Influence of nano graphenes on structure and properties of polymers

To obtain polymer composites with good operational properties, it is proposed to use nano carbon fillers - nano graphenes and nano graphites. The objects of study were a crystalline polymer - low-density polyethylene with a molecular weight of M = 6·104, amorphous polymethylmethacrylate with M = 8·104, solvents bromobenzene and toluene grade, fillers were nano graphenes, which were obtained by irradiation with gamma rays multilayer carbon nano tubes, and by the method of self-propagating high-temperature synthesis from lignin. When nano tubes are irradiated in air and lignin in a self-propagating high-temperature synthesis process, the resulting fragments of nanoparticles are apparently oxidized and represent graphene oxides. It is shown that with an increase in concentration of nanoparticles in low-density polyethylene, first a drop is observed, and then the retention of breaking strength σρ with a sharp decrease in the value of breaking deformation ερ. If for other nano carbon-containing samples of low density polyethylene at filler concentrations C≥3%, σp decreases and εp drops sharply, then in the composites studied this decrease is relatively weak, that is, a sufficiently large preservation of resource of mechanical properties is observed. This behavior of mechanical properties of nano composites indicates a change in physical state of amorphous areas of polymer, that is, their transition from a highly elastic state to a glassy one. Thermographic studies of composites showed that an increase in the concentration of nanoparticles is not accompanied by changes in melting and crystallization temperatures, that is, the structure of the composite becomes relatively stable. With increase of concentration of nanoparticles in composites of polymethyl methacrylate, an increase of strength is observed with a slight decrease of deformation, changes (increase) of softening and decomposition temperatures. (author)