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What is GLASS TRANSITION? What does GLASS TRANSITION mean? GLASS TRANSITION meaning & explanation
 
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What is GLASS TRANSITION? What does GLASS TRANSITION mean? GLASS TRANSITION meaning - GLASS TRANSITION definition - GLASS TRANSITION explanation. Source: Wikipedia.org article, adapted under https://creativecommons.org/licenses/by-sa/3.0/ license. The glass–liquid transition or glass transition for short is the reversible transition in amorphous materials (or in amorphous regions within semicrystalline materials) from a hard and relatively brittle "glassy" state into a viscous or rubbery state as the temperature is increased. An amorphous solid that exhibits a glass transition is called a glass. The reverse transition, achieved by supercooling a viscous liquid into the glass state, is called vitrification. The glass-transition temperature Tg of a material characterizes the range of temperatures over which this glass transition occurs. It is always lower than the melting temperature, Tm, of the crystalline state of the material, if one exists. Hard plastics like polystyrene and poly(methyl methacrylate) are used well below their glass transition temperatures, that is in their glassy state. Their Tg values are well above room temperature, both at around 100 °C (212 °F). Rubber elastomers like polyisoprene and polyisobutylene are used above their Tg, that is, in the rubbery state, where they are soft and flexible. Despite the change in the physical properties of a material through its glass transition, the transition is not considered a phase transition; rather it is a phenomenon extending over a range of temperature and defined by one of several conventions. Such conventions include a constant cooling rate (20 kelvins per minute (36 °F/min)) and a viscosity threshold of 1012 Pa·s, among others. Upon cooling or heating through this glass-transition range, the material also exhibits a smooth step in the thermal-expansion coefficient and in the specific heat, with the location of these effects again being dependent on the history of the material. The question of whether some phase transition underlies the glass transition is a matter of continuing research. The glass transition of a liquid to a solid-like state may occur with either cooling or compression. The transition comprises a smooth increase in the viscosity of a material by as much as 17 orders of magnitude without any pronounced change in material structure. The consequence of this dramatic increase is a glass exhibiting solid-like mechanical properties on the timescale of practical observation. This transition is in contrast to the freezing or crystallization transition, which is a first-order phase transition in the Ehrenfest classification and involves discontinuities in thermodynamic and dynamic properties such as volume, energy, and viscosity. In many materials that normally undergo a freezing transition, rapid cooling will avoid this phase transition and instead result in a glass transition at some lower temperature. Other materials, such as many polymers, lack a well defined crystalline state and easily form glasses, even upon very slow cooling or compression. The tendency for a material to form a glass while quenched is called glass forming ability. This ability depends on the composition of the material and can be predicted by the rigidity theory. Below the transition temperature range, the glassy structure does not relax in accordance with the cooling rate used. The expansion coefficient for the glassy state is roughly equivalent to that of the crystalline solid. If slower cooling rates are used, the increased time for structural relaxation (or intermolecular rearrangement) to occur may result in a higher density glass product. Similarly, by annealing (and thus allowing for slow structural relaxation) the glass structure in time approaches an equilibrium density corresponding to the supercooled liquid at this same temperature. Tg is located at the intersection between the cooling curve (volume versus temperature) for the glassy state and the supercooled liquid.
Views: 6652 The Audiopedia
Ep3 Sizes and shapes of polymers, dihedral angles, gauche and trans, UCSD NANO 134 Darren Lipomi
 
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Conformation vs. configuration, physical dimensions of polyethylene, gauche and trans, entropic springs. NANO 134 Polymeric Materials - UC San Diego - Prof. Darren Lipomi http://lipomigroup.org
Views: 1777 Darren Lipomi
Polymers
 
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Polymers
Time temperature superposition
 
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Time temperature superposition Prof. Abhijit P Deshpande Department of chemical Engineering IIT Madras
Views: 1644 Rheology - IITM
Polymers: Introduction and Classification
 
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This lecture introduces to the basics of Polymers, their classifications and application over wide domains.
Polystyrene
 
