Method to produce a composite material
Method of producing an elastic composite material comprising the step of impregnating a fiber fabric with a liquid epoxy system comprising a non-aromatic epoxy resin and a hardener, and curing the impregnated fabric, whereby the epoxy system exhibits a tensile modulus lower than 15 MPa after cure.
1. Method of producing an elastic composite material comprising the step of
a) impregnating a fiber fabric with a liquid epoxy system formed by mixing a non-aromatic epoxy diglycidyl ether resin selected from 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether and 1,4-cyclohexanediol diglycidyl ether and one cycloaliphatic polyamine compound hardener having a viscosity of 300-400 mPa·s measured at 25° C. at a resin/hardener ratio in parts by weight of 100/67 to 100/96;
b) and curing the impregnated fabric, characterized in that the epoxy system exhibits a viscosity less than 170 mPa·s measured at 25° C. and a tensile modulus lower than 15 MPa when cured and an onset of the glass transition temperature Tg at a temperature lower than 0° C. and the elastic composite material comprises 20 to 80 vol % of fibers, based on the total volume of the composite and exhibits a flexural modulus lower than 15 GPa.
2. Method according to claim 1 whereby the epoxy system exhibits a yellowness index lower than 20 after an exposure of 200 hrs in a weather-ometer WOM Xenon Ci 5000, according to SAE J 1960 test conditions.
3. Method according to claim 1 whereby the fiber fabric comprises carbon, glass, aramide or natural fibers.
4. Composite material obtained by a method according to claim 1 .
5. Composite material according to claim 4 comprising from 30% to 70% volume fraction of fibers based on the total volume of the composite material.
6. Part of a car or racing car comprising a composite material according to claim 4 .
7. Concrete comprising a composite material according to claim 4 .