Abstract: Thermoplastic cycloolefin copolymers (COCs) having low melt viscosity and low optical attenuation, a process for their preparation, and their use as optical waveguides (optical fibers).

Abstract: Cycloolefin/alpha-olefin copolymers in a molar ratio from 5/95 to 95/5, optionally including long linear alpha-olefin, branched alpha-olefins and/or polyenes as additional comonomers, are prepared using a cyclopentadienyl metallocene catalyst system based on a transition metal compound from Group 4 of the Periodic Table of Elements. The copolymers have a high molecular weight, a narrow molecular weight distribution and a substantially uniform, random comonomer distribution.

Abstract: A process for effectively producing a cyclic olefin polymer and a cyclic olefin/alpha-olefin copolymer without opening the cyclic olefin, is disclosed. Further, a novel cyclic olefin/alpha-olefin copolymer prepared by the above-mentioned process, compositions and molded articles comprising the novel copolymer, are also disclosed. In the process for producing a cylcic olefin based polymer according to the present invention, homopolymerization of a cyclic olefin or copolymerization of a cyclic olefin and an alpha-olefin is effected in the presence of a catalyst comprising, as main ingredients, the following Compounds (A) and (B), and optionally Compound (C):(A) a transition metal compound;(B) a compound capable of forming an ionic complex when reacted with a transition metal compound; and(C) an organoaluminum compound.

Abstract: The present invention relates to a cycloolefin polymer having a solution viscosity >0.25 dl/g and containing polymerized units of at least one cycloolefin and, if desired, polymerized units of one or more acyclic olefins, wherein the cycloolefin polymer has at one or both ends an olefinically unsaturated group having at least 3 carbon atoms.

Abstract: This invention relates to a process for preparation of non-crosslinked linear monofunctional and telechelic difunctional unsaturated polymers wherein the functional groups are acrylate or methacrylate groups. The average functionality number of the monofunctional unsaturated polymers is at least 0.7, as determined by nuclear magnetic resonance spectroscopy (NMR). The average functionality number of the telechelic difunctional polymers is at least 1.7, as determined by NMR. Alkyl acrylates or alkyl methacrylates are reacted with cyclic olefinic non-conjugated compounds or unsaturated hydrocarbon polymers to prepare monofunctional and difunctional polymers. The process is substantially free of side reactions comprising double bond migration and cyclization.

Abstract: A copolymerization process suitable for the preparation of high crystalline melting point cyclic olefin copolymers comprising contacting ethylene, and at least one cyclic olefin with an active polymerization catalyst comprising a Group 4 transition metal compound containing an asymmetrically substituted monocyclopentadienyl ancillary ligand, a bulky substituent-containing heteroatom ligand, the monocyclopentadienyl and heteroatom ligands being covalently bridged is disclosed. Ethylene/norbornene copolymers prepared in accordance with the invention exhibited crystalline melting points of about 250.degree. C., and were prepared at high catalyst activity levels with feed ratios less than 6:1 of norbornene to ethylene.

Abstract: The present invention relates to a cycloolefin polymer having a solution viscosity <0.25 dl/g, comprising polymerized units of at least one cycloolefin and, if desired, polymerized units of one or more acyclic olefins, wherein the cycloolefin polymer has at one or both ends an olefinically unsaturated group having at least 3 carbon atoms.

Abstract: Transparent cycloolefin copolymers having a high tensile strength are obtained by polymerization of a polycyclic olefin, ethylene and, if desired, an acyclic olefin and/or a monocylcic olefin in the presence of a catalyst system which comprises a cocatalyst and an asymmetrical metallocene compound of the formula ##STR1## in which R.sup.16 is cyclopentadienyl and R.sup.17 is indenyl.

Abstract: A polyolefin molding composition essentially comprising a polyolefin derived from an olefin having at least 3 carbon atoms, of the formula R.sup.a --CH.dbd.CH--R.sup.b, in which R.sup.a and R.sup.b are identical or different and are hydrogen or C.sub.1 -C.sub.15 -alkyl, straight-chain or branched, or R.sup.a and R.sup.b, together with the atoms connecting them, form a ring, where the polyolefin molding composition may contain up to 10% by weight of ethylene or a second olefin as defined above as comonomer, having a molecular weight M.sub.w of >80,000 g/mol, a polydispersity M.sub.w /M.sub.n of from 1.8 to 3.5, a viscosity of >70 cm.sup.3 /g, a melting point of from 130.degree. to 160.degree. C., an aligned transparency of >30% and an ether-extractable content of less than 2% by weight.

