FPEG) oligomers (Mn = 1000 and 1899, respectively), copolymerized to produce polyurethanes containing 5–100 wt % FPEG soft segment. The PTMO polyol in one sample was substituted with a tetrahydrofuran/ethylene oxide polyol (75 : 25 mole ratio) (Mn = 1140). The MDEA‐extended polymer was ionized using 1,3‐propane sultone. The bulk and surface properties of these polymers were evaluated by a variety of techniques. Differential scanning calorimetry (DSC) and dynamic mechanical analysis showed that the incorporation of 5–14 wt % FPEG into the soft segment had essentially no effect on the polymer's multiphase structure. The ultimate tensile strength and elongation was reduced by the addition of FPEG. Chain extending with BD as opposed to MDEA improved phase separation and the ultimate tensile strength. In vacuum, surface enrichment of the low surface energy FPEG was observed for all the polymers, using X‐ray photoelectron spectroscopy (XPS). The dynamic contact angle results indicate that the polymer surfaces rearranged in an aqueous environment to minimize their interfacial free energy.
Structure—property relationships of polyurethane ionomers with star chain architecture
Authors: Thompson Patrick A. , Yu Xuehai , Cooper Stuart L.
Published: April 2003

The effects of chain architecture, polyol chemistry and polyol molecular weight on the properties of elastomeric polyurethane ionomers were investigated. The type of polyol and its molecular weight had a strong influence on the rubbery modulus and tensile properties. Variations in chain architecture showed little impact on mechanical and thermal properties. Linear ionomers, threearm ionomers, and six‐arm ionomers had similar mechanical and thermal behavior.
Preparation and cationic electrodeposition of amine—functional epoxy resins
Authors: Yang Chin‐Ping , Lee Lung‐Ta
Published: April 2003

2‐Ethylhexanol‐blocked toluene diisocyanate (2‐EH‐blocked TDI) modified resin was first prepared from epoxy resin and 2‐EH partially blocked TDI and subsequently reacted with di(2‐methylisobutylketiminoethyl)amine to obtain ketimine‐terminated resins. These ketimine‐terminated resins were hydrolyzed and partially neutralized with acetic acid to give macrocations. The resulting cationic resins were dissolved in suitable solvents and mixed with deionized water to form various emulsions. The formation of a stable emulsion is strongly dependent on the pH value of the emulsion and the amount of solvent added. Electrodeposition of the emulsion produced films of amine‐terminated and 2‐EH‐blocked TDI modified epoxy resins on the surface of a cathode. Factors such as the pH value of the emulsion, the content of organic solvents, the amount of 2‐EH‐blocked TDI, applied voltage, and electrodeposition time on the electrodeposition properties (such as deposition yield and throwing power of the resins) were investigated. Moreover, the deposited film could be thermally cured to have a crosslinked structure. It was found that a temperature above 160°C is required to crosslink the deposited resins.
Studies on flame retardancy of polyacrylonitrile fiber treated by flame‐retardant monomers in cold plasma
Authors: Akovali G. , Gundogan G.
Published: April 2003

Plasma polymer hexamethyldisiloxane, ethyldichlorophosphate and tris(butoxyethyl)phosphate modified polyacrylonitrile fibers were examined by FTIR, XRF, and SEM and the extend of flame retardancy introduced were checked. Certain levels of concentrations of flame‐retardant elements grafted or coated at the fiber surface during plasma treatment are believed to overcome some negative effects of a number of reactions that usually are concurrent with plasma polymerization, such as crosslinking.
Optical anisotropy of polyimide
Authors: Nakagawa Koichi
Published: April 2003

Optical anisotropy of polyimide films prepared from polyamic acid solutions was investigated by conoscopic observation and refractive index measurements. The conoscopic figure (crossed pattern) characteristic of a negative uniaxial crystal with its optic axis perpendicular to the film plane was observed for samples imidized on substrates. Uniaxial drawing of a polyamic acid cast film with 40 wt % solvent gave a highly oriented sample with an elongation of more than 80%. This sample had a conoscopic figure characteristic of a positive uniaxial crystal with its optic axis equivalent to the molecular c axis (parallel to the film plane). A large optical anisotropy (bire‐fringence 0.18) was observed in the film plane. The TE‐mode refractive index (parallel to the film plane) ranged from 1.64 to 1.82 at a wavelength of 633 nm according to the sample rotation. These values corresponded to the refractive indices perpendicular and parallel to the c axis, respectively. The optical system change of the polyimide film was explained in terms of the uniaxial orientation of the in‐plane oriented molecular c axis.
Pervaporation separation of ethanol–water mixtures using crosslinked blended polyacrylic acid (PAA)–nylon 66 membranes
Authors: Zhao X. P. , Huang R. Y. M.
Published: April 2003

