bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sulfone‐Containing polymers as high barrier materials
Authors: Zhang Tianhong , Litt Morton H. , Rogers Charles E. 
Published: April 2003

AbstractThree types of sulfone‐containing polymers, poly(carbonate‐sulfone)s, poly(ester‐sulfone)s, and poly(urethane‐sulfone)s, were characterized as high barrier materials. They were made by condensing sulfone‐containing diol, 1,3‐bis(3‐hydroxypropylsulfonyl)propane (Diol‐333), or 1,4‐bis(3‐hydroxypropylsulfonyl)butane (Diol‐343), with diphenyl carbonate, diphenyl esters, and diisocyanates, respectively. The incorporation of polar sulfone groups into polymer backbones increases the glass transition temperature of polymers in all cases; however, the increment is different with different functional linkages. The increments in polycarbonates and polyesters are higher than that in polyurethanes. This is because the interactions between carbonate or ester groups are much weaker than the interactions between sulfone groups, whereas the hydrogen bonding between urethane groups is comparable with the polar interaction between sulfone groups. The polymers were coated on 50‐μm‐thick Kapton films by solution casting and their permeabilities toward carbon dioxide were measured at 25°C using the ASTM D1434 volumetric method. The sulfone‐containing polymers have carbon dioxide permeability coefficients at least 50 times smaller than the corresponding polymers without sulfone groups. The carbon dioxide barrier properties of sulfone‐containing polymers are comparable with ethylene/vinyl alcohol copolymers (EVAL), which are commercial high barrier polymers. An isomer effect on polymer permeability was observed in the aromatic‐aliphatic poly(ester‐sulfone) series. The permeability coefficients of the aromatic‐aliphatic poly(ester‐sulfone)s decrease from terephthalate to isophthalate to phthalate, corresponding to the increase of chain flexibility above the Tg. These results support the hypothesis that high chain flexibility in the rubbery state and a glass transition temperature above room temperature are two key factors that promote low permeability. © 1994 John Wiley & Sons, Inc.
The effect of counterions on the chain conformation of polyelectrolytes, as assessed by extensibility in elongational flow: The influence of multiple valency
Authors: Narh K. A. , Keller A. 
Published: April 2003

AbstractAn elongational flow technique was used to determine the effect of counterions on the chain conformation of polyelectrolyte molecules in solution, by means of the extensibility of the chains in the flow field. It is demonstrated that adding excess cations of seven low molecular weight salts, NaCl, CaCl2, BaCl2, SrCl2, MgCl2, AlCl3, and SnCl4, to a very dilute solution of fully sulphonated polystyrene (NaPSS) reduces the extensibility of the chains, that is, the facility by which a chain can be extended to varying degrees, an effect associated with chain contractions. In the case of multivalent counterions, these contractions, which with monovalent counterions are primarily due to screening of charges by excess counterions, are greatly enhanced, which we attribute to the formation of intramolecular ionic bridges. When, in the case of multivalent counterions, the polymer concentration is increased, in inversion of the effect, namely increase in chain extensibility on addition of ions, is observed. We attribute this latter effect to the ionic bridges becoming increasingly intermolecular, leading to effectively large molecules, and eventually to a gel. All these effects were accentuated with increase in valency. They could also be accompanied by precipitation which were of two kinds: one due to formation of insoluble ionic associations and a second attributable to enhanced hydrophobic interaction within the contracted chain itself. © 1994 John Wiley & Sons, Inc.
Miscibility of tetramethyl‐hexafluoro copolycarbonates with styrene‐methyl methacrylate copolymers
Authors: Takakuwa K. , Gupta S. , Paul D. R. 
Published: April 2003

AbstractThe compositions for which blends of copolycarbonates of tetramethyl bisphenol‐A and hexafluoro bisphenol‐A (TMPC‐HFPC) with styrene‐methyl methacrylate copolymers (SMMA) are miscible were determined experimentally. These copolymer compsition boundaries were compared to predictions based on the Flory‐Huggins theory combined with the binary interaction model. The theoretical predictions employed interaction energies from the literature for the TMPC/PS, PS/PMMA, and TMPC/PMMA pairs, and values for the TMPC/HFPC, HFPC/PS, and HFPC/PMMA pairs were established or verified using independent experiments. The recommended set of interaction energies predicts that miscibility occurs in two separate regions of copolymer compositions. These predictions agree well with the experimental observations. The theoretical requirements for a single, continuous miscible region versus two disjointed miscible regions when the two limiting homopolymer pairs exhibit miscibility, that is, TMPC‐PS and HFPC‐PMMA in this example, are described. © 1994 John Wiley & Sons, Inc.
Dynamic scattering properties of branched polymers in the high‐wave vector region
Authors: Benoît H. , Benmouna M. , Borsali R. , Rinaudo M. 
Published: April 2003

