Modifying the structural properties of epoxy resins
To what extent do modifiers affect the properties of epoxy resin? Austrian researchers have investigated the thermomechanical, mechanical and fracture mechanical properties of modified epoxy resins with two different modifiers.
Carboxyl-terminated butadiene-acrylonitrile (CTBN) was used as toughening agent and hexanediole diglycidyl ether (HDDGE) as reactive diluent. Both modifiers were admixed in contents from 0 up to 100 parts per hundred resin (phr) and exhibited flexibilising and toughening qualities.
Higher toughness but reduced glass transition temperature
The glass transition temperature was strongly depressed by the admixed reactive diluent, whereas the tensile modulus exhibited greater dependency on the toughening agent contents. The tensile strength and strain at break values were higher for the formulations with diluent compared to resins with toughening agent. Up to a content of 45 phr both modified systems showed comparable fracture toughness values. Only the toughened systems comprised increasing values for modifier amounts higher than 45 phr. For the formulation with both modifiers (toughening agent and diluent) a significantly higher toughness but a reduced glass transition temperature was obtained.
The study is published in: Journal of Applied Polymer Science, Volume 134, Issue 44, November 20, 2017
Event tip
Interested in epoxy coatings? The European Coatings Seminar Epoxy Coatings on October 10 2017 in Amsterdam gives an overview on what modern epoxy resins can do, optimisation of properties of epoxy coatings and what standards apply for epoxies in the regulated heavy-duty corrosion protection.
