A Review of Liquid-Glass Transitions
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Predicting Polymers' Glass Transition Temperature by a Chemical
polymers Article Predicting Polymers’ Glass Transition Temperature by a Chemical Language Processing Model Guang Chen 1 , Lei Tao 1 and Ying Li 1,2,* 1 Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269, USA; [email protected] (G.C.); [email protected] (L.T.) 2 Polymer Program, Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA * Correspondence: [email protected] Abstract: We propose a chemical language processing model to predict polymers’ glass transition temperature (Tg) through a polymer language (SMILES, Simplified Molecular Input Line Entry System) embedding and recurrent neural network. This model only receives the SMILES strings of a polymer’s repeat units as inputs and considers the SMILES strings as sequential data at the character level. Using this method, there is no need to calculate any additional molecular descriptors or fingerprints of polymers, and thereby, being very computationally efficient. More importantly, it avoids the difficulties to generate molecular descriptors for repeat units containing polymerization point ‘*’. Results show that the trained model demonstrates reasonable prediction performance on unseen polymer’s Tg. Besides, this model is further applied for high-throughput screening on an unlabeled polymer database to identify high-temperature polymers that are desired for applications in extreme environments. Our work demonstrates that the SMILES strings of polymer repeat units can be used as an effective feature representation to develop a chemical language processing model for predictions of polymer Tg. The framework of this model is general and can be used to construct structure–property relationships for other polymer properties. Citation: Chen, G.; Tao, L.; Li, Y. -
Colorless and Transparent High – Temperature-Resistant Polymer Optical Films – Current Status and Potential Applications in Optoelectronic Fabrications
Chapter 3 Colorless and Transparent high – Temperature-Resistant Polymer Optical Films – Current Status and Potential Applications in Optoelectronic Fabrications Jin-gang Liu, Hong-jiang Ni, Zhen-he Wang, Shi-yong Yang and Wei-feng Zhou Additional information is available at the end of the chapter http://dx.doi.org/10.5772/60432 Abstract Recent research and development of colorless and transparent high-temperature- resistant polymer optical films (CHTPFs) have been reviewed. CHTPF films possess the merits of both common polymer optical film and aromatic high-temperature- resistant polymer films and thus have been widely investigated as components for microelectronic and optoelectronic fabrications. The current paper reviews the latest research and development for CHTPF films, including their synthesis chemistry, manufacturing process, and engineering applications. Especially, this review focuses on the applications of CHTPF films as flexible substrates for optoelectrical devices, such as flexible active matrix organic light-emitting display devices (AMOLEDs), flexible printing circuit boards (FPCBs), and flexible solar cells. Keywords: colorless polymer films, high temperature, synthesis, flexible substrates 1. Introduction Various polymer optical films have been widely applied in the fabrication of optoelectronic devices [1]. Recently, with the ever-increasing demands of high reliability, high integration, high wiring density, and high signal transmission speed for optoelectronic fabrications, the service temperatures of polymer optical films have dramatically increased [2, 3]. For instance, © 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. -
3 About the Nature of the Structural Glass Transition: an Experimental Approach