The pervaporation separation of ethanol–water mixtures was carried out through a series of ionically crosslinked polyacrylic acid (PAA)–nylon 66 blended membranes crosslinked to varying degrees in aluminum nitrate solution. Optimum pervaporation results were obtained from crosslinked blends containing 75 wt % nylon 66 and 25 wt % PAA. The optimum crosslinking time was found to be between 30 and 40 h. The optimum operating temperatures of the pervaporation runs were found to be 2–3°C below the boiling points when the highest permeation flux reached 857.6 (g/m2 h) and the best separation factors (water/ethanol) were 10.1.
Kinetic effects on the impurities in epoxy‐resin/m‐xylylenediamine reaction
Authors: Abuín Senén Paz , Pellín Mercedes Pazos , Núñez Lisardo
Published: April 2003

Different isolated or competitive mechanisms have been experimentally observed in order to predict the kinetics of an epoxy—amine reaction in terms of various mathematical models based on different possibilities of reaction. Impurities such as water, glycols, and in general all donors of active hydrogen even at low concentrations significantly change the course of the reaction. We therefore decided to study the curing reaction of the epoxy resin, first as a commercial product and later purified, with m‐xylylenediamine of known purity. The extent of cure has been followed and determined by differential scanning calorimetry (DSC) and infrared spectroscopy (FT‐IR). Purity, epoxy content and OH content were measured by liquid chromatography HPLC and wet analysis.
Study of critical phenomena of polystyrene—poly(vinyl methyl ether) blends by solid state NMR
Authors: Chu C. W. , Dickinson L. C. , Chien James C. W.
Published: April 2003

Thermally induced phase separation in PS/PVME blends was studied by solid state NMR. The proton spin—lattice relaxation in both the laboratory and the rotating frame were measured for the entire range of blend composition. Under conditions in which the blends are said to be compatible by other techniques T results obtained at −5°C showed microheterogeneity at a 10−°A scale. T1pH values at room temperature are closer to the longer relaxation time of PS than that expected from simple weighted average of the relaxation times of the constituent homopolymers. This indicates incomplete averaging by spin diffusion and a restraining effect of PS on segmental motions of PVME. The blends were heated to cause phase separation and quenched. From the biphasic decay of 13C magnetization, the compositions of the separated phases were estimated to give a lower critical solution temperature phase diagram. NMR relaxation in PVME blends with PS molecular weights of 9, 100, and 900 K were compared.
Transport of a gas through asymmetric polysulfone membranes with deposited plasma‐polymerized thin layer
Authors: Sada E. , Kumazawa H. , Xu P. , Inoue H.
Published: April 2003

A plasma‐polymerized thin layer was deposited on the top surface of the skin layer of the asymmetric polysulfone (PSF) membrane to plug ultrafine pores passing through it. Trifluoromethane was used as the monomer gas of plasma polymerization. The steady‐state permeation rates for oxygen and nitrogen through the asymmetric PSF membranes with the plasma modification were measured to evaluate the permselectivity and permeability. If ultrafine pores passing through the asymmetric membrane can be plugged by the plasma‐polymerized thin layer, the separation factor of oxygen relative to nitrogen can be increased with the permeation rate coefficient of oxygen still kept large. This condition was met when the vaporization time of the cast solution during the preparation of an asymmetric membrane ranged from 10 to 120 s and the plasma polymerization time ranged from 15 to 30 min.
Crosslinking of an epoxy with a mixed amine as a function of stoichiometry. II. Final properties via dynamic mechanical spectroscopy
Authors: Wingard Charles D. , Beatty Charles L.
Published: April 2003

