bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactive‐ion etch resistant polysulfones for microlithography
Authors: Bowden Murrae J. , Gozdz Antoni S. , DeSimone Joseph M. , McGrath James E. , Ito Seiki , Matsuda Minoru 
Published: March 2011

AbstractThe various chemical approaches aimed at improving the reactive‐ion etch resistance of poly(olefin sulfone)s are described. Resist systems based on incorporation of RIE‐resistant moieties via random copolymerization, blending and block copolymer formation are described and lithographic properties noted.
Design and characterization of polymers and polymer blends for high temperature structural applications
Authors: Jaffe Michael , Chenevey Edward , Cooper William , Glick Morton , Haider M. Ishaq , Rafalko Joseph 
Published: March 2011

AbstractReviewing the development of new polymeric materials for high temperature structural applications (T > 200°C) over the past several decades, reveals a paradox which, to date, has not been completely resolved. Polymers which exhibit very high temperature stability tend to be either intractable or brittle, whereas, easily processible polymers tend to fall short of property targets. Approaches to resolving this paradox include modification of the chain backbone chemistry and polymer blending (especially to form miscible systems). Recent research has shown that, in contrast to low temperature flexible polymers, many high temperature aromatic heterocyclic polymers form miscible systems which permit the design of the desired processibility and performance into the blend. An example of such a system is the blend of Poly(2,2′‐(meta‐phenylene‐5,5′‐bibenzimidazole) (PBI) with a series of polyamides, including commercially available polyether imide (PEI) and imide copolymers containing sulfone and fluorinated isopropylidene (6F) units. Other examples include all polyimide blends and blends of polyimides with polyethersulfone.
Interfacial behaviour of block polyelectrolytes, III. Formation of surface micelles
Authors: Zhu J. , Hanley S. , Eisenberg A. , Lennox R. B. 
Published: March 2011

AbstractThe aggregation of (poly)styrene/quaternized (poly)‐4‐vinylpyridine diblocks into regular circular structures has been observed in Langmuir‐Blodgett films removed from a pure water surface. These novel aggregates, termed surface micelles, form at low surface pressures (< 2 mN/m) and exhibit rich isotherm behaviour as Langmuir films. A distinct first order phase transition is observed for the decylated derivatives of a series of diblocks (i.e. (PS)260(C10PVP+I−)n; n = 70, 120, 240) which has been interpreted as a transition from an entirely surface‐adsorbed micelle to a surface micelle whose polyelectrolyte chains have been forced into the aqueous subphase. Transmission electron and atomic force micrographs of LB films provide for direct visualization of these surface micelles as well as the means to estimate their aggregation numbers, N.
Molecular coils and their deformation
Authors: Kausch H. H. , Nguyen T. Q. 
Published: March 2011

AbstractThe study of stress‐effects on chain conformation has always been a fruitful ‐ and sometimes highly controversial ‐ issue in macromolecular science. In this paper chain scission in transient elongational flow is investigated. Particular attention is given to the possible nature of stress transfer from the deforming highly dilute polymer solution to the embedded molecular (PS) chain. The dependencies of the measured degradation efficiency on molecular weight, solvent viscosity, nozzle geometry and flow rate exclude the classical mechanism of chain loading through strain‐rate dependent viscous friction. On the basis of their findings the authors propose a model where the loading of hairpin‐like segments in almost static friction works against the internal relaxation of these structures.
Band texture formation of sheared polymeric liquid crystalline state
Authors: Qian Renyuan , Chen Shouxi 
Published: March 2011

AbstractThe phenomenon of band texture formation of sheared main chain liquid crystalline polymers is reviewed. The bands seen in a polarizing microscope are optical effects. The macromolecular chains are aggregated into zig‐zag bent fibrils perpendicular to the bands. The band texture is formed during shear relaxation. The induction period depends on the shear rate applied, the shearing time, solution concentration (lyotropic), solution layer thickness, temperature and the nature of the polymer. There exists a critical shear deformation to bring a multi‐domain nematic or cholesteric phase into a monodomain continuous phase, from which the band texture is formed. These two phases show quite different rheological behavior. In certain cases randomly oriented regions of bands can also be formed during quenching of a thermotropic nematic polymer melt or during standing of a lyotropic nematic polymer solution, where the nematic domains in the melt or in the solution have grown to a sufficient size.
Reactions of atomic oxygen [O(3P)] with polymer films
Authors: Golub Morton A. 
Published: March 2011

