Processes for preparing thermoset compositions and tougheners

Abstract

Liquid rubbers that are ordinarily immiscible in liquid thermoset resins can be made miscible by the addition of at least one non-functional aromatic end-group to the polymer chains of such liquid rubber compositions. Processes for preparing such new liquid rubber compositions and miscible rubber/resin blends are also provided. In addition, these new liquid rubber compositions can be controlled to phase separate into rubbery microdomains upon curing of thermoset resins, including unsaturated polyester thermoset resins. The resulting new composite materials are found to improve the fracture toughness of cured thermoset resins while maintaining dimensional and heat resistance.

1 - 8 . (canceled)  
     
     
         9 . A process for preparing single phase uncured thermoset composition, the process comprising the steps of mixing: 
 a) at least one uncured thermoset resin; and    b) at least one liquid rubber, said liquid rubber comprising polymer chains having at least one non-functional aromatic terminal end-group, said polymer chains having a weight average molecular weight of at least 1069 g/mol, and said polymer chains characterized as having a glass transition temperature less than −40° C.    
     
     
         10 . A process according to  claim 9 , wherein said at least one uncured thermoset resin comprises at least one of the following: an epoxy-based resin, a vinyl ester-based resin, and an unsaturated polyester-based resin.