Thermoset compositions, tougheners, and composites thereof

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 . A single phase uncured thermoset composition, comprising: 
 a) at least one uncured thermoset resin; and    b) at least one liquid rubber comprising polymer chains having a glass transition temperature less than −40° C. and a weight average molecular weight of at least about 1069 g/mol, said polymer chains having at least one non-functional aromatic terminal end-group, and said at least one liquid rubber being immiscible in said thermoset resin in the cured state of said thermoset resin.    
     
     
         2 . A thermoset composition according to  claim 1 , wherein said polymer chains comprise at least 20 weight percent of polymerized units derived from one or more C 1  to C 20  alkyl acrylate monomers.  
     
     
         3 . A thermoset composition according to  claim 1 , wherein said non-functional aromatic terminal end-group is provided by at least one of the following: residues of at least one aromatic-containing free radical initiator molecule on said polymer chains; chain transfer of said polymer chains to an aromatic-containing molecule; and post-reaction of said polymer chains with an aromatic-containing molecule.  
     
     
         4  (Cancelled).  
     
     
         5 . A thermoset composition according to  claim 1 , wherein said liquid rubber further comprises polymer chains having a glass transition temperature of at least 25° C.  
     
     
         6 . A thermoset composition according to  claim 1 , wherein the thermoset resin comprises at least one of the following: an alkyd resin, an allyl diglycol carbonate resin, a diallyl isophthalate resin, a diallyl phthalate resin, a melamine resin, a melamine/phenolic resin, a phenolic resin, a vinyl ester resin; an epoxy resin; an unsaturated polyester resin; a cyanoacrylate resin; a melamine-formaldehyde resin; a polyurethane resin; a polyimide resin; and a polyphenol resin.  
     
     
         7 . and  8 . (Cancelled).  
     
     
         9 . A polymeric composition for cured thermoset resins, said polymeric composition comprising: 
 polymer chains having a glass transition temperature less than −40° C. and a weight average molecular weight of at least about 1069 g/mol, said polymer chains comprising at least one non-functional aromatic terminal end-group;    wherein said polymeric composition is miscible in the uncured state of said thermoset resins and immiscible in the cured state of said thermoset resins,    wherein said polymer chains comprise at least 20 weight percent of polymerized units derived from one or more C 1  to C 20  alkyl acrylate monomers, wherein said polymer chains are characterized as having a weight average molecular weight of at least 1069 g/mol, and    wherein said polymer chains further comprise from 0.1 to 15 weight percent of polymerized units capable of crosslinking as the thermoset resins cure.    
     
     
         10 . A composite material, comprising: 
 a) at least one cured thermoset resin matrix; and    b) rubbery domains dispersed in said matrix, said rubbery domains comprising: 
 polymer chains having a glass transition temperature less than −40° C. and a weight average molecular weight of at least about 1069 g/mol, and having at least one non-functional aromatic terminal end-group, and said polymer chains being miscible with said thermoset resin in the uncured state of said thermoset resin matrix.