Mechanical properties of conductive composites on the nano-level

Z vmešavanjem delcev prevodnega polnila (v našem primeru: bakrene luske) v polimerno matrico (v našem primeru: polietilen nizke gostote – LDPE) dobimo polimerni kompozit, ki prevaja električni tok. Tako izdelanemu kompozitu se v primerjavi z matričnim LDPE polimerom spremenijo tudi mehanske lastnosti. Spreminjanje mehanskih lastnosti je povezano z deležem polnila v polimerni matrici. Tako smo pripravili polimerne kompozite, ki so vsebovali različne volumske deleže (od 0 do 40 vol%) bakrenih lusk v LDPE polimerni matrici. V tej nalogi smo se osredotočili na določitev trdote, elastičnega modula in hrapavosti površine kompozitov, kar smo okarakterizirali s pomočjo nanoindentacije z metodo kontinuirnega merjenja togosti in z metodo stopenjske obremenitve. Ugotovili smo, da sta trdota in elastični modul skoraj linearno povezana z vsebnostjo dodanih lusk, hrapavost pa se odziva skoraj eksponentno.Mixing conductive composite particles (in our case: copper flakes) into a polymer matrix (in our case: LDPE) results in a polymer composite material that conducts electrical current. In comparison to pure LDPE polymer, the mechanical properties of the polymer composite change. The change of mechanical properties was correlated to the percentage of filler particles in the polymer matrix. We prepared poymer composites with different volumetric percentages (from 0 to 40 vol%) of copper flakes in the LDPE polymer matrix. In this thesis, we focused on the determination of hardness, elastic modulus and surface roughness, which we tested with the help of continuous stiffness measurement and ramped load topography methods. The findings are that hardness and elastic modulus increase almost linearly with the percentage of flakes added while the behavior of surface roughness is almost exponential