E. Bittmann et Gw. Ehrenstein, OPTIMIZATION OF CYCLOALIPHATIC EPOXY-RESINS WITH SILICONE ELASTOMERS, Die Angewandte makromolekulare Chemie, 258, 1998, pp. 93-98
The high crosslink density of epoxy resins with high glass transition
temperature, high strength, etc., used in many high-performance applic
ations, causes the undesired brittleness of these materials and, hence
, internal stress. For the optimization of their properties, cycloalip
hatic epoxy resins were modified with elastomeric silicone. Two differ
ent modifying concepts, i.e. dispersion and mixing, were characterized
using mechanical testing, dynamic-mechanical analysis and scanning el
ectron microscopic studies as well as measurement of the expansion coe
fficient and the shrinkage. The modification with silicone, in general
, reduces the modulus and improves the fracture toughness of the resin
s. Due to the two-phase structure of the resins prepared by the disper
sion method, the glass transition temperature of the epoxy matrix is p
ractically not depressed, and the tendency to enhance stress is less m
arked compared to the mixing method.