DETERMINATION OF DYNAMICS IN EPOXY NETWORKS REINFORCED WITH POLYHEDRAL OLIGOMERIC SILSESQUIOXANES

U radu je ispitan utjecaj monomera i oligomera poliedarskih oligomernih silseskvioksana (POSS) na dinamiku lanaca epoksidne mreže temeljene na diglicidil eteru bisfenola A (DGEBA) i poli(oksipropilen)diaminu (Jeffamine D2000). Staklišta čiste epoksidne matrice i ispitivanih nanokompozita određena su metodom razlikovne pretražne kalorimetrije (DSC). Promjene u dinamici lanaca polimera ispitane su metodom spinske probe u elektronskoj spinskoj rezonanciji (ESR). Rezultati pokazuju da nakon ugradnje monomera POSS ne dolazi do značajnijeg ojačanja epoksidne matrice. Pri većem udjelu molekula POSS dolazi do njihove agregacije čime se stvaranju šupljine u polimernoj matrici. Zbog toga se povećava gibljivost lanaca polimera te smanjuje staklište ispitivanih nanokompozita. Nasuprot tome, prisutnost oligomera POSS uzrokuje snažne interakcije sa epoksidnom matricom što se očituje velikim porastom staklišta i znatnim smanjenjem mobilnosti lanaca polimera. In this thesis, the influence of monomers and oligomers of polyhedral oligomeric silsesquioxanes (POSS) on the dynamics of epoxy network based on bisphenol A diglycidyl ether (DGEBA) and poly(oxypropylene)diamine (Jeffamine D2000) has been investigated. The glass transition temperature of pure epoxy matrix and investigated nanocomposites was determined by differential scanning calorimetry (DSC). Changes in polymer chain dynamics were investigated by spin probe electron spin resonance spectroscopy (ESR). The results show that the incorporation od POSS monomers does not lead to a significant reinforcement of the epoxy matrix. Higher amount of POSS molecules causes their aggregation and formation of cavities in the polymer matrix. As a result, the mobility of polymer chains increases and the glass transition temperature of the investigated nanocomposites decreases. In contrast, the presence of POSS oligomer causes strong interactions with epoxide matrix which is reflected in the large increase of glass transition temperature and significant reduction in the mobility of polymer chains.