AbstractThe reactions of polymer films with oxygen atoms are reviewed. Emphasis is on work from this laboratory on polybutadienes having different amounts of 1,4 or 1,2 double bonds and their polyalkenamer homologues, on a polyimide (Kapton), and on a series of polyolefins with increasing fluorine content ranging from polyethylene (PE) to polytetrafluoroethylene (PTFE). Interest in this topic stems from a need to understand the mechanism(s) of surface erosion, or etching, that occurs in organic polymers when exposed to the low Earth orbital (LEO) environment, where ground‐state atomic oxygen [O(3P)] is the most abundant constituent. The major findings for O atom reactions with the polyalkenamers were: (1) etch rates increase with decrease in ‐CH=CH‐unsaturation, starting with 1,4‐polybutadiene and reaching the maximum rate with PE or ethylene‐propylene rubber; (2) in polybutadienes having both 1,4 and 1,2 double bonds, the rate of O(3P)‐induced etching is lower the higher the 1,2 content; and (3) the reactions are confined to the polymer surface. Relative etch rates for various commercial polymer films (e.g., Kapton, Teflon, PE) exposed to O(3P) downstream from a low‐pressure, radio‐frequency O2 plasma were compared with corresponding literature data for films exposed to O(3P) either during a Space Shuttle flight or in the plasma glow (where many species besides O(3P) are present). The use of O2 discharge reactors – whether exposures are conducted “out of the glow” or “in the glow” – cannot serve as a routine, ground‐based simulation of exposures of a polymer to the LEO environment. ESCA analysis of the surfaces of Kapton and other polymers, before and after reaction with O(3P), showed that there is a steady‐state competition between surface recession and oxidation. In a series of fluorine‐containing polyolefins exposed to O(3P), the maximum oxygen uptake increased regularly with decrease in fluorine content, ranging from a minimum in PTFE to a maximum in PE.
Universality in polymer viscoelasticity
Authors: Lin Y.‐H. 
Published: March 2011

AbstractThis paper brings together seven aspects of universality in viscoelasticity of linear flexible polymers: (1) the stress relaxation modulus G(t) being a universal function of the normalized molecular weight (MW), M/Me; (2) the MW dependence of the zero shear viscosity; (3) the MW dependence of the steady state compliance; (4) the MW dependence of the diffusion constant; (5) the damping functions; (6) slip‐stick melt fracture being a universal phenomenon; and (7) the number of entanglement strands per cubed entanglement distance being a universal constant. As presented in the text, the consistency, agreement and relation among these different aspects of universality can be properly brought to light.
The slip‐link model: A constitutive equation for general biaxial extension of polymer melts
Authors: Wagner M. H. 
Published: March 2011

AbstractStarting from a slip‐link model, we derive a general strain measure for polymer melts. Predictions are compared to experimental data of uniaxial, planar, ellipsoidal, and equibiaxial extensions of a polyisobutylene (PIB) melt. The data do not support Doi's assumption that the tube diameter remains unchanged by deformation. The relative tube diameter and its inverse, the molecular stress function, can be extracted directly from the data. At small strains, the relative cross section of the tube is inversely proportional to the average stretch of the tube.
Rheometry towards complex flows: Squeeze flow technique
Authors: Laun Hans Martin 
Published: March 2011

AbstractDisk‐like samples are submitted to controlled squeezing forces between parallel plates and the time‐dependent sample height is measured. Isothermal tests at constant force enable the determination of viscosity functions of melts. Experiments using a constant disk radius and a constant disk volume are compared. Creep and creep recovery tests are made possible by a height‐dependent control of the force. The evaluation of a pressure‐dependent yield stress is demonstrated for wax powder. The squeeze flow technique is of advantage for systems with a layer structure or matrices containing long fibres or mats. In non‐isothermal experiments on solidifying materials, either by crystallization or polymerization, the total deformation and the speed of solidification in processes like stamp moulding can be determined.
Rheology of heterophase polymer systems
Authors: Kotaka Tadao , Shikata Toshiyuki 
Published: March 2011

