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:
Use of vinylidenfluoride (VDF) copolymers for preparing electrolyte polymers, wherein the VDF copolymers have the following polymeric structure (I): (CH2—CF2)m—(CXY—C(ORf)Z)n—(CF2—CF(CF3))p) wherein: Rf is a perfluoroalkyl group having from 1 to 3 carbon atoms; X, Y, and Z equal to or different from each other are selected from F, Cl or H; m,n and p are integers, n or p can be 0 but not simultaneously; said VDF copolymers being obtainable by emulsion polymerization at 75-120° C., preferably 95°-120° C., in the presence of organic initiators.
摘要:
Use of amorphous perfluoropolymers based on homopolymers of the TTD dioxole or its amorphous copolymers to prepare solutions in fluoro-containing solvents, to obtain solutions for coatings, wherein TTD has the formula: ##STR1## wherein R.sub.F is a perfluoroalkylic radical with 1-5 carbon atoms, linear or branched when possible; X.sub.1 and X.sub.2 equal to or different from each other being F or CF.sub.3 ; the TTD amount ranges from 40 to 100% by moles.
摘要翻译:使用基于TTD二氧杂环戊烯或其无定形共聚物的均聚物的无定形全氟聚合物在含氟溶剂中制备溶液,以获得涂料溶液,其中TTD具有下式:其中RF是具有1-5个碳的全氟烷基 原子,可以是直链或支链的; X 1和X 2彼此相同或不同,是F或CF 3; TTD量为40-100摩尔%。
摘要:
Fluoroelastic copolymers, suitable for the manufacture of O-rings, comprising by weight:48-65% of VDF units21-36% of HFP units3-9% of PAVE units0-17% of TFE units
摘要:
Fluoroelastomers characterized by the presence of iodine or bromine atoms at the end of the polymeric chain in an amount equal to or lower than 1 iodine or bromine atom per polymeric chain, and by a bromine content in the chain ranging from 0.05 to 2% by weight referred to the total weight of the monomeric units.Said fluoroelastomers exhibit improved characteristics of processability, particularly as regards the utilization in injection molding processes and the detaching from the molds, as well as of stability to heat.A process for preparing fluoroelastomers containing iodine or bromine atoms at the ends of the polymeric chain, in an amount equal to or lower than 1 iodine or bromine atom per polymeric chain, which process comprises polymerizing mixes of fluorinated monomers (VDF, TFE, HFP, FVE) in bulk, in suspension, in aqueous emulsion, or in solution of organic solvents by means of radical starters, in the presence of compounds capable of providing I.sup.- or Br.sup.- ions in the polymerization medium and conditions.
摘要:
Copolymers formed by TFE and FMVE containing FMVE in percent by moles from 2.5% to 8%; the % TFE moles being the complement to 100% of the FMVE moles.
摘要:
New fluoroelastomers are described, having iodine atoms in terminal position and monomeric units in the chain deriving from an iodinated olefin of formula: CHR═CH—Z—CH2CHR—I (I) wherein: R is —H or —CH3; Z is a (per)fluoroalkylene radical C1-C18, linear or branched, optionally containing one or more ether oxygen atoms, or a (per)fluoropolyoxyalkylene radical. These products, upon peroxide curing, require extremely short post-curing treatments (around 30-60 minutes at 180°-230° C.) and are characterized by compression set values lower than 25% (measured on O-rings at 200° C. for 70 hours according to ASTM Standard D395 Method B).
摘要:
Purification process of amorphous polymers comprising the following steps:a) the amorphous polymer is dissolved in a fluorinated solvent;b) the solution containing the polymer is microfiltered by semipermeable membranes having a porosity in the range 0.05-0.5 .mu.m, and the permeate forms the polymeric solution purified by contaminants in suspension;c) the permeate coming from b) is ultrafiltered/nanofiltered by membranes with porosity in the range 10-500 kDa, and the retentate is formed by the polymeric solution purified from the contaminants in solution.
摘要:
New fluoroelastomers are described, having iodine atoms in terminal position and monomeric units in the chain deriving from an iodinated olefin of formula: CHR.dbd.CH--Z--CH.sub.2 CHR--I (I) wherein: R is --H or --CH.sub.3 ; Z is a (per)fluoroalkylene radical C.sub.1 -C.sub.18, linear or branched, optionally containing one or more ether oxygen atoms, or a (per) fluoropolyoxyalkylene radical. These products, upon peroxide curing, require extremely short post-curing treatments (around 30-60 minutes at 180.degree.-230.degree. C.) and are characterized by compression set values lower than 25% (measured on O-rings at 200.degree. C. for 70 hours according to ASTM Standard D395 Method B).