3 About the Nature of the Structural Glass Transition: An Experimental Approach J. K. Kr¨uger1,2, P. Alnot1,3, J. Baller1,2, R. Bactavatchalou1,2,3,4, S. Dorosz1,3, M. Henkel1,3, M. Kolle1,4,S.P.Kr¨uger1,3,U.M¨uller1,2,4, M. Philipp1,2,4,W.Possart1,5, R. Sanctuary1,2, Ch. Vergnat1,4 1 Laboratoire Europ´een de Recherche, Universitaire Sarre-Lorraine-(Luxembourg) [email protected] 2 Universit´edu Luxembourg, Laboratoire de Physique des Mat´eriaux,162a, avenue de la Fa¨ıencerie, L-1511 Luxembourg, Luxembourg 3 Universit´eHenriPoincar´e, Nancy 1, Boulevard des Aiguillettes, Nancy, France 4 Universit¨atdes Saarlandes, Experimentalphysik, POB 151150, D-66041 Saarbr¨ucken, Germany 5 Universit¨at des Saarlandes, Werkstoffwissenschaften, POB 151150, D-66041 Saarbr¨ucken, Germany Abstract. The nature of the glassy state and of the glass transition of structural glasses is still a matter of debate. This debate stems predominantly from the kinetic features of the thermal glass transition. However the glass transition has at least two faces: the kinetic one which becomes apparent in the regime of low relaxation frequencies and a static one observed in static or frequency-clamped linear and non-linear susceptibilities. New results concerning the so-called α-relaxation process show that the historical view of an unavoidable cross-over of this relaxation time with the experimental time scale is probably wrong and support instead the existence of an intrinsic glass transition. In order to prove this, three different experimental strategies have been applied: studying the glass transition at extremely long time scales, the investigation of properties which are not sensitive to the kinetics of the glass transition and studying glass transitions which do not depend at all on a forced external time scale. -
Determination of Supercooling Degree, Nucleation and Growth Rates, and Particle Size for Ice Slurry Crystallization in Vacuum
crystals Article Determination of Supercooling Degree, Nucleation and Growth Rates, and Particle Size for Ice Slurry Crystallization in Vacuum Xi Liu, Kunyu Zhuang, Shi Lin, Zheng Zhang and Xuelai Li * School of Chemical Engineering, Fuzhou University, Fuzhou 350116, China; [email protected] (X.L.); [email protected] (K.Z.); [email protected] (S.L.); [email protected] (Z.Z.) * Correspondence: [email protected] Academic Editors: Helmut Cölfen and Mei Pan Received: 7 April 2017; Accepted: 29 April 2017; Published: 5 May 2017 Abstract: Understanding the crystallization behavior of ice slurry under vacuum condition is important to the wide application of the vacuum method. In this study, we first measured the supercooling degree of the initiation of ice slurry formation under different stirring rates, cooling rates and ethylene glycol concentrations. Results indicate that the supercooling crystallization pressure difference increases with increasing cooling rate, while it decreases with increasing ethylene glycol concentration. The stirring rate has little influence on supercooling crystallization pressure difference. Second, the crystallization kinetics of ice crystals was conducted through batch cooling crystallization experiments based on the population balance equation. The equations of nucleation rate and growth rate were established in terms of power law kinetic expressions. Meanwhile, the influences of suspension density, stirring rate and supercooling degree on the process of nucleation and growth were studied. Third, the morphology of ice crystals in ice slurry was obtained using a microscopic observation system. It is found that the effect of stirring rate on ice crystal size is very small and the addition of ethylene glycoleffectively inhibits the growth of ice crystals. -
Lecture #16 Glass-Ceramics: Nature, Properties and Processing Edgar Dutra Zanotto Federal University of São Carlos, Brazil [email protected] Spring 2015
Glass Processing Lecture #16 Glass-ceramics: Nature, properties and processing Edgar Dutra Zanotto Federal University of São Carlos, Brazil [email protected] Spring 2015 Lectures available at: www.lehigh.edu/imi Sponsored by US National Science Foundation (DMR-0844014) 1 Glass-ceramics: nature, applications and processing (2.5 h) 1- High temperature reactions, melting, homogeneization and fining 2- Glass forming: previous lectures 3- Glass-ceramics: definition & applications (March 19) Today, March 24: 4- Composition and properties - examples 5- Thermal treatments – Sintering (of glass powder compactd) or -Controlled nucleation and growth in the glass bulk 6- Micro and nano structure development April 16 7- Sophisticated processing techniques 8- GC types and applications 9- Concluding remmarks 2 Review of Lecture 15 Glass-ceramics -Definition -History -Nature, main characteristics -Statistics on papers / patents - Properties, thermal treatments micro/ nanostructure design 3 Reading assignments E. D. Zanotto – Am. Ceram. Soc. Bull., October 2010 Zanotto 4 The discovery of GC Natural glass-ceramics, such as some types of obsidian “always” existed. René F. Réaumur – 1739 “porcelain” experiments… In 1953, Stanley D. Stookey, then a young researcher at Corning Glass Works, USA, made a serendipitous discovery ...… 5 <rms> 1nm Zanotto 6 Transparent GC for domestic uses Zanotto 7 Company Products Crystal type Applications Photosensitive and etched patterned Foturan® Lithium-silicate materials SCHOTT, Zerodur® β-quartz ss Telescope mirrors Germany -