AbstractThis lecture attempts to elucidate rheological behavior of multiphase polymer systems through a comparison with our studies on much simpler systems such as suspensions of (a) non‐aggregating and (b) aggregating monodisperse spheres in viscoelastic media, (c) polymer latex in the same polymer liquids, and (d) emulsions or blends of two polymers with or without an emulsifying block copolymer. For the system (a) not only the viscosity η but also the modulus obey the known simple dependence on volume fraction ϕ of hard‐sphere suspensions, while for the system (b) the flow induced‐aggregation and dissociation of the particles govern the rheology. In the system (c), relaxations of entanglements of the adsorbed chains as well as the spatial distribution of the latexes are essential. For the emulsion (d) of a biased composition range (e.g., ϕ1 > ϕ2) the matrix phase 1 dominates, unless η1 << η2. When η1 ≥ η2, deformation and/or bursting of the dispersed phase 2 take place. For those of an even composition, the viscosity is additive of those of the components and is enhanced by adding the emulsifying block copolymer component.
Mathematical tools for solving new, more realistic models of polymer melts
Authors: Öttinger Hans Christian 
Published: March 2011

AbstractStochastic processes play an important role in the kinetic theory of polymeric liquids. Various concepts, such as “configurational distribution functions”, “diffusion equations”, “Brownian motion”, “white noise”, “generalized Langevin equations”..., are indispensable in the theory of polymer dynamics. We review the mathematical description of various types of stochastic processes in order to provide (i) a sound basis for the formulation of new kinetic theory models, (ii) recipes for the development of computer simulation algorithms, and (iii) a feeling for the possible pitfalls in the naïve use of stochastic calculus. Various possible applications of the mathematical background presented here are discussed in connection with particular models of polymer melts.
Molecular tube models of branched polymer melts
Authors: McLeish T.C.B. , O'Connor K. P. 
Published: March 2011

AbstractWe apply the tube model to a specific problem in polymer melt dynamics ‐ the rheology of star polymers as an additive to a monodisperse linear matrix. We find that the tube dilation picture of constraint release may be applied to the relaxation of the star fraction. There are four qualitatively different cases depending on the relative concentrations and relaxation times of the two fractions. Terminal relaxation times and relaxation spectra are calculated for each case and compared with available experimental data. The existence of a modified Rouse relaxation such that G(t)∼t−3/2 is argued.
Processing/morphology/rheology relationships in polymer blends
Authors: Favis Basil D. 
Published: March 2011

AbstractIn this paper certain aspects concerning the influence of rheological parameters on the morphology of immiscible polymer blends are considered. The author reviews his own work with reference to other key studies carried out in the field. The influence of the viscosity ratio on morphology for compatibilized and non‐compatibilized systems are treated, as well as the influence of shear stress. The role of viscosity and viscosity ratio in controlling co‐continuous and complex composite droplet morphologies are also discussed.
Prerequisites for successful recycling of polymer waste
Authors: Brandrup Johannes 
Published: March 2011

AbstractAn increasing awareness of ecological problems will enhance all activities towards recycling of polymers. In other words, we have to expect a fast increasing amount of recycled polymers. Today, most activities concentrate on the economical feasible part of recycling ‐ waste of higher prized plastics, only slightly contaminated plastic waste.Public pressure and legislation request solutions for heavily contaminated commodity plastics from household waste as well. The strategy to produce thick walled, profiles out of comingled plastics will be a contribution towards, but not the solution of the problem. We have to make the serious attempt to separate specific polymers like PE, PS, PET from the waste and to introduce these recyclates into the plastic market. In other words, we have to establish closed loops for all our products. Tremendous problems lay ahead of us in order to accomplish it. We need markets for recyclate, we have to change specifications accordingly, we have to improve existing technologies for work up, we have to develop “raw material” specifications when we turn waste in an economic good, we have to develop scenarios for unsufficient economics.The paper will deal with all these aspects in detail and will discuss the present situation in Germany.
Separation of poly(vinyl chloride) from poly(ethylene terephthalate) by micronyl process
Authors: Famechon René 
Published: March 2011