Variation of the epoxy/curing agent 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 and final dynamic mechanical properties of both the neat resin and glass reinforced epoxy. For a partial B‐stage cure to an ultimate C‐stage cure, optimum cure temperatures were obtained as a function of stoichiometry. For the ultimately cured (C‐stage) resin, the molecular weight between crosslinks (Mc) passed through a minimum, and both the glass transition temperature (Tg) and a secondary (sub‐Tg) transition passed through a maximum at the stoichiometric ratio. In addition, the activation energy of the ultimately cured resin passed through a maximum at or near the stoichiometric ratio for both the Tg and sub‐Tg transitions.
Study on tribochemical interaction of metals or metal oxides with polytetrafluoroethylene by X‐ray photoelectron spectroscopy
Authors: Gong De‐Li , Zhang Bing , Xue Quin‐Ji , Wang Hong‐Li
Published: April 2003

Tribochemical reactions of PTFE with aluminum, silicon, and iron during rubbing were detected by ESCA. No apparent relationship between this chemical reaction of the fillers with the PTFE in the composite and the wear‐reducing action of those fillers on the composite material was found.
Effects of temperature and catalyst level on the cure rate of fiber‐reinforced plastic (FRP)
Authors: Ozokwelu Enuma Dickson
Published: April 2003

In order to allow manufacturers of fiber‐reinforced plastic (FRP) products to determine an optimum catalyst level for their application, an investigation was made of the effects of ambient temperature and catalyst level on the gel time of polyester resins. Gel times were determined using standards set by the Society of the Plastics Industries, Inc.5 The gel times thus obtained compared favorably with published gel times for general purpose polyester resins. It will be left to the individual manufacturer to determine the optimum catalyst level for his or her application, as very short gel times will cause the resin to harden too quickly to allow fabrication of large parts. In general, the optimum catalyst level is defined as that which produces the shortest usable gel time.
Physical characterization of incompatible blends of polymethylmethacrylate and polycaprolactone
Authors: Iannace S. , De Luca N. , Nicolais L. , Carfagna C. , Huang S. J.
Published: April 2003

Blends of polymethylmethacrylate (PMMA) and poly‐ε‐caprolactone (PCL) were prepared and characterized. The analysis of the glass transition temperature indicates no compatibility of the two polymers, which segregated into two distinct phases. The fracture strength of the blends can be explained on the basis of a constitutive model of spheres of PCL embedded in a PMMA matrix. The trend of water sorption confirms the hypothesis of phase segregation of PCL in the glassy matrix of PMMA.
Synthesis and evaluation of methyl methacrylate copolymers and terpolymers as electron‐beam resists. I. Poly(methyl methacrylate–methacrylic acid–methacryloyl chloride)
Authors: Gitsov Ivan , Madjarova Nikolina A.
Published: April 2003

Terpolymers of methyl methacrylate with methacrylic acid and methacryloyl chloride [poly(MMA‐MAA‐MAC)] were synthesized with high yields by slow radical polymerization. The influence of the temperature of prebaking on the changes in the chemical composition and the molecular weight characteristics of poly(MMA‐5%MAA‐5%MAC) was studied by infrared spectroscopy and gel permeation chromatography. It was found that resists containing terpolymer with molecular weight (M̄w) of 41,000, which were prebaked at 100°C, were able to produce high contrast images (γ = 3.3) at doses of 16 μC/cm2.
Improvement of wood properties by impregnation with multifunctional monomers
Authors: Mathias Lon J. , Lee Soo , Wright John R. , Warren Stephen C.
Published: April 2003

Southern pine samples with different dimensions and bulk densities were impregnated with the multifunctional monomer ethyl α‐hydroxymethylacrylate (EHMA) and 5 mol % of fluorinated or nonfluorinated crosslinking agent. The maximum impregnation yield (105% by weight) was achieved under vacuum with good improvement of water repellency.

Impregnation with EHMA plus another multifunctional monomer 2‐vinyl‐4,4‐dimethyl‐2‐oxazolin‐5‐one (vinyl azlactone) was carried out to improve the mechanical properties of wood samples. Water repellency was also improved depending on the amount of vinyl azlactone in the monomer solution. A maximum of 41% antiswell efficiency (ASE) was obtained by impregnation with a 9 : 1 w/w mixture of EHMA and vinyl azlactone. Improvements of 38–54% in impact strength and 27–44% in compression modulus were achieved depending on the relative amount of vinyl azlactone incorporated. FT‐IR and solution or solid‐state NMR spectroscopy were used for chemical characterization of the polymers themselves and the wood‐polymer composites.
Highly fluorinated epoxy resin. II. Behavior in blend applications
Authors: Twardowski T. E. , Geil P. H.
Published: April 2003

