Synonyms: 2-Butenedioic acid (E)-, polymer with 1,3-isobenzofurandione and 2,2'-oxybis(ethanol);2-butenedioic acid (e)-, polymer with1,3-isobenzofurandione and 2,2'-oxybis[ethanol];2-Butenedioic acid(E)-,polymer with 1,3-isobenzofurandione and 2,2'-oxybis(ethanol);Gelcoat resin 21;Unsaturated polyester resin 21