A polymer blend consisting of (a) 60-96 percent by weight of a high molecular weight elastomeric polymer, (b) 4-35 percent by weight of a low molecular weight aromatic hydrocarbon polymer, and optionally (c) 0-13 percent by weight of an extender oil, wherein the amounts of the components (a), (b) and (c) are based on the total weight of the polymer blend.

A polymer blend consisting of (a) 60-96 percent by weight of a high molecular weight elastomeric polymer, (b) 4-35 percent by weight of a low molecular weight aromatic hydrocarbon polymer, and optionally (c) 0-13 percent by weight of an extender oil, wherein the amounts of the components (a), (b) and (c) are based on the total weight of the polymer blend.

A method of production of modified conjugated diene rubber includes causing an aromatic compound having three or more carbon atoms directly bonded to an aromatic ring in one molecule to react with an alkali metal atom so as to obtain an alkali metal-reacted aromatic compound; polymerizing a monomer at least containing a conjugated diene compound by using the alkali metal-reacted aromatic compound so as to obtain a conjugated diene rubber having an active end; causing the active end of the conjugated diene rubber having an active end to react with an activity control agent so as to obtain a conjugated diene rubber reacted with an activity control agent; and causing the active end of the conjugated diene rubber reacted with an activity control agent to react with a modifier having an alkoxy group and a halogen atom-containing group so as to obtain a modified conjugated diene rubber.

Methods are described for quantifying an amount of natural rubber in a plant from a sample of the plant by obtaining a NMR spectrum and analyzing the signal peaks for the natural rubber in the plant sample and a standard component tested in combination with the plant sample. The NMR testing is conducted on a liquid state sample of a solution containing dissolved plant sample and standard component. A pre-determined and known amount of standard component is present in the liquid state sample and provides a reference for calculating an estimated amount of natural rubber in the plant sample. The estimated amount of natural rubber in the sample can be used to quantify the amount of extractable rubber in the sampled plant.

Methods are described for quantifying an amount of natural rubber in a plant from a sample of the plant by obtaining a NMR spectrum and analyzing the signal peaks for the natural rubber in the plant sample and a standard component tested in combination with the plant sample. The NMR testing is conducted on a liquid state sample of a solution containing dissolved plant sample and standard component. A pre-determined and known amount of standard component is present in the liquid state sample and provides a reference for calculating an estimated amount of natural rubber in the plant sample. The estimated amount of natural rubber in the sample can be used to quantify the amount of extractable rubber in the sampled plant.

A copolymer has low levels of isoprenoid (short chain branching) structures. A process for producing the copolymer having low isoprenoid content involves contacting at least one isoolefin monomer with at least one multiolefin and/or -pinene monomer in the presence of at least one Lewis acid and at least one initiator in a diluent. The diluent may contain a hydrofluorinated olefin (HFO) comprising at least three carbon atoms and at least three fluorine atoms. Hydrofluorinated olefins used in the present invention are better diluents for butyl slurry cationic polymerization than saturated hydrofluorocarbons. Blends of saturated hydrofluorocarbons (e.g. 1,1,1,2-tetrafluoroethane) with an inert solvent (e.g. methyl chloride) may also be used as diluents.

One aspect of the present invention provides an end-modified conjugated diene polymer represented by Formula 1 below: ##STR00001## wherein p is a conjugated diene polymer chain; R.sup.1 to R.sup.7 are each independently C.sub.1-C.sub.20 saturated or unsaturated hydrocarbon chains; X is carbon (C), silicon (Si), or nitrogen (N); a is 1 or 2; and n is an integer of 1 to 200, and a method for preparing the same.

A process for producing a copolymer involves contacting at least one isoolefin monomer with at least one multiolefin and/or -pinene monomer in the presence of at least one Lewis acid and at least one initiator in a diluent. The diluent contains a hydrofluorinated olefin (HFO) comprising a tetrafluorinated propene. Copolymers produced by a process of the present invention have a cyclic oligomer content lower than comparable polymers produced in a butyl rubber slurry process using 1,1,1,2-tetrafluoroethane and/or methyl chloride as a diluent as well as a more favorable ratio of C21/C13. Hydrofluorinated olefins used in the present invention are better diluents for butyl slurry cationic polymerization than saturated hydro fluorocarbons.

An object of the present invention is to provide a polymer composition having properties resembling those of natural rubber, e.g. good durability (fracture resistance, wear resistance, and crack growth resistance), and a method for manufacturing the polymer composition. Specifically, the present invention provides a method for manufacturing a polymer composition including a mixture of polyisoprene and polystyrene/polybutadiene, comprising: polymerizing styrene monomer or butadiene monomer in the presence of a catalyst to synthesize polystyrene or polybutadiene; adding isoprene monomer to the polystyrene or polybutadiene thus synthesized, to synthesize polyisoprene and thus generate said mixture, wherein content of the styrene monomer or the butadiene monomer is set to be 10 mol % or less with respect to the total quantity of the styrene monomer/the butadiene monomer and the isoprene monomer.

An object of the present invention is to provide a polymer composition having properties resembling those of natural rubber, e.g. good durability (fracture resistance, wear resistance, and crack growth resistance), and a method for manufacturing the polymer composition. Specifically, the present invention provides a method for manufacturing a polymer composition including a mixture of polyisoprene and polystyrene/polybutadiene, comprising: polymerizing styrene monomer or butadiene monomer in the presence of a catalyst to synthesize polystyrene or polybutadiene; adding isoprene monomer to the polystyrene or polybutadiene thus synthesized, to synthesize polyisoprene and thus generate said mixture, wherein content of the styrene monomer or the butadiene monomer is set to be 10 mol % or less with respect to the total quantity of the styrene monomer/the butadiene monomer and the isoprene monomer.