The behavior of a highly fluorinated epoxy resin blended with Epon 828 was studied. The two resins are immiscible, resulting in 10–20‐μm spherical domains and a surface layer of fluorinated resin. A B stage for the blend providing for good ply lamination is indicated. The mechanical properties of the blend were commensurate with the Epon phase.
Modeling the bulk polymerization of methyl methacrylate with glycol dimercapto acetate as chain transfer agent
Authors: Destruel P. , Taufer M. , Granel C.
Published: April 2003

This paper investigates the bulk polymerization of methyl methacrylate (MMA) when chain transfer to a low‐molecular‐weight agent is important. A transfer rate constant and a transfer efficiency are introduced into the equations. Calculations of the kinetics of polymerization and of the weight‐average molecular weight distribution are in good agreement with experimental results.
Solubility parameters of polymethacrylonitrile, poly(methacrylic acid) and methacrylonitrile/methacrylic acid copolymer
Authors: Ho Bang‐Chein , Chin Wei‐Kuo , Lee Yu‐Der
Published: April 2003

The solubility behaviors of polymethyacrylonitrile (PMAN), poly(methacrylic acid) (PMAA), and its random copolymer methacrylonitrile (MAN)/methacrylic acid (MAA) in various solvents were investigated. The results were used in a computer program to obtain a 3‐dimensional representation of the polymer solubility region in the Hansen space. Thus, the values of dispersion (δd,p), polar (δp,p) and hydrogen bonding (δh,p) components of the total solubility parameter (δt,p) were obtained. Comparisons between the experimental results and the estimated values are discussed. Also, prediction for solubility parameter values for MAN/MAA copolymer via their homopolymers, PMAN, and PMAA has been evaluated.
Lifetime prediction of carboxyl‐terminated polybutadiene (CTPB)
Authors: Bilgin Ferda , Sage Tubitak , Orbey Nese , Guven Olgun
Published: April 2003

Carboxyl‐terminated polybutadiene (CTPB) was subjected to temperature and humidity aging in order to estimate its useful lifetime as a solid propellant binder. CTPB samples were temperature aged from 1 week to 7 months at various temperatures ranging from 50 to 100°C. At various stages of temperature aging, viscosity of the samples were measured, end group analyses were performed, and the samples, after being crosslinked with MAPO, were mechanically tested. As far as mechanical properties are concerned, the ultimate tensile stress of the samples decreases with temperature aging and strain at break increases. End group analyses indicate that acid value of the samples decreases with aging and viscosity increases. The results of temperature aging were applied to an Arrhenius type time‐temperature superposition relation and useful lifetime of CTPB as binder at 20°C was predicted to be around 10 years. The CTPB samples were also humidity‐aged and the effects of humidity aging on mechanical properties were investigated. The results indicate that similar to temperature aging, ultimate tensile strength decreases and strain at break increases with aging. The effects of humidity aging, however, is much less pronounced in comparison to temperature aging.
Radiation curable, micelle forming, block copolymers as soil release finishes for polyester fabrics
Authors: Warburton C. E.
Published: April 2003

Polyester fabrics were treated with aqueous solutions of block copolymers prepared from a polyethylene oxide diol, a diisocyanate, and 2‐hydroxyethyl acrylate. The copolymers formed micelles in aqueous solution. Electron beam irradiation in the wet state produced fabrics with much improved release of oily soil on laundering.
A comparative study on polymers containing different ultraviolet stabilizer moieties
Authors: Pasch H. , Shuhaibar K. F. , Attari S.
Published: April 2003

A number of styrene and methylmethacrylate copolymers containing different UV stabilizer units (benzophenone, phenylbenzotriazole, and naphthylbenzotriazole) fixed to the polymer backbone were characterized by UV spectroscopy and size exclusion chromatography. UV spectroscopy was found to be suitable for the determination of the copolymer composition and the stability of intramolecular hydrogen bonds, which are important for the performance of UV stabilizer molecules. The highest stability of the intramolecular hydrogen bond was obtained for phenylbenzotriazole containing polymers. Using size exclusion chromatography with refractive index and ultraviolet detection, it was shown that the UV stabilizer units were statistically distributed along the different molar mass fractions.
Effect of metal cation type on the structure and properties of ethylene ionomers
Authors: Hirasawa Eisaku , Yamamoto Yoshimasa , Tadano Kenji , Yano Shinichi
Published: April 2003

