Modified asphalt using epoxide-containing polymers

A polymer-modified asphalt composition comprising:

• (a) about 80 to about 99.4 weight% of an asphalt;
• (b) about 0.5 to about 20 weight% of an E/X/Y/Z epoxy-functionalized ethylene copolymer, wherein E is the copolymerized repeat unit -(CH2CH2)- derived from ethylene;
• X is the copolymerized repeat unit -(CH2CR1R2)-, wherein R1 is a hydrogen atom, a methyl group, or an ethyl group, and R2 is a carboalkoxy, acyloxy, or alkoxy group comprising 1 to 10 carbon atoms;
• Y is the copolymerized repeat unit -(CH2CR3R4)-, wherein R3 is hydrogen or methyl and R4 is carboglycidoxy or glycidoxy;
• and Z is a copolymerized repeat unit derived from one or more comonomers selected from the group consisting of carbon monoxide, sulfur dioxide, and acrylonitrile;
• wherein the E/X/Y/Z epoxy-functionalized ethylene copolymer comprises 0 to 40 wt% of X, 1 to 25 wt% of Y, and 0 to 10 wt% of Z;
• wherein the weight percentages of the copolymerized repeat units E, X, Y and Z are complementary and based on the total weight of the E/X/Y/Z epoxy-functionalized ethylene copolymer;
• and wherein the E/X/Y/Z epoxy-functionalized ethylene copolymer has a melt flow index of from 50 to 1000 g/10 min, measured according to ASTM D 1238-65T, Condition E, at 190° C. and under a load of 2160 g;
• and, optionally,
• (c) about 0.025 to about 1 weight% of a co-reactant;
• wherein the weight percentages of the asphalt, the E/X/Y/Z epoxy-functionalized ethylene copolymer, and the co-reactant are complementary and based on the total weight of the asphalt, the E/X/Y/Z epoxy-functionalized ethylene copolymer, and the co-reactant.