دانلود رایگان مقاله گرافن / کائوچو و مواد مرکب ترکیبی چند منظوره فایبر گلاس پلی پروپیلن

abstract

The effect of the simultaneous addition, using a melt-mixing procedure, of glass fibres (GFs) and graphene in the form of graphene nanoplatelets (GNPs) upon the properties of polypropylene (PP) has been studied in detail. Composite samples containing GFs and GNPs alone were also prepared for comparative purposes. The crystalline microstructure of the composites was characterised by X-ray diffraction (XRD), while scanning electron microscopy (SEM) was used to study the interface between the matrix and the fillers. The orientation of the glass fibres was evaluated using SEM while polarized Raman spectroscopy was utilized to determinate the orientation of the GNPs in the composite samples. The mechanical properties of the composites were evaluated by tensile testing and it was found that the Young's modulus of the hybrid material is higher than that of the materials containing the fillers individually, showing an additive effect. Raman spectroscopy employed simultaneously with deformation of the composites was used to show that there was good interfacial stress transfer between the PP matrix and the GNPs. Finally, the thermal conductivity of the materials was measured and found to be significantly higher for the composites containing GNPs alone.

4. Conclusions

The effect of the incorporation of graphite nanoplatelets and short glass fibres, both separately and in combination, upon the structure and mechanical properties of polypropylene has been studied in detail. It has been found that the addition of the glass fibres decreases both the degree of crystallinity and glass transition temperature of the polypropylene whereas both of these parameters are increased significantly upon the addition of the graphite nanoplatelets, improving the thermal properties of the material. The addition of both of these fillers to polypropylene increases the Young's modulus of the polymer to a similar extent for a given volume fraction and there is some evidence from Raman spectroscopy and from the use of a 3-phase modified rule of mixtures that, when added together, the two fillers may give better reinforcement by acting additively. The addition of the glass fibres is found to increase the fracture stress but reduces the failure strain of the polymer whereas the addition of the graphite nanoplatelets causes less reduction in the failure strain. Finally, the presence of glass fibres in the polypropylene is found to have little effect upon the thermal conductivity of the polymer whereas the addition of the graphene nanoplatelets is found to increase it by more than a factor of five.