Thermal properties by DSC, stiffness, melt viscosity, tensile properties, and dynamic mechanical properties were measured for the Na+, K+, Mg2+, Zn2+, Cu2+, Mn2+, and Co2+ salts of poly(ethylene‐co‐methacrylic acid) (EMAA). The changes in the structure and properties with increasing neutralization are larger in the alkaline and alkaline earth metal salts than in the transition metal salts. The stiffness shows a maximum at 33% neutralization in both the alkaline and alkaline earth metal salts, while no maxima are found up to 60% neutralization in the transition metal salts. The microphase separation of salt group aggregates is observed in both the alkaline and alkaline earth metal salts, but is not seen in the transition metal salts. These differences were attributed to both the stronger ionic interactions and the larger number of carboxyl groups associated with the alkaline and alkaline earth metal salts in the ordered structure of ionic salt groups (ionic crystallites). The mechanical properties measured at low strain, such as stiffness and yield stress, strongly depend on the degree of the crystalline order of the ionic crystallites. The high‐strain properties, such as tensile strength and elongation at break, depend on the strength of the ionic interactions and the valence of the cation.
The heterogeneous character of the dilute acid hydrolysis of crystalline cellulose. II. Hydrolysis in sulfuric acid
Authors: Lin Chyong‐Huey , Conner Anthony H. , Hill Charles G.
Published: April 2003

Nine prehydrolyzed cellulose samples, including native, mercerized, and regenerated celluloses were hydrolyzed in 2% sulfuric acid at 150, 160, and 170°C. The first‐order rate constants and the weight average degrees of polymerization (by size exclusion chromatography) were determined for each sample. The results indicate that Sharples' end‐attack model [Trans. Faraday Soc., 53, 1003 (1957)] is consistent with kinetic data for cellulose II samples, but is not appropriate for characterizing the reactions of cellulose I samples.
Acid–Base interactions in filler characterization by inverse gas chromatography
Authors: Tiburcio Astrophel C. , Manson John A.
Published: April 2003

Glass beads as model fillers were characterized by inverse gas chromatography (IGC) according to the Lewis acid–Lewis base (donor–acceptor) concepts as adapted by Fowkes. A range of organic probes (acidic chloromethanes, neutral n‐alkanes, and basic acetone and diethylether) was used to elucidate the acid–base nature of the glass bead surface. The untreated glass bead surface was found to contain predominantly acidic sites while the treated glass bead (treated with an aminopropyltriethoxysilane coupling agent) was more basic than its unmodified counterpart. Calculation of the enthalpies of acid–base interactions (ΔHab) form the retention behavior of the basic probes with the two glass beads produced at least an 8‐kJ/mol difference between the two glass types, the ΔHab of the untreated glass being greater than the treated glass. A difference of this magnitude is sufficient to produce a corresponding difference in the interfacial behavior of the two glass types. Therefore, IGC can be used as a quantitative technique for characterizing filler surfaces.
Studies on the preparation and properties of conductive polymers. Part II. Novel method to prepare metallized plastics from metal chelates of polyamides
Authors: Yen Chih‐Chao , Huang Chueh‐Jung , Chang Teh‐Chou
Published: April 2003

New metallized films were obtained by the reduction of polyamide metal chelate films with reducing agents. Polyamide metal chelates films exhibited excellent surface resistivity around 10°–101 Ω/cm2 when treated with sodium borohydride aqueous solutions. Aqueous solutions of polyamide–formic acid with metal salts, and films prepared from those solutions, were analyzed by UV‐visible and IR spectroscopy, respectively, in order to investigate and identify the structure of the polyamide metal chelates. Factors that include kinds and concentrations of metal salts, kinds and concentrations of reducing agents, and reduction time, which may affect the conductivity of metallized films, were investigated. The surfaces of these films were treated with sodium borohydride aqueous solution to form a definite metallic luster appearance. The surfaces of these conductive films were proved to be metallized, by means of ESCA analysis. The strongly adhered metal on the films was believed to be responsible for the improvement in electrical conductivity. The mechanical properties and scanning electron microscope (SEM) observations were also studied.