A method for recovering an unreacted α,β-ethylenically unsaturated nitrile monomer contained in a latex of a nitrile rubber obtained by emulsion polymerizing a monomer mixture comprising an α,β-ethylenically unsaturated nitrile monomer and a carboxyl group-containing monomer is provided. The method includes the steps of: adjusting a pH of the latex of the carboxyl group-containing nitrile rubber to 6.5 or more; decompressing the latex of the carboxyl group-containing nitrile rubber having the pH adjusted to 6.5 or more under a heating condition; and recovering a component evaporated by the decompression under the heating condition.

A method for recovering an unreacted α,β-ethylenically unsaturated nitrile monomer contained in a latex of a nitrile rubber obtained by emulsion polymerizing a monomer mixture comprising an α,β-ethylenically unsaturated nitrile monomer and a carboxyl group-containing monomer is provided. The method includes the steps of: adjusting a pH of the latex of the carboxyl group-containing nitrile rubber to 6.5 or more; decompressing the latex of the carboxyl group-containing nitrile rubber having the pH adjusted to 6.5 or more under a heating condition; and recovering a component evaporated by the decompression under the heating condition.

The invention relates to a vinyl aromatic/diene-block copolymer A, obtained by an anionic polymerization of a monomer composition, comprising: Al: 60-95 wt.-% of at least one vinyl aromatic monomer, and A2:5-40 wt.-% of at least one diene monomer, wherein the vinyl aromatic/diene-block copolymer A in total comprises less than 10 parts per million (ppm) of acetaldehyde, methacrolein and styrene based on the total amount of vinyl aromatic/diene-block copolymer A; the vinyl aromatic/diene-block copolymer A has improved orgnoleptic properties and is in particular suitable for producing food packaging materials.

The invention relates to a vinyl aromatic/diene-block copolymer A, obtained by an anionic polymerization of a monomer composition, comprising: Al: 60-95 wt.-% of at least one vinyl aromatic monomer, and A2:5-40 wt.-% of at least one diene monomer, wherein the vinyl aromatic/diene-block copolymer A in total comprises less than 10 parts per million (ppm) of acetaldehyde, methacrolein and styrene based on the total amount of vinyl aromatic/diene-block copolymer A; the vinyl aromatic/diene-block copolymer A has improved orgnoleptic properties and is in particular suitable for producing food packaging materials.

The invention relates to a vinyl aromatic/diene-block copolymer A, obtained by an anionic polymerization of a monomer composition, comprising: Al: 60-95 wt.-% of at least one vinyl aromatic monomer, and A2:5-40 wt.-% of at least one diene monomer, wherein the vinyl aromatic/diene-block copolymer A in total comprises less than 10 parts per million (ppm) of acetaldehyde, methacrolein and styrene based on the total amount of vinyl aromatic/diene-block copolymer A; the vinyl aromatic/diene-block copolymer A has improved orgnoleptic properties and is in particular suitable for producing food packaging materials.

The present invention discloses methods for removing volatile components from an ethylene polymer effluent stream from a polymerization reactor, and related polyethylene recovery and volatile removal systems. In these methods and systems, the polymer solids temperature is increased significantly prior to introduction of the polymer solids into a purge column for the final stripping of volatile components from the polymer solids.

The present invention discloses methods for removing volatile components from an ethylene polymer effluent stream from a polymerization reactor, and related polyethylene recovery and volatile removal systems. In these methods and systems, the polymer solids temperature is increased significantly prior to introduction of the polymer solids into a purge column for the final stripping of volatile components from the polymer solids.

An ethylene-vinyl alcohol copolymer may have an ethylene unit content of 1 mol % or more and less than 15 mol %, a saponification degree of 85 mol % or more and less than 99.9 mol %, and a viscosity-average degree of polymerization of 200 or more and less than 3000. The copolymer may contain a molecule containing a structure (I)

##STR00001##

Y being H or —CH.sub.3, at an end; and a molecule containing a structure (II)

##STR00002##

Z being H or —CH.sub.3, at an end, a total content of the structure (I) and the structure (II) in all monomer units is 0.001 mol % or more and less than 0.1 mol %, and a molar ratio R [I/(I+II)] of the structure (I) to the total of the structure (I) and the structure (II) satisfies formula (1):

[00001]$\begin{array}{cc}R<0.92-\mathrm{Et}/100,& \left(1\right)\end{array}$

Et being ethylene unit content (mol %).

An ethylene-vinyl alcohol copolymer may have an ethylene unit content of 1 mol % or more and less than 15 mol %, a saponification degree of 85 mol % or more and less than 99.9 mol %, and a viscosity-average degree of polymerization of 200 or more and less than 3000. The copolymer may contain a molecule containing a structure (I)

##STR00001##

Y being H or —CH.sub.3, at an end; and a molecule containing a structure (II)

##STR00002##

Z being H or —CH.sub.3, at an end, a total content of the structure (I) and the structure (II) in all monomer units is 0.001 mol % or more and less than 0.1 mol %, and a molar ratio R [I/(I+II)] of the structure (I) to the total of the structure (I) and the structure (II) satisfies formula (1):

[00001]$\begin{array}{cc}R<0.92-\mathrm{Et}/100,& \left(1\right)\end{array}$

Et being ethylene unit content (mol %).

A method for separating polybutene, the method including: (1) introducing a polybutene solution into a distillation column, the solution including polybutene, a halogenated hydrocarbon solvent, and a non-polar hydrocarbon solvent and having a viscosity of 1 cp to 50 cp measured at 25° C. using a rotational viscometer; (2) collecting an upper stream including the halogenated hydrocarbon solvent and a portion of the non-polar hydrocarbon solvent from an upper portion of the distillation column, and collecting a lower stream including the polybutene and a remaining portion of the non-polar hydrocarbon solvent from a lower portion of the distillation column, where the lower stream has a viscosity of 10 cp to 150 cp; and (3) separating the remaining portion of the non-polar hydrocarbon solvent and the polybutene from the lower stream.