bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydration behavior of heart muscle studies by nuclear magnetic relaxation: Deuterium exchange of water protons in the myocardium
Authors: Lee Jeonghae Rho , Baianu Ion C. , Bechtel Peter J. 
Published: March 2011

AbstractProton transverse relaxation, deuterium and oxygen‐17 NMR measurements on functional animal heart muscle were employed to study the distribution and exchange of water protons in the heart. Our nonlinear regression analysis of such data showed the presence of three proton transverse relaxation components that are likely to correspond, respectively, to two major types of water compartments in the heart muscle and the heart muscle matrix. A deuterium exchange study was undertaken to obtain additional information concerning the chemical exchange of water protons/deuterium within these two water compartments, and the effects of proton intermolecular dipolar interactions on the transverse relaxation of water protons. Our results are likely to influence the analysis and interpretation of MRI data for myocardium since it provides details of the microscopic water distribution in the myocardium which is important to the heart function.
Vibrational and 29Si NMR spectroscopies of soluble silicate oligomers
Authors: Bass Jonathan L. , Turner Gary L. , Morris Michael D. 
Published: March 2011

AbstractVibrational spectroscopy has been used to correlate the features of silicate solution spectra with 29Si NMR spectra, as a function of SiO2:Na2O ratio and SiO2 concentration. Assignments of infrared and Raman component bands have been made for different anion types and are consistent with results reported for crystalline silicates and silicate glasses. The extent of depolymerization of larger anions has been found to differ, depending on both the degree of dilution and alkalinity. The relative amounts of polymeric (Q4) silica and larger three dimensional (Q34R) anions are greater for the more siliceous solutions (3.3 and 2.95 ratio) at high concentrations. These large anions continue to be major contributors to the anion distribution even at 15 to 50 fold dilution. In the case of more alkaline solutions, especially below 2.5 ratio, the relative contribution of the large anions to the distribution drops rapidly, even with 2 or 3 fold dilution. At low concentrations, in very alkaline solutions, the anion distribution is mainly monomer, dimer and cyclic trimer. Vibrational spectroscopies show great promise for observing changes in anion distribution on a much shorter time scale than is possible with 29Si NMR and can be useful for following reactions involving silicate solutions.
Multi‐dimensional spectroscopy of polymer films; surface and interfacial interactions
Authors: Urban Marek W. 
Published: March 2011

AbstractBehavior of macromolecules near surfaces and interfaces of polymeric thin films and coatings may play a vital role in numerous applications. Therefore, understanding of molecular level processes responsible for durability, adhesion, and many other macroscopic processes is of a particular importance. This presentation will focus on stratification processes in multi‐component polymeric films, with particular emphasis to polymer‐surfactant interactions in latexes, responsiveness of individual components during coalescence of water‐borne polyurethanes, and behavior of thermoplastic olefins (TPO). The presence of macromolecular arrangements and interactions among various components near the film‐air (F‐A) and the film‐substrate (F‐S) interfaces can be effectively monitored using attenuated total reflectance (ATR) and step‐scan photoacoustic (SS‐PA) Fourier transform infrared (FT‐IR) spectroscopy. Both approaches are capable of obtaining information from various surface depths and complement each other if one seeks molecular level information from 0 – 150 μm into the film. If one combines ATR and PA information with IR and/or Raman surface imaging, it is possible to obtain a 3‐dimensional representation of polymeric films.
Shedding light upon macromolecular behaviour: Luminescence studies of polymers
Authors: Soutar I. , Swanson L. , Cowie J. M. G. , Barker I. C. , Flint N. J. , Conroy M. J. 
Published: March 2011

AbstractIn this paper the use of two time‐resolved luminescence techniques in the study of polymer behaviour is illustrated.Time‐resolved anisotropy measurements, TRAMS, have been used to study macromolecular mobilities both in solution and bulk phases. The first use of TRAMS involving phosphorescent labels in the study of synthetic polymers is reported and the potential of the technique for future applications in polymer science is discussed.Time‐resolved energy transfer has been used to study polymer compatibility and interdiffusion in blends of PS‐PMMA. The data offer clear evidence of the fact that the local concentration of chain termini in phase‐separated systems is enriched in the interphase regions compared to that in the two bulk phases of the blend.
A polymer double‐layer studied by step‐scan FTIR photoacoustic spectroscopy
Authors: Wahls M. W. C. , Leyte J. C. , Swart J. M. F. , van Woerkom P. C. M. 
Published: March 2011

