Provided are a tread rubber composition that can achieve a balanced improvement in fuel economy, wet-grip performance, and abrasion resistance, and a pneumatic tire including the composition. The tread rubber composition includes: a rubber component; silica; and a silane-coupling agent containing a mercapto group, the rubber component including per 100% by mass thereof 5% by mass or more of a conjugated diene polymer (A), the polymer (A) including a monomer unit derived from a conjugated diene, a monomer unit derived from a compound of formula (1), and a monomer unit derived from a compound of formula (2), at least one end of the copolymer (A) being modified by the following compound (G) or an alkoxysilane compound, the composition including 5-150 parts by mass of the silica per 100 parts by mass of the rubber component, Compound (G): at least one compound selected from the group consisting of compounds containing an optionally-substituted amino group and a carbonyl group and compounds containing an optionally-substituted amino group and a thiocarbonyl group,
V.sup.1-S.sup.1  (1)
V.sup.2-A.sup.2  (2)
wherein V.sup.1 and V.sup.2 each represent a hydrocarbyl group containing a polymerizable carbon-carbon double bond; S.sup.1 represents a substituted silyl group, and A.sup.2 represents a substituted amino group or a nitrogen-containing heterocyclic group.

A rubber composition for tires of the present technology contains a diene rubber, silica, a silane coupling agent, a fatty acid metal salt, and a predetermined alkyltrialkoxysilane; the diene rubber containing 60 mass % or greater of a modified conjugated diene rubber and 30 mass % or greater of a particular conjugated diene rubber which corresponds to a part or all of the modified conjugated diene rubber; an average glass transition temperature of the diene rubber being from −45 to −20° C.; the particular conjugated diene rubber being a conjugated diene rubber produced by a particular production method and having predetermined ranges of aromatic vinyl unit content, vinyl bond content, and weight average molecular weight.

A rubber composition for tires of the present technology contains a diene rubber, silica, a silane coupling agent, a fatty acid metal salt, and a predetermined alkyltrialkoxysilane; the diene rubber containing 60 mass % or greater of a modified conjugated diene rubber and 30 mass % or greater of a particular conjugated diene rubber which corresponds to a part or all of the modified conjugated diene rubber; an average glass transition temperature of the diene rubber being from −45 to −20° C.; the particular conjugated diene rubber being a conjugated diene rubber produced by a particular production method and having predetermined ranges of aromatic vinyl unit content, vinyl bond content, and weight average molecular weight.

Disclosed herein are a process for preparing a modified high-cis polybutadiene polymer, a modified high-cis polybutadiene polymer, and tire components made using the modified high-cis polybutadiene polymer. The processes make use of a functionalizing compound of formula (I) to prepare the modified high-cis polybutadiene from a quantity of 1,3-butadiene monomer using a specified catalyst system.

Disclosed are polymeric compositions comprising polyhydroxyalkanoates. These compositions can comprise a blend comprising a polyhydroxyalkanoate (PHA) polymer, and a rubber polymer. The blend can comprise a biphasic mixture comprising a first phase comprising the PHA polymer, and a second phase comprising the rubber polymer dispersed with the first phase. The rubber polymer can be crosslinked, for example, through reaction with a free radical initiator. By incorporating the dynamically crosslinked rubber polymer, the polymer composition can exhibit one or more improved characteristics relative to PHA alone, including improved thermal stability, improved melt strength, improved flexibility, improved toughness, or a combination thereof. Also provided are articles formed at least in part from these polymeric compositions, as well as methods of making these polymeric compositions.

A modified liquid diene rubber (A) has a functional group (a) derived from an acid anhydride, and satisfies all the requirements (I) to (III) below: (I) The functional group equivalent weight of the functional groups (a) is in the range of 400 to 3,500 g/eq. (II) The polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is in the range of 5,000 to 20,000. (III) The melt viscosity at 38° C. is not less than 3 Pa.Math.s and X (K) is not less than 6100 K wherein X is the slope of a linear line passing through two points in a graph in which the two points are values of melt viscosity η (Pa.Math.s) at 38° C. and 60° C. measured with a Brookfield viscometer which are plotted as Ln[η/(Pa.Math.s)] on ordinate versus 1/T (K.sup.−1) on abscissa (with the proviso that T is temperature (K)).

A modified liquid diene rubber (A) has a functional group (a) derived from an acid anhydride, and satisfies all the requirements (I) to (III) below: (I) The functional group equivalent weight of the functional groups (a) is in the range of 400 to 3,500 g/eq. (II) The polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is in the range of 5,000 to 20,000. (III) The melt viscosity at 38° C. is not less than 3 Pa.Math.s and X (K) is not less than 6100 K wherein X is the slope of a linear line passing through two points in a graph in which the two points are values of melt viscosity η (Pa.Math.s) at 38° C. and 60° C. measured with a Brookfield viscometer which are plotted as Ln[η/(Pa.Math.s)] on ordinate versus 1/T (K.sup.−1) on abscissa (with the proviso that T is temperature (K)).

1) Hydrocarbon-based copolymer comprising two end groups preceded by an ester function and chosen from a 2-oxo-1,3-dioxolan-4-yl (or cyclocarbonate), a dithiocyclocarbonate, an exo-vinylene cyclocarbonate and a 2-oxo-1,3-dioxolen-4-yl, the main chain of which comprises units (I) and (II) ##STR00001## in which R.sup.0 is notably a methyl radical; and the number-average molecular mass Mn of which is between 400 and 100 000 g/mol. 2) Process for preparing said copolymer, comprising: (i) a step of heating a statistical bipolymer A chosen from a poly(butadiene-isoprene), a poly(butadiene-myrcene) and a poly(butadiene-farnesene); and then (ii) a step of heating the product formed, in the presence of a chain-transfer agent. 3) Use as adhesive, as a mixture with an amine compound comprising at least two amine groups.

1) Hydrocarbon-based copolymer comprising two end groups preceded by an ether function and chosen from a 2-oxo-1,3-dioxolan-4-yl (or cyclocarbonate), a dithiocyclocarbonate, and a 2-oxo-1,3-dioxolen-4-yl, the main chain of which comprises units (I) and (II) ##STR00001## in which R.sup.0 is notably a methyl radical; and the number-average molecular mass Mn of which is between 400 and 100 000 g/mol. 2) Process for preparing said copolymer, comprising: (i) a step of heating a statistical bipolymer A chosen from a poly(butadiene-isoprene), a poly(butadiene-myrcene) and a poly(butadiene-farnesene); and then (ii) a step of heating the product formed, in the presence of a chain-transfer agent. 3) Use as adhesive, as a mixture with an amine compound comprising at least two amine groups.

Disclosed are compositions comprising a liquid carrier, a polysulfide rubber curing agent, a metal cation, and an ionic liquid. Also disclosed are methods for curing a surface of an uncured polysulfide rubber. These methods involve applying the disclosed compositions to the surface of the uncured polysulfide rubber.