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Artykuły w czasopismach na temat "Polymer Melt Films"
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Enose, Arno A., Priya K. Dasan, H. Sivaramakrishnan i Sanket M. Shah. "Formulation and Characterization of Solid Dispersion Prepared by Hot Melt Mixing: A Fast Screening Approach for Polymer Selection". Journal of Pharmaceutics 2014 (12.03.2014): 1–13. http://dx.doi.org/10.1155/2014/105382.
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Solid dispersion is molecular dispersion of drug in a polymer matrix which leads to improved solubility and hence better bioavailability. Solvent evaporation technique was employed to prepare films of different combinations of polymers, plasticizer, and a modal drug sulindac to narrow down on a few polymer-plasticizer-sulindac combinations. The sulindac-polymer-plasticizer combination that was stable with good film forming properties was processed by hot melt mixing, a technique close to hot melt extrusion, to predict its behavior in a hot melt extrusion process. Hot melt mixing is not a substitute to hot melt extrusion but is an aid in predicting the formation of molecularly dispersed form of a given set of drug-polymer-plasticizer combination in a hot melt extrusion process. The formulations were characterized by advanced techniques like optical microscopy, differential scanning calorimetry, hot stage microscopy, dynamic vapor sorption, and X-ray diffraction. Subsequently, the best drug-polymer-plasticizer combination obtained by hot melt mixing was subjected to hot melt extrusion process to validate the usefulness of hot melt mixing as a predictive tool in hot melt extrusion process.
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Winey, K. I., A. Faldi i R. J. Composto. "Morphology of polymer-polymer dewetting in thin films". Proceedings, annual meeting, Electron Microscopy Society of America 53 (13.08.1995): 182–83. http://dx.doi.org/10.1017/s0424820100137288.
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Two or more thin polymer layers are frequently combined for industrial applications such as protective coatings, lubricants, packaging, and adhesives. One might refer to such multi-layered polymeric structures as planar nanocomposites. The use of multiple polymer thin films requires the control of spreading and dewetting of these films. Our studies have identified a number of important characteristics of the kinetics and morphology of polymer melt / polymer melt dewetting. Particularly noteworthy is our ability to distinguish the two polymer melts in a cross-sectional view. At 190°C a 200 nm film of polycarbonate (PC) was found to dewet a 200 nm film of poly(styrene-co-acrylonitrile) (SAN) which had been deposited onto a rigid substrate. An optical micrograph of an intermediate stage of polymer-polymer dewetting shows the characteristic features: a circular hole in the upper layer (light gray), a rim surrounding the hole, and a small dimple in the center of the hole (dark gray), Figure 1.
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Seemann, Ralf, Stephan Herminghaus, Chiara Neto, Stefan Schlagowski, Daniel Podzimek, Renate Konrad, Hubert Mantz i Karin Jacobs. "Dynamics and structure formation in thin polymer melt films". Journal of Physics: Condensed Matter 17, nr 9 (19.02.2005): S267—S290. http://dx.doi.org/10.1088/0953-8984/17/9/001.
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Barbosa, Renata, Tatianny Soares Alves, Dayanne Diniz Souza Morais, Laura Hecker Carvalho i Osanildo Damião Pereira. "Preparation of Biodegradable Polymer Nanocomposites and Vermiculite Clay by Melt Intercalation Technique". Materials Science Forum 775-776 (styczeń 2014): 357–62. http://dx.doi.org/10.4028/www.scientific.net/msf.775-776.357.
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The consumption of plastic products over the years has been producing large numbers of waste material, which accumulate by landfill generating considerable environmental problems. Among biodegradable polymers, there is the PHB (poly-3-hydroxybutyrate), which has attracted more attention once it is obtained from renewable sources. This study aimed to prepare biodegradable nanocomposites by melt intercalation of PHB polymer in the natural vermiculite clay, in the ratios of 1, 3 and 6 wt%. The nanocomposites were obtained in an internal mixer coupled to a torque rheometer by Haake-Blucher, operating at 170°C, 50 rpm for 10 minutes. The material was triturated and then films were molded by compression under the conditions: 3 tons at 170°C for 3 minutes. The films were characterized by X-ray diffraction (XRD) and Infrared (FTIR). These analyzes were used to evaluate the intercalation and / or exfoliation of nanocomposites. In general, results indicated changes in structure as a function of clay content employed in the systems of PHB / vermiculite.
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Didenko, Andrey, Danila Kuznetcov, Valentina Smirnova, Gleb Vaganov, Alexey Ivanov, Vladimir Yudin i Vladislav Kudryavtsev. "The Co-Poly(Urethane-Imide) Heat Resistant Thermoplastic Elastomers". Nano Hybrids and Composites 34 (23.02.2022): 23–28. http://dx.doi.org/10.4028/p-rcjpez.
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Co-Pоly (Urethane-Imide) s (CPUI) based on pоly (diethyleneglycol) adipate diol, tolylenediisocyanate, multinucleate dianhydrides and diamines were synthesized. The films and moldings from CPUI were processed and their mechanical characteristics were evaluated. Distinctions of specifications of the films formed from polymer solutions and the moldings formed from melt polymers are indicated when using the same starting CPUI. It appears that films and moldings possess typical properties of elastomers. The reprocessing of studied copolymers by using the injection molding method allows to assign CPUI to the thermoplastic elastomers or so-called thermoelastoplasts.
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Gupta, Rakesh K., i Kim F. Auyeung. "Crystallization in polymer melt spinning". Journal of Applied Polymer Science 34, nr 7 (20.11.1987): 2469–84. http://dx.doi.org/10.1002/app.1987.070340711.
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Skoura, Eva, Peter Boháč, Martin Barlog, Helena Palková, Martin Danko, Juraj Šurka, Andreas Mautner i Juraj Bujdák. "Modified Polymer Surfaces: Thin Films of Silicate Composites via Polycaprolactone Melt Fusion". International Journal of Molecular Sciences 23, nr 16 (15.08.2022): 9166. http://dx.doi.org/10.3390/ijms23169166.
