Effect of carbon nanotube networking on polyethylene and mechanical properties of nanocomposites

Polietilen je zaradi svojih mehanskih in kemičnih lastnosti eden najpogosteje uporabljanih polimernih materialov, tudi za matrični material kompozitov. V kombinaciji z ogljikovimi nanocevkami, ki zagotavljajo izredne karakteristike, tvorijo revolucionarne nanokompozite, katere je možno aplicirati v najzahtevnejša področja današnje znanosti. V sklopu naloge smo obravnavali vpliv omrežja ogljikovih nanocevk na mehanske lastnosti, kjer smo z uporabo nanoindenterja določili elastični modul, trdoto, ter površinske lastnosti, kot so hrapavost ter odpornost na praske. Teste smo izvedli na vzorcih polietilena nizke in visoke gostote z različno vsebnostjo enostenskih ogljikovih nanocevk. Rezultati so pokazali da omrežje (geometrijski preplet nanocevk) nastane pri ?0.7% in je glavni faktor pri ojačitvi oziroma izboljšanju mehanskih lastnosti nanokompozitov. V primeru LDPE-nanokompozitov se elastični modul izboljša za 250% ter trdota za 225%, v primeru HDPE-nanokompozitov pa se omenjeni lastnosti izboljšata za 122% in 130%. Ugotovljeno je bilo tudi to, da se hrapavost z dodajanjem nanopolnila poveča za 100nm, tako v primeru LDPE- kot HDPE-nanokompozitov.Polyethylene is since its mechanical and chemical properties one of the most common used polymer materials additionally as matrix composite material. In combination with carbon nanotubes, thus hold extraordinary characteristics, they form revolutionary nanocomposites that are possible of application into the most demanding fields of nowadays\u27 science. Within the framework of the thesis, we discussed the influence of the carbon nanotube networking on mechanical properties, where we determined the elastic modulus, hardness, and surface properties, such as roughness and resistance to scratch, using a nanoindenter. The tests were performed on low- and high-density polyethylene samples with different mass frictions of single-walled carbon nanotubes. The results showed that the network (geometric entangling of nanotubes) is formed at ~0.7% and is the main factor in strengthening or improving the mechanical properties of nanocomposites. In the case of LDPE nanocomposites, the elastic modulus improves by 250% and the hardness by 225% , while in the case of HDPE nanocomposites, the mentioned properties improve by 122% and 130%. It was also found that the roughness increases by 100 nm with the addition of nanofillers in both LDPE and HDPE nanocomposites