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THEORY OF NEMATIC PHASES IN SOLUTIONS OF RODLIKE MOLECULES WITH HYDROGEN-BONDS

JOURNAL OF CHEMICAL PHYSICS 1995年第6期103卷 2237-2246页

作者： VEYTSMAN, BA Polymer Science Program The Pennsylvania State University 320 Steidle Building University Park Pennsylvania 16802

Nematic phases in dilute transitions of rodlike molecules with carboxylic acid functional groups are studied using an Onsager-like theory with the additional term in the free energy describing hydrogen bonding. It is shown that the hydrogen bonds with a proper geometry enhance nematic ordering. The behavior of the system turns out to be completely different in the cases when molecules can form only dimers and when then can form hydrogen-bonded ''polymers.'' In the latter case the molecules tend to form a completely ordered phase at low temperatures. The numbers of hydrogen bonds in the ordered phase and isotropic liquid are different. Therefore IR spectroscopy can be used for study of these systems. (C) 1995 American Institute of Physics.

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FOURIER-TRANSFORM INFRARED-SPECTROSCOPY OF NYLON-6 BLENDS - BINARY BLENDS WITH POLY(METHYL METHACRYLATE) AND ETHYLENE VINYL ESTER ALCOHOL COpolymer

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polymer 1985年第1期26卷 45-49页

作者： VENKATESH, GM GILBERT, RD FORNES, RE Fiber and Polymer Science Program North Carolina State University Raleigh NC 27650 USA

Films of blends of nylon-6 with poly(methyl methacrylate), (PMMA) and poly(ethylene-vinyl alcohol) were cast from formic acid solutions and examined by Fourier transform infra-red spectroscopy. At high contents of nylon-6 the vinyl alcohol of the copolymer reacts with formic acid to form vinyl formate. In contrast, the films of 100% copolymer and of the 25 75 and 10 90 blends contained both the alcohol and the ester groups. The FT i.r. results indicate that there are specific interactions between the amide group on nylon-6 and the ester group of PMMA or the copolymer. Data are also presented which show that there are at least two amorphous phases - one miscible containing both the polymers and the other containing almost pure noncrystallizable component. The differences in the specific interactions in the two blend systems are largely due to the inversion of the ester group in the pendant chain.

关键词： polyblends nylon-6 PMMA ethylene-vinyl formate copolymer FT i.r. miscibility

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Novel epoxynorbornane monomers .2. Cationic photopolymerization

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MACROMOLECULES 1996年第1期29卷 439-445页

作者： Crivello, JV Narayan, R Polymer Science and Engineering Program Department of Chemistry Rensselaer Polytechnic Institute Troy New York 12180

The reactivity of a novel series of mono-, di-, and multifunctional monomers bearing the epoxynorbornane group in photoinduced cationic polymerization was determined using Fourier transform real-time infrared spectroscopy and differential scanning photocalorimetry. Comparisons were made between the monomers of this investigation containing the epoxynorbornane group with monomers of similar structure bearing epoxycyclohexane groups. Although the cationic polymerizations of the epoxynorborane functional monomers are rapid they, are slower than the aforementioned epoxycyclohexane analogues. This was attributed mainly to steric hindrance effects.

关键词： Photopolymerization Monomers Cationic polymerization Ethers Reactivity

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AQUEOUS-SOLUTION PROPERTIES OF A POLYVINYL IMIDAZOLIUM SULFOBETAINE)

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polymer 1978年第10期19卷 1157-1162页

作者： SALAMONE, JC VOLKSEN, W OLSON, AP ISRAEL, SC Polymer Science Program Department of Chemistry University of Lowell Lowell Massachusetts 01854 USA

In this investigation the aqueous solution properties of an ampholytic poly(vinyl imidazolium sulphobetaine) are discussed. This class of polymer is water insoluble and its solubilization is related to the type and concentration of added salt. Cloud point determinations, intrinsic viscosity and light scattering studies are presented to illustrate the solution behaviour of this polyampholyte as a function of the type of cation and anion present. An explanation of its solubility in certain salt solutions is presented.