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Polymer/layered silicate composites have gained huge attention in terms of research and industrial applications. Traditional nanocomposites contain particles regularly dispersed in a polymer matrix. In this work, a strategy for the formation of a composite thin film on the surface of a polycaprolactone (PCL) matrix was developed. In addition to the polymer, the composite layer was composed of the particles of saponite (Sap) modified with alkylammonium cations and functionalized with methylene blue. The connection between the phases of modified Sap and polymer was achieved by fusing the chains of molten polymer into the Sap film. The thickness of the film of several μm was confirmed using electron microscopy and X-ray tomography. Surfaces of precursors and composite materials were analyzed in terms of structure, composition, and surface properties. The penetration of polymer chains into the silicate, thus joining the phases, was confirmed by chemometric analysis of spectral data and changes in some properties upon PCL melting. Ultimately, this study was devoted to the spectral properties and photoactivity of methylene blue present in the ternary composite films. The results provide directions for future research aimed at the development of composite materials with photosensitizing, photodisinfection, and antimicrobial surfaces.
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Shmakova, N. S., I. A. Kirsh i V. A. Romanova. "Influence of cationic surfactants on physical and mechanical properties of polymer compositions". Proceedings of the Voronezh State University of Engineering Technologies 82, nr 1 (15.05.2020): 225–29. http://dx.doi.org/10.20914/2310-1202-2020-1-225-229.
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When creating filled polymer composite materials, difficulties often arise due to poor compatibility of polymers with modifying additives. To solve such problems, surface-active substances (SAS) are successfully used in many industries, but they are practically not used in polymer processing. This is largely due to the insufficient assortment of surfactants produced that are suitable for introduction into polymers, especially film-forming ones. Anionic and nonionic surfactants are used in the synthesis and processing of elastomers, but they are not used in the production of film materials. As for the use of cationic surfactants, there are still no data at all. They differ from other types of surfactants in a variety of structures, in the number and relative positions of cationic centers and hydrophobic radicals, and also in antimicrobial properties. The prospects of using quaternary ammonium salts for the modification of packaging materials are shown. The expediency of using cationic surfactants for the modification of polymeric materials is proved. It is shown that the use of quaternary ammonium salts improves the physical and mechanical properties of films based on polyethylene and polypropylene. It is proved that cationic surfactants are technologically compatible with polyolefins, which allows the processing of polymer compositions by extrusion. Today, the most common polymers for food packaging are polyethylene and polypropylene. This is due to their low cost, safety in contact with food products, and suitability for processing into films of different thicknesses. More and more attention is being paid to the creation of packaging materials with antimicrobial properties. The imparting of such properties is achieved by introducing an antimicrobial additive into the polymer melt. It is most expedient to introduce additives directly into the melt of the polymer composition during processing, since, for example, during the extrusion process, polymer homogenization with the additive.
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Zhou, Yang, Qiming He, Fan Zhang, Feipeng Yang, Suresh Narayanan, Guangcui Yuan, Ali Dhinojwala i Mark D. Foster. "Modifying Surface Fluctuations of Polymer Melt Films with Substrate Modification". ACS Macro Letters 6, nr 9 (14.08.2017): 915–19. http://dx.doi.org/10.1021/acsmacrolett.7b00459.
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Zhang, Fan, Qiming He, Yang Zhou, Suresh Narayanan, Chao Wang, Bryan D. Vogt i Mark D. Foster. "Anomalous Confinement Slows Surface Fluctuations of Star Polymer Melt Films". ACS Macro Letters 7, nr 7 (25.06.2018): 834–39. http://dx.doi.org/10.1021/acsmacrolett.8b00278.
Pełny tekst źródłaRozprawy doktorskie na temat "Polymer Melt Films"
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Zhang, Fan Mr. "BRANCHING AND CHAIN END EFFECTS ON SURFACE FLUCTUATIONS OF POLYSTYRENE MELT FILMS". University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1542541224707819.
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Song, Hyunmin. "Melt-Processable Polymeric Photonic Crystals and Their Applications as Nanolayered Laser Films". Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1333111539.
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He, Qiming. "SYNTHESIS OF CYCLIC AND MULTICYCLIC POLYSTYENES AND THEIR SURFACE FLUCTUATIONS IN MELT POLYMER FILMS". University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1493720701063113.
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Yang, Feipeng. "Nanoscale Characterization of Electrolyte Diffusion, Interface Morphology Disruption and Surface Dynamics of Polymer Melt Films Adsorbed on Graphene". University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1542133274117037.
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Repka, Michael Andrew. "Physical-mechanical and chemical properties of topical films produced by hot-melt extrusion /". Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Uvieghara, Mathias N. "The Effect of Deborah Number and Aspect Ratio on the Film Casting of LLDPE Melts". Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/UviegharaMN2004.pdf.
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Schune, Claire. "Fondus de polymère en mouillage pseudo-partiel sur la silice : morphologie, structure et dynamique des films précurseurs". Electronic Thesis or Diss., Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLS017.
