Epoxy resin in the application process often encounter the following situation:

mica cable tape pouring, potting, molding and other parts after curing or storage will produce cracks during the resulting waste. EP parts in the low temperature or hot and cold alternating when there will be cracks. The larger the part, the more the insert, the more prone to cracks. It is generally believed that this is due to the fact that the curing stress and the temperature stress are greater than the strength of the material. So as long as the strength of EP can be improved to avoid cracking. However, high-intensity EP is often only low impact toughness. Structural elements made of high strength EP (such as structural adhesives, advanced composites, etc.) are often brittle in use and are less stressful than acetate cloth tapes. Fracture surface was brittle fracture morphology. Known as low stress brittle fracture. EP cured products are highly crosslinked polymers with high brittleness.
    For the toughening of epoxy resin, due to the rubber toughening epoxy resin system in the fracture process, the main structure and the structure of the microstructure of rubber, but also the two-phase interface and particle volume fraction has a certain relationship. The toughening rate is mainly determined by the toughness of the microparticles, the average network length of the matrix, and the interface bonding force and the chemical structure of the network chain itself.