AbstractAn analysis of dynamic scattering behavior of branched polymers in the high‐wave vector region is presented. In particular the first cumulant of the dynamic structure factor Ω(q) is examined. This quantity is calculated using the standard formula which defines Ω(q) within a proportionality constant as a ratio of the generalized mobility M(q) and the static structure factor S(q), where q is the amplitude of the scattering wave vector. The latter quantity has already been calculated by Benoît et al. who obtained a general formula for a branched polymer with an arbitrary architecture. Here, this calculation is extended to the mobility M(q) including hydrodynamic interaction with the angular pre‐averaged Oseen tensor. This result may be useful in the cases where the measurement of the first cumulant by quasi‐elastic scattering techniques can be made to complete the information obtained by the absolute intensity measurements. © 1994 John Wiley & Sons, Inc.
Phase equilibrium and mutual diffusion in the poly(sulfone)–dimethylsulfoxide system
Authors: Mikhailov Yu. M. , Ganina L. V. , Ye. Chalykh A. 
Published: April 2003

AbstractPhase equilibrium and mutual diffusion in the poly(sulfone) (PSF)–dimethylsulfoxide (DMSO) system have been studied at temperatures from 20 to 110°C over a wide solution composition range. The phase diagram for this system has been obtained and the effect of water on boundary concentrations has been studied. It is shown that the presence of water in DMSO has a considerable effect on the binodal curve. Thus, increasing the water content up to 1.3% by weight results in the displacement of the upper critical solution temperature by 30°C and the widening of the two‐phase region. The kinetic regularities in mutual dissolution of components have been investigated. The concentration dependencies of the mutual diffusion coefficients in the systems studied are presented. The effect of moisture in DMSO on the mutual diffusion coefficients appears near the phase transition in the system. © 1994 John Wiley & Sons, Inc.
Estimation of interaction energies by the critical molecular weight method: 2. Blends with polysulfones
Authors: Callaghan T. A. , Paul D. R. 
Published: April 2003

AbstractThe interaction energies between PS, Pα‐MS, and PMMA, as well as acrylonitrile and maleic anhydride units, with a series of polysulfones were quantitatively determined from oligomer/oligomer, oligomer/homopolymer, and homopolymer/copolymer blends. Interaction energies were calculated from the Flory‐Huggins theory and the Sanchez‐Lacombe equation of state theory using experimental cloud points or miscibility boundaries. Alkyl addition to the phenyl rings of polysulfone is favorable for miscibility with polystyrene whereas halogenation of the bisphenol connector unit favors miscibility with poly(methyl methacrylate). Interaction energies are quantitatively ranked and described qualitatively in terms of changes in the electronic charge distribution of the polymer repeat units as calculated by SYBYL software. © 1994 John Wiley & Sons, Inc.
Optical properties of cholesteric (2‐hydroxypropyl) cellulose (HPC) esters
Authors: Rusig I. , Godinho M. H. , Varichon L. , Sixou P. , Dedier J. , Filliatre C. , Martins A. F. 
Published: April 2003

