摘要:
A method for preparing nanocomposites and nanocomposite polymeric products by dispersing nanoparticles in a polymer either by melt processing or by solution processing and bringing about migration of the nanoparticles from the bulk interior to the surface of the nanocomposites so as to produce a new asymetric type of nanocomposite in which the concentration of the nanoparticles on the surface is many times higher than in the interior bulk of the nanocomposite. These surfaces impart highly enhanced properties to the nanocomposites as compared to the pristine polymer and to nanocomposites that have not undergone the migration process, including stability against aging, longer shelf life, higher hydrophobicity, higher wear resistance, higher hardness and lower friction. The new surfaces of the nanocomposite polymeric products are produced by inducing migration of the nanoparticles to the surface thereby producing a concentration gradient below the surface.
摘要:
A flame retardant polyolefin composition comprises at least about 25% by weight magnesium hydroxide and, preferably, at least about 30%, at least about 5% by weight melamine and, preferably, at least about 20%, and at least about 0.5% by weight novolac and, preferably at least about 1%.
摘要:
A flame retardant polymer composition comprising at least one polymer selected from the group consisting of a polyamide, polyolefin, polyester, polyacrylic, polystyrene, polyurethane and polycarbonate, a flame retardant effective amount of an additive comprising at least one(a) hexavalent oxygenated sulfur compound and optionally at least one of(b) a char forming agent,(c) a metal compound,(d) a filler or reinforcing agent, and(e) a flow modifier.By excluding halogens and phosphorus beneficial results are achieved without the negative consequences attending their presence.
摘要:
An improved process is provided for simultaneously drawing and false-twist texturing of partially oriented polyester yarn. The process is of the type wherein the yarn from a supply source is passed through a yarn feed system; a heating zone in which the yarn is heated to a temperature of from about 175.degree. to about 235.degree. C; a cooling zone in which the yarn is cooled to a temperature below about 80.degree. C; a false-twisting means; and take-up means whereby the yarn is drawn to a desired draw ratio; to winding up means; and is characterized in that the yarn emerging from said heating zone and before entering said cooling zone is passed through a heat-maintenance zone, in which the yarn is maintained at a temperature and for a time sufficient to permit substantially complete crystallization of the yarn so that the fully-drawn textured yarn product has a tenacity of at least 3.5 gram per denier. Apparatus for carrying out said improved process is also provided.
摘要:
A method for preparing nanocomposites and nanocomposite polymeric products by dispersing nanoparticles in a polymer either by melt processing or by solution processing and bringing about migration of the nanoparticles from the bulk interior to the surface of the nanocomposites so as to produce a new asymmetric type of nanocomposite in which the concentration of the nanoparticles on the surface is many times higher than in the interior bulk of the nanocomposite. These surfaces impart highly enhanced properties to the nanocomposites as compared to the pristine polymer and to nanocomposites that have not undergone the migration process, including stability against aging, longer shelf life, higher hydrophobicity, higher wear resistance, higher hardness and lower friction. The new surfaces of the nanocomposite polymeric products are produced by inducing migration of the nanoparticles to the surface thereby producing a concentration gradient below the surface.
摘要:
A method of improving the sorption capacity of a substantially hydrophobic, thermoplastic polymer, which comprises introducing into the polymer a halogen by contacting the polymer with a solution containing the halogen under conditions which avoid chemical reaction of the halogen with the polymer, separating the free halogen-containing polymer from the solution, and contacting the polymer with a reagent which pervades the polymer and reacts with the free halogen contained therein so as to produce a gas as one of the reaction products. The product polymers have increased sorption capacity and improved dyeability and are capable of sorbing and retaining useful substances such as medicaments, pesticides and perfumes.
摘要:
Compositions are disclosed for the flame retardation of polymeric compositions including fillers such as glass fibers. The compositions contain a flame retarding effective additive of at least one polyphosphate, a sulfur containing compound, catalyst and a nitrogen containing compound such as melamine.