|
Polybenzoxazine
Polybenzoxazines, also called benzoxazine resins, are cured polymerization products derived from benzoxazine monomers. Monomers Benzoxazines are bicyclic heterocyclic compounds containing one oxygen and one nitrogen atom in a doubly unsaturated six-member ring, specifically a 1,3-oxazine ring, fused with a benzene ring. The systematic IUPAC name of the prototypical unsubstituted monomer is 3,4-dihydro-3-phenyl-2''H''-1,3-benzoxazine. Benzoxazines are products of condensation between an amine, a phenol and formaldehyde, used to produce thermoset resins or thermosetting polymer. Because of the wide availability and low-cost of starting materials (amines, phenols and formaldehyde), as well as ease of preparation (one-pot reaction) diverse benzoxazines are available. Numerous research focus on the different curing temperature, and polymer properties, such as cross-linking, from benzoxazines derived from substituted phenols. Commercial benzoxazines by Huntsman are based on bisphenols ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzoxazine
Benzoxazines are a group of isomeric bicyclic heterocyclic chemical compounds that consist of a benzene ring fused to an oxazine ring. The different isomers depend on the relative positions of the oxygen and nitrogen atoms in the oxazine ring, on the location of ring fusion, and on the position of the double bond in the oxazine ring. They have the molecular formula C8H7NO. Preparation 1,3-Benzoxazines can be synthesized by the Mannich reaction using a phenol, an amine, and formaldehyde. Uses Pharmaceutical drugs Benzoxazine rings form the central chemical structure of a number of pharmaceutical drugs including, for example, apararenone, elbasvir, and etifoxine. Polymers Polybenzoxazine Polybenzoxazines, also called benzoxazine resins, are cured polymerization products derived from benzoxazine monomers. Monomers Benzoxazines are bicyclic heterocyclic compounds containing one oxygen and one nitrogen atom in a doubly unsaturated ...s, also called benzoxazine resins, are a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermoset
In materials science, a thermosetting polymer, often called a thermoset, is a polymer that is obtained by irreversibly hardening (" curing") a soft solid or viscous liquid prepolymer (resin). Curing is induced by heat or suitable radiation and may be promoted by high pressure or mixing with a catalyst. Heat is not necessarily applied externally, and is often generated by the reaction of the resin with a curing agent (''catalyst'', '' hardener''). Curing results in chemical reactions that create extensive cross-linking between polymer chains to produce an infusible and insoluble polymer network. The starting material for making thermosets is usually malleable or liquid prior to curing, and is often designed to be molded into the final shape. It may also be used as an adhesive. Once hardened, a thermoset cannot be melted for reshaping, in contrast to thermoplastic polymers which are commonly produced and distributed in the form of pellets, and shaped into the final product ... [...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] |
Oxazine
Oxazines are heterocyclic compound, heterocyclic organic compounds containing one oxygen and one nitrogen atom in a cyclohexa-1,4-diene ring (a doubly unsaturated six-membered ring). Isomers exist depending on the relative position of the heteroatoms and relative position of the double bonds. By extension, the derivatives are also referred to as oxazines; examples include ifosfamide and morpholine (tetrahydro-1,4-oxazine). A commercially available dihydro-1,3-oxazine is a reagent in the Meyers synthesis of aldehydes. Fluorescent dyes such as Nile red and Nile blue are based on the aromatic compound benzophenoxazine. Cinnabarine and cinnabaric acid are two naturally occurring dioxazines, being derived from biodegradation of tryptophan. Dioxazines Dioxazines are pentacyclic compounds consisting of two oxazine subunits. A commercially important example is the pigment pigment violet 23. Benzoxazines Benzoxazines are bicyclic compounds formed by the ring fusion of a benzene ring w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dielectric Loss
In electrical engineering, dielectric loss quantifies a dielectric material's inherent dissipation of electromagnetic energy (e.g. heat). It can be parameterized in terms of either the loss angle or the corresponding loss tangent . Both refer to the phasor in the complex plane whose real and imaginary parts are the resistive (lossy) component of an electromagnetic field and its reactive (lossless) counterpart. Electromagnetic field perspective For time-varying electromagnetic fields, the electromagnetic energy is typically viewed as waves propagating either through free space, in a transmission line, in a microstrip line, or through a waveguide. Dielectrics are often used in all of these environments to mechanically support electrical conductors and keep them at a fixed separation, or to provide a barrier between different gas pressures yet still transmit electromagnetic power. Maxwell’s equations are solved for the electric and magnetic field components of the propag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dielectric Constant