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Les wafers de silicium oxydés sont des surfaces dites de haute énergie : la plupart des liquides recouvrent spontanément la totalité de leur surface. Ainsi, lorsqu’une goutte y est déposée, un film d’épaisseur nanométrique appelé film précurseur s’étale en premier lieu autour de celle-ci. Les liquides que nous considérons sont des fondus de polymères(polybutadiène, polyisoprène, polystyrène) en mouillage pseudo-partiel sur ces surfaces : une goutte de liquide immobile, d’angle de contact non nul, coexiste avec un film. Grâce à la microscopie ellipsométrique, la morphologie et la dynamique de ces films ont pu être étudiées, et cela a permis de sonder de manière quantitative les interactions entre les segments de polymère et la surface. Nous montrons que les films précurseurs sont composés de deux parties : le film primaire, d’épaisseur submoléculaire, et le film secondaire, dense. Dans le film primaire, les chaînes de polymères ont dans un état bidimensionnel semi-dilué : elles ne couvrent pas toute la surface et interagissent entre elles. A partir des profils spatio-temporels des films, le coefficient de diffusion des chaînes sur le substrat peut être mesuré. Celles-ci diffusent selon un mécanisme de Rouse activé thermiquement, qui peut être décrit par le seul frottement des segments de polymère sur la surface, via une énergie d’activation qui caractérise les interactions polymère/substrat. Nous mesurons que celles-ci dominent largement les interactions entre chaines. Ce modèle a été généralisé au cas dechaînes possédant un groupement terminal spécifique. Il a également été étendu au cas où la mobilité conformationnelle des monomères le long de la chaine dépend de leur position au sein de la chaine et module le frottement fixé par les interactions avec le substrat. Le film secondaire raccorde quant à lui le film primaire à la goutte. Les chaînes y sont dans un état dense. Aux temps longs, le film secondaire est en forme de marche d’épaisseur uniforme proportionnelle à la racine de la longueur des chaînes. De façon remarquable, cette épaisseur d’équilibre est indépendante de la chimie du polymère et de l’état de la surface – température, présence d’eau adsorbée, épaisseur de la couche d’oxyde, etc. L’évolution vers cet état d’équilibre peut être modélisée en tenant compte à la fois du frottement des segments de polymère avec la surface et du frottement des segments entre eux. Dans la littérature, les films précurseurs n’ont que peu été étudiés lorsque le liquide est en mouillage pseudo-partiel. Outre la mesure robuste des interactions en jeu à l’échelle des chaînes de polymère, nos travaux mettent en évidence la nécessité de repenser le cadre théorique existant pour l’étude des films précurseurs, et ouvrent de nombreuses perspectivesOxidized silicon wafers are high energy surfaces : most liquids spontaneously spread on the entire surface. When a dropletis deposited, a nanometric film called a precursor film first spreads ahead of the droplet. The liquids that we considerin this study are polymer melts (polybutadiene, polyisoprene, polystyrene) in pseudo-partial wetting condition on these surfaces : a sessile droplet coexists with a film. By taking advantage of ellipsometric microscopy, we study the morphologyand dynamics of such films, and quantitatively probe the interactions at stake between the polymer segments and thesurface. Two different parts can be distinguished in the precursor films : the primary film of subnanometric thickness, and the secondary film, which is dense. In the primary film, polymer chains are in a 2D semi-dilute state : they do not cover theentire substrate and do not interact with each other. From the spatio-temporal thickness profiles, we measure the diffusion coefficient of the chains on the surface. We show that they diffuse with a thermally activated Rouse motion, that can be described by the sole friction of the chains on the surface, with an activation energy that reveals the interactions at stake.We measure that the polymer/surface interactions largely dominate the polymer/polymer interactions. We generalize thismodel for polymers with specific terminal groups, and to the case of chains with monomer conformational mobility that depends on the monomer position along the chain. The secondary film connects the primary film to the droplet, and is comprised of chains in a dense state. At long times, its thickness profile is a step of uniform thickness, which is proportionalto the square root of the chain length. Remarkably, this equilibrium thickness does not depend on the polymer chemistrynor on the surface state – temperature, water adsorbed, oxide layer thickness, etc. The evolution toward this equilibriumstate can be modeled by taking into account both the polymer/surface friction and the polymer/polymer friction. In the literature, only few studies deal with precursor films when the liquid is in pseudo-partial wetting condition. In addition tothe robust measurement of the interactions at stake at the scale of the polymer chains, our work highlights the necessityto re-think the theoretical existing framework for precursor films, and opens many perspectives
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Yonger, Marc. "Dynamique du mouillage pseudo-partiel de la silice par des fondus de polymère". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066274/document.
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La silice de précipitation, poreuse à l'échelle de 10 nm, a de nombreuses applications industrielles dans lesquelles elle est mélangée avec des fondus de polymère, composés de molécules de dimension nanométrique. La surface de la silice est de haute énergie, si bien qu'elle tend à être recouverte par la plupart des liquides. Par conséquent, lorsqu'une goutte de liquide est déposée sur la surface de la silice, un film " précurseur " s'étale au-devant de celle-ci, avec une épaisseur de l'ordre du nm. A l'aide d'observations macroscopiques et par imagerie ellipsométrique, nous avons mis en évidence que le polybutadiène et le polystyrène sont en conditions de mouillage pseudo-partiel avec la silice : une goutte macroscopique coexiste à l'équilibre avec le film précurseur en raison de la présence de forces à longue portée attractive à l'échelle du film. Le film précurseur est en fait formé de molécules quasi-isolées qui diffusent avec un coefficient de diffusion égal au coefficient d'auto diffusion mesuré en volume. Ceci nous donne des indications précieuses sur les interactions polymère/silice. Par ailleurs nous observons dans certains cas la croissance d'une instabilité, prenant la forme d'un film " secondaire " d'épaisseur supérieure à celle du film précurseur. Le polydiméthylsiloxane est quant à lui en conditions de mouillage total sur la silice, et seul un film existe à l'équilibre, les forces à longues portées étant répulsives. L'imbibition de la silice poreuse peut également se relier à ces observations. Finalement, nous déduisons que le film précurseur pour des faibles masses de polymères a peu d'impact sur la dynamique d'imbibition de pastilles de silice poreusePrecipitated silica, which is porous at the 10 nm scale, has various industrial uses where it is mixed with polymer melts, with characteristic molecular sizes in the nanometer range. Having a high surface energy, silica tends to be covered by most liquids. As a consequence, when a liquid droplet is deposited on silica surfaces, a thin “precursor” film spreads in front of the droplet, with a thickness of a few nanometers. By combining macroscopic observations and ellipsometry imaging, we found that polybutadiene and polystyrene melts on silica are in pseudo-partial wetting conditions, for which a droplet coexists with a precursor film at equilibrium, due to attractive long range forces at the film length scale. The precursor film is composed of quasi-isolated molecules diffusing in two dimensions with a diffusion coefficient equal to the bulk self-diffusion coefficient. This provides valuable information on the polymer/silica interactions. Furthermore, we occasionally observe the growth of an instability, as a “secondary” film which is thicker than the precursor film. In contrast, polydimethylsiloxane melts are in total wetting conditions on silica: at equilibrium, a polymer film covers the silica surface and no droplets coexist with the film, due to repulsive long range forces. Our observations of the imbibition of porous silica by polymer melts were related to these results. Eventually, for low molar mass polymers, we find that the precursor film has no significant impacts on porous silica pellets imbibition
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Begam, Nafisa. "Study of Dynamics, Thermal and Rheological Properties of Polymer Grafted Nanoparticle-polymer Blend". Thesis, 2016. https://etd.iisc.ac.in/handle/2005/4063.
