| Electrospinning of thermosetting elastomers is a method for developing nonwoven membranes with a microporous structure. These membranes have potential for applications in breathable, stretchable protective clothing. The most challenging concerns are the ability to control pore sizes, fiber diameter, permeability, and physical properties. One factor in controlling the membrane's properties is the type of carbon black used in the elastomer. The properties of the membrane can be influenced by the carbon black particle size, structure, and surface area. This research focuses on the effect of carbon black type on electrospun butyl rubber nonwoven mats. The first part of the investigation considers fiber structure and mechanical properties of electrospun butyl rubber nonwoven mats with different carbon black types. The fiber morphology of electrospun butyl rubber was found to depend not only on the concentration of the solution, but also on the electrical conductivity of the solution. Higher structure and smaller particle size carbon black produced an increase in electrical conductivity and a decrease in concentration of solution. These two effects resulted in thinner smaller fibers. Mechanical properties were explained by variation in density and fiber morphology of the membranes. Decreasing carbon black particle size and increasing structure reduced density, and increased tensile strength, ultimate elongation and modulus.;In the second part of the investigation, the effect of carbon black type on electrical resistivity and morphology of electrospun butyl rubber nonwoven mats using a series of carbon black types with variation in particle size and structure was investigated. Carbon black dispersion along the electrospun fiber was examined by Transmission Electron Microscope (TEM). The addition of carbon black to butyl rubber resulted in fibers that maintained their shape without merging, but resulted in a roughening of the fiber surface. It was found that smaller carbon black size and higher carbon black structure lead to smaller gaps between carbon particles and, thus, lower electrical resistance. Higher structure blacks and smaller aggregates led to greater conductivity of the material.;Finally, the effect of carbon black type on the static moisture water permeation, liquid water permeation, and static carbon tetrachloride vapor permeation of electrospun butyl rubber nonwoven membranes was studied and compared with a commercial expanded poly(tetrafluoroethylene) (PTFE) membrane. Static moisture vapor permeation, static chemical vapor permeation, and liquid water permeation was unaffected by either particle size or structure of the carbon black. |
