bluuebunny/crossref_metadata_2025_split huggingface dataset:
The formation of polymerizable tubules
Authors: Lando J. B. , Hansen J. E. , Sudiwala R. V. , Rickert S. E. 
Published: April 2003

AbstractWe have been investigating the crystallization behavior of the phospholipid amphiphile, 1,2 bis (10, 12‐tricosadiynol)‐sn‐glycero‐3‐phosphocholine, DC8,9PC, which forms both vesicles and hollow tubules as well as Langmuir Blodgett monolayers and multilayers. This material has polymerizable diacetylene groups in equivalent positions on the two hydrocarbon tails. The direct crystallization from solution of this amphiphile has been studied using different solvent mixtures and temperatures. The Langmuir Blodgett technique was also used to compress and orient the tubules.
Development of polyaniline–lithium secondary battery
Authors: Matsunaga Tsutomu , Daifuku Hideharu , Nakajima Tadashi , Kawagoe Takahiro 
Published: April 2003

AbstractA series of coin‐type lithium secondary batteries with polyaniline positive electrodes was developed and commercialized which might be not only the first practical polymer battery but also the first industrial application of conducting polymers. Performances of the commercialized batteries were described in detail in this paper.In order to achieve the development the most important thing was the optimization of molecular structure and molphology of multiguise polyaniline as the electrode material. According to the findings obtained during the development, polyaniline sheet was prepared substantially to be composed of imino‐1,4‐phenylene (IP) and the cation radical of IP (IP+) by the novel procedure, not to include quinoid configuration of polyaniline (NP) which was proved to be electrochemically inactive in non‐aqueous systems.
Mechanical and dielectric relaxations in liquid crystalline copolyesters
Authors: Green D. I. , Davies G. R. , Ward I. M. , Alhaj‐Mohammed M. H. , Jawad S. Abdul 
Published: April 2003

AbstractDynamic mechanical measurements in tension and torsion on oriented tapes and monofilaments of a range of liquid crystalline polyesters have been combined with dielectric measurements to obtain a molecular understanding of the relaxation processes.This paper extends our previous work [1,2,3] on polyesters of hydroxybenzoic acid (HBA) and hydroxynaphthoic acid (HNA) to related polymers containing dihydroxynaphthalene (DHN) and terephthalic acid (TPA) or biphenyl (BP) and TPA in place of the HNA. It confirms the association of the β and γ processes with naphthyl and phenyl moieties but shows that the processes cannot be due simply to the independent motions of single units.
Synthesis and degradation of cyano‐containing aramids
Authors: Kim S. , Pearce E. M. , Kwei T. K. 
Published: April 2003

AbstractVarious aramids having a cyano group on the diamine ring were synthesized. Aramids containing a cyano group ortho to the amide bond underwent thermal degradation via a two step mechanism, whereas those containing a cyano group meta to the amide bond did not. The first step represented the loss of HCN resulting in benzoxazole polymers, which degraded further in the second stage producing high char yield at 900°C. The thermal studied of copolyamides from m‐phenylenediamine, 2,4‐diaminobenzonitrile, and iso‐ or terephthaloyl chloride showed that as the mole fraction of 2,4‐DABN increased the initial decomposition temperature decreased, but the char yield and glass transition temperature increased gradually from the poly(1,3‐phenylene isophthalamide) to the polycyanamide homopolymer. To confirm the nucleophilic displacement reaction mechanism rather than isomerization cyclization suggested by Barashkov et al. for aramids with the cyano group ortho to the amide bond, a high‐temperature cell attached to a FT‐IR spectrometer were employed. Model compound studies also showed evidence for the benzoxazole ring formation.
Raman spectroscopic study of the effect of take‐up speed on conformation, orientation, and crystallinity in PET fibers
Authors: Bulkin Bernard J. , Deblase Frank J. , Lewin Menachem 
Published: April 2003

AbstractThe dependence of the Raman spectrum of PET fibers on take‐up speed (TUS) during high‐speed spinning is examined. It is found that conformational change, orientation, and crystallinity, all different functions of TUS as a processing variable, are reflected in the spectra. The data, as well as those from thermal annealing of PET fibers, are shown to be consistent with those from other techniques, leading to a set of equations from which a number of properties of the PET fibers can be determined from the Raman spectrum alone.
The thermal properties of poly(oxy‐1,4‐benzoyl), poly(oxy‐2,6‐naphthoyl), and its copolymers
Authors: Cao Mao‐Yong , Varma‐Nair Manika , Wunderlich Bernhard 
Published: April 2003

