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Mayo–Lewis Equation
The Mayo–Lewis equation or copolymer equation in polymer chemistry describes the distribution of monomers in a copolymer. It was proposed by Frank R. Mayo and Frederick M. Lewis.''Copolymerization. I. A Basis for Comparing the Behavior of Monomers in Copolymerization; The Copolymerization of Styrene and Methyl Methacrylate'' Frank R. Mayo and Frederick M. Lewis J. Am. Chem. Soc.; 1944; 66(9) pp 1594 - 1601; The equation considers a monomer mix of two components M_1\, and M_2\, and the four different reactions that can take place at the reactive chain end terminating in either monomer (M_1^*\, and M_2^*\,) with their reaction rate constants k\,: :M_1^* + M_1 \xrightarrow M_1M_1^* \, :M_1^* + M_2 \xrightarrow M_1M_2^* \, :M_2^* + M_2 \xrightarrow M_2M_2^* \, :M_2^* + M_1 \xrightarrow M_2M_1^* \, The reactivity ratio for each propagating chain end is defined as the ratio of the rate constant for addition of a monomer of the species already at the chain end to the rate constant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymer Chemistry
Polymer chemistry is a sub-discipline of chemistry that focuses on the structures, chemical synthesis, and chemical and physical properties of polymers and macromolecules. The principles and methods used within polymer chemistry are also applicable through a wide range of other chemistry sub-disciplines like 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 related to synthetic and organic compositions. Synthetic polymers are ubiquitous in commercial materials and products in everyday use, such as plastics, and rubbers, and are major components of composite materials. 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.Hans-Heinrich Moretto, Manfred Schulz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Block Copolymer
In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are sometimes called ''bipolymers''. Those obtained from three and four monomers are called ''terpolymers'' and ''quaterpolymers'', respectively. Copolymers can be characterized by a variety of techniques such as Nuclear magnetic resonance spectroscopy, NMR spectroscopy and size-exclusion chromatography to determine the molecular size, weight, properties, and composition of the material. Commercial copolymers include acrylonitrile butadiene styrene (ABS), styrene/butadiene co-polymer (SBR), nitrile rubber, styrene-acrylonitrile, styrene-isoprene-styrene (SIS) and ethylene-vinyl acetate, all of which are formed by chain-growth polymerization. Another production mechanism is step-growth polymerization, which is used to produce the nylon-12/6/66 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonlinear Least Squares
Non-linear least squares is the form of least squares analysis used to fit a set of ''m'' observations with a model that is non-linear in ''n'' unknown parameters (''m'' ≥ ''n''). It is used in some forms of nonlinear regression. The basis of the method is to approximate the model by a linear one and to refine the parameters by successive iterations. There are many similarities to linear least squares, but also some significant differences. In economic theory, the non-linear least squares method is applied in (i) the probit regression, (ii) threshold regression, (iii) smooth regression, (iv) logistic link regression, (v) Box–Cox transformed regressors (m(x,\theta_i) = \theta_1 + \theta_2 x^). Theory Consider a set of m data points, (x_1, y_1), (x_2, y_2), \dots, (x_m, y_m), and a curve (model function) \hat = f(x, \boldsymbol \beta), that in addition to the variable x also depends on n parameters, \boldsymbol \beta = (\beta_1, \beta_2, \dots, \beta_n), with m\ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fourier Transform Infrared Spectroscopy
Fourier transform infrared spectroscopy (FTIR) is a technique used to obtain an infrared Electromagnetic spectrum, spectrum of Absorption (electromagnetic radiation), absorption or Emission (electromagnetic radiation), emission of a solid, liquid, or gas. An FTIR spectrometer simultaneously collects high-resolution spectral data over a wide spectral range. This confers a significant advantage over a Dispersion (optics), dispersive spectrometer, which measures intensity over a narrow range of wavelengths at a time. The term ''Fourier transform infrared spectroscopy'' originates from the fact that a Fourier transform (a mathematical process) is required to convert the raw data into the actual spectrum. Conceptual introduction The goal of absorption spectroscopy techniques (FTIR, Ultraviolet-visible spectroscopy, ultraviolet-visible ("UV-vis") spectroscopy, etc.) is to measure how much light a sample absorbs at each wavelength. The most straightforward way to do this, the "dispe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon-13 Nuclear Magnetic Resonance
Carbon-13 (C13) nuclear magnetic resonance (most commonly known as carbon-13 NMR spectroscopy or 13C NMR spectroscopy or sometimes simply referred to as carbon NMR) is the application of nuclear magnetic resonance (NMR) spectroscopy to carbon. It is analogous to proton NMR ( NMR) and allows the identification of carbon atoms in an organic molecule just as proton NMR identifies hydrogen atoms. 13C NMR detects only the isotope. The main carbon isotope, does not produce an NMR signal. Although ca. 1 mln. times less sensitive than 1H NMR spectroscopy, 13C NMR spectroscopy is widely used for characterizing organic and organometallic compounds, primarily because 1H-decoupled 13C-NMR spectra are more simple, have a greater sensitivity to differences in the chemical structure, and, thus, are better suited for identifying molecules in complex mixtures. At the same time, such spectra lack quantitative information about the atomic ratios of different types of carbon nuclei, because nuc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proton Nuclear Magnetic Resonance
