| Polyvinyl alcohol(PVA)has good water solubility, film forming, adhesion, and its applications involving food, medicine, construction, wood, papermaking, printing, agriculture, metallurgy, fine chemical and other fields and processing.Polyimides(PIs) are an important class of structural polymers with excellent physicochemical properties such as thermal and thermo-oxidative stability, superior mechanical and dielectrical properties, and favorable chemical and solvent resistance properties; therefore, they are widely used in the microelectronics and aerospace industries. However, with the development of high technology, conventional PVA and PIs materials could not well meet the requirements of high- tech products. Therefore, modification of pure polymer material has become a research focus in the field of polymer materials. Graphene, a new two-dimensional(2D) structure consists of sp2-hybridized carbon, it has attracted considerable attention owing to its unique nanostructure and a variety of fascinating thermal, mechanical, and electrical properties. This unique nanostructure also holds great promise for potential applications in many technological fields such as nanocomposites, sensors, catalysis, batteries, and supercapacitors. Employing graphene as reinforcing filler of nano-polymer composite material, which can effectively improve the performance of the single polymer materials, it is a facile way to prepare high performance polymer composites.Because of graphene oxide nanosheets contain rich hydrophilic functional groups, it exhibited excellent dispersibility and compatibility in poly(vinyl alcohol) matrix, which were successfully incorporated into poly(vinyl alcohol) through solution mixing; the mechanical properties and reinforced mechanism were investigated in detail.The composites show a higher tensile strength and Young’s mod ulus than those of pure poly(vinyl alcohol). Furthermore,both the tensile strength and modulus of the PVA/GO films increased with increasing graphene oxide component. The tensile strength of the composite containing 2 % of graphene oxide increased by 52.3 % from 55.1 to 83.9 MPa and the Young’s improved modulus by 94.2 % compared with the pure poly(vinyl alcohol) film. This is due to PVA and GO uniformly dispersed and chemical bonds effect and lead to the performance increasing of the composite materials.We use 3-aminopropyltriethoxysilane functionalized graphene oxide(APTSi-GO) as the reinforcing filler to fabricate high-performance polyimide(PI)-based nanocomposites. APTSi-GO nanosheets exhibit good dispersibility and compatibility with the polymer matrix because of the strong interfacial covalent interactions. PI-based nanocomposites with different loadings of functionalized graphene nanosheets(FGNS) were prepared by in-situ polymerization and thermal imidization. The mechanical performances, thermal stability, and electrical conductivity of the FGNS/PI nanocomposites are significantly improved compared to those of pure PI by adding only a small amount of FGNS. For example, a 79% improvement in the tensile strength and a 132% increase in the tensile modulus are achieved by adding 1.5 wt% FGNS. The electrical and thermal conductivities of 1.5 wt% FGNS/PI are 2.6 × 10?3 S/m and 0.321 W/m·K, respectively, which are ?1010 and two times higher than those of pure PI. Furthermore, the incorporation of graphene significantly improves the glass-transition temperature and thermal stability. The success of this approach provides a good rationale for developing multifunctional and high-performance PI-based composite materials. |
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