Movement Between Bonded Optics
MOVEMENT BETWEEN BONDED OPTICS Andrew Bachmann, Dr. John Arnold and Nicole Langer DYMAX Corporation, September 13, 2001 INTRODUCTION Controlling the movement of bonded optical parts depends, in large measure, on the properties of the adhesives used. Common issues include both shrinkage during cure and expansion during thermal excursions. Designers have historically had to limit their designs to optics whose thermal range fell below the then-available “high” glass transition temperature (Tg) epoxies; i.e., operating below the adhesive’s Tg. However, many of today’s optical devices employ even higher operating temperatures and require greater resistance to environmental conditions. The common minus 50ºC to plus 200ºC microelectronic test operating range challenges even classical “High Tg” optical epoxies. The NO SHRINK™ family of Optical Positioning adhesives features low total movement between bonded parts either on cure or when the optical device is thermally cycled. NO SHRINK™ products are based on novel, patent- applied-for technology. This technology was incorporated into light curing urethane-acrylics to create products with thermal characteristics that are different from those of older technology adhesives. Table 1. Dimensional changes (measured at 25ºC) Adhesive OP-60-LS Adhesive OP-64-LS < 0.1% (during UV Cure) < 0.1% (during UV Cure) < 0.1% (after 24 hr, 120°C) < 0.1% (after 24 hr, 120°C) Tg ~ 50ºC Tg ~ 125ºC “Rules of thumb” for comparing epoxy resins are not accurate for comparing other resins or other resins with epoxies. Novel NO SHRINK™ UV and visible light curing adhesives exhibit less total movement over a temperature range regardless of the Tg. -
A Supercooled Magnetic Liquid State in the Frustrated Pyrochlore Dy2ti2o7
A SUPERCOOLED MAGNETIC LIQUID STATE IN THE FRUSTRATED PYROCHLORE DY2TI2O7 A Dissertation Presented to the Faculty of the Graduate School of Cornell University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy by Ethan Robert Kassner May 2015 c 2015 Ethan Robert Kassner ALL RIGHTS RESERVED A SUPERCOOLED MAGNETIC LIQUID STATE IN THE FRUSTRATED PYROCHLORE DY2TI2O7 Ethan Robert Kassner, Ph.D. Cornell University 2015 A “supercooled” liquid forms when a liquid is cooled below its ordering tem- perature while avoiding a phase transition to a global ordered ground state. Upon further cooling its microscopic relaxation times diverge rapidly, and eventually the system becomes a glass that is non-ergodic on experimental timescales. Supercooled liquids exhibit a common set of characteristic phenom- ena: there is a broad peak in the specific heat below the ordering temperature; the complex dielectric function has a Kohlrausch-Williams-Watts (KWW) form in the time domain and a Havriliak-Negami (HN) form in the frequency do- main; and the characteristic microscopic relaxation times diverge rapidly on a Vogel-Tamman-Fulcher (VTF) trajectory as the liquid approaches the glass tran- sition. The magnetic pyrochlore Dy2Ti2O7 has attracted substantial recent attention as a potential host of deconfined magnetic Coulombic quasiparticles known as “monopoles”. To study the dynamics of this material we introduce a high- precision, boundary-free experiment in which we study the time-domain and frequency-domain dynamics of toroidal Dy2Ti2O7 samples. We show that the EMF resulting from internal field variations can be used to robustly test the predictions of different parametrizations of magnetization transport, and we find that HN relaxation without monopole transport provides a self-consistent de- scription of our AC measurements. -
Effect of Cladding Layer Glass Transition Temperature on Thermal Resistance of Graded-Index Plastic Optical fibers