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ACRYLIC AMPHOLYTIC IONOMERS

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polymer 1982年第6期23卷 843-848页

作者： SALAMONE, JC MAHMUD, NA MAHMUD, MU NAGABHUSHANAM, T WATTERSON, AC Polymer Science Program Department of Chemistry University of Lowell Lowell Massachusetss 01854 USA

In a continuing study of the preparation of ampholytic ionomers from the polymerization of ion-pair comonomers (cationic-anionic monomer pairs) with nonionic comonomers, the preparation of such ionomers from methyl methacrylate and n-butyl acrylate is described. For both systems, ionomers of varying ion contents were obtained. In the n-butyl acrylate system, a linear relationship of T q vs. mol % ion content was found, but this did not occur for the methyl methacrylate ionomers. The solubilities of these materials in a wide variety of solvents is discussed. It appears that for n-butyl acrylate ionomers of high ion content in aqueous solution, a new form of polymeric surfactant is obtained.

关键词： Ion-pair comonomers ampholytic ionomers polyampholytes polymerization

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Novel epoxynorbornane monomers .1. Synthesis and characterization

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MACROMOLECULES 1996年第1期29卷 433-438页

作者： Crivello, JV Narayan, R Polymer Science and Engineering Program Department of Chemistry Rensselaer Polytechnic Institute Troy New York 12180

The synthesis of a series of mono-, di-, and multifunctional monomers bearing the epoxynorbornane group has been carried out. Key to their preparation is the chemoselective epoxidation of 5-vinyl-2-norbornene, which affords the 5-vinyl-exo-2,3-norbornane epoxide in high yields. Monomers were prepared using this substrate and carrying out hydrosilations to make mono-, di-, tri-, and tetrafunctional epoxides. The esterification and etherification of 5-norbornene-2-methanol with succinic acid and 1,4-butanediol gives the corresponding bisnorbornene compounds, which were epoxidized to give diepoxynorbornane monomers containing ester and ether linkages. All monomers were fully characterized by means of IR and H-1 and C-13 NMR spectroscopy and by elemental analysis.

关键词： Ethers Hydrocarbons Organic compounds Monomers Organic reactions

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DETERMINATION OF THE ALIPHATIC AND AROMATIC CH CONTENTS OF COALS BY FT-IR - STUDIES OF COAL EXTRACTS

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FUEL 1992年第10期71卷 1105-1125页

作者： SOBKOWIAK, M PAINTER, P Polymer Science Program Penn State University University Park PA 16802 USA

The pyridine-soluble extracts of 44 US coals and 17 Polish coals were characterized by FT-i.r. and proton n.m.r., allowing the determination of absorption coefficients for aliphatic and aromatic vibrational modes. Various aspects of methodology are discussed and it is demonstrated that the absorption coefficients of the stretching modes vary not only with rank - lignite and subbituminous coals being different from bituminous coals - but also with the origin of the parent coal. It is also demonstrated that the use of the out-of-plane bending modes to determine aromatic CH content introduces a systematic error into the results;although the size of this error remains undefined at this point, it is probably small,

关键词： PYRIDINE EXTRACTS OF COAL LIGNITE

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Assessing the Potential of Biodegradable Plastics in a Circular Economy: A Methodological Outlook

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Circular Economy and Sustainability 2025年第2期5卷 1291-1305页

作者： Scheers, Quinten Nimmegeers, Philippe Galant, Or Spatari, Sabrina Van den Brande, Niko Brancart, Joost Billen, Pieter Faculty of Applied Engineering Intelligence in Processes Advanced Catalysts and Solvents (iPRACS) University of Antwerp Groenenborgerlaan 171 Antwerp 2020 Belgium Faculty of Business and Economics Department of Engineering Management Environmental Economics (EnvEcon) University of Antwerp Prinsstraat 13 Antwerp 2000 Belgium Flanders Make@UAntwerp Antwerp 2000 Belgium Faculty of Civil and Environmental Engineering Technion– Israel Institute of Technology Haifa 3200003 Israel Grand Technion Energy Program Technion– Israel Institute of Technology Haifa 3200003 Israel Physical Chemistry and Polymer Science (FYSC) Vrije Universiteit Brussel Pleinlaan 2 Brussels 1050 Belgium IVL Swedish Environmental Research Institute Valhallavägen 81 Stockholm 11428 Sweden

