The glass transition temperature is the temperature below which the physical properties of amorphous materials vary in a manner similar to those of a solid phase (glassy state), and above which amorphous materials behave like liquids (rubbery state). A material’s glass transition temperature, T_g, is the temperature below which molecules have little relative mobility. T_g is usually applicable to wholly or partially amorphous phases such as glasses and plastics. For inorganic or mineral glasses, such as common silicon dioxide (SiO₂) glass, it is the mid-point of a temperature range in which they gradually become more viscous and change from being liquid to solid. Thermoplastic (non-crosslinked) polymers are more complex because, in addition to a melting temperature, T_m, above which all their crystalline structure disappears, such plastics have a second, lower T_g below which they become rigid and brittle, and can crack and shatter under stress. Small molecular weight pure substances such as water have just one such condensed-phase temperature, below which they are solid crystals (or amorphous ice if cooled below T_g fast enough) and above which they are liquids. An amorphous solid is a solid in which there is no long-range order of the positions of the atoms. ... For other uses, see Temperature (disambiguation). ... 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ... This article is about the material. ... This article or section does not cite any references or sources. ... Inorganic chemistry is the branch of chemistry concerned with the properties and reactions of inorganic compounds. ... For other uses, see Mineral (disambiguation). ... R-phrases R42 R43 R49 S-phrases S22 S36 S37 S45 S53 Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... Viscosity is a measure of the resistance of a fluid to deformation under shear stress. ... A liquid will usually assume the shape of its container A liquid is one of the main states of matter. ... For other uses, see Solid (disambiguation). ... For other uses, see Plastic (disambiguation). ... Vulcanization is an example of cross-linking. ... The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. ... For other uses, see Crystal (disambiguation). ... The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Everyday ice is a crystal, which means its molecules are lined up in a repeating pattern. ...

Above T_g, the secondary, non-covalent bonds between the polymer chains become weak in comparison to thermal motion, and the polymer becomes rubbery and capable of elastic or plastic deformation without fracture. This behavior is one of the things which make most plastics useful. But such behavior is not exhibited by crosslinked thermosetting plastics which, once cured, are set for life and will shatter rather than deform, never becoming plastic again when heated, nor melting. Covalent bonding is a form of chemical bonding characterized by the sharing of one or more pairs of electrons between atoms, in order to produce a mutual attraction, which holds the resultant molecule together. ... thermal is related to heat, and motion means moving. ... In solid mechanics, elasticity is the property of materials which undergo reversible deformations under applied loads. ... In physics and materials science, plasticity is a property of a material to undergo a non-reversible change of shape in response to an applied force. ... Thermosetting plastics (thermosets) refer to a range of polymer materials that cure, through the addition of energy, to a stronger form. ... In polymer chemistry and Process Engineering, curing refers to the toughening or hardening of a polymer material by cross-linking of polymer chains, brought about by chemical additives, ultraviolet radiation, Electron beam (EB) or heat. ... In physics, melting is the process of heating a solid substance to a point (called the melting point) where it turns into a liquid. ...

Time dependency

Consider a molecular liquid which is slowly cooling down. At a certain temperature, the average kinetic energy of molecules no longer exceeds the binding energy between neighboring molecules and growth of organized solid crystal begins. Formation of an ordered system takes a certain amount of time since the molecules must move from their current location to energetically preferred points at crystal nodes. As temperature falls, molecular motion slows down further and, if the cooling rate is fast enough, molecules never reach their destination — the substance enters into dynamic arrest and a disordered, glassy solid (or supercooled liquid) forms. In fact, Kauzmann has argued that if such an arrest did not happen, at still lower temperatures a thermodynamically paradoxical situation would arise, where the undercooled liquid would have to be denser and of a lower enthalpy than the crystalline phase. Such arrest apparently takes place at certain temperature, which is called the calorimetric ideal glass transition temperature T_0c. This means that glass transition is not merely a kinetic effect, i.e. merely the result of fast cooling of a melt, but there is an underlying thermodynamic basis for glass formation ^[1]. The glass transition temperature T_g → T_0c as ^dT/_dt → 0. The kinetic energy of an object is the extra energy which it possesses due to its motion. ... Binding energy is the energy required to disassemble a whole into separate parts. ... In thermodynamics, the Kauzmann Paradox is the apparent result that it is possible to obtain a supercooled liquid with an entropy lower than that of its corresponding crystal. ... A simplistic view of a materials glass transition temperature (Tg) is the temperature below which molecules have very little mobility. ... In physical chemistry, chemical kinetics or reaction kinetics is the study of reaction rates in a chemical reaction. ... Thermodynamics (Greek: thermos = heat and dynamic = change) is the physics of energy, heat, work, entropy and the spontaneity of processes. ...