Abstract: A polymer having a repeating unit of ##STR1## and a method for preparing it through Zr-catalyzed polymerization of methylenecyclopropane is disclosed.

Abstract: This invention relates to difunctional telechelic linear non-crosslinked polyolefins without pendant chain branched groups. The polyolefin compounds of this invention are useful for preparing high molecular weight polyesters, polyamides, polyureas and polyurethanes of high density without branching of the polymer chains, and with low permeability to gases and solvents.

Abstract: Addition polymers derived from norbornene-functional monomers are terminated with an olefinic moiety derived from a chain transfer agent selected from a compound having a terminal olefinic double bond between adjacent carbon atoms, excluding styrenes, vinyl ethers, and conjugated dienes and at least one of said carbon atoms has two hydrogen atoms attached thereto. The addition polymers of this invention are prepared from a single or multicomponent catalyst system including a Group VIII metal ion source. The catalyst systems are unique in that they catalyze the insertion of the chain transfer agent exclusively at a terminal end of the polymer chain.

Abstract: Addition polymers derived from norbornene-functional monomers are terminated with an olefinic moiety derived from a chain transfer agent selected from a compound having a terminal olefinic double bond between adjacent carbon atoms, excluding styrenes, vinyl ethers, and conjugated dienes and at least one of said carbon atoms has two hydrogen atoms attached thereto. The addition polymers of this invention are prepared from a single or multicomponent catalyst system including a Group VIII metal ion source. The catalyst systems are unique in that they catalyze the insertion of the chain transfer agent exclusively at a terminal end of the polymer chain.

Abstract: A thermoplastic elastomer consisting essentially of a copolymer comprising a mixture of ethylene; one or more alpha-olefins having 3 to 12 carbon atoms; and, optionally, a diene, said copolymer being in an uncrosslinked state and having a crystallinity in the range of about 2 to about 40 percent by weight based on the weight of the copolymer wherein about 15 to about 85 percent by weight of the crystallinity melts at a temperature above 80.degree. C.; about 15 to about 85 percent by weight of the crystallinity melts at a temperature below 80.degree. C.; and the crystalline melting temperatures differ by at least about 30.degree. C.

Abstract: There is provided a process for producing a cyclic olefin copolymer by copolymerizing (A) ethylene and (B) a particular cyclic olefin in the presence of (C) a metallocene catalyst and (D) a small amount of an .alpha.-olefin having 3 to 20 carbon atoms. According to the said process, said copolymer can be produced at a high activity and its molecular weight can be controlled in a wide range. The copolymer produced by the said process has excellent properties inherent to the cyclic olefin copolymer.

Abstract: This invention relates to difunctional telechelic linear non-crosslinked polyolefins without pendant chain branched groups. The polyolefin compounds of this invention are useful for preparing high molecular weight polyesters, polyamides, polyureas and polyurethanes of high density without branching of the polymer chains, and with low permeability to gases and solvents.

Abstract: Chlorine-free, non-drying copolymer of isobutene with C.sub.4 -C.sub.10 -dienes having isolated or conjugated double bonds and containing at least 60 mol % of terminal double bonds, and a process for their preparation.

Abstract: An at least monoaxially stretched polypropylene film made of a composition comprising a crystalline polypropylene and a monocyclic olefin polymer (e.g. a polycyclobutene or a polycyclopentene), wherein the content of the monocyclic olefin polymer is 0.1-1,000 ppm by weight.The polypropylene film is superior not only in transparency but also in image clarity by which an image is clearly seen through the film.The polypropylene film, when further comprising talc having an average particle diameter of 0.1-10 .mu.m in an amount of 50-4,000 ppm by weight, can prevent the surface roughening or edge roughening of sheet during the sheet formation conducted before stretched film production.The polypropylene film, when further comprising an anti-blocking agent and a polyethylene together, can prevent the generation of voids caused by the anti-blocking agent.

Abstract: Tackifiers having Mn's of 5,000 or less and Tg's above 0.degree. C. are produced by combining a single site catalyst with an alpha-olefin and a cyclic monomer under conditions designed to produce low molecular weight.