The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insulator measures the ability of the insulator to store electric energy in an electrical field. Permittivity is a material's property that affects the Coulomb force between two point charges in the material. Relative permittivity is the factor by which the electric field between the charges is decreased relative to vacuum. Likewise, relative permittivity is the ratio of the capacitance of a capacitor using that material as a dielectric, compared with a similar capacitor that has vacuum as its dielectric. Relative permittivity is also commonly known as the dielectric constant, a term still used but deprecated by standards organizations in engineering as well as in chemistry. Definition Relative permittivity is typically denoted as (som ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrophobicity
In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly intermolecular force, repelled from a mass of water. In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be chemical polarity#Nonpolar molecules, nonpolar and, thus, prefer other neutral molecules and nonpolar solvents. Because water molecules are polar, hydrophobes do not dissolution (chemistry), dissolve well among them. Hydrophobic molecules in water often cluster together, forming micelles. Water on hydrophobic surfaces will exhibit a high contact angle. Examples of hydrophobic molecules include the alkanes, oils, fats, and greasy substances in general. Hydrophobic materials are used for oil removal from water, the management of oil spills, and chemical separation processes to remove non-polar substances from polar compounds. The term ''hydrophobic''—which comes from the Ancient Greek (), "having a fear of water", constructed Liddell, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maleimide
Maleimide is a chemical compound with the formula H2C2(CO)2NH (see diagram). This unsaturated imide is an important building block in organic synthesis. The name is a contraction of maleic acid and imide, the -C(O)NHC(O)- functional group. Maleimides are also a ''class'' of derivatives of the parent maleimide where the N''H'' group is replaced with alkyl or aryl groups such as a methyl or phenyl, respectively. The substituent can also be a small molecule (such as biotin, a fluorescent dye, an oligosaccharide, or a nucleic acid), a reactive group, or a synthetic polymer such as polyethylene glycol. Human hemoglobin chemically modified with maleimide-polyethylene glycol is a blood substitute called MP4. Reactions Many analogues of maleimide are prepared by treating maleic anhydride with amines followed by dehydration. A defining feature of the reactivity of maleimides is their susceptibility to additions across the double bond either by Michael additions or via Diels-Alder react ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Room Temperature
Room temperature, colloquially, denotes the range of air temperatures most people find comfortable indoors while dressed in typical clothing. Comfortable temperatures can be extended beyond this range depending on humidity, air circulation, and other factors. In certain fields, like science and engineering, and within a particular context, room temperature can mean different agreed-upon ranges. In contrast, ambient temperature is the actual temperature, as measured by a thermometer, of the air (or other medium and surroundings) in any particular place. The ambient temperature (e.g. an unheated room in winter) may be very different from an ideal ''room temperature''. Food and beverages may be served at "room temperature", meaning neither heated nor cooled. Comfort temperatures Comfort temperature is interchangeable with neutral temperature in the scientific literature, which can be calculated through regression analysis between thermal sensation votes and indoor temperature. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centipoise
The poise (symbol P; ) is the unit of dynamic viscosity (absolute viscosity) in the centimetre–gram–second system of units (CGS). It is named after Jean Léonard Marie Poiseuille (see Hagen–Poiseuille equation). The centipoise (1 cP = 0.01 P) is more commonly used than the poise itself. Dynamic viscosity has dimensions of \mathrm, that is, mathsf^1 \mathsf^ \mathsf^/math>. 1~\text = 0.1~\text^ \text \text^ = 1~\text^ \text \text^ = 1~\text \text \text^. The analogous unit in the International System of Units is the pascal-second (Pa⋅s): 1~\text \text = 1~\text \text \text^ = 1~\text^ \text \text^ = 10~\text. The poise is often used with the metric prefix ''centi-'' because the viscosity of water at 20 °C (standard conditions for temperature and pressure) is almost exactly 1 centipoise. A centipoise is one hundredth of a poise, or one millipascal-second (mPa⋅s) in SI units (1 cP = 10−3 Pa⋅s = 1 mPa⋅s). The CGS symbol f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