Proton nuclear magnetic resonance (proton NMR, hydrogen-1 NMR, or 1H NMR) is the application of nuclear magnetic resonance in NMR spectroscopy with respect to hydrogen-1 Atomic nucleus, nuclei within the molecules of a substance, in order to determine the structure of its molecules. In samples where natural hydrogen (H) is used, practically all the hydrogen consists of the isotope 1H (hydrogen-1; i.e. having a proton for a nucleus). Simple NMR spectra are recorded in Solution (chemistry), solution, and solvent protons must not be allowed to interfere. deuterium, Deuterated (deuterium = 2H, often symbolized as D) solvents especially for use in NMR are preferred, e.g. heavy water, deuterated water, D2O, deuterated acetone, (CD3)2CO, deuterated methanol, CD3OD, deuterated dimethyl sulfoxide, (CD3)2SO, and deuterated chloroform, CDCl3. However, a solvent without hydrogen, such as carbon tetrachloride, CCl4 or carbon disulfide, CS2, may also be used. Historically, deuterated solvents ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Composition Drift
Composition or Compositions may refer to: Arts and literature *Composition (dance), practice and teaching of choreography *Composition (language), in literature and rhetoric, producing a work in spoken tradition and written discourse, to include visuals and digital space *Composition (visual arts), the plan, placement or arrangement of the elements of art in a work * ''Composition'' (Peeters), a 1921 painting by Jozef Peeters *Composition studies, the professional field of writing instruction * ''Compositions'' (album), an album by Anita Baker *Digital compositing, the practice of digitally piecing together a still image or video *Musical composition, an original piece of music, or the process of creating a new piece Computer science *Compose key, a key on a computer keyboard *Compositing window manager a component of a computer's graphical user interface that draws windows and/or their borders *Function composition (computer science), an act or mechanism to combine simple functi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Styrene
Styrene is an organic compound with the chemical formula C6H5CH=CH2. Its structure consists of a vinyl group as substituent on benzene. Styrene is a colorless, oily liquid, although aged samples can appear yellowish. The compound evaporates easily and has a sweet smell, although high concentrations have a less pleasant odor. Styrene is the precursor to polystyrene and several copolymers, and is typically made from benzene for this purpose. Approximately 25 million tonnes of styrene were produced in 2010, increasing to around 35 million tonnes by 2018. Natural occurrence Styrene is named after storax balsam (often commercially sold as ''styrax''), the resin of Liquidambar trees of the Altingiaceae plant family. Styrene occurs naturally in small quantities in some plants and foods (cinnamon, coffee beans, balsam tree (other), balsam trees and peanuts) and is also found in coal tar. History In 1839, the German apothecary Eduard Simon isolated a volatile liquid from t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maleic Anhydride
Maleic anhydride is an organic compound with the formula . It is the acid anhydride of maleic acid. It is a colorless or white solid with an acrid odor. It is produced industrially on a large scale for applications in coatings and polymers. Structure and bonding Maleic anhydride is a planar molecule. By virtue of the acid anhydride group, the alkene is electrophilic. On account of its cycle of 4 π electrons in an array of 5 atoms with p orbitals, maleic anhydride was long thought to exhibit antiaromaticity. However, a thermochemical study concluded that only 8 kJ/mol of destabilization energy can be ascribed to this effect, making it weakly antiaromatic at best. Production Maleic anhydride is produced by vapor-phase oxidation of butane, ''n''-butane. The overall process converts the methyl groups to carboxylate and dehydrogenation, dehydrogenates the backbone. The selectivity of the process reflects the robustness of maleic anhydride, with its conjugated double-bond system. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alternating Polymer
In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are sometimes called ''bipolymers''. Those obtained from three and four monomers are called ''terpolymers'' and ''quaterpolymers'', respectively. Copolymers can be characterized by a variety of techniques such as NMR spectroscopy and size-exclusion chromatography to determine the molecular size, weight, properties, and composition of the material. Commercial copolymers include acrylonitrile butadiene styrene (ABS), styrene/butadiene co-polymer (SBR), nitrile rubber, styrene-acrylonitrile, styrene-isoprene-styrene (SIS) and ethylene-vinyl acetate, all of which are formed by chain-growth polymerization. Another production mechanism is step-growth polymerization, which is used to produce the nylon-12/6/66 copolymer of nylon 12, nylon 6 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homopolymer
A polymer () is a substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeating subunits derived from one or more species of monomers. Due to their broad spectrum 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, high elasticity, viscoelasticity, and a tendency to form amorphous and semicrystalline structures rather than crystals. Polymers are studied in the fields of polymer science (which includes polymer chemistry and polymer physics), biophy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
