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Syndiotactic Polypropene
Tacticity (from , "relating to arrangement or order") is the relative stereochemistry of adjacent chirality (chemistry), chiral centers within a macromolecule. The practical significance of tacticity rests on the effects on the physical properties of the polymer. The regularity of the macromolecular structure influences the degree to which it has rigid, Crystallinity, crystalline long range order or flexible, amorphous long range disorder. Precise knowledge of tacticity of a polymer also helps understanding at what temperature a polymer melting, melts, how soluble it is in a solvent, as well as its mechanical properties. A tactic macromolecule in the IUPAC definition is a macromolecule in which essentially all the configurational (repeating) units are identical. In a hydrocarbon macromolecule with all carbon atoms making up the backbone in a tetrahedral molecular geometry, the zigzag backbone is in the paper plane with the substituents either sticking out of the paper or retreati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Backbone Chain
In polymer science, the polymer chain or simply backbone of a polymer is the main chain of a polymer. Polymers are often classified according to the elements in the main chains. The character of the backbone, i.e. its flexibility, determines the properties of the polymer (such as the glass transition temperature). For example, in Silicone, polysiloxanes (silicone), the backbone chain is very flexible, which results in a very low glass transition temperature of . The polymers with rigid backbones are prone to crystallization (e.g. polythiophenes) in thin films and in Solution (chemistry), solution. Crystallization in its turn affects the optical properties of the polymers, its optical band gap and electronic levels. Organic polymers : Common synthetic polymers have main chains composed of carbon, i.e. C-C-C-C.... Examples include polyolefins such as polyethylene ((CH2CH2)n) and many substituted derivative ((CH2CH(R))n) such as polystyrene (R = C6H5), polypropylene (R = CH3), and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polypropylene
Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer Propene, propylene. Polypropylene belongs to the group of polyolefins and is Crystallization of polymers#Degree of crystallinity, partially crystalline and Chemical polarity#Nonpolar molecules, non-polar. Its properties are similar to polyethylene, but it is slightly harder and more heat-resistant. It is a white, mechanically rugged material and has a high chemical resistance. Polypropylene is the second-most widely produced Commodity plastics, commodity plastic (after polyethylene). History Phillips Petroleum chemists J. Paul Hogan and Robert Banks (chemist), Robert Banks first demonstrated the polymerization of propylene in 1951. The stereoselective polymerization to the isotactic was discovered by Giulio Natta and Karl Rehn in March 1954. This pioneering discovery led to large-scale commercial producti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IUPAC Definition For A Tactic Block In A Polymer
The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is a member of the International Science Council (ISC). IUPAC is registered in Zürich, Switzerland, and the administrative office, known as the "IUPAC Secretariat", is in Research Triangle Park, North Carolina, United States. IUPAC's executive director heads this administrative office, currently Greta Heydenrych. IUPAC was established in 1919 as the successor of the International Congress of Applied Chemistry for the advancement of chemistry. Its members, the National Adhering Organizations, can be national chemistry societies, national academies of sciences, or other bodies representing chemists. There are fifty-four National Adhering Organizations and three Associate National Adhering Organizations. IUPAC's Inter-divisional Committee o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon-13 NMR
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 n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bernoulli Process
In probability and statistics, a Bernoulli process (named after Jacob Bernoulli) is a finite or infinite sequence of binary random variables, so it is a discrete-time stochastic process that takes only two values, canonically 0 and 1. The component Bernoulli variables ''X''''i'' are identically distributed and independent. Prosaically, a Bernoulli process is a repeated coin flipping, possibly with an unfair coin (but with consistent unfairness). Every variable ''X''''i'' in the sequence is associated with a Bernoulli trial or experiment. They all have the same Bernoulli distribution. Much of what can be said about the Bernoulli process can also be generalized to more than two outcomes (such as the process for a six-sided die); this generalization is known as the Bernoulli scheme. The problem of determining the process, given only a limited sample of Bernoulli trials, may be called the problem of checking whether a coin is fair. Definition A ''Bernoulli process'' is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meso Compound
