Abstract: Disclosed are copolymers and terpolymers chlorotrifluoroethylene and vinyl chloride having improved properties, and particularly a high glass transition temperature, for use in membranes, coatings, barrier films, and other applications and process for forming such copolymers and terpolymers, which are useful in reverse osmosis desalination, nanofiltration, ultrafiltration, microfiltration, membrane distillation, pervaporation, selective gas separation, batteries and fuel cells.

Abstract: The invention relates to a process for the manufacture of a-iodoperfluoroalkanes and ?,?-diiodoperfluoroalkanes of general formula: (1) A(C2F4)n1, wherein: A is selected from F, CF3 and I and n is an integer equal to or higher than 1, with the proviso that, when A is F, n is an integer higher than 1 said process comprising heating a mixture [mixture (M1)] containing: —a compound selected from I2, CF3I, CF3CF2I and C2F4I2; —TFE; —and CO2 at definite temperatures and concentrations of CO2.

Abstract: A polymer comprising recurring units derived from vinylidene fluoride (VDF) and trifluoroethylene (TrFE), such polymer comprising end groups of formula —CF2H and/or —CF2CH3 in an amount of at least 60 mmoles per kg of VDF recurring units [polymer (F)], a process for its manufacture and the use thereof as ferroelectric, piezoelectric, dielectric or pyroelectric material in electric/electronic devices.

Abstract: Composition which contains polymerizable binder and an initiator according to the following Formula I: R1—X—O—O—[Y—O—O—-]nR2??(Formula I) and having a large through-curing depth and a sufficiently long processing time and which cures without the development of high temperatures.

Abstract: A polymer comprising recurring units derived from vinylidene fluoride (VDF) and trifluoroethylene (TrFE), such polymer comprising end groups of formula —CF2H and/or —CF2CH3 in an amount of at least 60 mmoles per kg of VDF recurring units [polymer (F)], a process for its manufacture and the use thereof as ferroelectric, piezoelectric, dielectric or pyroelectric material in electric/electronic devices.

Abstract: Disclosed herein are a novel perfluoroalkyl vinyl ether compound, a process for preparing a copolymer by using the perfluoroalkyl vinyl ether compound, and an optical plastic material comprising a copolymer prepared by the process. More specifically, the perfluoroalkyl vinyl ether has a particular molecular structure; the process is performed by copolymerizing the perfluoroalkyl vinyl ether compound with a common fluorinated olefin in the presence of a perfluorinated radical initiator; and, the optical plastic material comprises a copolymer prepared by the process and optionally a dopant. The copolymerization of the perfluoroalkyl vinyl ether with a common fluorinated olefin can provide a copolymer having a high molecular weight. In addition, appropriate control of the composition of the monomers can provide a completely amorphous copolymer.

Abstract: A polymerization process comprising initiating a first polymerization of monomers using an initiator functionalized with an ATRP initiating site, wherein the first polymerization is selected from the group of cationic polymerization, anionic polymerization, conventional free radical polymerization, metathesis, ring opening polymerization, cationic ring opening polymerization, and coordination polymerization to form a macroinitiator comprising an ATRP initiating site and further initiating an ATRP polymerization of radically polymerizable monomers using the macroinitiator comprising an ATRP initiating site. Novel block copolymers may be formed by the disclosed method.

Abstract: The invention relates to a process to make and use specific diacyl peroxides in polymerization reactions. The peroxides are produced and used in a polymerization process within a short timeframe in order to overcome stability issues associated with them.

Abstract: A polymer comprises polymer chains having a glass transition temperature of less than 25° C. and a weight average molecular weight of less than 20,000 wherein the polymer chains contain at least one non-functional aromatic end-group. The polymer is miscible in the uncured state of said thermoset resins and immiscible in the cured state of the thermoset resins.

Abstract: A process for preparing a liquid rubber composition comprises: (a) Forming a reaction mixture of (i) from 1.0 to 99.999 weight percent of the reaction mixture of at least one C1-C20 alkyl acrylate monomer; and (ii) from 0.001 to 20 weight percent of the reaction mixture of at least one aromatic-containing initiator; (b) charging the reaction mixture into a reactor maintained at a reaction temperature of up to 400° C.; and (c) polymerizing said monomer with said aromatic-containing initiator to form a liquid rubber with polymer chains having at least one non-functional aromatic end-group.

