bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of vacuum‐ultraviolet laser wavelengths on the surface treatment of polyolefinic polymers
Authors: Kesting Wolfgang , Bahners Thomas , Schollmeyer Eckhard 
Published: April 2003

AbstractThe laser‐induced modification of the surface morphology of poly(propylene) fibers and films was investigated. It is known that strongly absorbing fibers such as poly(ethylene terephthalate) and polyamide obtain characteristic surface morphologies after treatment with 193 or 248 nm laser irradiation. Polyolefinic material cannot be modified directly (i.e., without doping) by irradiation with these wavelengths. Therefore experiments were carried out using a 157 nm F2‐laser. After irradiation in a vacuum chamber at fluences in excess of 50 mJ/cm2 poly(propylene) also reveals the well‐known surface morphology. Compared with aromatic polymers a rather high number of pulses is needed to generate the effect. © 1993 John Wiley & Sons, Inc.
Glass transition, crystallization, and morphology relationships in miscible poly(aryl ether ketones) and poly(ether imide) blends
Authors: Hsiao Benjamin S. , Sauer Bryan B. 
Published: April 2003

AbstractThe relationships among glass transition, crystallization, melting, and crystal morphology of poly(aryl ether ketone) (PAEK)/poly(other imide) (PEI) blends was studied by thermal, optical and small‐angle x‐ray scattering (SAXS) methods. Two types of PAEK were chosen for this work: poly(aryl ether ether ketone), PEEK, and poly(aryl ether ketone ketone), PEKK, which have distinctly different crystallization rates. Both PAEKs show complete miscibility with PEI in the amorphous phase. As PAEK crystallizes, the noncrystallizable PEI component is rejected from the crystalline region, resulting in a broad amorphous population, which was indicated by the broadening and the increase of Tg over that of the purely amorphous mixture. The presence of the PEI component significantly decreases the bulk crystallization and crystal growth rate of PAEK, but the equilibrium melting temperature and crystal surface free energies are not affected. The morphology of the PEI segregation was investigated by SAXS measurements. The results indicated that the inter(lamellar‐bundle) PEI trapping morphology was dominant in the PEEK/PEI blends under rapid crystallization conditions, whereas the interspherulitic morphology was dominant in the slow crystallizing PEKK/PEI blends. These morphologies were qualitatively explained by the expression δ=D/G, where G was the crystal growth rate and D was the mutual diffusion coefficient. © 1993 John Wiley & Sons, Inc.
Structure/permeability relationships of polyimides with branched or extended diamine moieties
Authors: Stern S. A. , Liu Y. , Feld W. A. 
Published: April 2003

AbstractMean permeability coefficients for CO2, O2, N2, and CH4 in seven types of 6FDA polyimides with branched or extended diamine moieties were determined at 35.0°C (95.0°F) and at pressures up to 10.5 atm (155 psia). In addition, solubility coefficients for CO2, O2, N2, and CH4 in six of these polyimides were determined at 35.0°C and at 6.8 atm (100 psia). Mean diffusion coefficients for the six gas/polyimide systems were calculated from the permeability and solubility data. The relationships between the chemical structure of the polyimides, some of their physical properties (glass transition temperature, mean interchain spacing, specific free volume), and their gas permeability, diffusivity, and solubility behavior are discussed. The 6FDA polyimides studied here exhibit a considerably lower selectivity for the CO2/CH4 and O2/N2 gas pairs than 6FDA polyimides with short and stiff aromatic diamines with comparable CO2 and O2 permeabilities. © 1993 John Wiley & Sons, Inc.
Rotor‐synchronized two‐dimensional 13C CP/MAS NMR studies of the orientational order of polymers. I. High‐performance ultrahigh molecular weight polyethylene fibers
Authors: Tzou D. L. , Huang T. H. , Desai P. , Abhiraman A. S. 
Published: April 2003