A full discussion of T_g requires an understanding of mechanical loss mechanisms (vibrational and resonance modes) of specific (usually common in a given material) functional groups and molecular arrangements. Factors such as heat treatment and molecular re-arrangement, vacancies, induced strain and other factors affecting the condition of a material may have an effect on T_g ranging from the subtle to the dramatic. T_g is dependent on the viscoelastic materials properties, and so varies with rate of applied load. The silicone toy 'Silly Putty' is a good example of this: pull slowly and it flows; hit it with a hammer and it shatters. In organic chemistry, functional groups (or moieties) are specific groups of atoms within molecules, that are responsible for the characteristic chemical reactions of those molecules. ... Heat treatment is a method used to alter the physical, and sometimes chemical, properties of a material. ... Look up strain in Wiktionary, the free dictionary. ... Viscoelasticity, also known as anelasticity, describes materials that exhibit both viscous and elastic characteristics when undergoing plastic deformation. ... Silicones (more accurately called polymerized siloxanes or polysiloxanes) are inorganic-organic polymers with the chemical formula [R2SiO]n, where R = organic groups such as methyl, ethyl, and phenyl. ... Silly putty dripping through a hole Silly Putty shown as a solid cube Silly Putty (originally called nutty putty, and also known as Potty Putty) is a silicone plastic, marketed today as a toy for children, but originally created as a fortuitous accident during the course of research into potential...

In contrast to the melting points of crystalline materials the glass transition temperature is therefore somewhat dependent on the time-scale of the imposed change. To some extent time and temperature are interchangeable quantities when dealing with glasses, a fact often expressed in the time-temperature superposition principle. An alternative way to discuss the same issue is to say that a glass transition temperature is only truly a point on the temperature scale if the change is imposed at one particular frequency. This is why the ability to modulate the temperature in a DSC experiment has made determining T_g considerably more precise. Since T_g is cooling-rate (or frequency) dependent as the glass is formed, the glass transition is not considered a true thermodynamic phase transition by many in the field. They reserve this epithet rather for a transition that is sharp and history-independent. Differential scanning calorimetry or DSC is a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference are measured as a function of temperature. ... Thermodynamics (from the Greek θερμη, therme, meaning heat and δυναμις, dynamis, meaning power) is a branch of physics that studies the effects of changes in temperature, pressure, and volume on physical systems at the macroscopic scale by analyzing the collective motion of their particles using statistics. ... In physics, a phase transition, (or phase change) is the transformation of a thermodynamic system from one phase to another. ...

The glass-liquid transition has universal characteristics of phase transitions including symmetry breaking for the system of bonds.^[2]

The IUPAC Compendium of Chemical Terminology, 1997, 66, 583 defines the glass transition as a second order phase transition in which a supercooled melt yields, on cooling, a glassy structure and properties similar to those of crystalline materials e.g. of an isotropic solid material. Phase transitions are associated with the symmetry breaking^{[citation needed]}. The translation-rotation symmetry in the distribution of atoms and molecules is unchanged at the liquid-glass transition, which retains the topological disorder of fluids. Symmetry changes at glass transition can be viewed when considered not for atoms but for bonds. The disordered material changes its symmetry, namely the Hausdorff dimension of bonds, from Euclidian 3D below to fractal 2.55±0.05- dimensional above the glass transition temperature.^[3] Image File history File links Density_on_Temperature. ... Image File history File links Density_on_Temperature. ...

