Loading...

The Effect of Graphene Nano-Sheet on Antioxidant Stability in Polyethylene Pipes

Ghadami Karder, Hamid Reza | 2022

146 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55245 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Pircheraghi, Gholamreza
  7. Abstract:
  8. PE pipes and specially PE100 are commonly used for the transportation of drinking water, transferred water was mostly disinfected by disinfectants such as chlorine, chlorine dioxide and chloramine. Long-term contact with water containing disinfectants led to morphological and mechanical changes and followed by oxidative degradation and failure. Antioxidants are stabilizers which are used in PE pipes to postpone oxidation and increase the durability of these pipes. Migration of antioxidants is possible during the terms of service, in this case antioxidants can be washed by water and left the pipe. As a result, the loss of antioxidants decreases the stability of pipes and leads to oxidative degradation. It’s just reported that the extended network of graphitic nano-sheets acts as antioxidants and absorb free radicals to retard the degradation of polymers. In this research, the effect of graphene polarity on durability of antioxidants, mechanical and rheological properties of polyethylene was investigated. In this regard, two kinds of graphene, the first “SG” synthesized by electrochemical method with high polarity and the second “CG” commercially available with lower polarity, were used. Studies showed that HD1CG, compared to HDPE (control sample), increases the oxidative induction time (OIT) to 33 minutes more. This subject is related to the proper distribution of graphene and the oxygen gas barrier of graphene sheets. Thermal aging has shown that SG graphene, because of more oxygen groups, agglomerates in the matrix of PE100 and trapped antioxidants, which help the durability of antioxidants in the polymer. HD6CG, after 3 weeks of aging in water containing chlorine dioxide, showed 200 percent elongation at break, however the elongation of polyethylene sample in the same situation was 50 percent. This result showed the effect of graphene nano sheets on the durability of antioxidants and retaining mechanical properties. Rheological research indicates adding CG and SG has no impressive impact on PE100 elastic behavior, because of PE100’s high elasticity. Hence processability, the function of pipes during the process and durability of pipes won't be affected. All of the results showed that HD6CG with chlorine dioxide barrier and scavenging of free radicals created during aging, improve the durability of antioxidants and stability of the sample
  9. Keywords:
  10. Polyethylene Pipe ; Antioxidant ; Graphene ; Aging ; Free Radicals Polymerization ; Electrochemical Exfoliation ; Water Containing Chlorine Dioxide

 Digital Object List

 Bookmark

No TOC