Increased biodegradability, in other words reduced environmental recalcitrance, has the potential to be an important asset in the battle against plastics pollution. It can partially mitigate global plastic leakages into the environment, which is next to their impact on climate change the biggest concern regarding plastics use. Biodegradation should be regarded as an optimal safety net in many applications and should often not be the targeted waste management option for biodegradable plastics. Biodegradability should not preclude reuse or proper recyclability, which are impactful means to reduce the carbon intensity of plastics lifecycles. Despite the added advantages, the market penetration of biodegradable plastics is only very slowly growing. Moreover, policy recommends its use only in limited applications, driven by sometimes-higher cost and limited recyclability. In this article, we posit that arguments against widespread application of biodegradable plastics are largely driven by misperceptions arising from intrinsic limitations of contemporary sustainability assessments and offer an alternative viewpoint that could compensate for this. In general, sustainability assessments fail to properly assess learning curves, often do not take littering potential into account, and are rather conservative with respect to background systems. Hence, recyclability– or better: circularity– judgements often do not resolve the paradoxical situation in which increased market shares lead to easier and more profitable recycling schemes and vice versa. Judging disruptive innovations by incorporating thermodynamics-inspired, less data-intensive, state-based methods, based on, e.g., statistical entropy analysis, into the decision support framework could allow to forecast packaging markets with performant materials that are intrinsically circular, having reduced environmental recalcitrance. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.

关键词： Biodegradable Plastics Decision Making Statistical Entropy Sustainability Assessments

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PROPERTIES OF ETHYLENE - METHACRYLIC ACID COpolymerS AND THEIR SODIUM SALTS - MECHANICAL RELAXATIONS

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JOURNAL OF APPLIED PHYSICS 1967年第11期38卷 4208-+页

作者： MACKNIGHT, WJ MCKENNA, LW READ, BE Chemistry Department and Polymer Science and Engineering Program University of Massachusetts Amherst Massachusetts

A study has been made of the mechanical‐relaxation behavior of an ethylene‐methacrylic acid copolymer containing 4.1 mole % acid units and its partially ionized sodium salts. Degrees of ionization, estimated from infrared analysis, ranged from 0% to 78%. The weight‐percent crystallinity of the samples, determined by differential‐scanning calorimetry, varied from about 15 for the acid copolymer to about 7 for the 78% ionized copolymer. Four relaxation regions have been observed. They are labelled α, β′, β and γ, and each has been assigned to motions within the amorphous phase of the polymer. In plots of the logarithmic decrement against temperature (at 1 cps), the α peak for the annealed acid copolymer occurs at 50°C and shifts to higher temperatures with increasing degree of ionization. This trend is consistent with the increase in melt flow viscosity with increasing ionization and, on this basis, the α process is attributed to the long‐range diffusional motions of chain segments. The β′ peak occurs at 23°C for the annealed acid copolymer and decreases in magnitude with increasing ionization. Hence the β′ mechanism is attributed to the micro‐Brownian motions of chain segments involving the breaking and reforming of intermolecular hydrogen bonds between dimerized carboxylic‐acid groups. The latter assignment is supported by infrared studies of hydrogen bonding as a function of temperature. The β peak is absent for the acid copolymer but appears at −10°C for the ionized polymers and increases in height with increasing ionization. Thus, the β process is attributed to motions of branched chain segments including the ionic (carboxylate) side groups. The onset of the γ peak is observed at −120°C and is associated with the local motions of linear methylene sequences. The observation that the β peak is located at a temperature very close to the β peak (−20°C) for ordinary branched polyethylene, must cast considerable doubt on the widely held view that the ionic side groups

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THE CHAIN-LENGTH DEPENDENCE OF THE CHEMICAL-POTENTIALS OF MACROMOLECULAR SYSTEMS AT ZERO DENSITY - EXACT CALCULATIONS AND MONTE-CARLO SIMULATIONS

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JOURNAL OF CHEMICAL PHYSICS 1992年第2期96卷 1490-1497页

作者： KUMAR, SK Department of Materials Science and Engineering Polymer Science Program Pennsylvania State University University Park Pennsylvania 16802

In a previous paper we illustrated a Monte Carlo method to calculate the incremental chemical potential between polymer chains of length nu and nu + 1 at all densities. In this document we present a statistical mechanics model that allows for its quantitative evaluation as a function of chain length and temperature for macromolecular systems at zero density. Through this approach the incremental chemical potential at zero density is shown to be a strong function of chain length at low temperatures, but becomes chain length independent even for short chains (nu greater-than-or-equal-to 3) at higher temperatures. The temperature where the chemical potential becomes essentially chain length independent is a definition of the Boyle transition for finite chain length polymers, and we show that this transition temperature has a well defined chain length dependence. Chain dimensions and incremental entropies associated with chain segments are also found to decrease significantly when the temperature is reduced below this theta-temperature thus providing that chain segments are localized in the vicinity of other segments in the collapsed state. The consequences of these results on the modeling of the phase equilibria of polymer solutions are also examined.

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