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Study of Crystalline Structure in Random Co-polypropylene and Its Influence on Melting Behavior

Khedri, Faezeh | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50557 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Bagheri, Reza; Asgari, Sirus
  7. Abstract:
  8. In today’s world the growth in population make food production and also the packaging industry increase. Finding new ways to enhance the efficiency of packaging is become so important beyond researchers. As the randomized co-polypropylene is the most suitable materials for this industry many attempts have been made to control its melting behavior with the aim of expanding their application in the packaging industry. The study in this field indicate the dependence of the melting behavior on the structural characteristics of the material such as molecular mass, chain structure, type of crystalline structure, and the amount of dispersion of the crystals thickness. Due to the lack of proper grade for this material in the domestic petrochemical industry, in this research, we tried to achieve a good grade for physical and mechanical properties by using the method of mixing in the downstream industry. In order to achieve this goal, at first, the crystalline structure of two grades of internal copolymers with commercial names MR230C and RP340R was fully identified. Then the film produced from a combination of these two randomly selected co-polymers. Finally, the effect of some additives on the crystalline structure on control of the melting behavior was studied. The results of the experiments showed that the combination of these two randomly selected copolymers introduce suitable physical and mechanical properties. For instance the melt flow index should be between 5 to 7 gr/10min and in this work become 6.25 gr/10min with weighing 2.16 kg, achieved a suitable welding strength for 200 g weight and also, the sample had a good opacity. Moreover, the addition of rubber and nucleating agent to the compound obtained as an improvement in the melting behavior. Because this addition made the seal initiation temperature of the compound reduce
  9. Keywords:
  10. Weld Strength ; Copolymer Polypropylene ; Crystalline Structure ; Random-Copdypropylene ; Melting Behavior ; Seal Initiation Temperature ; Lamella Thickness Distribution

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