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We studied dispersion state and dynamics of polymer grafted nanoparticle in photopolymer matrix nanoparticle-polymer blend- and their thermal and rheological properties. While thinking about a nanoparticle-polymer blend, the first question comes in is the dispersion state of nanoparticle in polymer. Especially in case of a blend film, dispersion of nanoparticle is very crucial in deciding its properties. It is still a challenging problem to get the dispersed blend even after 30 years of its invention. So, we started our work with the investigation of nanoparticle dispersion in polymer melt film and its evolution with time at high temperature. Eventually we studied the dynamics of nanoparticle in polymer melts at high temperature and the rheological and thermal properties of these blends.
In chapter 1, I have provided the introductory discussion about polymer’s conformation, dynamics etc. Polymer grafted nanoparticle dispersion and its dynamical behaviour in polymer matrix has been discussed in this chapter briefly. The experimental techniques used for this work have been explained in chapter 2. It is well known that preparation process of a blend film has a significant contribution to the final dispersion state of nanoparticle. A good practice to prepare such blend films is to anneal the film after it spincoated on a hard substrate. The purpose is to remove the trapped solvent as well as removing the unstable/meta-stable state achieved by sudden freezing of the polymers during spincoating. It was observed that the dispersion state of nanoparticle is improved after annealing. We study this evolution of dispersion at annealing temperature using in-situ X-ray scattering measurement and presented in chapter 3. We found super-diffusive in-plane and very slow out of plane motion of polystyrene grafted gold nanoparticle (PGNP) in polystyrene (PS) matrix at high temperature (T>Tg). The PGNP dispersion becomes homogeneous throughout the film which is otherwise a segregated film. After cooling down to room temperature, even though a partial reversal of the segregation occurs, the final dispersion state is better than that before annealing. We have shown a method of capturing the well dispersed state (the high temperature dispersion state) of PGNP at room temperature.
In chapter 4 we presented the study of PGNP dynamics in the polymer melt film at high temperature where the particles are expected to be almost homogeneously dispersed as we found in the previous observations. Anomalous relaxation dynamics is observed leading to an unusual temperature dependence of effective viscosity of the film and the anomaly increases under confinement. The observed anomalous behaviour could be explained in terms of the hydrodynamic slip experienced by the PGNP while the system has a dewetting PGNP-polymer interface. We estimated approximate slip length at the PGNP-polymer interface as a function of temperature and thickness. The slip length diverges at low temperature. Thickness dependent study reveals an increase of slip length under confinement resulting in a stronger anomaly for thinner films. Slip length at a polymer melt-polymer grafted wall interface (flat interface) as well as polymer melt-polymer grafted spherical particle interface (spherical interface) has been calculated by varying temperature and miscibility parameter, f (f=ratio of grafted and matrix chain molecular weight) using molecular dynamics simulations. A good agreement established between the simulation and the observed experimental results. In associated with the interface slip, the PGNP-polymer interface layer seems to have an effective interface viscosity which is different from bulk polymer viscosity.
A strong wave vector dependent hydrodynamic interaction between PGNPs was indicated by the observed temperature and wave vector dependent short time diffusion coefficient. This phenomenon could be explained in terms of the full slip boundary condition at the PGNP-polymer interface.
It is not surprising that the properties, e.g. thermal, rheological properties would get affected by the dispersion of PGNP as well as their dynamics. In chapter 5 we explored rheological propertis of nanoparticle-polymer blend film such as viscosity using force-distance spectroscopy for different miscibility parameters, f and temperature. A reduction in the viscosity of the blend film was observed with respect to its pristine polymer film for a smaller f value. The deviation of blend film viscosity from pristine polymer film viscosity reduces with increase in f. The extent of the viscosity reduction for smaller f increases towards lower temperature. Further, we have studied demixing temperature of a two component polymer blend system (Polystyrene (PS)/Poly (vinyl methyl ether) (PVME) blend) getting influenced by the presence of PGNP dispersed in it.
When the grafted chain length is much higher than the matrix PS chain, the demixing temperature gets increased, while the grafted chain length is much smallerthan matrix PS leads almost no change. The PGNPs are observed to be present inthe PVME phase while the grafted PS chains are too short compared to the matrix
PS chains and in opposite case while grafted chain is larger compared to matrix PSchains, the PGNPs are located at the PS matrix Rheological property of the PGNP suspensions in presence of linear PS chains hasbeen studied using diffusing wave spectroscopy and presented in chapter 6. A change in frequency dependence of viscous modulus was observed in a case where the linear PS chain is much longer than the grafted PS chains with increasing concentrations of PS linear chains indicating a shear thickening behaviour at higher linear PS concentrations.
