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Ultem
Polyetherimide (PEI; branded as Ultem) is an amorphous, amber-to-transparent thermoplastic with characteristics similar to the related plastic PEEK. When comparing PEI to PEEK, the former is cheaper but has lower impact strength and a tighter temperature range. PEI plastics were first introduced into the market by General Electric (GE) in 1982 under the trade name Ultem resulting from the work of J.G. Wirth's research team in the early 1970s. Due to its adhesive properties and chemical stability it became a popular bed material for FFF 3D printers. Structure The molecular formula of the PEI repeating unit is and the molecular weight is 592.61 g/mol. It contains phthalimide and bisphenol A sub-units. Properties The glass transition temperature of PEI is 217 °C (422 °F). Its amorphous density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fused Filament Fabrication
Fused filament fabrication (FFF), also known as fused deposition modeling (with the trademarked acronym FDM), or ''filament freeform fabrication'', is a 3D printing process that uses a continuous filament of a thermoplastic material. Filament is fed from a large spool through a moving, heated printer extruder head, and is deposited on the growing work. The print head is moved under computer control to define the printed shape. Usually the head moves in two dimensions to deposit one horizontal plane, or layer, at a time; the work or the print head is then moved vertically by a small amount to begin a new layer. The speed of the extruder head may also be controlled to stop and start deposition and form an interrupted plane without stringing or dribbling between sections. "Fused filament fabrication" was coined by the members of the RepRap project to give an acronym (FFF) that would be legally unconstrained in use. Fused filament printing has in the 2010s-2020s been the most popular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bisphenol A
Bisphenol A (BPA) is a chemical compound primarily used in the manufacturing of various plastics. It is a colourless solid which is Solubility, soluble in most common organic solvents, but has very poor solubility in water. BPA is produced on an industrial scale by the condensation reaction of phenol and acetone. Global production in 2022 was estimated to be in the region of 10 million tonnes. BPA's largest single application is as a co-monomer in the production of polycarbonates, which accounts for 65–70% of all BPA production. The manufacturing of epoxy resins and vinyl ester resins account for 25–30% of BPA use. The remaining 5% is used as a major component of several high-performance plastics, and as a minor additive in polyvinyl chloride (PVC), polyurethane, thermal paper, and several other materials. It is not a plasticizer, although it is often wrongly labelled as such. The health effects of BPA have been the subject of prolonged public and scientific debate. BPA is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyethylenimine
Polyethylenimine (PEI) or polyaziridine is a polymer with repeating units composed of the amine group and two carbon Aliphatic_compound, aliphatic ''CHCH'' spacers. Linear polyethyleneimines contain all Amines#Classification_of_amines, secondary amines, in contrast to branched PEIs which contain primary, secondary and tertiary amino groups. Totally branched, dendrimeric forms were also reported. PEI is produced on an industrial scale and finds many applications usually derived from its polyelectrolyte, polycationic character. Properties The linear PEI is a semi-crystalline solid at room temperature while branched PEI is a fully amorphous polymer existing as a liquid at all molecular weights. Linear polyethyleneimine is soluble in hot water, at low pH, in methanol, ethanol, or chloroform. It is insoluble in cold water, benzene, Diethyl ether, ethyl ether, and acetone. Linear polyethylenimine has a melting point of around 67 °C. Both linear and branched polyethylneimine c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Acid Anhydride
An organic acid anhydride is an acid anhydride that is also an organic compound. An acid anhydride is a compound that has two acyl groups bonded to the same oxygen atom. A common type of organic acid anhydride is a carboxylic anhydride, where the parent acid is a carboxylic acid, the formula of the anhydride being (RC(O))2O. Symmetrical acid anhydrides of this type are named by replacing the word ''acid'' in the name of the parent carboxylic acid by the word ''anhydride''. Thus, (CH3CO)2O is called ''acetic anhydride.'' ''Mixed'' (or ''unsymmetrical'') acid anhydrides, such as acetic formic anhydride (see below), are known, whereby reaction occurs between two different carboxylic acids. Nomenclature of unsymmetrical acid anhydrides list the names of both of the reacted carboxylic acids before the word "anhydride" (for example, the dehydration reaction between benzoic acid and propanoic acid would yield "benzoic propanoic anhydride"). One or both acyl groups of an acid anhydrid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlorinated Solvent
Organochlorine chemistry is concerned with the properties of organochlorine compounds, or organochlorides, organic compounds that contain one or more carbon–chlorine bonds. The chloroalkane class (alkanes with one or more hydrogens substituted by chlorine) includes common examples. The wide structural variety and divergent chemical properties of organochlorides lead to a broad range of names, applications, and properties. Organochlorine compounds have wide use in many applications, though some are of profound environmental concern, with TCDD being one of the most notorious. Organochlorides such as trichloroethylene, tetrachloroethylene, dichloromethane and chloroform are commonly used as solvents and are referred to as "chlorinated solvents". Physical and chemical properties Chlorination modifies the physical properties of hydrocarbons in several ways. These compounds are typically denser than water due to the higher atomic weight of chlorine versus hydrogen. They have higher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Environmental Stress Cracking