Abstract: A film including semi-crystalline cycloolefin copolymers which have a content of catalyst residues of <100 ppm and their use as capacitor films, reproduction films, film keyboards and film switches, substrates for liquid crystal displays and packaging films.

Abstract: Process for preparing cycloolefin copolymers Process for preparing cycloolefin polymers from cyclic and acylcic olefin monomers using a catalyst system in a reaction space, wherein the residence time of the monomers in the reaction space is separated from the residence time of the catalyst system in the reaction space.

Abstract: A hydrocarbon resin is prepared by (1) thermally polymerizing a mixture consisting essentially of (a) about 40% to 90% by weight based on total monomers of a cyclic diolefin component comprising at least about 50% by weight dicyclopentadiene, and (b) about 60% to 10% by weight based on total monomers of a specified vinyl aromatic component, preferably alpha-methylstyrene; para-methyl-.alpha.-methylstyrene; 2,4-diphenyl-4-methyl-1-pentene, or mixtures thereof, and (2) recovering a product having a Ring and Ball softening point of about 70.degree. to about 150.degree. C. Hydrogenation of this resin produces light colored, thermally stable products that are useful as tackifiers in adhesives.

Abstract: A material of a cycloolefin copolymer has a structure of alternating cycloolefin sequences, and has crystallinity in a temperature range from 210.degree. to 320.degree. C. The cycloolefin is prepared by polymerization of at least one polycyclic olefin, monocyclic and/or acyclic olefin with an open-chain olefin using a catalyst of a metallocene and an aluminoxane.

Abstract: A polymer having a repeating unit of ##STR1## and a method for preparing it through Zr-catalyzed polymerization of methylenecyclopropane is disclosed.

Abstract: A single component ionic catalyst consists essentially of an organonickel complex cation, and a weakly coordinating neutral counteranion. The cation is a neutral bidentate ligand removably attached to a Group VIII transition metal in an organometal complex. The ligand is easily displaced by a norbornene-type (NB-type) monomer in an insertion reaction which results in an unexpectedly facile addition polymerization. A NB-type monomer includes NB or substituted NB, or a multi-ringed cycloolefin having more than three rings in which one or more of the rings has a structure derived from NB, and a ring may have an alicyclic alkyl, alkylene or alkylidene substituent. The insertion reaction results in the formation of a unique propagating species more soluble in a polar than in a non-polar solvent and devoid of an available .beta.-hydrogen for termination. The ensuing propagation of a polymer chain proceeds without measurable unsaturation.

Abstract: A catalyst system and process for the polymerization of cyclic olefins, such as dicyclopentadiene, are disclosed. The catalyst system contains a transition metal hydrotrispyrazolylborate complex having the formula:Tp--M--L.sub.3wherein Tp is a hydrotrispyrazolylborate ligand, M is tungsten or molybdenum, and L is independently a ligand selected from the group consisting of oxo, phenoxy, alkoxy, and halides, provided that at least one L is a halide, and a co-catalyst.

Abstract: Polymers of polycyclic olefins such as, for example, norbornene or tetracyclododecene, or copolymers of polycyclic olefins with cycloolefins and/or 1-olefins with a very narrow molecular weight distribution are obtained without ring opening by a polymerization in which a catalyst which is composed of an aluminoxane and of a stereorigid, chiral metallocene compound of an element of groups IVb to VIb is used, and in which the reaction is stopped at a time when the molecular weight distribution Mw/Mn of the polymer formed is <2.

Abstract: The organolanthanide hydrides (Cp'.sub.2 LnH).sub.2 (Cp'=.eta..sup.5 -Me.sub.5 C.sub.5 ;Ln=Sm,Lu) rapidly catalyze the copolymerization of methylenecyclopropane and ethylene to cleanly yield high molecular weight polyolefins of microstructure {[CH.sub.2 CH.sub.2 ].sub.x [CH.sub.2 CH.sub.2 C(CH.sub.2)].sub.y }n via sequential olefin insertion and ring-opening/.beta.-alkyl shift processes. Homopolymerization of methylenecyclopropane likewise cleanly yields polymers of the structure [CH.sub.2 CH.sub.2 C(CH.sub.2)].sub.n.