Polymer Journal (2014) 46, 823–826 & 2014 The Society of Polymer Science, Japan (SPSJ) All rights reserved 0032-3896/14 www.nature.com/pj NOTE Effect of cladding layer glass transition temperature on thermal resistance of graded-index plastic optical fibers Hirotsugu Yoshida1, Ryosuke Nakao1, Yuki Masabe1, Kotaro Koike2 and Yasuhiro Koike2 Polymer Journal (2014) 46, 823–826; doi:10.1038/pj.2014.75; published online 27 August 2014 INTRODUCTION maleimide (cHMI) doped with diphenyl sulfide, and the cladding and Graded-index plastic optical fibers (GI POFs)1 are a highly over-cladding polymers were poly(methyl mathacrylate) and competitive transmission medium for short-range communications poly(carbonate), respectively. In this study, we used two types of such as local area networks and interconnections. Because GI POFs commercial poly(methyl mathacrylate) resins with different Tg values have a parabolic refractive index profile in the core region, modal and compared the long-term thermal reliability of the GI POFs in dispersion is minimized and high-speed data transmission of over a terms of fiber attenuation. gigabit per second is possible. Currently, most suppliers produce GI 2 POFs via coextrusion and a dopant diffusion method; the core EXPERIMENTAL PROCEDURE polymer, which contains a diffusible dopant that has a higher Materials refractive index than that of the base polymer, and the cladding TClEMA and cHMI were purchased from Osaka Organic Chemical Industry polymer are concentrically extruded. The core and cladding (Osaka, Japan) and Nippon Shokubai (Osaka, Japan), respectively. Diphenyl polymers flow together into a diffusion zone, and the dopant from sulfide and lauryl mercaptan were purchased from Sigma-Aldrich Japan the core layer diffuses toward the cladding layer, forming the (Tokyo, Japan), and di-tert-hexyl peroxide was purchased from NOF Corpora- GI profile. -
Crystalline Phase Characterization of Glass-Ceramic Glazes M.G
CORE Metadata, citation and similar papers at core.ac.uk Provided by Estudo Geral Ceramics International 33 (2007) 345–354 www.elsevier.com/locate/ceramint Crystalline phase characterization of glass-ceramic glazes M.G. Rasteiro a,*, Tiago Gassman b, R. Santos c, E. Antunes a a Chemical Engineering Department, Coimbra University, Po´lo II, Pinhal de Marrocos, 3030-290 Coimbra, Portugal b Colorobbia Portugal, Anadia, Portugal c Centro Tecnolo´gico da Ceraˆmica e do Vidro, Coimbra, Portugal Received 6 May 2005; received in revised form 2 September 2005; accepted 3 October 2005 Available online 18 January 2006 Abstract The firing process of five raw crystalline frits was investigated by means of DTA, XRD, heating microscopy and dilatometry. The chemical composition of the frits was determined by FAAS, to define the main glass-ceramic system of each frit. The final crystalline structure detected for the sintered frits conformed to the temperatures for which transformations were obtained during heating. The existence of a relationship between the crystallization process and sintering behaviour was confirmed. During devitrification, the sintering process stops, confirming that crystalline formation affects the sintering behaviour of the frits. In this case, the thermal properties of the final product are not only dependent on oxide composition but also on the crystalline phases. It was established that the addition of adequate compounds could induce the formation of crystalline phases on some glass-ceramic frits. # 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Keywords: A. Sintering; D. Glass-ceramics; D. Glass; Crystallization 1. Introduction Glazes are commonly applied on surfaces as aqueous suspensions of frits and other additives, also called enamels [2]. -
Makrolon Product Range Typical Values 2 ® Important Economic Regionsimportant Are the World
® Product range Typical values Makrolon ® Makrolon® is the brand name of our polycarbonate, which we produce in all the major economic regions of the world. For Makrolon®, the most important economic regions are AsiaPacific (APAC), Europe, Middle East, Africa and Latin America (EMEA/LA), and North America and Mexico (NAFTA). Makrolon 2 Characterization Compared with other thermoplastics, the amor- dimensional stability coupled with a high creep phous material Makrolon® has a very unique modulus and good electrical insulation properties. property profile. It is noted above all for its high Glass fiber reinforced Makrolon® has particularly transparency, heat resistance, toughness and high stiffness and outstanding dimensional stability. Makrolon® is available in: Grades for special applications Optical storage