Abstract: Perfluorodiacylperoxides having the following structures: 1

Abstract: Perfluorodiacylperoxides having the following structures: wherein: when Rf is F, Rf′, Rf″ are both —CF3; when Rf is —CF3, Rf′, Rf″, are C1-C3 linear or branched perfluorooxyalkyl groups; said perfluorodiacylperoxides being such as to meet the following proviso: the thermal decomposition constants Kd (sec−1) in the presence of water do not undergo substantial variations with respect to the thermal decomposition constants in absence of water.

Abstract: A method for producing a tetrafluoroethylene/perfluoro (alkyl vinyl ether) type copolymer (PFA), which comprises carrying out the polymerization in a polymerization medium (such as CHFClCF2CF2Cl) in the presence of a chain transfer agent of a C1 or 2 hydrofluorocarbon (such as CH3CF2H) by means of a polymerization initiator (such as (FCF2CF2CF2COO)2). PFA obtained by this method has a small amount of unstable terminal groups contained in its molecule and is excellent in thermal stability and cracking resistance against a liquid reagent. Further, the amount of elution of fluorine ions is little even when it is applied to a component of e.g. an equipment for the production of semiconductors.

Abstract: A new polymerization process (atom transfer radical polymerization, or ATRP) based on a redox reaction between a transition metal (e.g., Cu(I)/Cu(II), provides “living” or controlled radical polymerization of styrene, (meth)acrylates, and other radically polymerizable monomers. Using various simple organic halides as model halogen atom transfer precursors (initiators) and transition metal complexes as a model halogen atom transfer promoters (catalysts), a “living” radical polymerization affords (co)polymers having the predetermined number average molecular weight by &Dgr;[M]/[I]0 (up to Mn>105) and a surprisingly narrow molecular weight distribution (Mw/Mn), as low as 1.15. The participation of free radical intermediates in ATRP is supported by end-group analysis and stereochemistry of the polymerization. In addition, polymers with various topologies (e.g.

Abstract: The present invention relates to a process for the production of partially fluorinated fluoropolymers, in accordance with which fluoromonomers are free-radically polymerized in the presence of polyfluoropropanes or polyfluorobutanes of the formulae CF3—CH2—CF2H, CF3—CHF—CF2—H, CF3—CH2—CF3, CHF2—CF2—CH2F, CF3—CH2—CF2—CH3 AND CF3—CHF—CF2—CH3 and optionally a chain-transfer agent.

Abstract: A method for producing a fluorine-containing polymer, which comprises subjecting the following fluorine-containing monomer (a), (b), (c) or (d) to bulk polymerization by means of a polymerization initiator comprising a fluorine-containing organic peroxide having a 10 hour half value temperature of from 30 to 130° C., to obtain a fluorine-containing polymer having a fluorine-containing alicyclic structure in its main chain: (a) a fluorine-containing monomer having a fluorine-containing alicyclic structure, (b) a fluorine-containing monomer having at least two polymerizable double bonds, (c) the fluorine-containing monomer (a) and the fluorine-containing monomer (b), (d) at least one fluorine-containing monomer selected from the fluorine-containing monomers (a) and (b), and another fluorine-containing monomer other than the fluorine-containing monomers (a) and (b).

Abstract: The present invention provides a process for making fluorinated polymers and copolymers having stable end groups. The process includes (1) contacting a fluoromonomer, an initiator capable of producing stable end groups on the polymer chain, and a polymerization medium comprising carbon dioxide, and (2) polymerizing the fluoromonomer. The polymerization medium preferably comprises liquid or supercritical carbon dioxide. Advantageously, the process may also include the step of separating the fluoropolymer from the polymerization medium. The present invention also provides polymerization reaction mixtures useful in the processes of the present invention.

Abstract: The present invention provides a process for making fluorinated polymers and copolymers having stable end groups. The process includes (1) contacting a fluoromonomer, an initiator capable of producing stable end groups on the polymer chain, and a polymerization medium comprising carbon dioxide, and (2) polymerizing the fluoromonomer. The polymerization medium preferably comprises liquid or supercritical carbon dioxide. Advantageously, the process may also include the step of separating the fluoropolymer from the polymerization medium.The present invention also provides polymerization reaction mixtures useful in the processes of the present invention.