Abstract: An acid-functional polymer is obtained by the hydrolysis or half-ester ring opening reaction of an anhydride-functional polymer obtained by reacting under ene reaction conditions:(i) an unsaturated anhydride having the structure: ##STR1## wherein R.sub.1 and R.sub.2 are each independently hydrogen, alkyl of 1 to about 6 carbons, or alkoxy of 1 to about 6 carbons, or a halogen; and(ii) at least one polyolefin having at least two carbon-carbon double bonds in the polyolefin backbone and having an average of at least three carbon atoms in the polyolefin backbone between the carbon-carbon double bonds.

Abstract: An acid-functional polymer is obtained by the hydrolysis or half-ester ring opening reaction of an anhydride-functional polymer obtained by at least partially hydrogenating an unsaturated polymer which was obtained by reacting under ene reaction conditions:(i) an unsaturated anhydride having the structure: ##STR1## wherein R.sub.1 and R.sub.2 are each independently hydrogen, alkyl of 1 to about 6 carbons, or alkoxy of 1 to about 6 carbons, or a halogen; and(ii) at least one polyolefin having at least two carbon-carbon double bonds in the polyolefin backbone and having an average of at least three carbon atoms in the polyolefin backbone between the carbon-carbon double bonds.

Abstract: Tris(pentafluorophenyl)borane complexes having the general formula (C.sub.6 F.sub.5).sub.3 B.(YXH).sub.q wherein X is oxygen, or sulfur; q is i to 3; Y is a hydrogen atom, R.sup.1 --, (R.sup.2).sub.3 Si--, or (R.sup.3).sub.2 C.dbd.N--; R.sup.1 is a hydrocarbyl group containing 1 to 500 carbon atoms, and may contain a divalent oxygen and further may be a fluorine-containing hydrocarbyl group; R.sup.2 is independently a linear or branched alkyl group containing 1 to 25 carbon atoms, or a phenyl group, further R.sup.2 may contain a SiO-- group; and R.sup.3 is independently a hydrocarbyl group containing 1 to 25 carbon atoms, R.sup.3 may be a hydrogen atom provided both R.sup.3 groups selected are not hydrogen atoms; and to complexes containing the borane complexes with an organometallic compound, either as a neutral compound or as an acidic salt that are useful as catalysts for polymerization and copolymerization of olefins and to polymeric products prepared using these catalysts.

Abstract: An olefin metathesis catalyst system and process for the metathesis polymerization of cyclic olefins, such as dicyclopentadiene, are disclosed. The catalyst system comprises the reaction product of:(a) an imido transition metal halide complex of formula: ##STR1## wherein Ar is C.sub.6-20 aryl, preferably phenyl; M is a transition metal selected from the second and third rows of Groups 5, 6, 7 and 8 of the Periodic Table (IUPAC 1989 convention) and including for example niobium, tantalum, molybdenum, tungsten, rhenium, ruthenium or osmium, preferably tungsten or molybdenum; R is independently halide, C.sub.1-20 alkyl, C.sub.1-12 alkoxy, C.sub.1-12 haloalkyl, C.sub.6-20 aryl, C.sub.6-20 aryloxy, cyano or combinations thereof; L is independently a complexing ligand selected from carbonyl, C.sub.1-12 alkoxy, C.sub.1-12 haloalkoxy, C.sub.1-12 alkyl ethers, including mono-, di- and higher ethers, C.sub.12 alkylnitriles, C.sub.5-20 pyridines, C.sub.

Abstract: The regiospecific (1,2-Me.sub.2 C.sub.5 H.sub.3).sub.2 ZrMe.sup.+ MeB(C.sub.6 F.sub.5).sub.3 - mediated ring-opening polymerization of methylenecyclobutane and its copolymerization with ethylene to polyolefins of microstructure --{CH.sub.2 CH.sub.2 CH.sub.2 C(CH.sub.2)]--.sub.n and {--[CH.sub.2 CHR]--.sub.x [CH.sub.2 CH.sub.2 CH.sub.2 C(CH.sub.2)]--.sub.y }.sub.n, respectively is disclosed.

Abstract: Bulk polymerization using specific metallocene catalysts for the preparation of cycloolefin polymersPolymers of polycyclic olefins, such as, for example, norbornene or tetracyclododecene, or copolymers of polycyclic olefins with cycloolefins and/or 1-olefins are obtained without ring opening, in high space-time yield, with a high cycloolefin incorporation rate and at industrially favorable polymerization temperatures, by bulk polymerization in which a catalyst is used which comprises an aluminoxane and a stereorigid chiral metallocene compound of an element from groups IVb to VIb, where the hydrocarbon radicals forming the sandwich structure are different.