Presence of shorter linear chains do not show any such change in frequency dependence. To investigate about the observed shear thickening, dynamic light scattering measurement were performed on these samples. A large shrinkage of nanoparticlecorona in presence of large linear chains was observed which could lead to the observed shear thickening behaviour. The shorter linear chains inter-penetrate into the grafted chains resulting in a swelling of nanoparticle grafts. Comparatively lower resultant viscosity observed for shorter chains possibly due to the faster mobility of shorter chains penetrating into the grafts. Finally in chapter 7, I summarize my thesis work and express my future work plan.
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Martyn, Michael T., Philip D. Coates i M. Zatloukal. "Influence of coextrusion die channel height on interfacial instability of low density polyethylene melt flow". 2014. http://hdl.handle.net/10454/10737.
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NoThe effect of side stream channel height on flow stability in 30 degrees coextrusion geometries was investigated. The studies were conducted on a Dow LD150R low density polyethylene melt using a single extruder to feed a flow cell in which the delivered melt stream was split before, and rejoined after, a divider plate in a slit die. Wave type interfacial instability occurred at critical stream thickness ratios. Reducing the side stream channel height broadened the layer ratio operating range before the onset of interfacial instability, therefore improving process stability. Stress fields were quantified and used to validate principal stress differences of numerically modelled flow. Stress field features promoting interfacial instability in each of the die geometries were identified. Interfacial instability resulted when the stress gradient across the interface was asymmetric and accompanied by a non-monotonic decay in the stress along the interface from its inception.
Książki na temat "Polymer Melt Films"
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Damman, P. Instability of thin films. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198789352.003.0008.
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We will first discuss the stability of liquid films deposited on solid surfaces with an emphasis on the nature of intermolecular forces and thermal fluctuations that conspire to generate complex morphologies. We will see how the global dewetting dynamics is driven by the solid–fluid interface and that dewetting can be a powerful tool to study the nanorheology of complex fluids, such as polymer melts in ultra thin films. In the second part, we will consider thin elastic sheets constrained by mechanical forces. The canonical example of such a system is given by a simple paper ball. We will see how the global geometry of these constraints drastically affects the final shape adopted by the sheet.
Części książek na temat "Polymer Melt Films"
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Boateng, Joshua, i Dennis Douroumis. "Bioadhesion Properties of Polymeric Films Produced by Hot-Melt Extrusion". W Hot-Melt Extrusion: Pharmaceutical Applications, 177–99. Chichester, UK: John Wiley & Sons, Ltd, 2012. http://dx.doi.org/10.1002/9780470711415.ch8.
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Binder, K. "Phase Transitions of Polymer Blends and Block Copolymer Melts in Thin Films". W Polymers in Confined Environments, 1–89. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/3-540-69711-x_1.
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Ghijsels, A., J. J. S. M. Ente i J. Raadsen. "Melt Strength Behaviour of Polyethylenes and Polyethylene Blends and its Relation to Bubble Stability in Film Blowing". W Integration of Fundamental Polymer Science and Technology—2, 466–71. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-1361-5_70.
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Elehinafe, Francis Boluwaji, i Augustine Omoniyi Ayeni. "Processing of Polymer-Based Nanocomposites in Advanced Engineering and Military Application". W Polymer Nanocomposites for Advanced Engineering and Military Applications, 1–9. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7838-3.ch001.
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This chapter gives an overview of polymer-based nanocomposites (PMNC), focusing on the processing. Polymers such as condensation polymers, vinyl polymers, polyolefins, specialty polymers including biodegradable are used in production of PMNC. It is the reinforcement that is in the nanorange size in nanocomposites generally. Reinforcements used are metal powders, silica, clays, and metal oxides. The most important methods of preparing PMNC are intercalation of the polymer or pre-polymer from solution, in-situ intercalative polymerization, melt intercalation, direct mixture of polymer and particulates, template synthesis, in-situ polymerization; and sol-gel process. The structure of polymer-based nanocomposites consists of the matrix material containing the nanosized reinforcement components in the forms of whiskers, particles, nanotubes, fibers, etc. It is clear that polymer-based nanocomposites provide many benefits such as improved properties, minimization of solid wastes films, and lower and improved manufacturing capabilities.
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Han, Chang Dae. "Tubular Film Blowing". W Rheology and Processing of Polymeric Materials: Volume 2: Polymer Processing. Oxford University Press, 2006. http://dx.doi.org/10.1093/oso/9780195187830.003.0012.
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Tubular film blowing has long been used to produce biaxially oriented films using such thermoplastic polymers as low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP). Here, LDPE refers to a polymer that is synthesized by free-radical polymerization under high pressure (Fawcett et al. 1937). The discovery of linear low-density polyethylene (LLDPE) in the 1980s via the Unipol process (Beret et al. 1986; Jones et al. 1985), which uses a low-pressure gas-phase process, has led to additions to the family of tubular blown films during the past two decades. The discovery of metallocene catalysts (Stevens and Neithamer 1991; Welborn and Ewen 1994) in the 1990s further increased the number of LLDPEs that have been used to produce tubular blown films during the last decade. To distinguish LLDPE from LDPE, LLDPE is sometimes referred to as low-pressure low-density polyethylene (LP-LDPE) and LDPE is referred to as high-pressure low-density polyethylene (HP-LDPE) (see Chapter 6 of Volume 1). In this chapter, however, we use the terminologies LDPE and LLDPE. As described in Chapter 6 of Volume 1, LDPE has a high degree of long-chain branching, while LLDPE has short-chain branching with little or no longchain branching. However, the metallocene catalysts apparently allow one to produce LLDPEs having a wide range of side chains, including a certain degree of long-chain branching. The details of the synthetic procedures for producing such a variety of LLDPEs are closely guarded industrial secrets. Biaxially oriented film can be strong and tough in all directions in the plane of the film. As in fiber spinning, the polymer melt exiting from the die flows under a mechanical tension in the direction of flow. However, in the film blowing process, the tube of molten polymer is extended in both the transverse and the axial (machine) directions. Therefore, rheologically speaking, the film blowing process may be treated from the point of view of biaxial elongational flow, whereas the fiber spinning process may be treated from the point of view of uniaxial elongational flow.