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Polystyrene (PS) /ˌpɒliˈstaɪriːn/ is a synthetic aromatic polymer made from the monomer styrene, a liquid petrochemical. Polystyrene can be rigid or foamed. General purpose polystyrene is clear, hard and brittle. It is a very inexpensive resin per unit weight. It is a rather poor barrier to oxygen and water vapor and has a relatively low melting point. Polystyrene is one of the most widely used plastics, the scale of its production being several billion kilograms per year. Polystyrene can be naturally transparent, but can be colored with colorants. Uses include protective packaging (such as packing peanuts and CD and DVD cases), containers (such as "clamshells"), lids, bottles, trays, tumblers, and disposable cutlery. Polystyrene is used to make napalm-B, where it makes up about 46% of the formulation. As a thermoplastic polymer, polystyrene is in a solid (glassy) state at room temperature but flows if heated above about 100 °C, its glass transition temperature. It becomes rigid again when cooled. This temperature behavior is exploited for extrusion, and also for molding and vacuum forming, since it can be cast into molds with fine detail. This video is targeted to blind users. Attribution: Article text available under CC-BY-SA Creative Commons image source in video
Views: 879 Audiopedia
Mod-01 Lec-02 Introduction to Polymers (Contd.)
 
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Polymer Chemistry by Dr. D. Dhara,Department of Chemistry and Biochemistry,IIT Kharagpur.For more details on NPTEL visit http://nptel.ac.in
Views: 8497 nptelhrd
Polymer blend
 
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A polymer blend or polymer mixture is a member of a class of materials analogous to metal alloys, in which at least two polymers are blended together to create a new material with different physical properties. This video is targeted to blind users. Attribution: Article text available under CC-BY-SA Creative Commons image source in video
Views: 2638 Audiopedia
Polystyrene
 
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Polystyrene /ˌpɒliˈstaɪriːn/ is a synthetic aromatic polymer made from the monomer styrene, a liquid petrochemical. Polystyrene can be rigid or foamed. General purpose polystyrene is clear, hard and brittle. It is a very inexpensive resin per unit weight. It is a rather poor barrier to oxygen and water vapor and has a relatively low melting point. Polystyrene is one of the most widely used plastics, the scale of its production being several billion kilograms per year. Polystyrene can be naturally transparent, but can be colored with colorants. Uses include protective packaging , containers , lids, bottles, trays, tumblers, and disposable cutlery. Polystyrene is used to make napalm-B, where it makes up about 46% of the formulation. This video targeted to blind users. Attribution: Article text available under CC-BY-SA Public domain image source in video
Views: 1761 encyclopediacc
Copolymer
 
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When two or more different monomers unite together to polymerize, their result is called as copolymer and its process is called copolymerization. Commercially relevant copolymers include acrylonitrile butadiene styrene (ABS), styrene/butadiene co-polymer (SBR), nitrile rubber, styrene-acrylonitrile, styrene-isoprene-styrene (SIS) and ethylene-vinyl acetate. This video is targeted to blind users. Attribution: Article text available under CC-BY-SA Creative Commons image source in video
Views: 3756 Audiopedia
Lec 28 | MIT 3.091 Introduction to Solid State Chemistry
 
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Organic Glasses - Polymers: Synthesis by Addition Polymerization and by Condensation Polymerization View the complete course at: http://ocw.mit.edu/3-091F04 License: Creative Commons BY-NC-SA More information at http://ocw.mit.edu/terms More courses at http://ocw.mit.edu
Views: 31550 MIT OpenCourseWare
Lec 29 | MIT 3.091 Introduction to Solid State Chemistry
 
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Structure-property Relationships in Polymers, Crystalline Polymers View the complete course at: http://ocw.mit.edu/3-091F04 License: Creative Commons BY-NC-SA More information at http://ocw.mit.edu/terms More courses at http://ocw.mit.edu
Views: 29983 MIT OpenCourseWare
Lec 29 | MIT 3.091SC Introduction to Solid State Chemistry, Fall 2010
 
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Lecture 29: Polymers: Synthesis, Properties & Applications Instructor: Donald Sadoway View the complete course: http://ocw.mit.edu/3-091SCF10 License: Creative Commons BY-NC-SA More information at http://ocw.mit.edu/terms More courses at http://ocw.mit.edu
Views: 19655 MIT OpenCourseWare
Mod-03 Lec-10 Principles of Polymer Synthesis (Contd.)
 