AbstractAcetoxypropylcellulose (APC) and propionic, n‐butyric, isobutyric, valeric, isovaleric, hexanionic, and heptanionic acid esters of hydroxypropylcellulose (HPC) (respectively PPC, BPC, iBPC, VPC, iVPC, HexPc, and HepPc) were prepared and characterized by differential scanning calorimetry, chromatography, polarizing microscopy, chemical methods, and spectroscopy. All these esters form thermotropic cholesteric liquid crystalline phases. The glass (Tg) and clearing (Tc) transition temperatures were determined. The stability interval of the mesophases appears to be greater in the case of longer‐linear side chains. The mesophases of APC, PPC, iBPC, VPC, and iVPC exhibit reflection bands in the visible region, at wavelengths that depend on temperature, moisture content, size and number of substituents, and degree of polymerization (
\[
\overline {{\rm DP}}
\]
). The pitch of the cholesteric helical structure increases with side chain length and with increasing temperature. At room temperature, a fingerprint‐like pattern can be observed for HepPc. No reversal in the sense of the pitch with temperature variations was observed. The pitch of BPC increases with moisture content and with decreasing values of the degree of esterification (
\[
\overline {{\rm DE}}
\]
) and
\[
\overline {{\rm DP}}
\]
. A theory for cholesteric mesophases composed of helical rod‐like species and a model of elastic bend chain have been compared to the experimentally observed changes in the pitch with temperature and with the length of the side chain substituents (for iBPC, iVPC, BPC, PPC, and APC) and
\[
\overline {{\rm DE}}
\]
and
\[
\overline {{\rm DP}}
\]
(for BPC). © 1994 John Wiley & Sons, Inc.
Molecular weight dependence of diblock copolymer segregation at a polymer/polymer interface
Authors: Dai Kevin H. , Kramer Edward J. 
Published: April 2003

AbstractUtilizing forward recoil spectrometry (FRES), we have determined the segregation isotherm which describes the interfacial excess zi* of diblock copolymers of poly (d8‐styrene‐b‐2‐vinylpyridine) (dPS‐PVP) at the interface between the homopolymers PS and PVP as a function of ϕ∞, the volume fraction of diblock copolymer remaining in the host homopolymer. All the samples were analyzed after annealing at temperatures and times sufficient to achieve equilibrium segregation. The effect of the degree of polymerization of both the diblock copolymers and the host homopolymers on the segregation isotherm is investigated. When the degree of polymerization of the homopolymer is much larger than that of the diblock copolymer, the normalized interfacial excess (zi*/Rg), where Rg is the radius of gyration of an isolated block copolymer chain, is a universal function of that portion of the block copolymer chemical potential due to chain stretching. The existence of such a universal function is predicted by theory and its form is in good agreement with self‐consistent mean field calculations. Using these results, one can predict important aspects of the block copolymer segregation (e.g., the saturation interfacial excess) without recourse to the time‐consuming numerical calculations. © 1994 John Wiley & Sons, Inc.
Solution characterization of poly(isobornyl methacrylate) in tetrahydrofuran
Authors: Zhang X. Q. , Wang C. H. 
Published: April 2003

AbstractThermodynamic and hydrodynamic properties of dilute solutions of poly (isobornyl methacrylate) (PIMA) in tetrahydrofuran (THF) were characterized by using viscosity, static, and dynamic light scattering measurements. PIMA samples with different molecular weight were obtained by fractional precipitation of PIMA solution. Chain dimension parameters (Rg and RH), together with second virial coefficient A2 and intrinsic viscosity [η], were used to calculate various solution parameters characterizing polymer chains in polymer solutions. The experimental results are compared with calculation, indicating that PIMA behaves as a flexible coil in THF. © 1994 John Wiley & Sons, Inc.
On the glass transition temperature of styrene‐n‐butyl methacrylate copolymers in dependence on chemical composition, molecular weight, and mixtures
Authors: Schellenberg J. , Vogel J. 
Published: April 2003

AbstractFor statistic copolymers of styrene and n‐butyl methacrylate, the relation between the glass transition temperature and the chemical composition or molecular weight of the copolymers has been determined. Further, the dependence of the glass transition temperature on the composition of binary and ternary blends from statistical poly (styrene‐co‐n‐butyl methacrylates) of a nearly equal chemical composition but a very different molecular weight has been studied. Among several equations considered for the correlation between glass transition temperature and composition of the mentioned copolymers with relatively low molecular weights, the Gordon/Taylor and Couchman equations gave the best agreement with the experimental results. For the glass transition temperature of poly(styrene‐co‐n‐butyl methacrylate) with an n‐butyl methacrylate content of about 30 wt % in dependence on the molecular weight, the Kanig‐Ueberreiter and Fox‐Flory equations proved to be useful for the examined molecular weight range. The glass transition temperatures of the polymer blends have been studied for a low/high‐molecular component system, a system of two low‐molecular components, as well as for systems with a third component. The glass transition temperatures of the mixtures frequently exceeded those of their individual components. © 1994 John Wiley & Sons, Inc.
Influence of heat treatment conditions on the porosity changes of sulfonated styrene/divinylbenzene copolymers
Authors: Kolarz Bożena N. , Wojaczyńska Maria , Kaczmarczyk Jan , Siemieniewska Teresa , Tomków Kazimierz 
Published: April 2003

