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Incorporation of Friction Stir Processing Into Fabrication of Surface Composite in Polypropylene

Shohani, Milad | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39852 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Kokabi, Amir hossein; Bagheri, Reza
  7. Abstract:
  8. Engineering polymers are being increasingly used in a wide number of applications related to tribological properties. Many chemical and physical methods have been utilized to modify polymer surfaces by depositing thin inorganic films. Most of these techniques are based upon the use of high energy sources that ultimately can damage polymer surfaces either chemically or physically. Incorporation of fillers as reinforcing materials significantly changes various properties of thermoplastics. Friction stir processing (FSP) is a tool to modify the surface properties of materials. It has been developed for upper surface modification of metals in recent studies, exclusively by making surface composites; however it has never been used for modification of polymers. FSP parameters selection and the feasibility of introducing a composite layer on top of a neat polymer by this method were studied successfully in this research. Accordingly FSP was attempted to incorporate nano-sized CaCO3 into co- polypropylene to form particulate composite surface layer. Samples were subjected to various numbers of FSP passes with and without CaCO3 powder. The results show that increasing the number of FSP passes from one to four causes a more uniform distribution of particles. Fabricated surface composite layer showed an increase of 25% in scratch resistance in comparison with the base polymer. Macroscopic investigation of the bended samples showed that the surface layer is well bonded to the base polymer. Furthermore, it was observed that the increase in the number of FSP passes resulted in the formation of a transparent interfacial thin layer with low modulus. Consequently, results showed that the fabrication of a surface composite layer on the top surface of neat polymeric materials via FSP is practical.


  9. Keywords:
  10. Polypropylene ; Nanometric Calcium Carbonate ; Surface Composite ; Friction Stir Welding

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