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Mark, James E., Harry R. Allcock i Robert West. "Preceramic Inorganic Polymers". W Inorganic Polymers. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780195131192.003.0013.
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One of the most important interfaces in materials science is the one between polymers and ceramics. Ceramics can be viewed as highly cross-linked polymer systems, with the three-dimensional network providing strength, rigidity, and resistance to high temperatures. Although not generally recognized as such, a few ceramics exist that are totally organic (i.e., carbon-based). Melamine-formaldehyde resins, phenolformaldehyde materials, and carbon fibers are well-known examples. However, totally inorganic ceramics are more widely known, many of which are based on the elements silicon, aluminum, or boron combined with oxygen, carbon, or nitrogen. Among the inorganic ceramics, two different classes can be recognized—oxide ceramics and non-oxide materials. The oxide ceramics frequently include silicate structures, and these are relatively low melting materials. The non-oxide ceramics, such as silicon carbide, silicon nitride, aluminum nitride, and boron nitride are some of the highest melting substances known. Non-oxide ceramics are often so high melting that they are difficult to shape and fabricate by the melt- or powder-fusion techniques that are common for oxide materials. One major use for inorganic-organic polymers and oligomers is as sacrificial intermediates for pyrolytic conversion to ceramics. The logic is as follows. Linear, branched, or cyclolinear polymers or oligomers can be fabricated easily by solution- or melt-fabrication techniques. If a polymeric material that has been shaped and fabricated in this way is then cross-linked and pyrolyzed in an inert atmosphere to drive off the organic components (typically, the side groups), the resultant residue may be a totally inorganic ceramic in the shape of the original fabricated article. Thus, ceramic fibers, films, coatings, and shaped objects may by accessible without recourse to the ultra-high temperatures needed for melting of the ceramic material itself. Note, however, that although the final shape of the object may be retained during pyrolysis, the size will be diminished due to the loss of volatile material. If the pyrolysis takes place too quickly, this contraction process may cause cracking of the material and loss of strength.
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Han, Chang Dae. "Coextrusion". W Rheology and Processing of Polymeric Materials: Volume 2: Polymer Processing. Oxford University Press, 2006. http://dx.doi.org/10.1093/oso/9780195187830.003.0014.
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Coextruded products were first commercialized in the 1950s by the fiber industry, which produced conjugate fibers (Sisson and Morhead 1953; Hicks et al. 1960, 1967). Subsequently, in the 1960s and 1970s, the plastics industry developed coextrusion processes to produce multilayer films and sheets by extruding two or more polymers. Schrenk and coworkers (Schrenk 1974; Schrenk and Alfrey 1973; Schrenk et al. 1963) pioneered the concept of a coextrusion die system. However, there are a number of technological problems that must be understood in order to achieve successful coextrusion operations. In the 1970s, a number of research groups devoted their efforts to a better understanding of the fundamental problems associated with the coextrusion processes; namely, (1) interface deformation (i.e., encapsulation of one component by another component) during coextrusion (Everage 1975; Han 1973, 1975; Khan and Han 1976; Lee and White 1974; MacLean 1973; Southern and Ballman 1973, 1975; White and Lee 1975) and (2) interfacial instability during coextrusion (Han and Shetty 1978a; Khan and Han 1977; Schrenk et al. 1978). Those efforts are summarized in two monographs by Han (1976, 1981). Since then, further efforts have been made to investigate interface deformation during coextrusion via finite element analysis (Karagiannis et al. 1990; Matsunaga et al. 1998; Mavridis et al. 1987; Mitsoulis 1988; Mitsoulis and Heng 1987; Puissant et al. 1994) and to investigate interfacial instability, both experimentally (Han et al. 1984; Wilson and Khomami 1992, 1993) and theoretically (Anturkar et al. 1990; Khomami 1990; Su and Khomami 1992). Coextruded sheet for thermoformed high-barrier containers has become an important business sector for food and beverage packages for meats, baby food, beer, carbonated soft drinks, etc. Such packaging requires improved barrier protection to extend the shelf life of such products in thermoformed barrier containers. It should be mentioned that the coextruded sheets or films are of little commercial value unless the component polymers adhere together. This means that the component polymers must be compatible,1 at temperatures ranging from service temperature to the melt processing temperature in order to have good adhesion between the layers in the coextruded films or sheets.
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R. Kasai, Deepak, Devi Radhika, Raju K. Chalannavar, Ravindra B. Chougale i Bhagyavana Mudigoudar. "A Study on Edible Polymer Films for Food Packaging Industry: Current Scenario and Advancements". W Advanced Rheology and Its Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.107997.
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Over the past two decades, food packaging and packaging industry have paid close attention to create biodegradable and edible polymer films and coatings. In a broad way, edible polymers emerged as a new class of materials that garnered significant properties due to their advantages over synthetic petroleum-based films. When compared to conventional packaging materials, edible polymer films can fundamentally simplify products, improving their potential to be recycled. This work aims to give readers a thorough introduction to edible polymer films, by discussing present research trends, classification, functionality and composition, fabrication, and characterization. The work also emphasizes the advantages and disadvantages of edible polymer films based on meat, poultry, dairy products, fruits, nuts, and vegetables.
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Senarathna, Sandunika, Indira Wickramasinghe i Seneviratne Navaratne. "Current Applications of Seaweed-Based Polysaccharides in Edible Packaging". W Algal Functional Foods and Nutraceuticals: Benefits, Opportunities, and Challenges, 447–64. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815051872122010022.