AbstractThe orientational order of three morphological components, identified previously as two crystalline components, C1 and C2, and an amorphous component, A of four polyethylene fibers, including two gelspun ultrahigh molecular weight (PE‐I and PE‐II) and two meltspun moderate molecular weight (PE‐D and PE) polyethylene fibers are further analyzed by rotor‐synchronized two‐dimensional 13C CP/MAS (ROSMAS) nuclear magnetic resonance (NMR) techniques. Our results indicate that the orientational order of these components differ substantially among themselves in a given fiber and among different fibers of the same component. Values of β1/2, the polar angle at which the orientational distribution function (ODF) P 〈β〉 decays to half its maximum, are determined to be: 18° (C2 of PE‐II), 21° (C2 of PE‐I), 29° (C2 of PE‐D), 31° (C1 of PE‐I) and 50° (C2 of PE). No orientational sideband can be detected for component A, suggesting that the A component is due to the amorphous domain. The implication of this results and the technical limit of this technique are analyzed. © 1993 John Wiley & Sons, Inc.
Intramolecular interactions in poly(styrene‐co‐acrylonitrile)/poly(ε‐caprolactone) blends
Authors: Janarthanan V. , Kressler J. , Karasaz F. E. , Macknight W. J. 
Published: April 2003

AbstractSpecific interactions in blends of poly(ε‐caprolactone) (PCL) and poly(styrene‐co‐acry‐lonitrile) (SAN) were studied as a function of copolymer composition and blend ratio by using Fourier‐transform infrared spectroscopy (FTIR). It was shown that miscibility occurred within a certain range of copolymer compositions because the presence of PCL reduced the thermodynamically unfavorable repulsion between styrene and acrylonitrile segments in the random copolymer. This effect was observed in terms of a shift to higher frequencies in the 700 cm‐1 γ‐CH out‐of‐plane deformation vibration absorption of styrene and in the approximately 2236 cm−1 CN stretching frequency band in acrylonitrile segments. Specific intermolecular interactions between SAN and PCL were not observed in this study. © 1993 John Wiley & Sons, Inc.
Birefringence in polycarbonate: Molecular orientation induced by cooling stresses. II. Effects of sectioning
Authors: Wimberger‐Friedl R. , De Bruin J. G. 
Published: April 2003

AbstractBirefringence distributions in cross‐sections of quenched polycarbonate disks are investigated. The effects of the introduction of new surfaces by sectioning are studied by using different cross‐section widths, by quenching rod‐shaped specimens, and by measuring the birefringence with oblique incident light. The experimental results are confirmed by numerical calculations of stress distributions in rods with varying aspect ratios. Stress release by appropriate sectioning is used to distinguish between stress and orientation contribution to birefringence. It is found that cutting cross‐sections leads to a major stress redistribution in the width direction. This does not affect the birefringence measurement, but the decrease of the stress level in the long direction needs to be taken into account. The molecular orientation in the quenched samples cannot be explained only by the effect of transient thermal stresses above the glass transition. There is another orientation contribution, most likely related to stress relaxation below Tg. © 1993 John Wiley & Sons, Inc.
Miscibility of a polyarylate with a liquid crystalline copolyester
Authors: Wang Li‐Hui , Porter Roger S. 
Published: April 2003

AbstractThe miscibility has been investigated for binary blends of a polyarylate (PAr) with a liquid crystalline copolyester of p‐hydroxybenzoate and ethylene terephthalate units in a 6/4 molar ratio (PET/PHB). The binary blends were prepared by solution precipitation. The transitions of the PET/PHB have been measured with a rheometrics dynamic spectrometer. The phases in blends have been studied with a differential scanning calorimeter, by ther‐mogravimetry and with a polarizing optical microscope. The blends exhibit two glass transitions (Tgs) over the composition range 10–90 wt %. The amorphous PET phase from the PET‐PHB is found to be partially miscible with PAr, which leads to a decrease of the PAr Tg. The amount of this partially miscible portion of PET has been estimated by the Couch‐man equation. On heat treatment of the blends at 250 to 300°C, transesterficiation takes place, as judged by the shift of the higher of the two Tgs. © 1993 John Wiley & Sons, Inc.
Charge‐mosaic membrane from gamma‐irradiated poly(styrene‐butadiene‐4‐vinylpyridine) triblock copolymer
Authors: Liang Liang , Ying Shengkang 
Published: April 2003

AbstractPoly(styrene‐butadiene‐4‐vinylpyridine) triblock copolymers were prepared from styrene (S), butadiene (B), and 4‐vinylpyridine (P) by sequential anionic polymerization with n‐butyllithium as initiator and benzene as solvent. The triblock copolymer was characterizated by gel‐permeation chromatography (GPC), transmission electron microscopy (TEM), and viscoelastic spectrometry. Films of the triblock copolymer cast from solution in mixtures of chloroform and n‐butyraldehyde were subjected to gamma‐ray irradiation to form cross‐linked networks, Cationic and anionic groups were introduced by sulfonation and quater‐nization to obtain charge‐mosaic membranes. The resulting membrane had substantial cation‐exchange and anion‐exchange capacities. The membranes were very permeable to electrolyte (JKCI = 2.10×10−8 mol/cm2 s). © 1993 John Wiley & Sons, Inc.
Orientation distribution of liquid‐crystalline polyester sheets studied by polarized infrared spectroscopy
Authors: Kaito Akira , Kyotani Mutsumasa , Nakayama Kazuo 
Published: April 2003