AbstractMixed Poly(vinyl chloride) (PVC) and Poly(ethylene terephthalate)(PET) scraps can be separated by various methods based on the difference in their physical or chemical properties. A short review of the presently known methods is made. The presentation is focused on a method developed by MICRONYL WEDCO and based on the difference in impact strength resistance of the two polymers at room temperature.
Liquefaction of plastics
Authors: Hirota T. , Fagan F. N. 
Published: March 2011

AbstractA plastic liquefaction process which features a combination of thermal and catalytic cracking has been developed. The process can charge polyethylene, poly(propylene) or polystyrene and produces relatively low pour and highly aromatic liquid at a yield of about 85 %. Based on laboratory development a 500 ton per year prototype unit has been constructed and operated successfully both for testing and further development. An additional 1000 ton per year prototype unit is in the design phase and is scheduled for operation in 1992. The salient aspects of the process are described.
Recycling concepts for polyurethanes and polycarbonate
Authors: Müller Peter , Riess Reinhard 
Published: March 2011

AbstractThe opinion is that all thermoplastics are infinitely recyclable, while crosslinked polyurethanes (PUR) and thermosets are not recyclable. The present paper uses comparative data to show that the waste management problem associated with crosslinked PUR materials has been largely overcome on a pilot‐plant scale. Direct and indirect material recycling as well as thermal recycling are discussed. A direct recycling method in which granulated PUR‐RIM scrap is made to “flow” under heat and pressure to re‐mould it, is quoted as evidence that crosslinked polyurethane elastomers can be reclaimed and reused in a similar manner to thermoplastics. This process is called “compression molding”. Recycling methods for thermoplastics under consideration from an early stage, as well as entirely new possibilities that are emerging, are demonstrated, using polycarbonate Makrolon® as an example.
Glycolytic recycle of poly(ethylene terephthalate) (PET)
Authors: Gintis Daniel 
Published: March 2011

AbstractIn a comparison of PET waste recovery methods, glycolysis to monomer (DHET + low MW oligomers) represents a compromise between regeneration of starting ingredients by methanolysis or hydrolysis and direct remelt extrusion. It is less costly than the former and more versatile than the latter. The resultant easily filtered, low viscosity monomer is repolymerized to a useful molecular weight (MW), used as an ingredient for copolymers and used with additives for controlling luster, color, etc. Glycolytic recycle can be a batch or continuous process, the rate being dependent on temperature, catalyst, state of subdivision of the feedstock and the 2G/T ratio. In addition, the final monomer composition is controlled by the time of reaction and hold‐up time after depolymerization. Low 2G/T ratios permit higher temperatures and faster reactions but result in higher MW oligomers. Side reactions occurring in the depolymerization are minimized by addition of a buffer as sodium acetate and limiting storage time at high temperatures. PET scrap suitable for glycolytic recycle includes production waste, fibers, film, flake, bottles, etc., but ingredients leading to side reactions, copolymers, end caps or color must be minimized for critical products and satisfactory rates of polymerization.
Catalytic degradation of polyolefins
Authors: Audisio Guido , Bertini Fabio , Beltrame Pier Luigi , Carniti Paolo 
Published: March 2011

AbstractSilica, alumina, silica‐aluminas and zeolites were screened as catalysts for polyolefins degradation. The degradations were carried out at temperatures from 200°C till to 600°C under vacuum. The degradation products were analyzed using gas chromatography‐mass spectrometry (GC‐MS). The comparison between these products and those obtained by thermal degradation in the absence of catalyst gives us many informations about the different mechanisms of the two degradation reactions. Kinetic measurements and thermogravimetry provided further useful data for screening the catalysts, finding the best operating conditions.
Watergas from plastic waste and its possible uses
Authors: Kessler Birgit , Semel Joachim 
Published: March 2011