Abstract: A novel bis(mono- or diperoxyoxalate) composition of Structure A, ##STR1## and use of the novel bis(mono- or diperoxyoxalate) composition as an initiators for curing of unsaturated polyester resins and for polymerizing ethylenically unsaturated monomers are disclosed.

Abstract: The present invention provides a process for making fluorinated polymers and copolymers having stable end groups. The process includes (1) contacting a fluoromonomer, an initiator capable of producing stable end groups on the polymer chain, and a polymerization medium comprising carbon dioxide, and (2) polymerizing the fluoromonomer. The polymerization medium preferably comprises liquid or supercritical carbon dioxide. Advantageously, the process may also include the step of separating the fluoropolymer from the polymerization medium.The present invention also provides polymerization reaction mixtures useful in the processes of the present invention.

Abstract: The invention relates to a (co)polymerization process in suspension for preparing hydrogen containing thermoplastic fluoropolymers, such as for instance ethylene/chlorotrifluoro-ethylene or ethylene/tetrafluoroethylene copolymers, or vinylidenefluoride homopolymers or copolymers, wherein bis-dichlorofluoroacetylperoxide (CFCl.sub.2 --CO--O).sub.2 (DCFAP) is used as polymerization initiator. From such process products endowed with high thermal stability, remarkably higher than that obtainable using bis-trichloroacetylperoxide (TCAP), are obtained.

Abstract: A polymer comprising fluoroalkyl group has a structure in which one or two parts of the fluoroalkyl group at the one or both ends of the molecule are linked to a part of alkylene groups or alkylene groups substituted with halogen, a part of alkylene group substituted with functional groups, such as halogen, cyano group, alkylsulfonic acid group, amidoalkylsulfonic acid group, carboxylic acid group, carboxyl group, oxycarbonyl group, ether group, epoxy group and the like, and/or a part of silicone group. A method of preparation of the polymer comprising fluoroalkyl group contains reaction of a fluoroalkanoyl peroxide with a monomer comprising the functional group or a monomer comprising silicone group. A surface active agent comprises fluoroalkyl group and caroxylic acid salt group. A surface treatment agent comprises the polymer comprising fluoroalkyl group, hydrolysis products thereof, hydrolytic condensation products thereof, and mixtures thereof.

Abstract: A method for preparing a tetrafluoroethylene/hexafluoropropylene copolymer by polymerizing tetrafluoroethylene and hexafluoropropylene in an aqueous medium using a di(fluoroacyl) peroxide as a polymerization initiator characterized in that a fluoroalkylcarboxylic acid is added gives a stable molecular weight of the tetrafluoroethylene/hexafluoropropylene copolymer and an increased utilization efficiency of the polymerization initiator.

Abstract: A polymer comprising fluoroalkyl group has a structure in which one or two parts of the fluoroalkyl group at the one or both ends of the molecule are linked to a part of alkylene groups or alkylene groups substituted with halogen, a part of alkylene group substituted with functional groups, such as halogen, cyano group, alkylsulfonic acid group, amidoalkylsulfonic acid group, carboxylic acid group, carboxyl group, oxycarbonyl group, ether group, epoxy group and the like, and/or a part of silicone group. A method of preparation of the polymer comprising fluoroalkyl group contains reaction of a fluoroalkanoyl peroxide with a monomer comprising the functional group or a monomer comprising silicone group. A surface active agent comprises fluoroalkyl group and caroxylic acid salt group. A surface treatment agent comprises the polymer comprising fluoroalkyl group, hydrolysis products thereof, hydrolytic condensation products thereof, and mixtures thereof.

Abstract: Alkenylaminomethylenephosphonic acids of the formula ##STR1## in which R.sub.1 is hydrogen, C.sub.4 -C.sub.10 -alkyl, phenyl, naphthyl, methylphenyl, hydroxyphenyl, methoxyphenyl, methylnaphthyl, hydroxynaphthyl or methoxynaphthyl,R.sub.2 is hydrogen,R.sub.3, R.sub.4, R.sub.5 are hydrogen or methyl,R.sub.5 is hydrogen, C.sub.1 -C.sub.4 -alkyl or phenyl, andM is hydrogen or a cation,and copolymers comprising 0.1-99.9% by weight, preferably 1-50% by weight, of one or more monomers of the formula I, in which R.sub.2 is hydrogen or a group of the formula--CH.sub.2 PO.sub.3 M.sub.2, and 99.9-0.1% by weight, preferably 99-50% by weight, of one or more monomers of the formula IIR.sub.1 'R.sub.2 'C.dbd.CR.sub.3 'X (II)in whichR.sub.1 ' is hydrogen or a group of the formula --COOM,R.sub.2 ' is hydrogen, phenyl or a group of the formula --COOM,R.sub.3 ' is hydrogen, methyl or a group of the formula --COOM or --CH.sub.2 COOM,X is a group of the formula --COOM orR.sub.2 ' and R.sub.3 ' together are a C.sub.

