摘要:
New fluoroelastomers are described, comprising monomeric units deriving from a bis-olefin having general formula: ##STR1## wherein: R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, equal or different from each other, are H or alkyls C.sub.1 -C.sub.5 ; Z is an alkylene or cycloalkylene radical C.sub.1 -C.sub.18, linear or branched, optionally containing oxygen atoms, preferably at least partially fluorinated, or a (per)fluoropolyoxyalkylene radical.Such products are endowed with improved processability, especially during calendering of the vulcanization mixture, along with superior mechanical and workability properties during extrusion and injection molding, with a very good mold release.
摘要:
A polyvinylidenefluoride (PVDF) having high mechanical properties both at room temperature and at high temperatures, having very good processability and high thermochemical resistance to dehydrofluorination, is prepared by means of a polymerization process of vinylidenefluoride in aqueous emulsion at a temperature comprised between 95.degree. and 120.degree. C., in the presence of a chain transfer agent. In this way it is possible to obtain, using non-hazardous peroxidic initiators (for instance diterbutylperoxide), a PVDF particularly suitable for applications where high mechanical and thermochemical resistance properties are required, such as for instance the manufacture of articles for chemical industry (pipes, valves, fittings, tanks, heat exchangers, membranes, flanges, etc.).
摘要:
Fluoroelastomeric copolymers exhibiting high resistance to bases and alcohols, as well as high mechanical properties and low-temperature resistance, comprising, in moles:4-75% of units of vinylidene fluoride;12-40% of units of hexafluoropropene and/or perfluorovinylether and/or hydropentafluoropropene and/or chlorotrifluoroethylene;2-35% of units of an olefin containing up to 4 carbon atoms;2-60% of units of tetrafluoroethylene, provided that, when the sum of the olefin units and the perfluorovinylether units is equal to or greater than 70%, such copolymers possess a molecular weight sufficiently high to exhibit good mechanical characteristics.
摘要:
Use of perfluoropolyethers having perfluoroalkyl end groups with a molecular weight ranging from 500 to 1500, in amounts from 0.5 to 3 parts by weight per 100 parts by weight of elastomer and, optimally, in combination wit polytetrafluoroethylene having a molecular weight lower than about 200,000, as additives to the polymerization latex of rubbers vulcanizable by means of peroxides in order to improve the detachability of the vulcanizate from forming molds.
摘要:
Metal-fluoroelastomer composites constituted by a metal part and by a cured fluoroelastomer part bonded to each other with high adhesion strength, wherein the fluoroelastomeric part is constituted by a copolymer containing from 35 to 80 mol % T of vinylidene fluoride, from 15 to 35 mol % of hexafluoropropene, from 0 to 30 mol % of another comonomer selected from fluoro-olefins and/or perfluorovinyl ethers, and from 0.001 to 2 wt. % of bromine.
摘要:
A liquid composition comprising at least one aprotic organic solvent and at least one fluorinated ion exchange polymer which consists of recurring units derived from a chlorofluoroolefin of formula CF2═CCIY, wherein Y is F or CI, and from at least one fluorinated functional monomer selected among those of formula CF2═CF—O—(CF2CF(CF3)O)m—(CF2)nSO2X, wherein m is an integer equal to 0 or 1, n is an integer from 0 to 10 and X is chosen among halogens (CI, F, Br, I), —O−M+, wherein M+ is a cation selected among H+, NH4+, K+, Li+, Na+, or mixtures thereof is disclosed. The liquid composition is suitable for the preparation of ion exchange membranes, in particular composite membranes, for use in fuel cell applications.
摘要:
The present invention relates to (per)fluoropolymer compositions, in particular to (per)fluoropolyether compositions comprising:—a (per)fluoropolymer having more than two carboxy groups and—a polyamine. The invention further relates to processes for preparing said compositions and to molded articles obtained from said compositions.
摘要:
MEA 7-layer assemblies with gasket, comprising: a film of ionomeric membrane (3), containing functional acid groups —SO3H and/or —COOH, having in at least one direction, called direction x, a size variation lower than 0.08%; two GDL sheets (1) and (2) in porous material having on one surface an electrocatalytic layer, not shown in the Figures, of which: the first sheet DGL (1) is coextensive with the membrane (3) surface, positioned so as to overlap thereto; the second sheet GDL (2), having a lower width but the same length of the film of membrane (3), measured in the x direction; the two sheets (1) and (2) placed so that the electrocatalytic layer comes into contact, respectively, with each of the two membrane faces; a gasket positioned according to a frame shape along the assembly perimeter.
摘要:
A composition comprising at least one vinylidene fluoride (VDF) polymer [polymer (F)]; and inorganic particles at least partially coated with at least one perfluoropolyether block copolymer [polymer (E)] comprising: A) one or more (per)fluoropolyoxyalkylene segment (chain Rf), comprising recurring units having at least one catenary ether bond and at least one fluorocarbon moiety, and B) one or more polyalkylene segment (chain Ra) comprising recurring units of formula: —(CR1R2—CR3R4)—, wherein R1, R2, R3, R4, equal to or different from each other, are selected from the group consisting of H, halogens (preferably F, Cl); C1-C6 (hydro)carbon groups, optionally containing fluorine or other heteroatoms, referably perfluoroalkyl or (per)fluorooxyalkyl. The invention also discloses a method of coating various substrates using said composition.