Influence of aluminum particle concentration on mechanical properties of metal - polymer composites

Polimeri so v današnjem svetu široko uporabljeni materiali in zaradi velikega spektra lastnosti nemalokrat predstavljajo alternativo kovinam za izdelavo najrazličnejših izdelkov. So dobri električni in toplotni izolatorji, imajo dobro razmerje med natezno trdnostjo ter gostoto in izkazujejo časovno odvisnost. Pogosto si od materialov želimo drugačne, boljše ali celo nasprotne lastnosti, kot nam jih le-ti ponujajo. To lahko v neki meri dosežemo z dodajanjem polnila v polimer. Tako lahko iz toplotnih in električnih izolatorjev dobimo prevodnike, zmanjšamo časovno lezenje ali povečamo trdnost osnovnega materiala. V sklopu te naloge smo raziskovali, kako se spreminjajo mehanske lastnosti, če polimernemu materialu dodajamo trdne kovinske delce. Vzorci, ki smo jih testirali, so bili iz polipropilena z dodanimi aluminijastimi delci različnih koncentracij. Izvedli smo upogibni test ter DMA amplitudni in frekvenčni test. Ugotovili smo, da se mehanske lastnosti ne spreminjajo linearno z naraščajočo koncentracijo delcev. Povečanje deleža polnila iz 15 % na 45 % poveča elastični modul za nekaj več kot dvakrat, iz 45 % na 60 % pa ze več kot trikrat. Rezultati statičnih in dinamičnih testov se med seboj ujemajo, pri obeh so razmerja modulov podobna. Iz dobljenih rezultatov lahko sklepamo o obnašanju podobnih kompozitnih materialov.Polymers are widely used materials. Due to their wide range of properties, they often represent an alternative to different metals for the production of a wide variety of products. They are good electrical and thermal insulators, they have good ratio between tensile strength and density, but they show time dependence. However, we often want the material to exhibit different, better or even opposite properties. This can be to some extent achieved by adding fillers and aditives to the polymer. By doing so, we can obtain conductors from thermal and electrical insulators, reduce creep or increase the strength of the base material. As part of this thesis, we investigated how the mechanical properties change when we add solid metal particles to the polymer material. The samples we have tested were made of polypropylene with added aluminum particles of various concentrations. We performed bending test and DMA amplitude and frequency test. The results showed that the mechanical properties do not change linearly by increasing the concentration of particles. When increasing the filler content from 15 % to 45 %, the elastic modulus increases by nearly double, and when the increase is from 45 % to 60 %, the modulus more than triples. The results of static and dynamic tests match, the modulus ratios being similar in both cases. From the obtained test results we could predict the behavior of similar composite materials