AbstractThe thermal properties, i.e., heat capacity, enthalpy, entropy, and Gibbs function, and the transition behavior of the copolymer system of 4‐hydroxybenzoic acid and 2,6‐hydroxynaphthoic acid have been studied based on differential scanning calorimetry. The heat capacities of the glass, crystal, and anisotropic melt are shown to be largely additive on a molar basis. Additivity is lost in the two transition regions, glass transition and disordering transition. Isothermal crystallization experiments on the copolymers revealed the existence of two types of crystals which melt at high temperature (fast‐grown crystals) and low temperature (slowly grown crystals). The ATHAS computation method is used to bring heat capacities of the solid state into agreement with approximate frequency spectra. The changes in heat capacity at the glass transitions occur at 434°K for the poly(oxy‐1,4‐benzoyl) [33.2 J/(K mol)] and at 420°K for poly(oxy‐2,6‐naphthoyl) [46.5 J/(K mol)]. The copolymers have a transition range of above 100°K. The anisotropic melt is linked to the well‐known condis state of poly(oxy‐1,4‐benzoyl) by a continuous changes in disorder and mobility without an additional first‐order transition.
Electro‐oxidative polymerization of 1,3‐Cyclohexadiene
Authors: Yamamoto Kimihisa , Asada Toshio , Nishide Hiroyuki , Tsuchida Eishun 
Published: April 2003

Abstract1,3‐Cyclohexadiene is electropolymerized at a lower applied potential, compared with the polymerization of other alkene compounds, to give insoluble polymer film on an electrode. The formed polymer contains a phenylene repeated unit, which is confirmed by IR, 1H‐ and 13C‐NMR spectroscopy. Poly(cyclohexene) produced by the electropolymerization is partially aromatized by the oxidation to form a phenylene unit which is accompanied by an elimination of a proton.
ESR imaging study of the spin distribution in ladder type polymer films containing spatially selective conducting patterns
Authors: Dahm J. , Davidov D. , Macho V. , Spiess H. W. , McLean M. R. , Dalton L. R. 
Published: April 2003

AbstractStable patterns with high local electrical conductivities and different local spin densities can be created in ladder type polymer films (5–20 μm thickness) by first preheating to a temperature (Tp) followed by spatically selective laser annealing. Two dimensional images of the spin distribution in such films were determined using ESR imaging. The 2‐D images of 20 μm films exhibit peaks or dips in the spin density at the laser illuminated regions, which strongly depend on the preheating conditions. These phenomena are attributed to spin density gradients caused by a temperature gradient across the film upon illumination; it should be noted that the laser beam does not penetrate completely through such relatively thick films.
Recoverable polyimides. (II): DSC studies of copolymers from 4, 4′‐dithiodianiline bismaleimide (DTDA‐BM) and aromatic diamines
Authors: Wu Yulong , Tesoro G. C. 
Published: April 2003

AbstractInterest in the recently reported polyimide resins containing disulfide bonds, which could be cleaved by reduction for reprocessing and/or recovery, prompted the present investigation of polymers and copolymers of the DTDA bismaleimide previously described. Differential scanning calorimetry (DSC) studies were carried out to identify the structures, curing conditions and modifications of reduced products of potential value for industrial applications. Results have shown that selected cured copolymers of DTDA bismaleimide with aromatic diamines can be solubilized by reduction and reset in subsequent reactions to yield thermosets of satisfactory properties.
The utilization of SANS to solve polymer latex structural problems: Basic science and engineering
Authors: Sperling L. H. , Klein A. , Yoo J. N. , Kim K. D. , Mohammadi N. 
Published: April 2003