Abstract: A method is provided for the direct synthesis of novel polymeric materials functionalized with desirable nitrogen-containing functional groups such as terminal azido, cyano, carbonylamino or thiocarbonylamino groups. Polymerization and functionalization occur in a substantially simultaneous manner. All necessary reactants for the functionalization are present when polymerization is initiated. The nitrogen-containing functional group is provided as a part of a molecule having a release moiety which is preferably resonance stabilized or of tertiary alkyl type and which acts to aid the nitrogen-containing species in functioning as a leaving group.

Abstract: A method for producing an acrylonitrile crosslinked copolymer, which comprises copolymerizing, as polymerizable monomers, acrylonitrile, an alkyl ester of acrylic acid or methacrylic acid, an aliphatic or alicyclic crosslinkable unsaturated monomer having at least two allyl groups, and an aromatic crosslinkable polyunsaturated monomer, in the presence of from 10 to 45% by weight, based on the total amount of the polymerizable monomers, of an inert organic solvent having a specific gravity of at least 1.0.

Abstract: A composition comprising a 1,2-dialkylidenecyclobutane such as 1,2-dimethylenecyclobutane, a polyacrylate monomer and an optional polyimide such as a bismaleimide can be thermally cured to a tough copolymer having a high glass transition temperature.

Abstract: The regiospecific (1,2-Me.sub.2 C.sub.5 H.sub.3).sub.2 ZrMe.sup.+ MeB(C.sub.6 F.sub.5).sub.3.sup.- mediated ring-opening polymerization of methylenecyclobutane and its copolymerization with ethylene to polyolefins of microstructure--{CH.sub.2 CH.sub.2 CH.sub.2 C(CH.sub.2)]--.sub.n and {--[CH.sub.2 CHR]--.sub.x [CH.sub.2 CH.sub.2 CH.sub.2 C(CH.sub.2)]--.sub.y }.sub.n' respectively, is disclosed.

Abstract: A catalyst and process for the polymerization of cyclic olefins, such as dicyclopentadiene, are disclosed. The catalyst comprises the reaction product of a transition metal halide and a 1,4-hydroquinone of the general formula: ##STR1## wherein R is independently selected from the group of hydrogen, C.sub.1-12 alkyl, C.sub.6-20 aryl, halide, and C.sub.1-6 haloalkyl. Optional co-catalysts include borohydrides, organo tin hydrides and organo aluminum compounds. Polymerization can be carried out in a reaction injection molding process to prepare a molded article.

Abstract: A catalyst and process for the metathesis polymerization of cyclic olefins, such as dicyclopentadiene, are disclosed. The catalyst comprises the reaction product of a transition metal halide preferably tungsten, molybdenum, or tantalum halides and a diaryl carbinol of the formula ##STR1## wherein G is independently C.sub.1-12 alkyl, C.sub.1-12 alkoxy, C.sub.1-12 alkylamino, C.sub.6-20 aryl, halide, or C.sub.1-6 haloalkyl; g is independently 0 to 4; R is independently hydrogen or G or the R's are combined as a single bond or as a bridging group X, where X is CH.sub.2, CH.sub.2 CH.sub.2, O, S, SO, SO.sub.2 or NR.sup.1, and R.sup.1 is H or C.sub.1-6 alkyl. Optional co-catalysts include borohydrides, organo tin hydrides and organo aluminum compounds. Polymerization can be carried out in a reaction injection molding process to prepare a molded article.

Abstract: Cyclic olefin metathesis polymerization catalyst comprising metal compounds wherein said metals consist essentially of a minor amount of a transition metal which Will initiate ring-opening metathesis polymerization of a cyclic olefin and a major amount of at least one second metal which will propagate the polymerization, wherein said catalyst is essentially devoid of pyrophoric metal compounds, e.g. metal alkyls, and preformed metal carbenes. A preferred transition metal is ruthenium. Said second metal can comprise aluminum, copper, hafnium, iron (III), iridium, manganese, molybdenum, nickel, niobium, rhenium, rhodium, tantalum, titanium, tungsten, yttrium, a Lanthanide, zinc or zirconium or a mixture thereof. Using such catalyst cyclic olefin, e.g. norbornene derivatives, can be polymerized, e.g. in an extruder, even in the presence of water.

