Polystyrene blends and a method of making same

Abstract

Disclosed are blends of polystyrene and at least one of syndiotactic polypropylene, ethylene propylene copolymers, and styrene-butadiene-styrene triblock copolymers. These blends are prepared using solution polymerization and have unique morphologies and desirable physical properties. The blends can also be prepared with graft-promoting or crosslinking agents and rubbers to prepare modified high impact polystyrene.

1 - 11 . (canceled)  
   
   
       12 . A polystyrene blend wherein the blend is a blend of polystyrene, rubber, and a polymer selected from the group consisting of syndiotactic polypropylene, ethylene propylene copolymer, styrene-butadiene-styrene copolymers, and mixtures thereof, and the blend is prepared by solution polymerization.  
   
   
       13 . The polystyrene blend of  claim 12  wherein the blend is composed primarily of polystyrene and rubber and syndiotactic polypropylene, and the weight ratio of polystyrene and rubber to syndiotactic polypropylene, HIP:sPP, is from about 19:1 to about 4:1.  
   
   
       14 . The polystyrene blend of  claim 12  wherein the blend is composed primarily of polystyrene and rubber and ethylene polypropylene copolymer, the weight ratio of polystyrene and rubber to ethylene polypropylene copolymer, HIP:EP, is from about 19:1 to about 4:1.  
   
   
       15 . The polystyrene blend of  claim 12  wherein the weight ratio of polystyrene to rubber, PS:RUBBER, is from about 99:1 to about 7:1.  
   
   
       16 . A process for preparing a polystyrene blend comprising admixing styrene and a polymer selected from the group consisting of syndiotactic polypropylene, ethylene propylene copolymer, and mixtures thereof to form a solution, and then polymerizing the styrene monomer.  
   
   
       17 . The process of  claim 16  wherein the process additionally comprises using a solvent to increase the solubility of the polymer in the styrene.  
   
   
       18 . The process of  claim 17  wherein the solvent is selected from the group consisting of ethylbenzene, toluene, xylenes, and cyclohexane and mixtures thereof.  
   
   
       19 . The process of  claim 16  additionally comprising using free radical catalyst.  
   
   
       20 . The process of  claim 19  wherein the catalyst is a peroxide catalysts selected from the group consisting of 1,1-di-(t-butylperoxy)cyclohexane; 1,1-di-(t-amylperoxy)cyclohexane; 1,1-di-(t-butylperoxy)-3,3,5-trimethyl-cyclohexane; OO-t-amyl-O-(2-ethylbexyl monoperoxy-carbonate; OO-t-butyl O-isopropyl monoperoxy-carbonate; OO-t-butyl-O-(2-ethylhexyl)monoperoxy-carbonate; N-butyl-4,4-di(t-butylperoxy)valerate; ethyl 3,3-Di-(t-butylperoxy)butyrate) and mixtures thereof.