Modification Of Graphite Nanosheets By Grafting Polystyrene Under Microwave Irradiation

Graphite nanosheets (GNs) is a new kind of conducting filler, with nanometer in thickness(30-80 nm) and micrometer in diameter(5-20μm). The GNs have a large aspect ratio (thickness to diameter) and possess an advantage in forming conducting network in polymer matrix, leading to much lower percolation threshold. Due to the incompatibility and weak interaction between GNs and polymer, polymer/GNs composites with ideal properties can not be achieved by those common methods. So, the purpose of the article is to obtain an effective method to get graphite particles dispersed uniformly in a continuous polymer matrix and improve the incompatibility between graphite and polymer.In this dissertation, we found that styrene oligomer was successfully and instantly grafted onto GNs surface with the help of microwave radiation. In a detailed study of two main impact factors which effect the graft ratio: the microwave energy and the time of microwave irradiation, the optimum preparation condition of the GNs-g-PSt were obtained. The GNs-g-PSt prepared under the optimum preparation condition was analyzed by using FTIR,TGA,XRD etc. Studies have shown that the crystal structure of the graphite nanosheets have not been destroyed during the graft process, and the amount of PSt grafted on GNs was estimated to be 8 wt %.The stability of the modified GNs dispersion and the electrical properties of the modified GNs composite were also studied in the thesis. The research indicated that the modified GNs showed better dispersed and evolved a more stable colloidal dispersion in non-polar organic solvent, such as toluene compared with that of without modification. The GNs-g-Polystyrene/Polystyrene (PSt) composite exhibited a low percolation threshold of approximately 0.88 wt% due to the greatly improved miscibility of GNs-g-PSt with PSt, and the uniformly dispersed GNs-g-PSt particles in the matrix of PSt. The conductivity of the nanocomposite exhibited about 0.32×10-4 S/cm while the content of the modified GNs in the composite was 2.0wt%.