Abstract: An improved process for the production of 1:1 molar adducts of 4-vinylcyclohexene and cyclopentadiene, primarily 5-(3-cyclohexen-1-yl)-2-norbornene, comprises contacting 4-vinylcyclohexene and dicyclopentadiene at elevated temperature in a suitable reactor, separating the resulting mixture of adducts into light product comprising predominately the 1:1 molar adduct and a heavy product comprising higher adducts and cyclopentadiene oligomers, and recycling the bottoms product to the reactor.

Abstract: A novel styrene copolymer comprising a styrene repeating unit (a) represented by the general formula: ##STR1## (wherein R.sup.1 is a hydrogen atom or a hydrocarbon group having not more than 20 carbon atoms; n is an integer of 1 to 3 and when n is 2 or 3, R.sup.1 s may be the same or different) and olefin repeating unit (b) represented by the general formula: ##STR2## (wherein R.sup.2 is a hydrogen atom or a saturated hydrocarbon group having not more than 20 carbon atoms) or diene repeating unit, which contains 0.1 to 99.9 wt. % of said olefin repeating unit (b) or diene repeating unit (c) wherein intrinsic viscosity measured in 1,2,4-trichlorobenzene at 135.degree. C. is 0.07 to 20 dl/g and the stereoregularity of the styrene repeating unit chain is a high degree of syndiotactic configuration. This styrene copolymer is excellent in heat resistance and chemical resistance, and further it can be injection molded at low temperature, and has good compatibility with other resine and the like.

Abstract: A composition comprising a 1,2-dialkylidenecyclobutane such as 1,2-dimethylenecyclobutane, a polyacrylate monomer and an optional polyimide such as a bismaleimide can be thermally cured to a tough copolymer having a high glass transition temperature.

Abstract: Polyphenylene is prepared by exposing a poly(1,2-disubstituted-cyclohexa-3,5-diene) precursor to ultraviolet light in the presence of an acid catalyst. The acid catalyst is activated by the ultraviolet radiation and forms polyphenylene by aromatizing the cyclohexene rings of the poly(1,2-disubstituted-cyclohexa-3,5-diene).

Abstract: Disclosed is a process for improving the unload power of a precursor elastic film comprising orienting the film to a draw ratio in the range of about 2:1 to about 20:1 followed by annealing. Further disclosed is an elastic film oriented to a draw ratio in the range of about 2:1 to about 20:1 and comprising a copolymer of ethylene polymerized with at least one comonomer selected from the group consisting of C.sub.3 to C.sub.20 alpha-olefins and C.sub.3 to C.sub.20 polyenes, wherein the copolymer has a density in the range of about 0.855 g/cm.sup.3 to about 0.9 g/cm.sup.3, a melt index in the range of about 0.5 to about 50, with a composition distribution index at least about 45 percent.

Abstract: Provided herein are a copolymer obtained by copolymerizing at least an ultraviolet-stable polymerizable monomer and a cycloalkyl group-containing polymerizable monomer, a process for producing said copolymer, and a coating composition containing said copolymer. The copolymers retains outstanding weather resistance over a long period of time owing to the multiplicated effect of an ultraviolet-stable monomer and a cycloalkyl group-containing polymerizable monomer, and the coating composition containing the copolymer forms a coating film having superior gloss, buildability, solvent resistance, and chemical resistance.

Abstract: A composition comprising a 1,2-dialkylidenecyclobutane such as 1,2-dimethylenecyclobutane, a triene such as myrcene and a polyimide such as a bismaleimide can be thermally cured to a tough copolymer having a high glass transition temperature.

Abstract: A composition comprising a 1,2-dialkylidenecyclobutane such as 1,2-dimethylenecyclobutane, a diallyl compound and a polyimide such as a bismaleimide can be thermally cured to a tough copolymer having a high glass transition temperature.

Abstract: Synthetic lubricant base stocks having improved properties are disclosed. The base stocks may be obtained by a two-step process, comprising the steps of (1) co-reacting vinylcyclohexene and long-chain linear olefin with a free-radical initiator; and (2) further reacting the mixture resulting from step (1) in the presence of an acidic montmorillonite clay.