Electronic Theses and Dissertations

Date of Award

1-1-2020

Document Type

Thesis

Degree Name

M.S. in Engineering Science

First Advisor

Ahmed Al-Ostaz

Second Advisor

Sasan Nouranian

Third Advisor

Hunain Alkhateb

School

University of Mississippi

Relational Format

dissertation/thesis

Abstract

After the discovery in 2004, graphene and its different forms have been studied as nanofillers into a wide range of polymers and elastomers. It is now known that these nanofillers can have a significant effect on the polymer’s or elastomer’s mechanical performance. One area that has been overlooked is the effect these nanofiller can have on the cutting resistance – an essential mechanical property when it comes to occupational safety products – when they are being incorporated into the polymer or elastomer matrix. Reported are the effects on the mechanical performance after adding graphene nanoplatelets, and a functionalized form thereof, to nitrile rubber. The mechanical properties reported are storage modulus and tensile strength, as well as the cutting resistance when being coated on a nylon substrate. The procedure followed three distinct phases. Phase 1 served as a screening phase. Phase 2 followed a statistical design-of-experiments approach to get an objective understanding of the effect of nanofiller concentration and curing temperature on the mechanical properties mentioned above. Lastly, Phase 3 explored the possibility of adding non-functionalized graphene nanoplatelets to reduce the cost of production as well as the coating thickness’ effect on the cutting resistance. In Phase 1, it is reported that by just adding 0.2 parts per hundred rubber (phr) of functionalized graphene nanoplatelets (fGNP) to the nitrile rubber, a 171% increase in tensile strength was achieved. Similarly, by adding 1 phr of fGNP, a 58% increase in storage modulus was obtained. Phase 2 reports that in order to maximize the storage modulus, the optimized combination is for the nanocomposite to be cured at 140C with a concentration of 1.8 phr. However, due to the degradation of the nylon substrate at higher curing temperatures, the curing temperature was fixed at 130C and the new optimal concentration was found to be 1.6 phr. During Phase 2, a 95% increase in storage modulus was obtained for a specimen with a 2.34 phr concentration and cured at 135C. Lastly, in Phase 3 it was found that the thickness of the coating seems to have a greater effect on the cutting resistance than the concentration of the nanofiller. However, the coating with 1.6 phr of graphene nanoplatelets, cured at 130C and with a 1 mm thickness, increased the cutting resistance by 29% in comparison to the pure nitrile rubber coating cured at the same temperature and with the same thickness. In conclusion, it was found that both the curing temperature and nanofiller concentration had a significant effect on storage modulus. An increase in storage modulus was found to increase the cutting resistance. Whilst the nanofiller concentration had an effect on the cutting resistance, the coating thickness was found to be of greater significance.

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