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The use of biopolymers instead of synthetic polymers for food packaging has become a recent trend since it successfully solves the global issue of plastic waste due to their biodegradability, biocompatibility and renewability. Moreover, edible packaging has gained the attention of the current research world. Thus, the natural polymer sources applicable in forming edible packaging materials, such as polysaccharides, proteins and lipids, are studied. Seaweed, referred to as marine macroalgae, is a rich source of polysaccharides. Different types of polysaccharides can be identified in the three main varieties of seaweed, carrageenan and agar in red algae, alginate, laminaran and fucoidan in brown algae, while ulvan is the major polysaccharide in green algae. The film-forming properties of these seaweed-based polysaccharides are enhanced due to their colloidal nature; meanwhile, the abundance and the low cost make them more applicable in edible packaging. Several modifications were carried out to achieve packaging materials with better mechanical and barrier properties. Hence, this chapter discusses the current applications of seaweed-based polysaccharides in edible packaging with improved properties in different sections such as fruits, vegetables and meat industries by analyzing recent research findings.
Streszczenia konferencji na temat "Polymer Melt Films"
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Singh, Satya Pal. "Self organized striping in ultra thin polymer films near melt: An investigation using Monte Carlo simulation". W 2ND INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC 2017). Author(s), 2018. http://dx.doi.org/10.1063/1.5032943.
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Yao, Donggang, Pratapkumar Nagarajan i K. R. T. Ramasubramani. "Constant-Temperature Embossing of Amorphous Poly(Ethylene Terephthalate) Films". W ASME 2007 International Manufacturing Science and Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/msec2007-31049.
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In the standard hot embossing process for thermoplastic polymers, thermal cycling is needed in order to soften and subsequently cool and solidify the polymer. This thermal cycling, however, not only results in long cycle times but also deteriorates the quality of embossed features. A new embossing method based on slowly crystallizing polymers was investigated to eliminate thermal cycling. Poly(ethylene terephthalate) was used as a model system for demonstration. Due to its slow crystallization, amorphous PET film can be made by casting a PET melt onto a chill roll. The amorphous PET film was embossed at a constant temperature of 180°C for a period of time comparable to or longer than PET’s half-time of crystallization. During constant-temperature embossing, the film first liquefies, caused by rubber softening of the amorphous phase, and then solidifies, resulting from the crystallization of the amorphous phase. Since the embossed film is hardened under the constant mold temperature, no cooling is needed. Selected micro features, including circular microchannels and high aspect ratio rectangular microchannels, were successfully embossed using a total cycle time about 40 s.
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Kuzmin, A. M. "Investigation of the Orientational Mechanical Properties of Biodegradable Extrusion Films Based on Polyolefins and Beet Pulp". W Modern Trends in Manufacturing Technologies and Equipment. Materials Research Forum LLC, 2022. http://dx.doi.org/10.21741/9781644901755-26.
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Abstract. The article discusses the possibility of obtaining biodegradable films based on polyolefins and beet pulp by the extrusion method. Biodegradable composites of two mixes with 15% and 25% beet pulp content have been obtained. Compounding was carried out on a twin-screw extruder, and then samples of biodegradable films were obtained by cast film extrusion. The influence of the vegetable filler particles’ orientation on the composites mechanical properties has been studied. It has been shown that composites mechanical properties significantly increase in the direction of polymer melt stretching.
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Pham, Giang T., Young-Bin Park i Ben Wang. "Development of Carbon-Nanotube-Based Nanocomposite Strain Sensor". W ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-82309.
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This paper presents the development of carbon-nanotube-based, polymer composite films that can be used as high-sensitivity strain sensors. The films were fabricated via either melt processing or solution casting of thermoplastic polymer matrices containing low concentrations of multi-walled carbon nanotubes. The electrical resistivities of the films were measured in situ using laboratory-designed fixtures and data acquisition system. The measured resistivities were correlated with the applied strains to evaluate the sensitivity of the nanocomposite film sensor. Various types of loading mode, including tension and flexure were considered. The paper suggests that conductive network formation, thus strain sensitivity of the conductive films, can be tailored by controlling nanotube loading, degree of nanotube dispersion, and film fabrication process. The developed sensors exhibited a wide range of sensitivity, the upper limit showing nearly an order of magnitude increase compared to conventional strain gages. Military and industrial applications of the sensitivity-tunable strain sensors are presented.
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Kim, Ickchan, Mihai G. Burzo, Pavel L. Komarov i Peter E. Raad. "Thermal Conductivity Measurements of Ultra-Thin Amorphous Poly(Methyl Methacrylate) (PMMA) Films". W ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-66507.
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As technology progresses towards smaller and higher density microelectronic devices, we are faced with working with atomic-scale dimensions that present us with challenges but also opportunities. Since mechanical and chemical properties of ultra-thin polymeric films can vary dramatically from their bulk, the thermophysical properties of thin films are also expected to vary. Ultra-thin poly(methyl methacrylate) (PMMA) films have been the focus of numerous investigations in recent years as a data storage medium. Employing Atomic Force Microscopy (AFM) technology, it is possible to store data bits by heating a target zone until it melts, which leaves a nano-dimple indentation in the PMMA polymer film. The AFM technology has great potential because it possesses considerable data density when compared to conventional magnetic data storage. Since the amount of heat that needs to be used to melt the nanoscale region of the polymer needs to be precisely controlled, knowing the thermophysical properties of such films is a critical factor in advancing this technology. It is known that heat carriers such as electrons and phonons in metallic and dielectric materials, respectively, are influenced by the “size effect” in the micro and nano-scale dimensions. Therefore, a goal for this investigation is to determine whether any dependence exists between the PMMA’s film thickness and its thermal conductivity. In this work we investigated whether a “scale effect” on intrinsic thermal conductivity actually exists for amorphous PMMA films with thicknesses ranging from 40 nm to 2 μm. The approach is based on the transient thermoreflectance (TTR) method, where the change in the surface temperature is measured by detecting the change in the reflectivity of the sample. The sample is heated by laser irradiation and probed using a continuous-wave laser that detects changes in the reflectivity of the heated material surface. The experimentally obtained transient temperature signature is then used to extract unknown values of thermal properties. Based on our previous experience with measuring a wide range of thin-film materials and the data available in the literature, we expected a lower thin-film thermal conductivity as compared to the bulk value. Surprisingly, the results show that the intrinsic thermal conductivity of layers thinner than 40 nm PMMA film deposited on native silicon oxide is about three times higher than the bulk PMMA value. A similar trend was observed for all ultra-thin (sub 100 nm) films.
