Relationship between fracture toughness and temperature in epoxy coatings

The fracture toughness K-IC of nine kinds of epoxy coating specimens was tested in the temperature range from 20 to -40 degrees C, and the influence of temperature on K-IC was discussed. The results showed that K-IC decreases sharply in unmodified systems but increases for some specimens with 20-50 portions of rubber impact modifier. The elastic modulus test indicated that K-IC is closely related with the modulus. Scanning Electron Microscopy images showed that the introduction of impact modifier to epoxy can enlarge the ductile deformation of the fracture surface. As a result, the addition of rubber modifier is a suitable path to improve the anti-cracking performance of epoxy coatings at low temperature due to an increase of fracture toughness and reduction of elastic modulus, which thus can reduce the thermal stress in the process of cooling.