AbstractSulfonic cation exchangers with two ion exchange group concentrations (0.5 and 2.4 mmol/g, samples A and B, respectively) were obtained by sulfonation of a porous styrene (S) and divinylbenzene (DVB) copolymer with chlorosulfonic acid. Strong thermal decomposition of the sulfonated copolymer A, accompanied by significant changes in its porous structure, starts at ca. 400°C. The char has no sulfonic groups. After heat treatment at 400°C in steam, a sorbent was obtained (yield 65%) that shows higher phenol sorption than the untreated sample when related to the bed volume. The chlorosulfonic derivatives of the initial copolymer were less thermally resistant than the sulfonic ones obtained by hydrolysis. Pyrolysis of the cation exchanger B, in its H+ and Ca2+ forms, was carried out at 900°C (yield of both chars close to 30%). By subsequent steam activation at 800°C to a 50% burn‐off of the char, sorbents with well‐developed, but distinctly different, porous structures were obtained. The activated char from the sulfonated copolymer in its hydrogen form was highly microporous and indicated an effective surface area of 1180 m2/g. However, because of a low contribution of mesopores, its ability to adsorb phenol from the liquid phase was not very high. The activated char from the calcium‐doped copolymer, indicating a smaller surface area (580 m2/g) but characterized by a well‐developed mesoporosity, was a better sorbent for phenol. © 1994 John Wiley & Sons, Inc.
FTIR investigation of cross‐linking and isomerization reactions of acetylene‐terminated polyimide and polyisoimide oligomers
Authors: Huang W. X. , Wunder S. L. 
Published: April 2003

AbstractThe interrelationship between the cross‐linking and isoimide‐imide isomerization reactions of oligomeric isoimides and imides was investigated using FTIR spectroscopy. It was found that cross‐linking of the acetylene units of Thermid IP‐600 retarded the local rearrangement of the isoimide to imide conversion of Thermid IP‐600 compared with an aniline‐terminated analog, decreasing the rate constant by a factor of about 2. The increased flexibility of both the isoimide (Thermid IP‐600) and imide (Thermid FA‐700) oligomers increased the cross‐linking rate of the acetylene end groups by a factor of 4 and 2, respectively, over that of the more rigid imide oligomer (MC‐600). With increasing conversion of the isoimide to imide linkages in Thermid IP‐600, the kinetic parameters, Eα and in A, for the cross‐linking reaction of this oligomer became the same as those for the oligomeric imide, Thermid MC‐600. © 1994 John Wiley & Sons, Inc.
High density polyethylene/hydrogenated oligo(cyclopentadiene) blends: Phase structure, thermal and mechanical properties
Authors: Cimmino S. , Di Pace E. , Martuscelli E. , Mendes L. C. , Silvestre C. 
Published: April 2003

AbstractThe article discusses the influence of an oligomeric resin, hydrogenated oligo (cyclopentadiene) (HOCP), on the morphology and properties of its blends with high density polyethylene (HDPE). HDPE/HOCP blends after solidification contain three phases: the crystalline phase of HDPE and two amorphous phases, one rich in amorphous HDPE and the other in HOCP. DSC thermograms and the loss modulus behaviors show that the γ transition is influenced by HOCP molecules and, in addition to the αc transition of HDPE, there is another transition that is attributed to the HOCP‐rich phase. The hypothesis of the two amorphous phases is confirmed by the optical microscopy observations performed on isothermally crystallized blend films. © 1994 John Wiley & Sons, Inc.
A synopsis of empirical gel fraction analytical methods: Application of the Wanxi equation to polyethylenes irradiated in vacuo and in the presence of acetylene
Authors: Jones Richard A. 
Published: April 2003

AbstractGel fraction data from linear low‐density polyethylene (LLDPE) films and high‐modulus polyethylene (HMPE) fibers, which had previously failed to give reasonable results when treated with Charlesby‐Pinner and Saito‐Kang‐Dole theory, have been fitted to a modified form of the Wanxi equation. The fitting yields parameters that compare very well with literature values derived by the Wanxi equation, confirming that fracture and cross‐linking densities are proportional to a power function (β) of the radiation dose. Extrapolated G(S) values have been obtained from LLDPE using the fit parameters and UV‐Vis spectroscopy data. A brief synopsis of the empirical analytical methods available for gel fraction analysis is given. © 1994 John Wiley & Sons, Inc.
Structural changes and chain orientational behavior during tensile deformation of segmented polyurethanes
Authors: Lee H. S. , Hsu S. L. 
Published: April 2003