AbstractPhotoacoustic (PA) magnitude and phase spectra of a polyethylene/polyurethane double‐layer are presented. The extension of the Rosencwaig‐Gersho theory to a double‐layered polymer film introduced by N.C. Fernelius in 1980 is applied to compare the experimental spectra with simulations. A reasonable agreement between experiment and simulation is observed. It is shown that FTIR‐PAS in combination with simulation provides an important technique for depth profiling in polymeric laminates.
Drift spectral study of polyacrylate (PAA) and polymethyl methacrylate (PMMA) on various ceramics and glasses
Authors: Lee Donghun , Condrate Robert A. 
Published: March 2011

AbstractCarboxylate‐containing organic coatings can be used for their dispersion, lubrication, durability or hydrophobic applications with ceramic or glass surfaces. Such applications intimately depend upon the nature of the structural interaction of the organic coating on the surface of the inorganic material. In this study, organic polymers such as polymethyl methacrylate (PMMA) and polyacrylate (PAA) were coated on either ceramic or silicate‐containing glass powders. Investigated ceramic materials included alumina, barium titanate and bismuth oxide‐containing cuprate superconductors. The structural interactions between the organic coatings and the inorganic materials were determined by analyzing and interpreting Diffuse Reflection Infrared Fourier Transform (DRIFT) spectra. Depending upon the nature of the investigated materials, various metal‐carboxylate complexes were formed at the interfaces along with hydrogen‐bonded or non‐hydrogen‐bonded protonated PAA or PMMA.
Two‐dimensional near‐infrared correlation spectroscopy studies of polymer blends I: Composition‐dependent spectral variations of blends of atactic polystyrene and poly[2,6‐dimethyl‐1,4‐phenylene ether]
Authors: Ren Yanzhi , Ozaki Yukihiro , Murakami Tsuyoshi , Nishioka Toshikatsu , Nakashima Kenichi 
Published: March 2011

AbstractGeneralized two‐dimensional (2D) near‐infrared (NIR) correlation spectroscopy has been applied to study the conformational changes and molecular interactions in blends of atactic polystyrene (PS) and poly[2,6‐dimethyl‐1,4‐phenylene ether] (PPE). NIR diffuse reflectance spectra have been measured for PS, PPE and their blends of different compositions, i.e., PS/PPE=90/10, 70/30, 50/50, 30/70, 10/90. The 2D synchronous correlation analysis of these composition‐dependent NIR spectral variations separates the bands of PS from those of PPE. The 2D asynchronous analysis identifies spectral features indicative of the conformational changes or the specific interaction of PS and PPE. It can also detect “blend bands” whose origin is attributed to the formation of the polymer blends. Two “blend bands” of PS are identified at 6887 and 4836 cm−1, and three “blend bands” of PPE are observed at 5752, 5679 and 4647 cm−1. These “blend bands” are due to vibrations of the aromatic rings of PS or PPE and of the CH3 of PPE. Thus, not only the aromatic rings of PS and PPE but also the CH3 groups of PPE play important roles in the formation of the blends.
Advantages of near infrared spectroscopy for the analysis of polymers and composites
Authors: Lachenal Gilbert , Ozaki Yukihiro 
Published: March 2011

AbstractThere is an ever increasing need for better quality control of polymers and polymeric composites in order to improve product quality and reduce production costs. Measurements need to be performed rapidly and give precise chemical and physical information to enable a good understanding to be made of the parameters leading to higher quality products. NIR spectroscopy is ideally suited for studies of a large variety of composites and requires minimal sample conditioning. The composition, degree of conversion, crystallinity, water content and interaction, and filler content can be monitored in real‐time using NIR spectroscopy. Moreover, the water content and the water interactions can be analyzed simultaneously. Water can be used therefore as a probe molecule to study polymers and composites.
Polyethyloxazoline monolayers for polymer supported biomembrane models
Authors: Lehmann Thomas , Rühe Jürgen 
Published: March 2011