AbstractSmall‐angle neutron scattering studies have been used to clarify several aspects of the internal structure of latexes and subsequent film formation modes. This paper reviews work both around the world and at Lehigh University on those subjects. Two points have been made clear: (1) The appearance of core‐shell phenomena in latexes depends on the size of the polymer chain to that of the latex particle; the phenomenon is most marked when the radius of gyration of the chain is about one fifth as big as the latex radius. (2) Strength build‐up during film formation depends on the extent of interdiffusion of the chains. For moderate molecular weights, interdiffusion distances of one radius of gyration yield maximum strength. For both moderate (250,000 g/mol) and high (2,000,000 g/mol) molecular weights, full strength was achieved in two hour's annealing time at 144°C.
Visible laser sensitive photopolymers initiated by dye sensitized peroxyester systems
Authors: Yamaoka Tsuguo , Nakamura Yasuo , Koseki Kenichi , Shirosaki Tsutomu 
Published: April 2003

AbstractThe photoinitiating systems comprising of the peroxide, 3,3′,4,4′‐tetrakis(t‐butylperoxycarbonyl)benzophenone and (keto)coumarin dyes were sensitive to visible light to give photopolymers for argon ion laser exposure. The sensitivity of the photopolymer depends on the matrix polymer, and the highest sensitivity to 488 nm light of the argon ion laser, 0.01 mJ/cm2, was obtained with a poly(N‐vinyl‐2‐pyrrolidone) matrix. The sensitization of the peroxide by the dye is due to electron transfer from the excited dye to the peroxide.
Bistable electro‐optical switching for (liquid crystalline polymer)/(low molecular weight liquid crystal) composite system
Authors: Kikuchi Hirotsugu , Moritomi Satoru , Hwang Jenn Chiu , Kajiyama Tisato 
Published: April 2003

AbstractA series of thin films composed of liquid crystalline polymer (LCP) and low molecular weight liquid crystal (LMWLC) was prepared by a solvent‐casting method. LMWLC is miscible over a whole range of LCP concentrations in isotropic and mesomorphic states. The composite system formed a smectic phase in a LCP weight fraction range above 50%. Reversible and bistable electro‐optical effects based on light scattering were recognized for a smectic phase of the binary composite composed of LCP and LMWLC. A light scattering state appeared in the case of application of an a.c. electric field below a threshold frequency (fc). Furthermore, application of an a.c. field above fc made the transmission light intensity increase. Such phenomena were induced in conjunction with the two types of effect: one is an electric field effect based on the dielectric anisotropy of the mesogenic side chain; and the other is an electric current effect based on the electrohydrodynamic motion of the main chain. In the case of a smectic mesophase, the turbid and transparent states remained unchanged, even though the electric field is removed (memory effect).
Reversible alignment change of nematic liquid crystals by photochromic polymer films
Authors: Kawanishi Yuji , Seki Takahiro , Tamaki Takashi , Ichimura Kunihiro , Ikeda Mitsuhiro , Aoki Koso 
Published: April 2003

AbstractThe alignment of a nematic liquid crystal (LC) was changed reversibly by a photochromic reaction of vinyl‐polymer films bearing azobenzene (Az) chromophores. Photoisomerization of Az in the polymer films proceeded slower than in solution systems with an irreversible nature, due to a limited free volume of polymers and the presence of Az aggregates. Photoregulative Az films were obtained by two procedures: (i) spin‐coating followed by baking processes: and (ii) adsorption from a LC/polymer mixture onto a lecithin‐coated glass surface. Perpendicular alignment, which is achieved both in the surface Az and in the LC layer, allows a parallel interaction between them and enables the photoregulation of the LC alignment.
Anionic living polymerization of 4‐[bis(trimethylsilyl)methyl]styrene and its properties as a resist material
Authors: Kato N. , Nagasaki Y. , Kato M. 
Published: April 2003

AbstractAn anionic polymerization of 4‐[bis(trimethylsilyl)methyl]styrene (BSMS) proceeded homogeneously to give a polymer with a narrow molecular weight distribution (MWD; Mw/Mn = 1.06–1.07) even at 20°C. The relative lower propagating rate owing to the electron‐donating character of the para standing bis(trimethylsilyl)methyl group in BSMS (σ—π hyperconjugation) plays an important role for formation of the poly(BSMS) with a narrow MWD, even at a high polymerization temperature. Poly(BSMS) thus obtained had a high silicon content (24.1 wt%) and a fairly high glass transition temperature (140–150°C). Properties as an electron‐beam resist for poly(BSMS) were investigated. The polymer was found to be a negative‐type resist with a high contrast value (γ = 4.7) and a sensitivity about twice on high as poly(styrene). These facts may be attributable to the high Tg content, the narrow molecular weight distribution, and the characteristic structure of poly(BSMS).
Novel graft copolymers for in vivo targeting of colloidal carriers
Authors: Arshady R. , Illum L. , Davis S. S. 
Published: April 2003