In polymers, T_g is often expressed as the temperature at which the Gibbs free energy is such that the activation energy for the cooperative movement of 50 or so elements of the polymer is exceeded. This allows molecular chains to slide past each other when a force is applied. From this definition, we can see that the introduction of relatively stiff chemical groups (such as benzene rings) will interfere with the flowing process and hence increase T_g. With thermoplastics, the stiffness of the material will drop due to this effect. This is shown in the figure below. It can be seen that when the glass temperature has been reached, the stiffness stays the same for a while, until the material melts. This region is called the rubber plateau. A polymer (from Greek: πολυ, polu, many; and μέρος, meros, part) is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ... In thermodynamics, the Gibbs free energy is a thermodynamic potential which measures the useful work obtainable from a closed thermodynamic system at a constant temperature and pressure. ... The sparks generated by striking steel against a flint provide the activation energy to initiate combustion in this Bunsen burner. ... For benzine, see petroleum ether. ...

Stiffness versus temperature

T_g can be significantly decreased by addition of plasticisers into the polymer matrix. Smaller molecules of plasticizer embed themselves between the polymer chains, increasing the spacing and free volume, and allowing them to move past one another even at lower temperatures. The "new-car smell" is due to the initial outgassing of volatile small-molecule plasticizers used to modify interior plastics (e.g., dashboards) to keep them from cracking in the cold, winter weather. The addition of nonreactive side groups to a polymer can also make the chains stand off from one another, reducing T_g. If a plastic with some desirable properties has a T_g which is too high, it can sometimes be combined with another in a copolymer or composite material with a T_g below the temperature of intended use. Note that some plastics are used at high temperatures, e.g., in automobile engines, and others at low temperatures. Image File history File links Rubber_plateau. ... Image File history File links Rubber_plateau. ... Plasticizers are plastic additives, most commonly phthalates, that give plastics flexibility and durability. ... The new car smell many of us find pleasurable comes from chemicals that can pose health risks. ... Outgassing (sometimes called Offgassing, particularly when in reference to indoor air quality) is the slow release of a gas that was trapped, frozen, absorbed or adsorbed in some material. ... The ability of a liquid to evaporate quickly and at relatively low temperatures. ... The term Side chain can have different meanings depending on the context: In chemistry and biochemistry a side chain is a part of a molecule attached to a core structure. ... A heteropolymer, also called a copolymer, is a polymer formed when two different types of monomer are linked in the same polymer chain. ... A cloth of woven carbon fiber filaments, a common element in composite materials Composite materials (or composites for short) are engineered materials made from two or more constituent materials with significantly different physical or chemical properties and which remain separate and distinct on a macroscopic level within the finished structure. ...

In glasses (including amorphous metals and gels), T_g is related to the energy required to break and re-form covalent bonds in a somewhat less than perfect (may be regarded as an understatement) 3D lattice of covalent bonds. The T_g is therefore influenced by the chemistry of the glass. E.g., add B, Na, K or Ca to a silica glass, which have a valency less than 4 and they help break up the 3D lattice and reduce the T_g. Add P which has a valency of 5 and it helps re-establish the 3D lattice, increasing T_g. This article is about the material. ... An amorphous metal is a metallic material with a disordered atomic-scale structure. ... In optical filters and theatrical lighting a color gel is a transparent or translucent colored panel used to change the color of transmitted light. ... “Covalent” redirects here. ... General Name, Symbol, Number boron, B, 5 Chemical series metalloids Group, Period, Block 13, 2, p Appearance black/brown Standard atomic weight 10. ... For sodium in the diet, see Edible salt. ... General Name, symbol, number potassium, K, 19 Chemical series alkali metals Group, period, block 1, 4, s Appearance silvery white Standard atomic weight 39. ... For other uses, see Calcium (disambiguation). ... silica glass is used to make the cores of fibre optic cables. ... In chemistry, valency is the power of an atom of an element to combine with other atoms measured by the number of electrons which an atom will give, take, or share to form a chemical bond. ... General Name, symbol, number phosphorus, P, 15 Chemical series nonmetals Group, period, block 15, 3, p Appearance waxy white/ red/ black/ colorless Standard atomic weight 30. ...