AbstractThe synthesis of polymer monolayers, which are designed to act as “cushions” for lipid membranes attached to solid surfaces, is described. Monolayers of poly(ethyloxazolines) which could act as a polymeric support for biomimetic membranes have been attached to silicon oxide or gold surfaces following different strategies for the surface‐attachment of the polymer chains. The polymers are either bound to the surface through a chemisorption process (“grafting‐to”) or “grown” on the surface of silicon oxide substrates through a cationic ring‐opening polymerization started from the surface of the substrate, creating a surface‐attached polymer monolayer in situ (“grafting from”). The characterization of the surface attached films by various surface analytical techniques and the swelling behavior of the surface‐attached polymer films in moist air are described. The non‐specific adsorption of fibrinogen as a typical example for a strongly adsorbing protein onto the surface attached monolayers is studied.
Synthesis of nonlinear optical polymers with large photoconductive sensitivity and transparency
Authors: Pyun Seong Yong , Moon Hyunsik , Lee Jin Kyun , Kim Nakjoong , Park Soo Young 
Published: March 2011

AbstractNovel nonlinear optical (NLO) chromophore, 2‐{3‐[2‐(4‐methylsulfonylphenyl)vinyl]carbazol‐9‐yl}ethanol was synthesized and subsequently reacted with methacryloyl chloride to give a photoconducting NLO monomer (M1). 2‐Methylacrylic acid 2‐[3‐(diphenylhydrazonomethyl)carbazol‐9‐yl]ethyl ester (M2) was also synthesized as a comonomer to enhance the carrier mobility of the NLO polymer. Photoconducting NLO polymers, P1 and P2 were obtained by the copolymerization of Ml with methyl methacrylate and M2, respectively. These polymers were well soluble in organic solvents and showed glass transition at 177 °C and 196 °C, respectively. Polymer films of P1 and P2 were optically clear, and were transparent at wavelengths longer than 420 nm. The electro‐optic coefficient (r33) of poled P1 films was measured to be ∼5 pm/V at 632.8 nm. The photoconductive sensitivities of P1 and P2 were 6.2 × 10−14 S·cm−1/mW·cm−2 and 5.6 × 10−11 S·cm−1/mW·cm−2.
Structure and properties of aromatic 6‐membered polyimides compared to 5‐membered ones
Authors: Jung Jin Chul , Baehr Christoph , Lee Chang‐Hun , Park Sang‐Bong , Son Young‐Sub , Kim Kwang S. 
Published: March 2011

AbstractWhen various properties of poly[2,5‐di(n‐alkyloxy)methyl‐p‐phenylenenaphthalene‐1,8:4,5‐diimide]s (Cm‐NAPIs, m = 4, 6, 8) as aromatic 6‐membered polyimides were compared with those of poly[2,5‐di(n‐alkyloxy)methyl‐p‐phenylenepyromellitimide]s (Cm‐PYPIs, m = 4, 6, 8) as 5‐membered ones, it was deduced that O atoms of C=O of Cm‐NAPIs are not coplanar with their imide ring plane. This noncoplanarity led us necessarily to assuming that the 6‐membered ring polyimide chains should have cis/trans‐like isomeric structures. Detailed spectroscopic studies and ab initio calculations for appropriate model compounds are provided to support our assumption.
Mechanism of inhibiting action of quinones in oxidizing polymers and model compounds
Authors: Denisov Evguenii T. 
Published: March 2011

AbstractQuinones (Q) do not affect the liquid‐phase oxidation of hydrocarbons and retard the solid‐phase oxidation of polymers terminating chains in reactions with alkyl macroradicals. This difference is the result of specific influence of a polymer matrix on the kinetics of free radical reactions. Quinones were found to terminate chains in oxidizing polypropylene containing hydroperoxide groups by the reaction with hydroperoxyl radicals. This is the result of peroxide group's decomposition with hydrogen peroxide production and chain termination in the following reactions:magnified imageThe equilibrium reaction between hydroquinone (QH2) and quinonimine (QI) was evidenced to proceed as a chain reaction with chain propagation in reactions of •QH with QI and HQI• with QH2. Analysis of the reactions of quinone with phenols (ArOH)magnified imageproved that it can be important as an additional way of chain termination in oxidizing polymers and hydrocarbons at elevated temperatures.
Design of new materials for environmental control
Authors: Economy James , Mangun Chris 
Published: March 2011