AbstractPolarized infrared spectroscopy was applied to evaluate the orientation distribution in extrusion‐molded sheets of a liquid‐crystalline copolyester consisting of 73 mol % of 4‐hydroxy benzoic acid units and 27 mol % of 2‐hydroxy‐6‐naphthoic acid units. The surface orientation function was evaluated from the polarized attenuated total reflection/Fourier transform infrared spectra and the polarized specular reflection spectra. In the case of the specular reflection method, the absorption and refractive indices were obtained from the specular reflectance using the Kramers–Kronig relation and the Fresnel equation. On the other hand, the microscopic orientation functions inside the sheets were evaluated by Fourier‐transform infrared microspectroscopy. The polarized FTIR microspectra of microtomed section of sheets were measured in a microscopic domain as small as 40 μ at various positions from the center of the sheet. The surface orientation function was shown to be higher than the interior orientation function. Orientation functions obtained by the spectroscopic techniques are lower than crystal orientation functions determined by wide‐angle x‐ray diffraction, implying that the crystal orientation function is higher than the orientation function of noncrystalline molecular chains. The orientation distribution in the sheet is discussed in relation to the morphological structures studied by scanning electron microscopy. © John Wiley & Sons, Inc.
Small‐angle x‐ray scattering of distorted lamellar structures
Authors: Sasanuma Yuji , Abe Akihiro , Sasanuma Takako , Kitano Yukishige , Ishitani Akira 
Published: April 2003

AbstractSmall‐angle x‐ray scattering (SAXS) intensity for the lamellar structure of polymeric materials has been formulated with consideration of structural defects such as the finiteness of the lamellar stack, the lamellar bend, and the paracrystalline distortions. In particular, the effects of the lamellar bend on the SAXS profile have been elucidated on the basis of Vonk'xss formula γ1(x) – γ(x)exp(−2x/d). Here, the scattering profile due to the lamellar bend is shown to be expressed by a Cauchy function. The integral breadth is equal to 2π/d, being independent of the order of scattering. As an example of the SAXS analysis based on the theory, the characterization of the lamellar structure in the “hard” elastic polypropylene films is reported. The long period and the lamellar thickness are evaluated from the correlation function, and the distortion length and Hosemann's g factor are estimated according to the procedure presented here. On the basis of these structural parameters, the relationship between the manufacturing process and the lamellar structure of the polypropylene films is discussed. © 1993 John Wiley & Sons, Inc.
Characterization of amorphous carbon films by 13C CP MAS NMR spectroscopy
Authors: Beamson G. , Brennan W. J. , Clayden N. J. , Jennings R. C. K. 
Published: April 2003

Abstract13C CP MAS NMR spectroscopy was used to characterize α‐C:H materials generated from methane and hydrogen mixtures using a microwave plasma. Dipolar dephasing experiments indicate a range of Tdd making quantification of quaternary “diamond”‐like carbons difficult. Unconstrained lineshape analysis is not suitable for the deconvolution of the NMR spectra, but linewidth constrained analyses gave reasonable results. © 1993 John Wiley & Sons, Inc.
Studies on solution cast perfluorocarbonsulfonic acid ionomers
Authors: Tsatsas A. T. , Risen W. M. 
Published: April 2003

AbstractThe thermal properties of perfluorocarbonsulfonic acid ionomer films cast from solution and their temperature‐dependent far infrared spectra have been investigated. In addition to the endotherms and spectral changes associated with the loss of solvent as the films were heated, a significant exotherm has been observed and assigned to the relaxation associated with rearrangements resulting in partially crystallized phases in insoluble thermally treated membranes. © 1993 John Wiley & Sons, Inc.
The morphology of poly(vinylidene fluoride) crystallized from blends of poly(vinylidene fluoride) and poly(ethyl acrylate)
Authors: Briber Robert M. , Khoury F. 
Published: April 2003

