Impact polymers

DETAILED DESCRIPTION OF THE INVENTION The monovinyl aromatic compounds which can be employed in producing the rubber modified polymers according to the invention include monovinyl aromatic compounds having the vinyl radical i.
e.
, the ethylenically unsaturated radical, attached directly to a carbon atom of the aromatic nucleus.
Styrene is the preferred monovinyl aromatic compound.
Examples of other compounds applicable herein are the alkyl and dialkyl derivatives of styrene such as the dimethylstyrenes, ethylstyrenes, isopropylstyrenes, butyl-styrenes, etc.
; the halogen derivatives of styrene, for example, chloro- and dichlorostyrene and the mono- and dibromostyrenes and alkylhalostyrenes as well as mixtures of these compounds with styrene or with each other.
Alphamethylstyrene may be substituted in a minor amount, for example 2 to 30% by weight, preferably from about 5 to 25% in the total composition for a portion of the monovinylaromatic monomer to improve properties of the interpolymers such as heat distortion temperature.
Broadly, the polymerized vinyl aromatic component comprises from about 75 to about 98% by weight of the final composition; in a more preferred aspect it comprises from about 88 to 96%.
The unvulcanized synthetic rubber materials used in preparing the interpolymer compositions according to the invention are polybutadiene (BR) and certain styrene-butadiene two-block copolymers.
The butadiene homopolymers employed to prepare the interpolymers preferably have a cis-1,4 content from about 30 to 99% by weight and more preferably from about 35 to about 96%.
Polybutadienes having a 1,2 content less than about 15% are preferred; those having a 1,2 content less than about 12% are particularly preferred.
The cis-1,4 content of the polybutadiene are conveniently determined by infrared technique on solution of the elastomer in carbon disulfide, e.
g.
, according to the procedure of Silas et al.
, Analytical Chemistry, Volume 31, page 529 (1959).
Conventional linear rubbery polybutadiene homopolymer may be employed to prepare the compositions, however, nonlinear polymers prepared, for example, according to U