Abstract: A free-radical initiated process for preparing fluorinated polymers wherein at least one gaseous fluoroolefin is polymerized in a stirred polymerizer, the improvement comprising preparing a non-volatile polymeric seed in a reaction zone separate from the polymerizer by decomposing initiator in the presence of fluoromonomer to form oligomeric free radicals and condensing said radicals onto previously prepared polymer; and conveying said non-volatile seed to the polymerizer.

Abstract: The polymerization of fluoromonomers can be accomplished without fouling by using gaseous monomers in the presence of at least one nonvolatile initiator and by recycling the initiator-free polymerizer gases through an external cooler.

Abstract: This disclosure relates to novel peroxy esters carrying a t-alkenyl, e.g. 2-methyl-3-buten-2-yl, peroxy group. These peroxy esters have shorter half-life periods of decomposition and are more reactive polymerization initiators and unsaturated polyester resin curing agents than the corresponding prior art peroxy esters carrying a t-alkyl, e.g. t-amyl, peroxy group.

Abstract: A process is provided for the free radical polymerization of monomers derived from substituted or unsubstituted acrylic acid/methacrylic acid and esters thereof for the production of a polymer having a narrow molecular weight distribution and an average molecular weight of less than 4000. These polymers are produced by the solution polymerizing of said monomers wherein 20-40% by weight of the monomer composition is hydroxyalkyl acrylate or methacrylate in the presence of a solvent system suitable for high solids coating applications and in the presence of an initiating amount of a tertiary alkyl hydroperoxide and/or its derivatives having at least 5 carbons wherein the initiator and monomers, alone or in combination, are added continuously at a programmed rate wherein the rate of addition corresponds approximately to the rate of decomposition of said monomer and initiator. These polymers are used for high solids coating applications.

Abstract: A novel fluorine-containing diacylperoxide of the formula:[RO-CH.sub.2 CF.sub.2 CF.sub.2 O-.sub.n CH.sub.2 CF.sub.2 COO-.sub.2 (I)wherein R is a C.sub.1 -C.sub.10 hydrocarbon group or halogen-containing hydrocarbon group, and n is an integer of 0 to 3, which can initiate polymerization of an ethylenically unsaturated monomer at a relatively low temperature.

Abstract: A process for the polymerization of fluorinated olefin monomers using a fluoroxy compound solution as initiator, wherein said solution has a fluoroxy compound concentration of at least 0.5 meq/liter. The concentration contains, based on the total number of fluoroxy compounds present, about 35 to 100% of an acyl hypofluorite of the formula RCOOF wherein R is X(CF.sub.2).sub.n -- or CF.sub.3 CF.sub.2 CF.sub.2 O[CF(CF.sub.3)CF.sub.2 O].sub.m CF(CF.sub.3)-- wherein n is 1 to 16, m is 0 to 50, and X is H or F.

Abstract: A process for the polymerization of fluorinated olefin monomers using a fluoroxy compound solution as initiator, wherein said solution has a fluoroxy compound concentration of at least 0.5 meq/liter. The concentration contains, based on the total number of fluoroxy compounds present, about 35 to 100% of an acyl hypofluorite of the formula X(CF.sub.2).sub.n COOF wherein X is H or F and n is 1 to 16.

Abstract: A copolymer comprising monomeric units of tetrafluoroethylene, ethylene and at least one monomeric compound selected from the group consisting of 2-trifluoromethylpropylene and 2-methyl-1,1,3,3,3-pentafluoropropylene, which has a improved crack resistance at a high temperature.

