Date on Master's Thesis/Doctoral Dissertation


Document Type

Master's Thesis

Degree Name

M. Eng.


Chemical Engineering

Committee Chair

Willing, Gerold A.


Rubber--Deterioration; Rubber chemistry; Drinking water--Purification


The use of monochloramines in the potable water supply industry has been selected as the disinfectant method of choice due to a longer term of effectiveness and less toxic by-products than the previous choice of chlorine. In spite of the benefits exhibited by the use of monochloramines much greater rates of elastomer degradation have been noted in the water industry. The modes of attack by monochloramines on the rubber parts are still poorly understood. A common ingredient in nearly all elastomer formulations is carbon black. In addition to its role as a filler material, carbon black is also known to add strength and durability to the elastomer. Degradation of average particle size showing that carbon black particles dissolve into the invasive liquid medium can be observed using phase images produced by atomic force microscopy. The nanoscale size of the carbon black particles makes the use of the AFM an ideal investigative tool. Elastomeric properties of the rubber coupons exhibit similar trends to the degradation of the carbon black material in the polymer matrix. Diffusion coefficients approximated by use of a simplified form of Fick's second law also shows a similar trend. Use of monochloramines as a disinfectant by the water supply industry produce fewer toxic by-products and maintain a longer useful potable water life than chlorine; however, rapid degradation of rubber parts will continue unless more suitable formulations can be found.