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The aminoxyl radical (N-O•) combines with free radicals in polymers: N-O• + R• → N-O-R Although they are traditionally considered as light stabilizers, they can also stabilize thermal degradation. Even though HALS are extremely effective in polyolefins, polyethylene and polyurethane, they are ineffective in polyvinyl chloride (PVC). It ...
Polymers become charged through the dissociation of the monomer side groups. If more monomer side groups are dissociated, the polymer has a higher charge. In turn, the charge of the polymer classifies the polyelectrolyte, which can be positive (cationic) or negative (anionic).
Hindered amine light stabilizers (HALS) are chemical compounds containing an amine functional group that are used as stabilizers in plastics and polymers. [1] These compounds are typically derivatives of tetramethylpiperidine and are primarily used to protect the polymers from the effects of photo-oxidation; as opposed to other forms of polymer degradation such as ozonolysis.
Polymerization in which polymer is formed in monomer, or monomer-solvent droplets in a continuous phase that is a nonsolvent for both the monomer and the formed polymer. Note 1: In suspension polymerization, the initiator is located mainly in the monomer phase. Note 2: Monomer or monomer-solvent droplets in suspension polymerization have
Crystal structure of β-glucosidase from Thermotoga neapolitana (PDB: 5IDI).Thermostable protein, active at 80°C and with unfolding temperature of 101°C. [1]In materials science and molecular biology, thermostability is the ability of a substance to resist irreversible change in its chemical or physical structure, often by resisting decomposition or polymerization, at a high relative ...
In polymer chemistry, emulsion polymerization is a type of radical polymerization that usually starts with an emulsion incorporating water, monomers, and surfactants.The most common type of emulsion polymerization is an oil-in-water emulsion, in which droplets of monomer (the oil) are emulsified (with surfactants) in a continuous phase of water.
In polymer science, dispersion polymerization is a heterogeneous polymerization process carried out in the presence of a polymeric stabilizer in the reaction medium. . Dispersion polymerization is a type of precipitation polymerization, meaning the solvent selected as the reaction medium is a good solvent for the monomer and the initiator, but is a non-solvent for the po
Plastic is a polymer compound which is polymerized by polyaddition polymerization and polycondensation. It is free to change the composition and shape. It is made up of synthetic resins and fillers, plasticizers, stabilizers, lubricants, colorants and other additives. [6] The main component of plastic is resin. Resin means that the polymer ...