AbstractDuring the past several years we have pursued a program here at UIUC to tailor the pore size and surface chemistry of activated carbon fibers (ACFs) to greatly increase their efficiency and selectivity for removal of trace contaminants from the environment. In addition we have evolved new ways of preparing the ACFs to sharply reduce their cost (typically ∼$100/lb) to be more competitive with activated carbon granules ($1‐2/lb), but also to greatly improve the abrasion resistance of the fibers. This was accomplished by coating glass fibers with a phenolic resin and then activating the coating under a controlled atmosphere to produce a variety of tailored micropores. Using chemically tailored ACFs, we describe major improvements over current activated carbons for adsorption of environmental contaminants.
Precision and control in polymer synthesis why it's important and some recent examples of how to do it
Authors: Feast W. James. , Cacialli Franco , Daik Rusli , Friend Richard H. , Herzog Erwin , Heywood Brigid R. , Hobson Lois , Megson Joanna L. , Snowden David 
Published: March 2011

AbstractThis paper discusses some of the reasons why precision and control in polymer synthesis is of importance. By way of illustration it describes in outline recent results from the authors' laboratories in three areas. Namely; the controlled syntheses of poly(arylene vinylene)s and the influence of cis/trans vinylene content on luminescence in such polymers; the living polymerisation of highly functionalised polymers in water and the regulation of the crystallisation of calcium carbonate from water by the resultant well‐defined water soluble polymers; and a simple route to hyperbranched polymers and the influence of the structure and topology of the products on solution properties. In each case the influence of control of architecture on properties will be discussed.
Structurally controlled polymers with ultimate precision ‐ synthesis, characterization and properties
Authors: Hatada Koichi , Kitayama Tatsuki , Ute Koichi , Nishiura Takafumi 
Published: March 2011

AbstractThe fusion of polymer synthesis and characterization and their interactive stimulation is inevitable not only for the formation of polymers with highly controlled structures but also for the development of polymer characterization, thereby bringing about the spiral progress of both fields. As a typical example of precise polymer synthesis, the preparation of uniform PMMA with 100% isotacticity is described. Stereospecific living polymerization of 1‐phenyldibenzosuberyl methacrylate with methyl α‐lithioisobutyrate in tetrahydrofuran at −78°C gave an isotactic polymer with narrow molecular weight distribution. The PMMA derived therefrom was found by 750 MHz 1H NMR spectroscopy to consist of 89% of the PMMA which is 100% isotactic in the whole chain, and 11% of the PMMA which is 100% isotactic in the chain with only one racemo diad at the initiating chain end. The PMMA was fractionated into uniform PMMAs by supercritical fluid chromatography. The isotactic uniform PMMAs, crystallized from methanol solutions, showed the degree of crystallinity close to 100%. Highly syndiotactic PMMA was derived from poly(trimethylsilyl methacrylate) prepared with t‐C4H9Li/bis(2,6‐di‐t‐butylphenoxy)methyl‐aluminum in toluene at −95°C. Stereocomplex formation of isotactic and syndiotactic uniform PMMAs were studied by on‐line GPC/NMR measurements at 750 MHz and −15°C in acetone/acetone‐d6. Stereocontrol of ditactic polymers of crotonates (structural isomers of methacrylates) has been achieved for several polymerization systems, i.e., threodiisotactic, disyndiotactic, and diheterotactic polymerizations, which demonstrates another state‐of‐the‐art structural control at ultimately high level.
Enthalpic relaxation and the glass transition in polymer blends
Authors: Hay James N. , Jenkins Michael J. 
Published: March 2011

AbstractThe kinetics of enthalpic relaxation are reviewed and applied to the ageing of a range of blends made from polyether imide and polyether ether ketone. DSC has been used to follow the development of enthalpic relaxation and a Williams‐Watt stretched exponential equation relating the extent of relaxation, ϕ(t), to the ageing time t and an average relaxation time, t́a', has been used to quantify the ageing process.magnified imagewhere β' is inversely related to the breadth of the relaxation spectrum such that 0<β>1.0. The relationship was modified to incorporate non‐linearity in the relaxation behaviour. ϕ(t) was measured directly from the enthalpy change observed in the endotherms on heating aged specimens through the glass transition in the DSC.The PEI/PEEK blends were compatible over the full composition range in that they exhibited a single glass transition with a temperature that varied almost linearly with composition between those of the homopolymers. Enthalpic relaxation was found to be a useful technique for probing the molecular relaxations of polymer blends and confirming the degree of compatibility of the system. The β' values changed systematically with the blend composition between those of the homopolymers suggesting that the breadth of the relaxation spectra were similar in the blends to that in the homopolymers.Physical ageing was observed to embrittle the blends, and there was a close correlation between the extent of enthalpic ageing and the change in mechanical and impact behaviour. The yield stress increased and the elongation to break decreased progressively with ϕ(t) in addition to a reduction in impact strength.The model of enthalpic relaxation and the kinetic relationships, outlined above, have been used to determine the onset of the glass transition temperature and subsequent progress of enthalpic relaxation at fixed ageing temperatures, for direct comparison with the change in specific heat observed in DSC experiments. Good agreement was observed between experiment and calculated glass transitions and the effect of variables, such as activation enthalpies, pre‐exponential factors, non‐linear factors such as X and β' and fictive temperature on the observed glass transition temperatures and the temperature range over which the glass transition occurred determined. Modifications to the model for the enthalpic relaxation have been suggested.
Surface, thermal and mechanical characteristics of polymeric solids
Authors: Kajiyama Tisato , Satomi Noriaki , Tanaka Keiji , Takahara Atsushi 
Published: March 2011

