Study On The Preparation And Properties Of Polymer-based Composites Reinforced By Graphene Materials

With excellent performance and structural characteristic, graphene materials are the ideal reinforcers for polymer-based composites, therefore, the electrical conductivity of bacterial cellulose (BC) and thermal properties of multi-layer grapheme oxide (MGO) improved respectively by graphene materials were studied in this paper.The electrical conductivity of BC improved by graphite nanoplateles(GNPs) was studied and GNPs/BC composite membranes were prepared. For comparison, multi-walled carbon nanotube (MWCNT)/BC composite membranes were also prepared. The dispersing stability of GNPs or MWCNT in absolute ethanol solution respectively with 0.3wt%NaDDBS, 0.3wt%A1100 or without surfactant were studied. The results showed that GNPs has the best dispersing stability in the absolute ethanol solution without surfantant, while MWCNT has the best dispersing stability in the absolute ethanol solution with 0.3wt%A1100. Based on the results, through sonication and immersion method respectively, the GNPs/BC composite membranes were prepared in GNPs-absolute ethanol suspensions and MWCNT/BC composite membranes were prepared in MWCNT-absolute ethanol suspensions stabilized with the assistance of 0.3wt% of A1100. The field emission scanning electron microscope (FESEM) analysis indicated that through effective physical(sonication) and chemical methods(surfactant), flake-shaped GNPs were embed in the BC surface network successfully and indeed fixed or trapped by the adjacent nanofibrils in the BC surface network; the rod-shaped MWCNTs were homogeneously inserted into the pores of BC membrane. The electrical conductivity of as-prepared composite membranes was measured using a four-probe, and the quality change of membrane before and after compound was also measured. The results showed that the electrical conductivity of sonication-prepared composite membranes is higher than immersion-prepared, and BC membrane with 8.7wt% incorporated GNPs reached the maximum electrical conductivity of 4.5S/cm, while MWCNT/BC composite membrane containing 13.9wt% MWCNTs achieved the maximum electrical conductivity of 1.2S/cm.The thermal properties of epoxy-based improved by multi-layer graphene oxide (MGO) was studied. Firstly, the effect of MGO on the curing behavior of epoxy was investigated by differential scanning calorimetry in detail. The result showed that with increasing MGO content(0.5、1、3wt%), the persistently increased hindrance of MGO on both the initial and the later vitrification curing stages, but this hindrance was found abated when MGO content increased from 1wt% to 2wt%. Then MGO/epoxy composites with different MGO content (0.5、1、2、3wt%) were prapared by in-situ polymerization. The exfoliated and dispersed level were analyzed by wide angle X ray diffraction and FESEM respectively, the results indicated that highly exfoliated and dispersed level of MGO in matrix as its content is less than 3 wt%, while MGO restacks and agglomerate in matrix when the content reaches 3wt%. The thermal properties of MGO/epoxy composites were measured, the results showed that the optium content MGO for composite material is 2wt%, which makes the composite has the higest structural thermal stability and maximum thermal conductivity(2.03 times that of pure resin matrix), and the thermal expansion coefficient of composite than pure resin matrix is reduced by 23%, reached the minimum.