Abstract: A process for preparing a tetrafluoroethylene/fluoro(alkyl vinyl ether) copolymer comprising polymerizing tetrafluoroethylene and fluoro(alkyl vinyl ether) in an aqueous suspension system which comprises a mixed medium of water and a fluorohydrocarbon or a chlorofluorohydrocarbon in a volume ratio of from 1:1 to 10:1 at a temperature of from 0.degree. to 25.degree. C. in the presence of a polymerization initiator of the formula:[Cl(CF.sub.2).sub.n --COO].sub.2 (I)wherein n is an integer of 1 to 10, the copolymer obtained by the process having a small number of unstable terminal groups and excellent flex life.

Abstract: A safe, dry and free-flowing solid peroxide/unsubstituted or alkyl substituted benzoic acid composition is prepared by mixing the solid peroxide, such as diacyl peroxide, dialkyl peroxydicarbonate, dialkyl peroxide or alkylidene diperoxide, which melts above 30.degree. C., with solid benozic acid or an alkyl substituted benzoic acid, which melts above 40.degree. C. This solid peroxide composition is used as an initiator for the polymerization of ethylenically unsaturated monomers, such as styrene, and for curing of unsaturated polyester resins and diethylene glycol bis(allyl carbonate). This solid peroxide composition exhibits improved safety characteristics such as delayed ignition times when in contact with a flame and increased thermal stabilities compared to similar prior art peroxide formulations.

Abstract: Stable aqueous dispersions of free radical-generating polymerization initiators that are solid at temperatures above 0.degree. C. are prepared safely and efficiently by homogenizing a suspension of the initiator in an aqueous system that contains small amounts of a suspending agent and a wetting agent.

Abstract: A cross-linkable positive-working ionizing radiation-resist or ultraviolet ray-resist polymer composition including: in polymerized form,(a) units derived from a methacrylic acid ester of the formula:CH.sub.2 .dbd.C(CH.sub.3).COORwhere R is an alkyl or haloalkyl group having from 1 to 6 carbon atoms, benzyl or cyclohexyl,(b) units derived from a monoolefinically unsaturated carboxylic acid having from 3 to 12 carbon atoms and from 1 to 3 carboxyl groups, and(c) units derived from methacrylic acid chloride.The amount of the units (c) in the polymer composition is such that the number of moles of the units (b), multiplied by the number of the carboxyl group or groups in each of the units (b), ranges from about 1 to about 20% based on the total number of moles of the units (a), (b) and (c); the amount of the units (c) ranges from about 0.05 to about 3.

Abstract: Compositions comprising organic phosphorus compounds having a peroxygen group which is either a hydroperoxyalkyl (H--OO--C--) group or a peroxyether (--C--OO--C--) group. There is at least one such group per 500 phosphorus atoms in the composition. These peroxygen compounds may be made by passing oxygen through a liquid comprising a phosphorus compound which has an aliphatic carbon, having an abstractable hydrogen, directly attached to a carbon of an aryl ring; for example, an isopropylphenyl phosphate. The peroxygen compounds may be added to compositions comprising peroxide-reactive organic polymers to increase flame resistance.

Abstract: Dialkyl diacyl peroxides in which the alpha carbon atom of one of the alkyl groups is secondary and substituted by chloro and alkyl. The compounds are useful as polymerization initiators of ethylenically unsaturated monomers such as vinyl chloride.

Abstract: Novel mono and di peroxyesters characterized by chloro-substitution of a tertiary carbon atom at the alpha position relative to the carbonyl group(s), the monoperoxyesters having no less than 9 carbon atoms and the diperoxyesters having no less than 16 carbon atoms, are utilized as polymerization initiators. Typical is the polymerization of styrene and the copolymerization of vinyl chloride and vinyl acetate.

Abstract: Dialkyl diacyl peroxides in which the alpha carbon atom of one of the alkyl groups is secondary and substituted by chloro and alkyl. The compounds are useful as polymerization initiators of ethylenically unsaturated monomers such as vinyl chloride.

Abstract: Novel mono and di peroxyesters characterized by chloro-substitution of a tertiary carbon atom at the alpha position relative to the carbonyl group(s), the monoperoxyesters having no less than 9 carbon atoms and the diperoxyesters having no less than 16 carbon atoms, are utilized as polymerization initiators. Typical is the polymerization of styrene and the copolymerization of vinyl chloride and vinyl acetate.