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Science and Technology of Polymers by Prof. B. Adhikari,Department of Metallurgy and Material Science,IIT Kharagpur.For more details on NPTEL visit http://nptel.ac.in
Views: 637 nptelhrd
Lec 28 | MIT 3.091SC Introduction to Solid State Chemistry, Fall 2010
 
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Lecture 28: Polymers: Structure & Composition Instructor: Donald Sadoway View the complete course: http://ocw.mit.edu/3-091SCF10 License: Creative Commons BY-NC-SA More information at http://ocw.mit.edu/terms More courses at http://ocw.mit.edu
Views: 16568 MIT OpenCourseWare
Polymer | Wikipedia audio article
 
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This is an audio version of the Wikipedia Article: Polymer 00:02:36 1 Common examples 00:04:05 2 Synthesis 00:05:46 2.1 Biological synthesis 00:06:37 2.2 Modification of natural polymers 00:07:50 3 Properties 00:08:44 3.1 Monomers and repeat units 00:09:55 3.2 Microstructure 00:10:31 3.2.1 Polymer architecture 00:11:34 3.2.2 Chain length 00:13:40 3.2.3 Monomer arrangement in copolymers 00:15:48 3.2.4 Tacticity 00:16:16 3.3 Morphology 00:16:32 3.3.1 Crystallinity 00:18:12 3.3.2 Chain conformation 00:18:42 3.4 Mechanical properties 00:19:02 3.4.1 Tensile strength 00:19:35 3.4.2 Young's modulus of elasticity 00:20:23 3.5 Transport properties 00:20:45 3.6 Phase behavior 00:20:54 3.6.1 Melting point 00:21:30 3.6.2 Glass transition temperature 00:22:02 3.6.3 Mixing behavior 00:24:29 3.6.4 Inclusion of plasticizers 00:25:23 3.7 Chemical properties 00:27:24 3.8 Optical properties 00:28:24 4 Standardized nomenclature 00:29:27 5 Characterization 00:31:48 6 Degradation 00:34:22 6.1 Product failure Listening is a more natural way of learning, when compared to reading. Written language only began at around 3200 BC, but spoken language has existed long ago. Learning by listening is a great way to: - increases imagination and understanding - improves your listening skills - improves your own spoken accent - learn while on the move - reduce eye strain Now learn the vast amount of general knowledge available on Wikipedia through audio (audio article). You could even learn subconsciously by playing the audio while you are sleeping! If you are planning to listen a lot, you could try using a bone conduction headphone, or a standard speaker instead of an earphone. You can find other Wikipedia audio articles too at: https://www.youtube.com/channel/UCuKfABj2eGyjH3ntPxp4YeQ You can upload your own Wikipedia articles through: https://github.com/nodef/wikipedia-tts "The only true wisdom is in knowing you know nothing." - Socrates SUMMARY ======= A polymer (; Greek poly-, "many" + -mer, "part") is a large molecule, or macromolecule, composed of many repeated subunits. Due to their broad range of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass relative to small molecule compounds produces unique physical properties, including toughness, viscoelasticity, and a tendency to form glasses and semicrystalline structures rather than crystals. The term "polymer" derives from the Greek word πολύς (polus, meaning "many, much") and μέρος (meros, meaning "part"), and refers to a molecule whose structure is composed of multiple repeating units, from which originates a characteristic of high relative molecular mass and attendant properties. The units composing polymers derive, actually or conceptually, from molecules of low relative molecular mass. The term was coined in 1833 by Jöns Jacob Berzelius, though with a definition distinct from the modern IUPAC definition. The modern concept of polymers as covalently bonded macromolecular structures was proposed in 1920 by Hermann Staudinger, who spent the next decade finding experimental evidence for this hypothesis.Polymers are studied in the fields of biophysics and macromolecular science, and polymer science (which includes polymer chemistry and polymer physics). Historically, products arising from the linkage of repeating units by covalent chemical bonds have been the primary focus of polymer science; emerging important areas of the science now focus on non-covalent links. Polyisoprene of latex rubber is an example of a natural/biological polymer, and the polystyrene of styrofoam is an example of a synthetic polymer. In biological contexts, essentially all biological macromolecules—i.e., proteins (polyamides), nucleic acids (polynucleotides), and polysaccharides—are purely polymeric, or are composed in large part of polymeric components—e.g., isoprenylated/lipid-modified glycoproteins, where small lipidic molecules and oligosaccharide modifications occur on the polyamide backbone of the protein.The simplest theoretical models for polymers are ideal chains.
Views: 2 wikipedia tts
Polymer
 