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Santare, Michael H., Wenzhong Tang, John E. Novotny i Suresh G. Advani. "Mechanical Characterization of a Nanotube-Polyethylene Composite Material". W ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-43351.
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High-density polyethylene (HDPE) was used as the matrix material for a carbon nanotube (CNT) polymer composites. Multi-wall carbon nanotube composite films were fabricated using the melt processing method. Composite samples with 0%, 1%, 3% and 5% nanotube content by weight were tested. The mechanical properties of the films were measured by the small punch test and wear resistance was measured with a block-on-ring wear tester. Results show increases in the stiffness, peak load, work-to-failure and wear resistance with increasing nanotube content.
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ANILAL, ASHISH, JUSTIN BENDESKY, SEHEE JEONG, STEPHANIE S. LEE i MICHAEL BOZLAR. "EFFECTS OF GRAPHENE ON TWISTING OF HIGH DENSITY POLYETHYLENE". W Proceedings for the American Society for Composites-Thirty Seventh Technical Conference. Destech Publications, Inc., 2022. http://dx.doi.org/10.12783/asc37/36468.
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High density polyethylene (HDPE) is known to form banded spherulites when crystallized from the melt. In such spherulites, concentric bands of alternating light and dark colors emanating from the spherulite nucleation center are observable between cross polarizers and appear as a function of the anisotropy of the dielectric susceptibility as crystal orientations continuously rotate about the growth direction. Recently, we identified PE to be a promising compound to induce twisting in conjugated carbonaceous systems, such as triisopropylsilylethynyl anthradithiophene (TIPS ADT). When blended together in ratios between 10 – 70 wt.% PE, TIPS ADT and PE crystals twist in concert with one another to form composite films of intertwined helicoidal fibrils. In this work, we investigate crystal twisting in HDPE-graphene oxide composites. In addition to its unique multifunctionality, graphene has also recently demonstrated peculiar twisting capabilities that strongly alter its physical properties. Here, we first produce graphene sheets through the chemical oxidation of natural graphite, and then investigate the influence of graphene on the twisting of HDPE composites under various processing parameters (graphene concentration, polymer cooling rate, etc). HDPE-graphene composites have been prepared using melt extrusion in the form of microfibers and films. We measured the influence of twisting on the mechanical and electrical properties of the composites, as well as the crystallographic structure using optical and electron microscopy, and X-Ray diffraction spectroscopy.
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Poga, C., R. J. Twieg i W. E. Moerner. "High Efficiency Photorefractive Polymer with Immunity to Crystallization". W Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/otfa.1995.wgg.4.
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In the few years since the first report of a photorefractive (PR) organic polymeric material [1], much research has been done [2] to improve the material characteristics in order to meet the requirements necessary for applications such as holographic optical storage. A potentially useful polymeric system would combine a wide variety of properties in the same material, such as high diffraction efficiency, long dark lifetime, fast response, excellent optical clarity, just to name a few.
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Rao, I. J. "Simulation of the Film Blowing Process Using a Continuum Model for Crystallization in Polymers". W ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-1993.
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Abstract In this paper we simulate the film blowing process using a model developed to study crystallization in polymers (see Rao (1999), Rao and Rajagopal (2000b)). The framework was developed to generate mathematical models in a consistent manner that are capable of simulating the crystallization process in polymers. During crystallization the polymer transitions from a fluid like state to a solid like state. This transformation usually takes place while the polymer undergoes simultaneous cooling and deformation, as in film blowing. Specific models are generated by choosing forms for the internal energy, entropy and the rate of dissipation. The second law of thermodynamics along with the assumption of maximization of dissipation is used to determine constitutive forms for the stress tensor and the rate of crystallization. The polymer melt is modeled as a rate type viscoelastic fluid and the crystalline solid polymer is modeled as an anisotropic elastic solid. The mixture region, where in the material transitions from a melt to a semi-crystalline solid, is modeled as a mixture of a viscoelastic fluid and an elastic solid. The anisotropy of the crystalline phase and consequently that of the final solid depends on the deformation in the melt during crystallization, a fact that has been known for a long time and has been exploited in polymer processing. The film blowing process is simulated using a generalized Maxwell model for the melt and an anisotropic elastic solid for the crystalline phase. The results of the simulation agree qualitatively with experimental observations and the methodology described provides a framework in which the film blowing problem can be analyzed.
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Ducharme, Stephen, Arosha Goonesekera, Brian Jones, James M. Takacs i Lei Zhang. "High Two-beam Coupling Gain in a Photorefractive Polymer". W Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/otfa.1993.thc.4.
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In the last three years, a number of researchers have succeeded in making polymers which exhibit the photorefractive effect.1-4 These polymers have numerous potential applications in integrated optics, optical processing, optical data storage, optical computing, communications, image processing, optical switching, thresholding, laser resonators, simulation of neural networks, and studies of nonlinear dynamics. Elements of these applications have been implemented in the laboratory using high-performance photorefractive crystals. However, the cost of crystal growth and preparation has been a primary impediment to commercial application of crystal photorefractive devices. Photorefractive polymers, on the other hand, have very low production cost and will be particularly suitable for formation of waveguide devices for use in, e.g., integrated optics. The photorefractive performance of the polymers must be greatly improved, to meet or exceed the performance of available crystals.