Environmental Stress Cracking (ESC) is one of the most common causes of unexpected brittle failure of thermoplastic (especially amorphous) polymers known at present. According to ASTM D883, stress cracking is defined as "an external or internal crack in a plastic caused by tensile stresses less than its short-term mechanical strength". This type of cracking typically involves brittle cracking, with little or no ductile drawing of the material from its adjacent failure surfaces. Environmental stress cracking may account for around 15-30% of all plastic component failures in service.H. F. Mark (2004). Encyclopedia of Polymers Science and Technology – 3rd Ed. Vol 12. John Miley & Sons Inc. This behavior is especially prevalent in glassy, amorphous thermoplastics. Amorphous polymers exhibit ESC because of their loose structure which makes it easier for the fluid to permeate into the polymer. Amorphous polymers are more prone to ESC at temperature higher than their glass tran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Density
Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be used: \rho = \frac, where ''ρ'' is the density, ''m'' is the mass, and ''V'' is the volume. In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume, although this is scientifically inaccurate this quantity is more specifically called specific weight. For a pure substance, the density is equal to its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity and packaging. Osmium is the densest known element at standard conditions for temperature and pressure. To simplify comparisons of density across different systems of units, it is sometimes replaced by the dimensionless quantity "relative den ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glass Transition Temperature
The glass–liquid transition, or glass transition, is the gradual and 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. ISO 11357-2: Plastics – Differential scanning calorimetry – Part 2: Determination of glass transition temperature (1999). 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 ''T''g of a material characterizes the range of temperatures over which this glass transition occurs (as an experimental definition, typically marked as 100 s of relaxation time). It is always lower than the melting temperature, ''T''m, of the crystalline state of the material, if one exists, because the glass is a higher energy state (or enthalpy at const ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phthalimide
Phthalimide is the organic compound with the formula C6H4(CO)2NH. It is the imide derivative of phthalic anhydride. It is a Sublimation (phase transition), sublimable white solid that is slightly soluble in water but more so upon addition of base (chemistry), base. It is used as a precursor to other organic compounds as a masked source of ammonia. Uses :image:Folpet.png, 160px, Folpet, a phthalimide, is a commercial fungicide., left Phthalimide is used as a precursor to anthranilic acid, a precursor to azo dyes and saccharin. Alkyl phthalimides are useful precursors to amines in chemical synthesis, especially in peptide synthesis where they are used "to block both hydrogens and avoid racemization of the substrates". Alkyl halides can be converted to the N-alkylphthalimide: : C6H4(CO)2NH + RX + NaOH → C6H4(CO)2NR + NaX + H2O The amine is commonly liberated using hydrazine: : C6H4(CO)2NR + N2H4 → C6H4(CO)2N2H2 + RNH2 Dimethylamine can also be used. Som ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DG 東莞 DongGuan 南城區 Nancheng 鴻福路 HongFu Road 東莞京東商場 JD Mall Electronics Showroom 3D Printers December 2024 R12S 06 (cropped)
DG may refer to: Arts and entertainment * Death Grips, an American experimental hip hop group * DG (character), in the science fiction series ''Tin Man'' * Dial Global, a radio network * Dragon Gate, a Japanese professional wrestling promotion * Drain Gang, a Swedish rap group Business and organizations * Data General, a minicomputer manufacturer * Desnoes & Geddes (DG, D&G), a Jamaican brand of soft drinks * Delta Gamma, a women's sorority * Deutsche Grammophon, a classical music record label * DG Flugzeugbau, a German airplane manufacturer * Dial Global, a radio network * Dolce & Gabbana, an Italian luxury fashion design * Dollar General, an American variety store (NYSE ticker DG) Places * DG postcode area, the Dumfries and Galloway postcode area in Scotland * Danilovgrad, a municipality in Montenegro, abbreviated DG on car plates * German-speaking Community of Belgium () * Diego Garcia, exceptionally reserved ISO 3166-1 alpha-2 country code for Science, mathematics and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Weight
A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemistry, and biochemistry, the distinction from ions is dropped and ''molecule'' is often used when referring to polyatomic ions. A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O2); or it may be heteronuclear, a chemical compound composed of more than one element, e.g. water (molecule), water (two hydrogen atoms and one oxygen atom; H2O). In the kinetic theory of gases, the term ''molecule'' is often used for any gaseous particle regardless of its composition. This relaxes the requirement that a molecule contains two or more atoms, since the noble gases are individual atoms. Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
