Morphological and Thermal Properties of Cellulose Nanofibrils Reinforced Epoxy Nanocomposites

Epoxy resins have gained attention as important adhesives because they are structurally stable, inert to most chemicals, and highly resistant to oxidation. Different particles can be added to adhesives to improve their properties. In this study, cellulose nanofibrils (CNFs), which have superior mechanical properties, were used as the reinforcing agent. Cellulose nanofi brils were added to epoxy in quantities of 1 %, 2 % and 3 % by weight to prepare nanocomposites. Morphological characterization of the composites was done with scanning electron microscopy (SEM). Thermal properties of the nanocomposites were investigated with Thermogravimetric Analyzer (TGA/DTG) and Differential Scanning Calorimeter (DSC). SEM images showed that the cellulose nanofibrils were dispersed partially homogenous throughout the epoxy matrix for 1 % CNF. However, it was observed that the cellulose nanofibrils were aggregated (especially for 2 and 3 % CNFs) in some parts of the SEM images, and the ratios of the aggregated parts increased as the loading rate of the cellulose nanofi brils increased. The TGA curve showed that DTG and decomposition temperature of pure epoxy was higher than that of the nanocomposites. The DSC curve showed that the glass transition temperature (Tg ) value of pure epoxy was found to be similar with Tg of the nanocomposites.Epoksi smole smatraju se važnim ljepilima jer su strukturno stabilne, inertne na većinu kemikalija i vrlo otporne na oksidaciju. Ljepilima se za poboljšanje njihovih svojstava mogu dodati različite čestice U ovom istraživanju, kao sredstvo za ojačanje kompozita upotrijebljeni su celulozni nanofibrili (CNFs), koji imaju izvrsna mehanička svojstva. Celulozni su nanofibrili dodani epoksi smoli u količini od 1 , 2 i 3 % mase radi izrade nanokompozita. Morfološka karakterizacija kompozita napravljena je skenirajućim elektronskim mikroskopom (SEM). Toplinska svojstva nanokompozita istražena su termogravimetrijskim analizatorom (TGA/DTG) i diferencijalnim skenirajućim kalorimetrom (DSC). SEM slike pokazale su da su celulozni nanofibrili raspršeni djelomično homogeno u matrici od epoksidne smole s 1 % CNFs-a. Međutim, uočeno je da su celulozni nanofibrili agregirani (pogotovo za 2 i 3 % CNFs-a) u nekim dijelovima SEM slike, a udjel agregiranih dijelova povećava se s udjelom celuloznih nanofibrila. TGA krivulja pokazala je da su DTG i temperatura raspadanja čiste epoksi smole veće od temperature raspadanja nanokompozita. DSC krivulja pokazala je da je temperatura staklastog prijelaza (Tg) čiste epoksi smole slična vrijednosti Tg za nanokompozite