Abstract: An improved dental composition having shortened hardening time and after hardening increased compressive strength and abrasion resistance, including a radical-inducing compound and a polymerizable acrylic or methacrylic acid ester or diester compound with at least 20 percent by weight of the polymerizable compound being the diacrylic or dimethacrylic acid ester of bishydroxymethyltricyclo [5.2.1.0.sup.2,6 ]-decane. Other monofunctional or difunctional acrylic or methacrylic acid esters as well as fillers, pigments and stabilizers can be included.

Abstract: A vulcanizable polyacrylate elastomer composition having improved resistance to hydrocarbon oils is provided which comprises one or more lower alkyl acrylic acid ester monomers polymerized with a comonomer containing either a halogen or an epoxy group, in the presence of from about 0.25 to 10 percent, by weight of total monomer, of a low molecular weight, unsaturated polymer of butadiene or isoprene or copolymers thereof with styrene or acrylonitrile. In addition, a process for preparing such elastomer compositions is also provided, together with the vulcanization of such elastomers and the resulting vulcanized polyacrylate.

Abstract: Organic peroxide polymerization co-initiator compositions and their use in the initiation of the polymerization of certain monomers and comonomers such as vinyl chloride, ethylene and methyl methacrylate. The co-initiator composition contains an alpha halo substituted diacyl peroxide and a coperoxide selected from t-alkyl peresters of t-hydroperoxides, peroxydicarbonates, acyl peroxycarbonic esters, and aliphatic diacyl peroxides. Typical is acetyl 2-chlorooctanoyl peroxide with t-butyl peroxy neodecanoate.

Abstract: Stable, pumpable, highly concentrated aqueous suspensions of organic peroxides containing (a) nonionic emulsifiers having a maximum HLB value of 12.5 and (b) nonionic emulsifiers having a minimum HLB value of 12.5 or anionic emulsifiers.

Abstract: Asymmetrical organic diacyl peroxide polymerization initiators having enhanced initiator efficiency and characterized by the presence of an acyclic acyl group of four or more carbon atoms having bromo or halo substitution at the alpha carbon atom, the other acyl group being different and heterosubstituted. However, when the alpha-halosubstituted acyl group is branched chain the other acyl group may be hydrocarbon.

Abstract: Stress-crack resistant terpolymers of from about 40 to 60 mol percent ethylene, about 60 to 40 mol percent of a halogenated comonomer selected from the group consisting of tetrafluoroetylene, chlorotrifluoroethylene and mixtures thereof and about 0.1 to 10 mol percent of a termonomer selected from the group consisting of 3,3,3-trifluoro-2-trifluoromethyl propene, a vinyl monomer which is free of telogenic activity and which provides a side chain having at least two carbon atoms, the side chain being aromatic or having its elements bonded by a single bond only, and mixtures thereof, and containing high and low molecular weight components such that: ##EQU1## WHEREIN X.sub.i represents the weight fraction of each high molecular weight component i;Mw represents the weight-average molecular weight of the terpolymer,Mw.sub.i represents the weight-average molecular weight of each component i, ##EQU2## WHEREIN X.sub.j represents the weight fraction of each low molecular weight component j;Mw.sub.

Abstract: Stress-crack resistant copolymers of from about 40 to 60 mol percent ethylene and 60 to 40 percent of a halogenated comonomer selected from the group consisting of tetrafluoroethylene and chlorotrifluoroethylene and mixtures thereof and containing high and low molecular weight components such that: ##EQU1## WHEREIN X.sub.i represents the weight fraction of each high molecular weight component i;Mw represents the weight-average molecular weight of the copolymer;Mw.sub.1 represents the weight-average molecular weight of each component i; ##EQU2## WHEREIN X.sub.j represents the weight fraction of each low molecular weight component j, andMw.sub.j represents the weight-average molecular weight of each component j, and0.1 .ltoreq. f .ltoreq. 0.95.

Abstract: Tough, stable copolymers of tetrafluoroethylene monomer and fluorovinyl ether monomers can be produced by polymerizing the monomers in perfluorinated or suitable non-perfluorinated hydrogen and chlorine containing fluorocarbon solvents by a process that requires that the reaction be carried out at from about 30.degree. to about 75.degree. C. in the presence of a low temperature initiator such as bis(perfluoro propionyl) peroxide and a hydrogen containing chain transfer agent such as methanol.