AbstractSurface molecular motions of amorphous polymeric solids have been directly measured on the basis of lateral force microscopic (LFM) and scanning viscoelasticity microscopic (SVM) measurements. SVM measurement revealed that the molecular motion at the surface of the monodisperse polystyrene (PS) film with Mn less than ca.30k was fairly activated compared with that in a bulk region, mainly due to the surface segregation of chain end groups. Temperature dependent LFM and SVM measurement revealed that the surface glass transition temperature, Tg of the monodisperse PS film was lower than the bulk one, even though Mn was fairly large as 140k and also, that the time‐temperature superposition was applicable to the surface relaxation process. The chain end group segregation at the air/PS interface was verified from the dynamic secondary ion mass spectroscopic (DSIMS) depth profiling of the proton and deuterium ion for the end‐labeled deutrated‐PS (dPS) film. These results suggest that the surface Tg is depressed due to an increase in free volume near surface region, being induced by the preferential surface localization of chain end groups.
Adherent and slippery walls for extrusion of entangled polymer melts and compounds
Authors: Piau Jean‐Michel 
Published: March 2011

AbstractA brief overview is given of the distortions observed when polymer melts or compounds are extruded. It appears that extrusion through steel dies can be done either with macroscopic slip or with no‐slip wall conditions.Recent experimental and theoretical progress made in understanding the various aspects of slip at the wall, and its measurement techniques, are presented. Boundary conditions for rubber compounds flowing through steel‐walled dies could be seen to be much more complex than those for melts. However many aspects of the methodologies developed are of common interest both for melts and rubber.It has already been suggested that advantages can be obtained from the use of slippery walls in extrusion. Such wall properties have already been used indeed for a long time with compounds, where processing additives are introduced.New experimental data are presented concerning two typical EPDM compounds series, obtained using several laboratory techniques at the same time. Constitutive equations for the bulk and for friction at the wall can be introduced at present and adjusted to experimental data. Die extrusion can be simulated numerically, and significant improvements can be expected in quality and productivity.
Biodegradable polymers derived from aminoacids
Authors: Huang Samuel J. , Ho Luang‐Hua 
Published: March 2011

AbstractPoly(amide‐ester)s derived from five α‐amino acid mixtures including glycine, DL‐and L‐alanines, DL‐ and L‐phenylalanines, and three different diols including 1,6‐hexanediol, 1,4‐butanediol and trans‐1,4‐cyclohexanedimethanol were synthesized by interfacial, solution and melt polymerizations. All of the polymers had Tg's ranging from −6 to 50°C. The incorporation of rigid trans‐1,4‐cyclohexanedimethanol in the main chain significantly increased the Tg of these polymers. The degree of crystallinity depended on the type of amino acid and decreased with the size of substituent on the α‐carbon in the amino acid. Biodegradation of these polymers were tested semi‐quantitatively by turbidity measurements. Enzymes used included subtilisin, pronase E, α‐chymotrypsin, fusarium, and lipase. The incorporation of trans‐1,4‐cyclohexanedimethanol unit slowed down degradation rate. Polymers containing L‐amino acid generally degraded faster than the polymers containing DL‐amino acids. Quantitative biodegradation testings using ninhydrin analysis, total organic analysis, and weight loss done on alanine derived polymers indicated that the degradation of the polymers by pronase E occurred at the ester bonds first and was specific against L‐amino acid. The degradation was followed by slower amide bond degradation.