摘要:
Ethylene-based polymer is made by a process comprising polymerizing a reaction mixture comprising ethylene and at least one chain transfer agent system; wherein the polymerization takes place in the presence of at least one free-radical initiator; and wherein the polymerization takes place in a reactor configuration comprising at least one tubular reactor with at least three reaction zones; and wherein at least two reaction zones receive an ethylene feed; and wherein the degree of polymerization in the first reaction zone is less than, or equal to, (5/LCBf)*3150; and wherein the ethylene-based polymer formed by the process comprises the following properties: (A) LCBf≥(4.7+0.5*log(I2)); and (B) I2 from 0.2 to 25 dg/min.
摘要:
An initiator composition, including: at least two compounds represented by the chemical formula of R—CO—O—O—CO—R and a compound represented by the chemical formula of R1—CO—O—O—R2, where R represents a C2-C12 alkyl or a C6-C10 aryl or substituted aryl, R1 represents a C1-C10 alkyl or a C6-C10 aryl, and R2 represents a C1-C10 alkyl.
摘要:
The invention relates to the preparation of branched fluoropolymers having long chain branches and little or no gels, by a process involving polymerization at high temperatures using persulfates and optionally multifunctional initiators. The invention also relates to gel-free, branched polymers with strain hardening produced by the process.
摘要:
Disclosed are high impact polystyrenes prepared using mixed initiators. The mixed initiators include at least one grafting initiator and one non-grafting initiator. The high impact polystyrenes prepared therewith have a continuous polystyrene phase and dispersed therein particles of rubber predominantly having a honeycomb structure of rubber with polystyrene inclusions.
摘要:
A process for continuously producing water-absorbing polymer particles, wherein the monomer stems from at least two different sources and the monomer from one source differs from the monomer from at least one other source in the content of at least one secondary component.
摘要:
The invention pertains to a process to polymerize one or more monomers wherein one or more initiators and optionally one or more surfactants are added to a polymerization mixture when the pressure in the polymerization reactor is dropping. This process allows a shorter polymerization time due to a higher pressure drop rate at the end of the polymerization reaction. Moreover, the cooling capacity of the polymerization reactor is used more efficiently.
摘要:
The present invention relates to an aqueous dispersion polymerization process for preparing a (co)polymer wherein an organic peroxide is used as initiator (as a source of free radicals) during the polymerization process in conjunction with an effective amount of an organic peroxide stabilizing additive (controlling agent). The invention also relates to formulations comprising an organic peroxide and an effective amount of an organic peroxide stabilizing additive suitable for use in said polymerization process. The invention finally relates to 10 (co)polymers obtainable by the dispersion polymerization process.
摘要:
Ethylene homopolymers and copolymers are prepared in a tube reactor at from 160° C. to 350° C. and pressures in the range from 500 to 5000 bar, with or without use of molar mass regulators, using a peroxide mixture comprising from 1 to 95 mol %, based on the total amount of the peroxide mixture, of at least one cyclic peroxide of the formula I, where the radicals R are identical or different and are selected from among alkyl groups and aryl groups, as polymerization initiator.
摘要:
A method of (co)polymerizing vinyl and/or diene monomers comprising contacting the monomers with a (co)polymeriztion composition under conditions effective to (co)polymerize the monomers, wherein the (co)polymerization composition comprises: (a) an organic peroxide component, and (b) a heteropoly acid, in an amount effective to lower the onset temperature of decomposition of the organic peroxide component with the proviso that if the heteropoly acid is phosphomolybdic acid the organic peroxide is not a peroxydicarbonate.
摘要:
There is provided a process of producing a vinyl chloride polymer wherein vinyl chloride monomer or a monomeric mixture containing vinyl chloride monomer is suspension polymerized in the presence of an oil-soluble polymerization initiator and a suspending agent in an aqueous medium in a polymerization vessel, said process comprising providing, as the oil-soluble polymerization initiator, a mixture of (A) t-butyl peroxyneoheptanoate with (B) a perester peroxide other than said t-butyl peroxyneoheptanoate, said perester peroxide being such that a 10-hour half-life period temperature of a benzene solution of said peroxide dissolved in an amount of 0.1 mole per 1 liter of benzene is 44 to 55.degree. C.; and completing the polymerization at a temperature higher than a preset temperature for the polymerization by from 10 to 20.degree. C. when or after the internal pressure of the polymerization vessel begin to drop at the terminal stage of the polymerization reaction. According to this process, it is possible to obtain a vinyl chloride polymer good in quality, particularly with low initial discoloration when processed into formed products, at a good yield in a short period of polymerization time.