AbstractCoal gasification technology should also be applicable to plastic waste. The resulting product is watergas or in general terms syngas which is used as a feedstock for several large chemical products. Based on theoretical considerations the study evaluates the costs related to syngas production from plastic waste and subsequent conversion to chemical raw products. Net waste disposal costs of 275 – 690 DM/ton are calculated depending upon the end product(s).
Chemical recycling of polyurethanes and separation of the components by supercritical ammonia
Authors: Lentz H. , Mormann W. 
Published: March 2011

AbstractChemical recycling of a polyurethane elastomer and a flexible foam based on methylenebis(phenyl isocyanate) (MDI) and a polyetherpolyol was performed by ammonolytic cleavage of urethane and urea bonds under supercritical conditions. Resulting products were the polyols, the amines corresponding to the isocyanates used, and unsubstituted urea. Under suitable conditions the polyetherpolyol was completely separated from the other ammonolysis products which in turn can be further separated and used for the manufacture of polyurethanes or for the synthesis of diisocyanates.
Compatibilization strategies for upgrading recycled plastics performance: Use of reactive rubbery polymers
Authors: Scobbo J. J. 
Published: March 2011

AbstractOne of the inherent problems in the recycling of polymers involves the wide variety of immiscible and incompatible polymer resins. For this reason, it is important to keep scrap from different sources separate, especially if it is known beforehand that the compositions are significantly different. Approaches to upgrading the performance of the scrap streams can then be tailored to each stream. Our work has been based, in part, upon one such approach. Reactive rubbery polymers have been used to modify several recycle streams. These models represent household scrap, business machine housings, and automobile bumpers. Dramatic property improvements can be obtained if specific reactive rubbery polymers are matched to certain recycle streams. Also, it was found that variability in the source and the composition of a given stream over time can dramatically affect results. These findings underscore the inherent difficulty in developing a universal approach to the recycling of mixed plastics.
Variations in the mechanical properties of end products from mixed plastics
Authors: Breant P. 
Published: March 2011

AbstractFrom well selected polymers, using an experimental plan methodology, we show the different influences (nature, processing conditions, composition) on the properties of end products from mixed plastics such as strain and stress at rupture, flexural modulus, impact strength and extrusion flow rate. From models, it is possible to adjust necessary formulations to obtain a good quality level and, eventually, an improvement of poor properties. Mixed plastics can be considered as a polyethylene matrix containing other polymers such as polypropylene (PP), polystyrene (PS) or poly(vinyl chloride) (PVC). Poly(ethylene terephthalate) (PET) is neglected in this study. Properties such as strain at rupture or impact strength are drasticly affected by the level of polypropylene, polystyrene or poly(vinyl chloride): 5 or 10% nullify these properties. Other properties such as stress at rupture, flexural modulus or extrusion flow rate highly depend on the relative ratio of polymers. To improve the poor properties or to obtain a good level in a property, it is necessary to add well adapted compatibilizers or to dope the mixed plastics material by one of the polymers.
Interaction of segmented polyurethanes and polyurethane‐ureas with water
Authors: Bohdanecký Miloslav , Petřík Stanislav , Hadobaš František , Šimek Lubomír 
Published: March 2011

AbstractSorption of water vapor by oligomeric homopolymers and triblock copolymers of ethylene oxide and propylene oxide, and by polyurethanes and polyurethane ‐ ureas derived from them is discussed. While the sorption isotherms (plots of ψ1 vs a1, where ψ is he volume fraction of sorbed water and a1 is activity) for most polymers investigated here are smooth and convex towards the abscissa, those found with polyurethane‐ureas containing long hard blocks have a “toe” at low activities. The plots of a1/ψ1 vs a1 are shown to facilitate the analysis of data and the interpretation in terms of the D'Arcy‐Watt theory.Smooth isotherms are fitted by a simple equation with two parameters. The first is related to the limiting value, χ0, (at ψ1 → 0) of the χ parameter characterizing the polymer‐water interaction. The dependences of χ0 on the polymer composition (content of hard segments or oxyethylene units) can provide information on the interaction between hard and soft segments.The second parameter is used in the computation of parameters characterizing the clustering tendency of water molecules. This tendency depends mainly on the content of oxypropylene units but is also raised by urethane or urea groups, though not so much as by oxypropylene groups.