AbstractA combined optical and electron microscopical study has been carried out of the crystallization habits of poly(vinylidene fluoride) (PVF2) when it is crystallized from blends with noncrystallizable poly(ethyl acrylate) (PEA). The PVF2/PEA weight ratios were 0.5/99.5,5/95, and 15/85. Isothermal crystallization upon cooling the blends from the single‐phase liquid region was carried out in the range 135–155°C, in which the polymer crystallizes in the α‐orthorhombic unit cell form. The 0.5/99.5 blend yielded multilayered and planar lamellar crystals. The lamellae formed at low undercoolings were lozenge shaped and bounded laterally by {110} faces. This habit is prototypical of the dendritic lateral habits exhibited by the crystals grown from the same blend at high undercoolings as well as by the constituent lamellae in the incipient spherulitic aggregates and banded spherulites that formed from the 5/95 and the 15/85 blends, respectively. In contrast with the planar crystals grown from the 0.5/99.5 blend, the formation of the aggregates grown from the 5/95 blend is governed by a conformationally complex motif of dendritic lamellar growth and proliferation. The development of these aggregates is characterized by the twisting of the orientation of lamellae about their preferential b‐axis direction of growth, coupled with a fan‐like splaying or spreading of lamellae about that axis. The radial growth in the banded spherulites formed from the 15/85 blend is governed by a radially periodic repetition of a similar lamellar twisting/fan‐like spreading growth motif whose recurrence corresponds to the extinction band spacing. This motif differs in its fan‐like splaying component from banding due to just a helicoidal twisting of lamellae about the radial direction. © 1993 John Wiley & Sons, Inc.
Coionomeric mixtures of polyhydroxyethers and ethylene methacrylic acid copolymers. I. Effects of cation concentration and ABA oligomeric miscibilisers on morphology and properties
Authors: Mascia L. , Moggi A. 
Published: April 2003

AbstractMixtures of a phenoxy polymer (polyhydroxyether of bis‐phenol A) and a polyolefin ionomer (sodium ionomer of ethylene methacrylic acid copolymer) were compatibilized by the addition of small amounts of sodium ethoxide and/or by the incorporation of varying amounts of A‐B‐A block oligomers. The latter were produced by reacting several bis‐phenol A epoxy resins, varying in molecular weight, with montanic acid in order to provide segments soluble in each of the two polymer components of the blend. Chemical miscibilization by the addition of sodium ethoxide changed the morphology into one containing larger amounts of cocontinuous phases, while the incorporation of substantial amounts of A‐B‐A oligomer brought about primarily the formation of irregular and highly elongated particles. The mixtures were found to exhibit the typical properties of ionomers which were enhanced by the addition of sodium ethoxide. Furthermore sufficient evidence was gathered to establish that the ionomeric aggregates are shared by both polymer components of the blend, from which the term coionomeric mixture is derived. © 1993 John Wiley & Sons, Inc.
Structure and melting of perfectly alternating ethylene‐carbon monoxide copolymers
Authors: Lommerts B. J. , Klop E. A. , Aerts J. 
Published: April 2003

AbstractThe perfectly alternating ethylene carbon monoxide copolymer (polyketone; POK) has been studied by means of 1H nuclear magnetic resonance and thermal analysis, and the crystal structure, determined by wide angle x‐ray scattering methods, is presented. The crystal structure of this polymer in well‐oriented fibers (POK‐α) is as follows: Space group Pbnm, α = 6.91 (2) Aå, b = 5.12 (2) Aå, c = 7.60 (3) Aå (fiber axis), pc = 1383 kg/m3. This differs from the structure reported earlier by Chatani et al. (POK‐β). The very dense packing in the POK‐α structure is a result of the arrangement of the dipoles in the crystal lattice, giving rise to strong lateral forces between the polymer chains. Owing to the all‐trans conformation of the polymer chain in the crystal lattice, high moduli can be achieved for well‐oriented fibers. A first approximation results in a value of 360 GPa for the theoretical modulus. From the melting data for a series of low molecular weight polyketone homologs, a first, estimate is derived for the crystalline heat of fusion (215–330 J/g) for infinite chain length. As a result of the strong lateral forces, this polymer shows a (very) high crystalline heat of fusion, whereas creep and compressive strength of oriented fibers are expected to be superior to those of high‐modulus polyethylene fibers. © 1993 John Wiley & Sons, Inc.
Structure‐property relationships in a reactively coupled ductile matrix/brittle dispersed phase blend
Authors: Liu T. M. , Xie H. Q. , O'callaghan K. J. , Rudin A. , Baker W. E. 
Published: April 2003

