Silicone modification of thermally and UV curing epoxy resins
Epoxy resins for challenging applications such as protecting metallic components in electronics are highly crosslinked which leads to high thermal limits and good chemical resistance. Disadvantageous is the brittleness, leading to cracks due to thermal cycling or other stresses originating from the usage. This may result in corrosion of neighboured metallic parts and by that failure of the assembly to be protected.
In this work cycloaliphatic epoxy resins are being mixed with elastomeric silicon in order to enhance toughness and lower internal stresses. Two different ways of modification are being investigated: "dispersion" and "mixing" modification. The first one consists of a system with disperse silicon particles in liquid epoxy resin; the second is a homogenous mixture of epoxy and silicon molecules that either shows phase separation during curing or remains one-phase, depending on the curing conditions. The modified resins have lower stiffness and hardness and are tougher than the neat resin. The dielectrical properties can be improved in all cases. The "dispersion" resins show a high glass transition temperature of the epoxy even with high silicon amounts. For all two-phase-systems the tendency towards building-up of internal stresses can be reduced. The UV curing is more complex than the thermal curing due to the absorption in the depth. The photoinitator concentration must be optimized for every different UV intensity.
The success shown for electronics applications can by all means be applied to other domains.Lesen Sie die deutsche Zusammenfassung auf Kunststoffe.de
epoxy resin, toughness, elastomer-modification, silicon, UV curing
Institute / chair: Technische Fakultät der Universität Erlangen-Nürnberg
Technical consultant for expert services: Prof. Dr.-Ing. Dr. h.c. Gottfried W. Ehrenstein (Betreuer), Prof. Dr.-Ing. Manfred Neitzel
Publication year: 1998
Provider: Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK) / Kunststoffe.de
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