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A polymer (/ˈpɒlɨmər/) (poly-, "many" + -mer, "parts") is a large molecule, or macromolecule, composed of many repeated subunits. Because of their broad range of properties, both synthetic and natural polymers play an essential and ubiquitous role in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass relative to small molecule compounds produces unique physical properties, including toughness, viscoelasticity, and a tendency to form glasses and semicrystalline structures rather than crystals. The term "polymer" derives from the ancient Greek word πολύς (polus, meaning "many, much") and μέρος (meros, meaning "parts"), and refers to a molecule whose structure is composed of multiple repeating units, from which originates a characteristic of high relative molecular mass and attendant properties. The units composing polymers derive, actually or conceptually, from molecules of low relative molecular mass. The term was coined in 1833 by Jöns Jacob Berzelius, though with a definition distinct from the modern IUPAC definition. The modern concept of polymers as covalently bonded macromolecular structures was proposed in 1920 by Hermann Staudinger, who spent the next decade finding experimental evidence for this hypothesis. This video is targeted to blind users. Attribution: Article text available under CC-BY-SA Creative Commons image source in video
Views: 773 Audiopedia
Polymer | Wikipedia audio article
 
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This is an audio version of the Wikipedia Article: https://en.wikipedia.org/wiki/Polymer 00:02:36 1 Common examples 00:04:05 2 Synthesis 00:05:47 2.1 Biological synthesis 00:06:38 2.2 Modification of natural polymers 00:07:50 3 Properties 00:08:45 3.1 Monomers and repeat units 00:09:56 3.2 Microstructure 00:10:33 3.2.1 Polymer architecture 00:11:36 3.2.2 Chain length 00:13:49 3.2.3 Monomer arrangement in copolymers 00:15:58 3.2.4 Tacticity 00:16:26 3.3 Morphology 00:16:42 3.3.1 Crystallinity 00:18:23 3.3.2 Chain conformation 00:18:52 3.4 Mechanical properties 00:19:12 3.4.1 Tensile strength 00:19:46 3.4.2 Young's modulus of elasticity 00:20:34 3.5 Transport properties 00:20:56 3.6 Phase behavior 00:21:04 3.6.1 Melting point 00:21:41 3.6.2 Glass transition temperature 00:22:13 3.6.3 Mixing behavior 00:24:40 3.6.4 Inclusion of plasticizers 00:25:34 3.7 Chemical properties 00:27:35 3.8 Optical properties 00:28:36 4 Standardized nomenclature 00:29:39 5 Characterization 00:31:38 6 Degradation 00:34:12 6.1 Product failure Listening is a more natural way of learning, when compared to reading. Written language only began at around 3200 BC, but spoken language has existed long ago. Learning by listening is a great way to: - increases imagination and understanding - improves your listening skills - improves your own spoken accent - learn while on the move - reduce eye strain Now learn the vast amount of general knowledge available on Wikipedia through audio (audio article). You could even learn subconsciously by playing the audio while you are sleeping! If you are planning to listen a lot, you could try using a bone conduction headphone, or a standard speaker instead of an earphone. Listen on Google Assistant through Extra Audio: https://assistant.google.com/services/invoke/uid/0000001a130b3f91 Other Wikipedia audio articles at: https://www.youtube.com/results?search_query=wikipedia+tts Upload your own Wikipedia articles through: https://github.com/nodef/wikipedia-tts "There is only one good, knowledge, and one evil, ignorance." - Socrates SUMMARY ======= A polymer (; Greek poly-, "many" + -mer, "part") is a large molecule, or macromolecule, composed of many repeated subunits. Due to their broad range of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass relative to small molecule compounds produces unique physical properties, including toughness, viscoelasticity, and a tendency to form glasses and semicrystalline structures rather than crystals. The term "polymer" derives from the Greek word πολύς (polus, meaning "many, much") and μέρος (meros, meaning "part"), and refers to a molecule whose structure is composed of multiple repeating units, from which originates a characteristic of high relative molecular mass and attendant properties. The units composing polymers derive, actually or conceptually, from molecules of low relative molecular mass. The term was coined in 1833 by Jöns Jacob Berzelius, though with a definition distinct from the modern IUPAC definition. The modern concept of polymers as covalently bonded macromolecular structures was proposed in 1920 by Hermann Staudinger, who spent the next decade finding experimental evidence for this hypothesis.Polymers are studied in the fields of biophysics and macromolecular science, and polymer science (which includes polymer chemistry and polymer physics). Historically, products arising from the linkage of repeating units by covalent chemical bonds have been the primary focus of polymer science; emerging important areas of the science now focus on non-covalent links. Polyisoprene of latex rubber is an example of a natural/biological polymer, and the polystyrene of styrofoam is an example of a synthetic polymer. In biological contexts, essentially all biological macromolecules—i.e., proteins (polyamides), nucleic acids (polynucleotides), and polysaccharides—are purely polymeric, or are composed in large part of polymeric components—e.g., isoprenylated/lipid-modified glycoproteins, where small lipidic molecules and oligosaccharide modifications occur on the polyamide backbone of the protein.The simplest theoretical models for polymers are ideal chains.
Views: 2 wikipedia tts
History of polymer chemistry | Wikipedia audio article
 
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This is an audio version of the Wikipedia Article: https://en.wikipedia.org/wiki/Polymer_chemistry 00:00:57 1 Polymers and their properties 00:03:12 2 Classification 00:04:43 2.1 Composites 00:04:59 3 History 00:08:33 4 See also Listening is a more natural way of learning, when compared to reading. Written language only began at around 3200 BC, but spoken language has existed long ago. Learning by listening is a great way to: - increases imagination and understanding - improves your listening skills - improves your own spoken accent - learn while on the move - reduce eye strain Now learn the vast amount of general knowledge available on Wikipedia through audio (audio article). You could even learn subconsciously by playing the audio while you are sleeping! If you are planning to listen a lot, you could try using a bone conduction headphone, or a standard speaker instead of an earphone. Listen on Google Assistant through Extra Audio: https://assistant.google.com/services/invoke/uid/0000001a130b3f91 Other Wikipedia audio articles at: https://www.youtube.com/results?search_query=wikipedia+tts Upload your own Wikipedia articles through: https://github.com/nodef/wikipedia-tts Speaking Rate: 0.959271508398178 Voice name: en-US-Wavenet-D "I cannot teach anybody anything, I can only make them think." - Socrates SUMMARY ======= Polymer chemistry is a sub-discipline of chemistry that focuses on the chemical synthesis, structure, chemical and physical properties of polymers and macromolecules. The principles and methods used for polymer chemistry are common to chemistry sub-disciplines organic chemistry, analytical chemistry, and physical chemistry. Many materials have polymeric structures, from fully inorganic metals and ceramics to DNA and other biological molecules, however, polymer chemistry is typically referred to in the context of synthetic, organic compositions. Synthetic polymers are ubiquitous in commercial materials and products in everyday use, commonly referred to as plastics, rubbers, and composites. Polymer chemistry can also be included in the broader fields of polymer science or even nanotechnology, both of which can be described as encompassing polymer physics and polymer engineering.
Views: 1 wikipedia tts

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