A meso compound or meso isomer is an optically inactive isomer in a set of stereoisomers, at least two of which are optically active. This means that despite containing two or more stereocenters, the molecule is not chiral. A meso compound is superposable on its mirror image (not to be confused with superimposable, as any two objects can be superimposed over one another regardless of whether they are the same). Two objects can be superposed if all aspects of the objects coincide and it does not produce a "(+)" or "(-)" reading when analyzed with a polarimeter. The name is derived from the Greek ''mésos'' meaning “middle”. For example, tartaric acid can exist as any of three stereoisomers depicted below in a Fischer projection. Of the four colored pictures at the top of the diagram, the first two represent the meso compound (the 2'' R'',3'' S'' and 2'' S'',3'' R'' isomers are equivalent), followed by the optically active pair of levotartaric acid (L-(''R,R'')-(+)-tartaric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rm Triad
RM, rm, R.M. or R&M may refer to: Arts and entertainment * Random map, a randomly generated map in strategy games * RauteMusik.FM, a German Internet Radio Station * RM (musician), born Kim Nam-joon, a South Korean rapper, composer and person who produces music * '' The R.M.'', a comedy film * ''Running Man'' (TV program), a South Korean variety television program Business and finance Companies * Récoltant-Manipulant, a designation for champagne producers with their own label * Reichle & De-Massari (R&M), a Swiss family tech business * RM, a clothing line by Roland Mouret * RM Education, a British computer firm * RM Sotheby's, a classic car auctioneers Currencies * Malaysian ringgit, Malaysia (ISO 4217: MYR) * Reichsmark (ℛℳ), German currency during the Weimar Republic and the Third Reich Methods and disciplines * Rapid manufacturing, computer-automated additive manufacturing method * Records management, an information archiving practice * Relationship marketing, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rr Triad
RR, Rr or rr may refer to: Arts and entertainment * ''RR'' (film), a 2007 experimental film by James Benning * Red Ribbon Army, a fictional army in the ''Dragon Ball'' series * Ruff Ryders Entertainment, a record label and East Coast rap collective * '' Fury from the Deep'' (production code: RR), a 1968 ''Doctor Who'' serial * ''RR'' (EP), a 2023 collaborative EP by Rosalía and Rauw Alejandro * RR, prefix for models of Jackson Rhoads electric guitars commissioned by guitarist Randy Rhoads Businesses and organizations * Rashtriya Rifles, an Indian counter-insurgency force * Rational Recovery, an addiction recovery program * Rekords Rekords (logo), an American record label * Rhodesia Regiment, Rhodesian Army unit * Royal Air Force (IATA airline designator) * Richard Rohac (logo), an Austrian art metal firm Language * rr (digraph) * Revised Romanization of Korean, the official Korean language romanization system in South Korea * Revised Romanization of Hangeul, the for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mm Triad
MM or variants may refer to: Alphabets * Meitei Mayek or Meetei Mayek, the writing system of Meitei language Arts, entertainment, and media Music * ''MM'' (album), 1989, by Marisa Monte * Maelzel's metronome, a music marking * Marilyn Manson, an American musician * Marshall Mathers, an American rapper (a.k.a. "Eminem") * Mother Mother, a Canadian band * Master of Music, an academic degree * ''Melody Maker'' British music publication * "MM", a 1993 song by Mr. President * Major Moment, an American rock music band from Boston, Massachusetts Television * MM (TV channel), Bulgaria * MM, the production code for the 1967 ''Doctor Who'' serial '' The Tomb of the Cybermen'' Other media * '' MM!'', a Japanese light novel, manga and anime series by Akinari Matsuno * '' Media Molecule'', a video game developer in England * '' Monster Manual'', a 1977 ''Dungeons & Dragons'' source book * Mother's Milk (character), aka "MM", a fictional character in ''The Boys'' comicbook franchi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meso Diad
Meso or mesos may refer to: * Apache Mesos, a computer clustering management platform * Meso, in-game currency for the massively multiplayer online role-playing game ''MapleStory'' * Meso compound, a stereochemical classification in chemistry * Mesolithic, archaeological period between the Upper Paleolithic and the Neolithic * Mesopotamia, the first major river civilization, known today as Iraq * Mesoamerica Mesoamerica is a historical region and cultural area that begins in the southern part of North America and extends to the Pacific coast of Central America, thus comprising the lands of central and southern Mexico, all of Belize, Guatemala, El S ..., Americas, or Native Americans * Mesothelioma, a form of cancer * Mesoscopic physics, subdiscipline of condensed matter physics that deals with materials of an intermediate size * Multiple Equivalent Simultaneous Offers, a strategy used in negotiation {{Disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