The Space Shuttle Challenger disaster was caused by rubber O-rings that were below their glass transition temperature on an unusually cold Florida morning, and thus could not flex adequately to form proper seals between sections of the two solid-fuel rocket boosters. Space Shuttle Challenger (NASA Orbiter Vehicle Designation: OV-099) was NASAs second Space Shuttle orbiter to be put into service, Columbia being the first. ... The Space Shuttle Solid Rocket Booster (SRB) is the rocket that provides 83% of liftoff thrust for the Space Shuttle. ...

Biophysics

Proteins also possess a glass transition temperature below which both anharmonic motions and long-range correlated motion within a single molecule are quenched. The origin of this transition is primarily due to "caging" by glassy water^[4], but can also be modeled in the absence of explicit water molecules, suggesting that part of the transition is due to internal protein dynamics.^[5] A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... For other uses, see Temperature (disambiguation). ...

Vitrification (glass formation below the melting point) can occur when starting with a liquid such as water, usually through very rapid cooling or the introduction of agents that suppress the formation of ice crystals. This is in contrast to ordinary freezing which results in ice crystal formation. Additives used in cryobiology or produced naturally by organisms living in polar regions are called cryoprotectants. Vitrification technology is being used to cryopreserve cells, tissues and organs for transplantation. A vitrification experiment for the study of nuclear waste disposal at Pacific Northwest National Labs Vitrification is a process of converting a material into a glass-like amorphous solid which is free of any crystalline structure, either by the quick removal or addition of heat, or by mixing with an... The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Snowflakes by Wilson Bentley, 1902 Ice is the name given to any one of the 14 known solid phases of water. ... In physics and chemistry, freezing is the process whereby a liquid turns to a solid. ... Cryobiology is the study of living organisms, organs, biological tissues or biological cells at low temperatures. ... Earths polar regions are the areas of the globe surrounding the poles, north of the Arctic circle, or south of the Antarctic Circle. ... A cryoprotectant is a substance that is used to protect biological tissue from freezing damage (damage due to ice formation). ... Cryopreservation of plant shoots. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... Biological tissue is a collection of interconnected cells that perform a similar function within an organism. ... Ş:For other uses, see Organ (disambiguation) In biology, an organ (Latin: organum, instrument, tool) is a group of tissues that perform a specific function or group of functions. ... “Transplant” redirects here. ...