AbstractA series of novel graft (comb) copolymers composed of a hydrophobic backbone and hydrophilic side chain grafts are described for the in vivo targeting of colloidal carriers. The new copolymers, when coated on nanometer size particles (nanospheres, nanocapsules), substantially reduce the capture of the particles by the reticuloendothelial system (RES) and show potential for targeting to the bone marrow.
Wavelength dependence of laser polymerization of acrylic monomers
Authors: Magan John D. , Blau Werner , Woods John G. 
Published: April 2003

AbstractPhotopolymerization of multifunctional acrylic monomers using excimer and Nd: YAG lasers operated at five different UV wavelengths is reported. The effects of different wavelengths on the surface and bulk cure both in air and under argon are investigated and discussed.
Properties of blends containing two liquid crystalline polymers
Authors: Kenig Samuel , DeMeuse Mark T. , Jaffe Michael 
Published: April 2003

AbstractBlends containing two, wholly aromatic, naphthalene‐based liquid crystalline polymers (LCPs) are studied. Experimental results show that the viscosities of the resulting blends are lower than the parent LCPs over the entire shear‐rate range investigated. The orientation development following capillary flow demonstrates, that over a defined blend composition range, some blends have higher orientability than the constituent polymers. This is further manifested in the tensile and flexural properties of injection‐molded specimens. A detailed analysis indicates that in the composition range where synergistic effects are observed in orientation development as well as in mechanical properties, only one glass transition temperature is detected. This suggests that “miscibility” is desirable for obtaining maximum properties in these blend systems.
Factors which affect the glass transition and damping capability of polymers
Authors: Sperling L. H. , Fay J. J. 
Published: April 2003

AbstractThe shape of the glass transition plays a critical role in the engineering performance of polymers in sound and vibration damping, as well as other applications. The transition may be affected by fillers, plasticizers, blending, IPN formation, etc. A collection of data, both original and literature, is presented which illustrates how the phenomenon works. Emphasis is placed on the role of the area under the linear loss modulus–temperature curve, which may be evaluated in a fashion similar to other spectroscopic techniques. In addition, the loss area can be significantly affected by morphological factors.
Real‐time X‐ray scattering study during heating of oriented injection‐molded polyethylene
Authors: Rueda D. R. , Ania F. , López‐Cabarcos E. , Baltá‐Calleja F. J. , Zachmann H. G. , Bayer R. K. 
Published: April 2003

AbstractHighly oriented linear polyethylene was prepared by elongational flow injection molding. The changes in crystal orientation were investigated as a function of temperature by real‐time wide‐angle X‐ray diffraction. Additionally, the influence of molecular weight upon the microstructure and the changes in orientation, during heating near the melting point, and after cooling have been examined. A shish‐kebab structure is inferred for the high molecular weight samples (Mw≥105) from SAXS observations, while for samples with Mw<105 only an oriented lamellar structure is found. Consequently, a higher thermal stability is shown by the higher molecular weight samples. Furthermore, a recovery of crystal orientation on rapid cooling of the samples from the melt is only observed for samples with Mw≥105. The results are discussed in terms of a preferential recrystallization of chain‐folded lamellae, on cooling, onto the shish fibrils which survive at high temperature.
POE incorporation into ionic clusters of ionomer and ion‐conduction behaviors
Authors: Takeoka S. , Sakai H. , Shin H. , Ohta T. , Tsuchida E. 
Published: April 2003

