The present master thesis aims at new approaches towards the improved recyclability of epoxy based composite materials. Two new epoxy monomers are synthetized that bear functional groups, which form a network or can be cleaved by external stimuli, in particular UV radiation. The thermal curing of the developed resin formulations is carried out with an anhydride based hardener. The mechanical properties (e.g. storage modulus) of the various resin systems can be adjusted by the functional groups of the new epoxy monomers. The employment of epoxy monomers with pendant anthracene groups enables the preparation of reversibly crosslinkable duromer materials. Upon UV illumination a photocycloaddition reaction of the anthracene moieties takes place which leads to a crosslinking of the resin. Cleavage of the covalent crosslinks is obtained by a subsequent heating step. The reversibility of the photodimerization is studied by means of UV/Vis spectroscopy and the thermo-mechanical properties are characterized over several bond formation and bond cleavage cycles. In a second approach, bifunctional o-nitrobenzyl ester derivates are added to epoxy based resins. These new UV sensitive thermosetting materials provide enhanced recycling properties. Controlled cleavage of the epoxy network is accomplished by the UV induced rearrangement of the o-nitrobenzyl ester groups. The effect of the exposure dose on the cleavage reaction of the crosslinks is monitored by FTIR spectroscopy and dynamic mechanical analysis. Additionally, the bifunctional o-nitrobenzyl ester derivates are immobilized on the surface of glass fibers. The UV induced cleavage reaction on the glass surface is evidenced by zeta-potential measurements and the feasibility of the new fiber-matrix systems in selected applications is evaluated by single fiber pull-out tests.