摘要:
A process for preparing a polymer having perfluorocyclobutane rings by the steps of (a) contacting monomers having aromatic polyester, aromatic polyamide, or polyimide groups or combination thereof, at least two dimerizable perfluorovinyl groups; and (b) exposing the monomers to sufficient heat and for a sufficient time that a polymer containing perfluorocyclobutane rings is formed. Chain extending oligomers of polymers having poor processing characteristics by this process results in polymers which are more easily processed. For instance, perfluorocyclobutane groups formed in an extruder to chain lengthen polyimide oligomers, in effect, render polyimides extrudable. The polymer formed by the method preferably has polyimide groups. New monomers and polymers having imide and perfluorovinyl or perfluorocyclobutane structures, respectively, are prepared.
摘要:
The present invention is a process for preparing a polymer having perfluorocyclobutane rings by the steps of (a) contacting monomers having at least two dimerizable perfluorovinyl groups; and (b) exposing the monomers to sufficient heat and for a sufficient time that a polymer containing perfluorocyclobutane rings is formed wherein at least about 0.05 mole percent of the monomer, have at least 3 dimerizable perfluorovinyl groups and polymers prepared thereby.
摘要:
A crosslinked polymer having perfluorocyclobutane rings is prepared in a process comprising the steps of: (a) contacting monomers having two dimerizable perfluorovinyl groups; (b) exposing the monomers to sufficient heat and for a sufficient time that a (linear) polymer containing perfluorocyclobutane rings is formed; and (c) exposing the polymer to sufficient crosslinking initiating means and for a sufficient time such that crosslinking occurs. Crosslinked polymers, so prepared are novel and have tensile strength and other physical properties enhanced over the properties of the corresponding linear polymer.
摘要:
A crosslinked polymer having perfluorocyclobutane rings is prepared in a process comprising the steps of: (a) contacting monomers having two dimerizable perfluorovinyl groups; (b) exposing the monomers to sufficient heat and for a sufficient time that a (linear) polymer containing perfluorocyclobutane rings is formed; and (c) exposing the polymer to sufficient crosslinking initiating means and for a sufficient time such that crosslinking occurs. Crosslinked polymers, so prepared are novel and have tensile strength and other physical proeprties enhanced over the properties of the corresponding linear polymer.
摘要:
Copolymers of propylene oxide and ethylene oxide have an inner block that contains from 65-90 weight percent oxyethylene units and from 10 to 35 weight percent oxypropylene units. This block has a molecular weight of from 150 to 350. The copolymer has an outer block which contains at least 95 weight % oxypropylene units and from 0 to 5% oxyethylene units. The equivalent weight of the copolymer is from 800 to 2000. The copolymers are useful in making polyurethane foams that have unexpectedly high tensile and/or tear strengths.
摘要:
Alkylene oxide polymerizations are performed in the presence of a double metal cyanide polymerization catalyst and certain magnesium, Group 3-Group 15 metal or lanthanide series metal compounds. The presence of the magnesium, Group 3-Group 15 metal or lanthanide series metal compound provides several benefits including more rapid catalyst activation, faster polymerization rates and the reduction in the amount of ultra high molecular weight polymers that are formed. The catalyst mixture is unexpectedly useful in making polyethers having low equivalent weights.
摘要:
Copolymers of propylene oxide and ethylene oxide have an inner block that contains from 65-90 weight percent oxyethylene units and from 10 to 35 weight percent oxypropylene units. This block has a molecular weight of from 150 to 350. The copolymer has an outer block which contains at least 95 weight % oxypropylene units and from 0 to 5% oxyethylene units. The equivalent weight of the copolymer is from 800 to 2000. The copolymers are useful in making polyurethane foams that have unexpectedly high tensile and/or tear strengths.
摘要:
Hybrid polyester-polyether polyols are prepared by polymerizing an alkylene oxide in the presence of a carboxylate initiator. The polymerization is catalyzed with a mixture of double metal cyanide catalyst complex and certain magnesium, group 3-group 15 metal or lanthanide series metal compounds. The presence of the magnesium, Group 3-Group 15 metal or lanthanide series metal (MG3-15LA) compound makes for consistently rapid activation of the double metal cyanide catalyst complex, even in the presence of carboxylate initiator compounds. This leads to greater productivity and reduced manufacturing costs due to shorter cycle times and less waste of raw materials due to the failure of the catalyst to become activated. Once the catalyst is activated, it often polymerizes the alkylene oxide at a faster rate that the DMC catalyst by itself.
摘要:
A two stage alkoxlyation process for preparing a short-chain polyether polyol from a starter compound comprising from 3 to 9 hydroxyl groups and at least one alkylene oxide, wherein said starter compound has a hydroxy equivalent weight of from 22 to 90 Da. Said process comprises a first stage alkoxlyation using a superacid catalyst to prepare an oligomeric alkoxylated starter compound that is further alkoxylated to the short-chain polyether polyol of the invention in a second stage using a DMC catalyst. The process of the present invention may be performed continuously, in a batch, or semi-batch process.
摘要:
Alkylene oxide polymerizations are performed in the presence of a double metal cyanide polymerization catalyst and certain magnesium, Group 3-Group 15 metal or lanthanide series metal compounds. The presence of the magnesium, Group 3-Group 15 metal or lanthanide series metal compound provides several benefits including more rapid catalyst activation, faster polymerization rates and the reduction in the amount of ultra high molecular weight polymers that are formed. The catalyst mixture is unexpectedly useful in making polyethers having low equivalent weights.