Glass transition temperature of some materials

These are only mean values, as the glass transition temperature depends on the cooling-ratio, molecular weight distribution and could be influenced by additives. This article does not cite any references or sources. ... Polyethylene or polyethene is one of the simplest and most inexpensive polymers. ... Polypropylene lid of a Tic Tacs box, with a living hinge and the resin identification code under its flap Micrograph of polypropylene Polypropylene or polypropene (PP) is a thermoplastic polymer, made by the chemical industry and used in a wide variety of applications, including food packaging, ropes, textiles, plastic parts... Polyvinyl acetate formula Polyvinyl acetate or PVA is a rubbery synthetic polymer. ... Polyethylene terephthalate (aka PET, PETE or the obsolete PETP or PET-P) is a thermoplastic polymer resin of the polyester family and is used in synthetic fibers; beverage, food and other liquid containers; thermoforming applications; and engineering resins often in combination with glass fiber. ... Chemical structure of polyvinyl alcohol Polyvinyl alcohol (PVOH, PVA, or PVAL) is a water-soluble synthetic polymer. ... Polyvinyl chloride Polyvinyl chloride, (IUPAC Polychloroethene) commonly abbreviated PVC, is a widely used thermoplastic polymer. ... Polystyrene (IPA: ) is a polymer made from the monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry. ... Polypropylene lid of a Tic Tacs box, with a living hinge and the resin identification code under its flap Micrograph of polypropylene Polypropylene or polypropene (PP) is a thermoplastic polymer, made by the chemical industry and used in a wide variety of applications, including food packaging, ropes, textiles, plastic parts... PHB can refer to several things: A Bachelor of Philosophy degree. ... Structure of methyl methacrylate, the monomer that makes up PMMA Polymethyl methacrylate (PMMA) or poly(methyl 2-methylpropenoate) is the synthetic polymer of methyl methacrylate. ... A chalcogenide is a binary compound consisting of a chalcogen and a more electropositive element. ... ZBLAN is a type of glass that is made of a mixture of Zirconium, Barium, Lanthium, Aluminum, and Sodium Flourides. ... Tellurite is a mineral, TeO2. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ...

Note also that for a semi-crystalline material such as Polyethylene that is 60-80% crystalline at room temperature the quoted glass transition refers to what happens to the amorphous part of the material as the temperature is dropped

References

1. ^ Baeurle SA, Hotta A, Gusev AA (2006). "On the glassy state of multiphase and pure polymer materials". Polymer 47: 6243-6253. DOI:10.1016/j.polymer.2006.05.076. 
2. ^ M. I. Ozhovan (November 2006). "Topological characteristics of bonds in SiO2 and GeO2 oxide systems upon a glass-liquid transition". Journal of Experimental and Theoretical Physics 103 (5): 819-829. DOI:10.1134/S1063776106110197. 
3. ^ I. O. Michael and E. L. William (2006). "Topologically disordered systems at the glass transition". Journal of Physics: Condensed Matter 18 (50): 11507. DOI:10.1088/0953-8984/18/50/007. 
4. ^ Vitkup D, Ringe D, Petsko GA, Karplus M (2001). "Solvent mobility and the protein 'glass' transition". Nature Structural Biology 7: 34–38.  Entrez PubMed 10625424
5. ^ Salsbury FR, Han WG, Noodleman L, Brooks CL (2003). "Temperature-dependent behavior of protein-chromophore interactions: A theoretical study of a blue fluorescent antibody". CHEMPHYSCHEM 4: 848–855.  Entrez PubMed 12961983

• For glass transition temperatures of various resins, see Engineered Materials Handbook -- Desk edition. (1995). ASM International. ISBN 0871702835. p. 369.
• For glass transition temperatures of various glasses, see Mazurin, O.V. Handbook of Glass Data. (1993). Elsevier. ISBN 0444816356.
• Prediction of high weight polymers glass transition temperature using RBF neural networks Journal of Molecular Structure: THEOCHEM, Volume 716, Issues 1-3, 7 March 2005, Pages 193-198 Antreas Afantitis, Georgia Melagraki, Kalliopi Makridima, Alex Alexandridis, Haralambos Sarimveis and Olga Iglessi-Markopoulou

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... The Entrez logo The Entrez Global Query Cross-Database Search System allows access to databases at the National Center for Biotechnology Information (NCBI) website. ... The Entrez logo The Entrez Global Query Cross-Database Search System allows access to databases at the National Center for Biotechnology Information (NCBI) website. ... The abbreviation ASM can mean several things: Abnormal Situation Management® in automation (more specifically, in industrial or process automation) Abstract State Machines, based on the concept of an abstract state machine in computer science Academy of Sciences of Moldova Acceleration Simulation Mode, a vehicle-emission test Activated Sludge Model Active... Elseviers logo. ...

External links

• Vogel-Tammann-Fulcher Equation Parameters
• Fragility thy name is glass
• On the glassy state of multiphase and pure polymer materials
• Liquid fragility and the glass transition in water and aqueous solutions