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Studying the Effect of Dynamic Vulcanization of EPDM on Scratch Resistance of Rubber-Modified Polypropylene

Zarrinbakhsh, Nima | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39060 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Bagheri, Reza
  7. Abstract:
  8. Polypropylene is a commodity thermoplastic with good physical and mechanical properties along with fair recyclability and cost. However, the application of polypropylene is limited in some cases, especially in automotive industry, as a result of inappropriate toughness of this material. Although rubber toughening of polypropylene is a method used to increase the toughness, it reduces scratch resistance. Studies performed in the polymer group of this department reveal that the cavitation resistance of elastomeric phase and its bonding to the matrix are two effective parameters in scratch resistance of this material. In this study, it is tried to alter the cavitation resistance of elastomeric phase and its bonding to the polypropylene matrix by cross linking of EPDM, i.e. the elastomeric phase, using dynamic vulcanization with two curing systems including sulfur and peroxide. The crystallinity of blends is studied by DSC and transmission optical microscopy. In addition, DSC and DMTA analyses are used to investigate the glass transition temperature of the elastomeric phase. Furthermore, the mechanical behavior of blends is studied via different approaches including tensile, impact and scratch tests as well as dynamic mechanical analysis. The deformation and scratch mechanisms are analyzed by transmission optical microscopy (TOM) and scanning electron microscopy (SEM). DSC, DMTA and mechanical test results show reduced crystallinity and mechanical properties by dynamic vulcanization via peroxide due to the polypropylene degradation. In the case of materials vulcanized by sulfur, the change in crystallinity and mechanical properties is negligible while the scratch resistance increases noticeably. An increase in cavitation resistance of the elastomeric phase and its bonding to the polypropylene matrix proved by TOM and SEM images is believed to be the source of improvement in scratch resistance in PP/EPDM blend
  9. Keywords:
  10. Scratch Rsistance ; Rubber-Modified Polypropylene ; Dynamic Vulcanization ; Cavitation Resistance

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