AbstractStructural changes and segmental orientation behavior of polyurethane have been studied during uniaxial deformation. The orientation function change of the two (free and hydrogen bonded CO stretching peaks) peaks during a full cycle of deformation has been observed to be distinctively different. Even though the hydrogen‐bonded CO peaks showed hysteresis behavior, the free CO peaks exhibited quite elastic behavior. It was thus concluded that the orientation behavior of free and hydrogen‐bonded CO stretching peak represents the deformation characteristics of soft and hard domains, respectively. The orientation behavior at different temperatures also has been studied. Temperature has a significant effect on the orientation behavior of the soft domain, whereas it has negligible effect on the hard domain orientation. It was also demonstrated that the structural change due to the deformation could be analyzed by infrared spectroscopy. Some of the hydrogen‐bonded carbonyl groups have been observed to be transferred to the free carbonyl groups, indicating that a small amount of the hard segments in the hard domain have been pulled out into the soft matrix upon deformation. The orientational relaxation also has been studied as a function of time. The segmental relaxation of the hard segments appears to be quite characteristic depending on the nature of the domain in which they reside. © 1994 John Wiley & Sons, Inc.
Deformation mechanisms in nylon 6/ABS blends
Authors: Majumdar B. , Keskkula H. , Paul D. R. 
Published: April 2003

AbstractThe deformation mechanisms during fracture of a Nylon 6/ABS blend compatibilized with an imidized acrylic polymer were compared to those of an uncompatibilized blend. A postmortem examination of deformed zones in samples loaded to failure in a double‐notch four‐point‐bend geometry was made using transmission electron microscopy (TEM). For the compatibilized blend, cavitation of the rubber particles followed by massive shear yielding of the polyamide matrix was concluded to be the sequence of events leading to toughness; while, for the brittle uncompatibilized blend, the evidence indicated that a lack of adhesion at the Nylon‐ABS interface prevented the rubber particles from cavitating and the subsequent plastic deformation of the polyamide matrix. © 1994 John Wiley & Sons, Inc.
Phase considerations in digital image analysis of polarized‐light images
Authors: Moneva I. T. 
Published: April 2003

AbstractThe phase statistics in digital imaging (DIA) is considered for the case when Fourier transformation is performed over images obtained in polarized light. An additional phase shift associated with “directionality” of scatterers is shown significant for the true simulation of nonisotropic scattering. The proof is based on analysis is particular of DIA simulated patterns and optical Fourier transforms of spherulitic particles, the latter transforms being obtained by optical modelling of spherulitic polarized light scattering. The constraints on the phase shift in the simulation process have been established. The phase analysis additionally implies that the nonisotropic scattering might be considered as a new special case of the apodization technique, with a number of potential applications. © 1994 John Wiley & Sons, Inc.
Elastic constant anisotropy, core structure of wedge disclinations and optical texture of main‐chain P‐4‐BCMU liquid crystals
Authors: Wang Wei , Hashimoto Takeji , Lieser Günter , Wegner Gerhard 
Published: April 2003

AbstractThe elastic constant anisotropy and the core structure of wedge disclinations with strengths s = ±½ of lyotropic liquid crystals of a soluble polydiacetylene, P‐4‐BCMU (Mw = 5.15 × 105, Mn = 2.16 × 105, and Mw/Mn = 2.4), in chloroform was studied. The Frank elastic constant anisotropy defined by ε = (k11 − k33)/(k11 + k33) for this polymer was determined by three different methods. The results show that the value of ε for this polymer is 0.5 (±0.05) in solid state and/or in liquid crystal state, indicating that the splay constant k11 is three time higher than the bend constant k33. This result further implies that splay is unfavorable in the liquid as it requires greater energy than bend. In the area adjacent to the core of a singularity the value of ε increases with decreasing distance to the core, indicating increasing anisotropy of the elastic constants toward the core. The influence of the elastic constant anisotropy on the optical texture of the LC polymer when viewed by polarizing light microscope is studied. © 1994 John Wiley & Sons, Inc.