AbstractPoly(oxyethylene) (POE) was incorporated into the ionic clusters of ionomers, ethylene and methacrylic acid (7.2% neutralized with KOH) copolymer membrane. The changes of properties were studied from SAXS, DSC, IR and ionic conductivity. The IR study suggested that the coordinated structures in ionic clusters of the membrane were destroyed by POE incorporation, and also SAXS suggested that ionic clusters were swollen by POE incorporation. The ionic conductivity, a carrier being K+ in this system, increases from 10−16 S/cm to 10−9 S/cm at 30°C by the incorporation of POE (20.5 wt%). On the other hand, a large amount of POE (63 wt%) could be incorporated into ionomer membrane by the esterification of methacrylic acid groups (93%) with POE. When LiClO4 was added, ionic conduction occurred in the phase‐separated POE domain, which had a low glass transition temperature (−55.2°C), showing an ionic conductivity 2.6 × 10−6 S/cm at 25°C.
Preparation of polymer nanocomposites with “ultrahigh” refractive index
Authors: Weibel M. , Caseri W. , Suter U. W. , Kiess H. , Wehrli E. 
Published: April 2003

AbstractNanocomposites of lead sulfide and several polymers, especially poly(ethyleneoxide), were prepared by coprecipitation of lead sulfide and polymer, followed by a drying and pressing procedure. Such nanocomposites consist of ca. 90% w/w (or ca. 50% v/v) lead sulfide, of particle dimensions of 2–40 nm. The refractive index of these materials is on the order of 3 and therefore, to the authors' best knowledge, is the highest reported for any polymer composite.
Design of high‐capacity, reversible polymeric adsorbents for acidic gases
Authors: Andreopoulos A. G. , Economy J. 
Published: April 2003

AbstractPolyethyleneimine (PEIM) samples crosslinked by a commercial epoxy resin (Epon 828) were prepared, and their adsorption capacity for acidic gases was studied. The swelling and deswelling characteristics of the crosslinked samples were also examined as part of this program. Reactivation of these adsorbents could be carried out by heat, or by a combination of heat and treatment in dilute alkalies.
Polystyrene microspheres with narrow particle size distribution
Authors: Wang Shen‐guo , Zhang Xiao‐qin 
Published: April 2003

AbstractCrosslinked polystyrene microspheres of a diameter of the order of more than 2 μm and a narrow particle diameter distribution were synthesized by emulsifier‐free emulsion polymerization. The dependence of various parameters such as an electrolyte (NaCl), an initiator (K2S2O8), the phase volume ratio, the reaction temperature and time on the diameter and the particle size distribution has been discussed.
Copolymerization of methacrylic acid alkali metal salts and polyether‐containing monomers in solid polymer electrolytes
Authors: Ohno Hiroyuki , Ito Kaori 
Published: April 2003

AbstractCopolymerization of methacrylic acid alkali metal salts (MAAM; M = Li, Na, K, Rb or Cs) and oligo(oxyethylene) methacrylate (MEO) was carried out in bulk or in poly(oligo(oxyethylene) methacrylate) (PMEO) at 60°C. The copolymers of MAAM and MEO which were obtained by bulk polymerization showed a cation conductivity of around 1 × 10−7 S/cm at room temperature. On the other hand, the copolymers obtained by radical polymerization in PMEO, showed a higher cation conductivity (10−6–10−5 S/cm). Furthermore, higher cation conductivity was observed for the copolymer systems containing alkali metal cations with a larger ion radius. This tendency was explained by the strength of the bond between alkali metal cation and ether oxygens. The degree of dissociation had little effect on this difference in the conductivity. The effective dissociation of methacrylic salts was enhanced in the copolymer compared to the homopolymer because of the suppression of the adjacent dissociative carboxylic acid groups. Arrhenius plots for ionic conductivity show the migration of ions along with the segmental motion of the polymer matrix.
Durability of polyurethanes elastomers
Authors: Buchman Alisa , Holdengraber Yitzhak , Dodiuk Hanna , Kenig Shmuel 
Published: April 2003

AbstractThe effect of thermal aging on three different elastomeric polyurethane adhesives was studied. Consequently, an attempt was made to predict the polyurethanes' service lifetimes from the changes in tensile properties, hardness of bulk specimens and adhesion strength properties (lap shear and butt joints) of polycarbonate bonded joints. Aging temperatures ranged from ambient to 70 °C (at 50% relative humidity) for durations from 20 days to 18 months.Experimental results were analyzed according to a kinetic rate theory and using limit values for the various properties. Consequently, service lifetimes were determined and compared to results from actual service life. Predictions of long‐term performance from accelerated tests proved to be reasonable for the properties and materials studied.