AbstractBlends of t‐butylaminoethyl methacrylate grafted polyethylene (PE‐g‐tBAEMA) with methyl methacrylate‐methacrylic acid copolymer (PMMA‐MAA) and polymethyl methacrylate (PMMA) were prepared in a Banbury type batch mixer. The effects of component proportions and processing conditions on the melt flow index, morphology, impact, and tensile properties of the resulting polymer blends were investigated. The interfacial chemical reaction was studied using Fourier transform infrared (FTIR) technique. It was observed that the melt index of the blends was reduced with increasing melt processing temperature and mixing time, indicating the formation of PE‐g‐PMMA block copolymer. New IR bands at 1554, 1628, 1800, and 1019 cm−1 were observed only for PE‐g‐tBAEMA/PMMA‐MAA, the reactive blends, but not for PE‐g‐tBAEMA/PMMA, the nonreactive blend. These IR bands were attributed to the amide, carboxylate anion and methacrylimide formation resulting from the chemical reaction between the secondary amine on the PE‐g‐tBAEMA/PMMA moiety and the carboxylic acid on PMMA‐MAA segment. The morphology of the blends in various compositions was examined using scanning electron microscopy (SEM) and related to their mechanical properties. All of the blends have a domain structure whose morphology is strongly dependent on the concentration of the dispersed phase. Furthermore, the PE‐g‐tBAEMA/PMMA‐MAA reactive blends were shown to have much finer morphology than the corresponding nonreactive blends. For the reactive polymer blends consisting of brittle particles dispersed in the ductile matrices, the PE‐g‐tBAEMA/PMMA‐MAA, impact and tensile result higher than predicted by the additivity rule were observed. The toughening of polyethylene by PMMA was explained by a “cold‐drawing” mechanism. The Young's modulus of the blends and the extent of interfacial adhesion were analyzed with Takayanagi and Sato‐Furukawa's theories. © 1993 John Wiley & Sons, Inc.
Modeling of penetrant diffusion in glassy polymers with an integral sorption deborah number
Authors: Wu J. C. , Peppas Nikolaos A. 
Published: April 2003

AbstractA mathematical model was developed to explain the anomalous penetrant diffusion behavior in glassy polymers. The model equations were derived by using the linear irreversible thermodynamics theory and the kinematic relations in continuum mechanics, showing the coupling between the polymer mechanical behavior and penetrant transport. The Maxwell model was used as the stress–strain constitutive equation, from which the polymer relaxation time was defined. An integral sorption Deborah number was proposed as the ratio of the characteristic relaxation time in the glassy region to the characteristic diffusion time in the swollen region. With this definition, an integral sorption process was characterized by a single Deborah number and the controlling mechanism was identified in terms of the value of the Deborah number. The model equations were two coupled nonlinear differential equations. A finite difference method was developed for solving the model equations. Numerical simulation of integral sorption of penetrants in glassy polymers was performed. The simulation results show that (1) the present model can predict Case II transport behavior as well as the transition from Case II to Fickian diffusion and (2) the integral sorption Deborah number is a major parameter affecting the transition. © 1993 John Wiley & Sons, Inc.
Dilation of poly[1‐(trimethylsilyl)‐1‐propyne] during sorption of n‐nonane
Authors: Witchey‐Lakshmanan L. C. , Hopfenberg H. B. , Chern R. T. 
Published: April 2003

AbstractThe linear expansion and contraction in the principal planar directions of poly[1‐(trimethylsilyl)‐1‐propyne] film were measured concurrently with the sorption of n‐nonane at 35°C. After the first sorption cycle, in which the polymer exhibited markedly nonisotropic volumetric dilation, the polymer expanded and contracted reproducibly during subsequent multiple sorption and desorption cycles. These reversible dilation isotherms were reproducible from sample to sample. The fractional change in length was identical in arbitrarily selected, orthogonal directions in the plane of the film, suggesting that the expansion and dilation of the sample are isotropic. When plotted versus the activity of n‐nonane, the linear expansions in the plane of the film are slightly concave to the activity axis, reaching levels over 10% at the highest activities. The experimental partial specific volume of the polymer is near its pure component value but that of the penetrant is much less than its pure component value. Moreover, the magnitude of dilation observed is described rather closely by the dilation which would result solely from the Henry's law portion of sorption, assuming zero volume‐change of mixing. These results are consistent with the explicit notions of “hole‐filling” associated with the Langmuir mode in the dual‐mode model. © 1993 John Wiley & Sons, Inc.