media General purpose grades Optical lenses Food contact grades Light guides Impact modified grades Lighting Flame retardant grades Automotive lighting Glass fiber reinforced (milled fiber) grades Automotive glazing Blow molding Glass fiber reinforced (normal fiber) grades Furniture Extrusion Structural foam Medical devices Nomenclature ..06 So-called “food contact“ grades that The non-reinforced, general purpose and food comply with the regulations of the EU and contact grades of Makrolon® are available in its member states with regard to plastics different viscosity classes. The first two digits in contact with foodstuffs, conform to the in the type designation usually characterize the relevant FDA regulations and also meet the -
An Experimental Investigation of Glass Transition Temperature of Composite Materials Using Bending Test
Journal of Energy and Power Engineering 10 (2016) 39-44 doi: 10.17265/1934-8975/2016.01.005 D DAVID PUBLISHING An Experimental Investigation of Glass Transition Temperature of Composite Materials Using Bending Test Noori Hassoon Mohammed Al-Saadi1 and Ammar Fadhil Hussein Al-Maliki2 1. Building and Construction Engineering Department, Dijlah University College, Baghdad 10001, Iraq 2. Mechanical Engineering Department, Al-Mustansiriyah University, Baghdad 10001, Iraq Received: October 29, 2015 / Accepted: November 27, 2015 / Published: January 31, 2016. Abstract: In this study, the bending test is used to investigate the glass transition temperature for epoxy reinforced with three types of fibers, fiberglass, Kevlar and synthetic wool, these materials have a wide used in many application which they are used composite materials. The glass transition temperature can be measured at the point of inflection for the curve of variation of the deflection and temperature. The results show that, the glass transition temperature is affected by the type of the reinforcement of the composites. On the other hand, the glass transition temperature of the wool composite is higher than the other. Key words: Glass transition, composite materials, bending test. 1. Introduction transition temperature (Tg), but since the transition often occurs over a broad temperature range, the use of The glass transition of a polymer matrix composite is a single temperature to characterize it may give rise to a temperature-induced change in the matrix material some confusion. The experimental technique used to from the glassy to the rubbery state during heating or obtain the T must be described in detail, especially from a rubber to a glass during cooling. -
Surface and Bulk Crystallization of Glass-Ceramic in the Na2o–Cao
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Digital.CSIC M Romero, J.Ma Rincón. Surface and Bulk Crystallization of Glass-Ceramic in the Na2O-CaO-ZnO- PbO-Fe2O3-Al2O3-SiO2 System Derived from a Goethite Waste Journal of the American Ceramic Society, 82 (1999) [5], 1313-1317 DOI: 10.1111/j.1151-2916.1999.tb01913.x Surface and Bulk Crystallization of Glass-Ceramic in the Na2O–CaO–ZnO–PbO–Fe2O3–Al2O3–SiO2 System Derived from a Goethite Waste Maximina Romero* and Jesús María Rincón Instituto E. Torroja de Ciencias de la Construccion (The Glass-Ceramics Laboratory), CSIC, 28033 Madrid, Spain Abstract A goethite waste from zinc hydrometallurgical processes has been used to produce a glass- ceramic in the Na2O–CaO–ZnO–PbO–Fe2O3–Al2O3–SiO2 system. The surface and bulk microstructure of this glass-ceramic have been studied by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The surface was comprised of crystalline and glassy areas. Two different types of crystalline growth and two morphologies were observed in the crystallized and glassy zones, respectively. The bulk microstructure was composed of a homogeneously distributed dendritic network comprised of small crystallites of magnetite. A glassy matrix was observed surrounding the magnetite network. Further heat treatment produced the precipitation of a non-stoechiometric zinc ferrite with magnetite crystals, being the nucleating agents of the secondary phase. I. Introduction Glass-ceramics prepared by controlled crystallization of glasses have become established in a wide range of technical and technological applications.1 In the “classical method” usually applied to produce glass-ceramics, an appropriate mixture of raw materials is melted and poured into a mold to produce a glass.