Polymer modified cyanate mixture and epoxy resins thereof

A composition which comprises a mixture of

• (A) from about 0.5 to about 95 percent by weight (%bw) of total composition of a product resulting from copolymerizing
• (1) from about 0.1 to about 50, %bw of the combined weight of components (A-1) and (A-2) of at least one alkenylphenyl cyanate represented by the formula ##STR11## wherein Z is a ##STR12## group;
• each R, R.sup.1 and R.sup.2 is independently hydrogen or a hydrocarbyl group having from 1 to about 3 carbon atoms;
• each X is independently hydrogen, a hydrocarbyl or hydrocarbyloxy group having from 1 to about 4 carbon atoms, chlorine, bromine or a phenyl group;
• and x has a value of 4;
• and
• (2) from 50 to about 99.9 %bw of the combined weight of components (A-1) and (A-2) of at least one ethylenically unsaturated monomer;
• and
• (B) from about 5 to about 99.5 %bw of total composition of a mixed cyanate of a polyphenol prepared by the reaction of at least 0.01 but not more than 0.95, mole of a cyanogen halide or mixture of cyanogen halides per mole of aromatic hydroxyl groups in the presence of a suitable base in a quantity of from about 0.01 to about 1.0, mole per mole of aromatic hydroxyl groups with an aromatic polyphenol represented by the formulas ##STR13## wherein each A is independently a divalent hydrocarbon group having from 1 to about 12, carbon atoms, ##STR14## and the like;
• each A' is a divalent hydrocarbyl group having from 1 to about 3, carbon atoms or a ##STR15## group;
• each R' is independently hydrogen or a hydrocarbyl group having from 1 to about 6 carbon atoms or a halogen;
• n has a value of zero or 1;
• n' has a value from about 0.001 to about 6;
• n" has a value from about 1 to about 100;
• and p has a value of from zero to about 10.