Preparation And Properites Of Aligned Graphene Reinforced Poly(Vinyl Alcohl) Composites

Mixing polymer with nano-materials can effectively improve the overall performance of the composite,and the extent of performance improvement is closely related to the arrangement of the nano-fillers in the polymer because of the anisotropy of the nano-materials.Compared with traditional polymer composites(internal fillers are randomly arranged),polymer composites reinforced with oriented nanomaterials tend to exhibit better mechanical,thermal and electrical properties,so this kind of composite is more valuable in research.However,in order to obtain the alignment of the nano-filler,it is necessary to use the corresponding physical and chemical principles to make a reasonable design for the preparation process,and at the same time,there should be corresponding testing means to visually and accurately characterize the degree of orientation of the filler.In this regard,this paper systematically studies the preparation process of aligned graphene reinforced polymer composites and the characterization of the degree of the orientation of internal fillers.Besides,the corresponding properties of the composites are tested.Firstly,the preparation process of aligned graphene reinforced polymer composites is studied.Using the shear-hinning property of graphene oxide(GO)/polyvinyl alcohol(PVA)/water suspension,shear force-assisted orientation method is applied to prepare GO/PVA fibers with slightly-oriented GO.Combining with the post processing of hot-drawing,highly-aligned GO/PVA fibers are successfully prepared.The oriented GO/PVA films are prepared by an environmentally friendly method using the principle of space limiting.In the preparation process,important parameters such as injection rate,initial viscosity of the suspension and the time used for ultrasonic treatment are investigated.The morphology of the composites is characterized by scanning electron microscopy(SEM).The physical and chemical states of the samples are characterized by X-ray diffraction(XRD),infrared spectroscopy and raman spectroscopy.Secondly,in order to obtain the orientation degree of the nanofillers in the composite,the composites are characterized by scanning electron microscopy,onedimensional small angle X-ray scattering,one-dimensional wide angle X-ray scattering and two-dimensional small angle X-ray scattering(2D-SAXS).The asspun fibres and samples with different drawing ratios are comparatively analyzed.The results show that the drawing ratio has a significant effect on the degree of alignment of graphene oxide in the composites.With the increase of the drawing ratio,the orientation degree of GO is greatly improved.In addition,the 2D-SAXS test results show that after shear-force assisted orientation and 5 times hot-drawing,the GO of the prepared GO/PVA fiber is highly oriented along the long axis of the fiber,with the parallelism of GO reaching approximately 82%.Finally,the mechanical properties,thermal stability and electrical conductivity of the composites are tested.Combining the relevant theories and the properties of graphene,the introduction of GO,rGO and the enhancement mechanism of the orientation structure are analyzed based on the enhancement of the properties.Overall,this work provides a reference for the design and preparation of aligned graphene reinforced polymer composites.