Date Approved


Embargo Period


Document Type


Degree Name

M.S. in Engineering


Chemical Engineering


Henry M. Rowan College of Engineering

First Advisor

Keil, Z. Otero


Electrophotography; Photographic chemicals


Chemical Engineering


The effect of particle size on the flow characteristics and tribo-electrical charge of dry electrophotographic (toner) powders was investigated. Toner samples, consisting of the same base formulation, but differing in particle size were prepared and studied using commercially available processing and analytical equipment. The effect of post-blending fumed silica into the toner was also investigated as part of this work. The results indicate that toner particle size has a strong effect on toner flow characteristics. The flowability measurements that were most affected by the particle size were the cohesiveness and compressibility properties of the toner powders. The data showed that as particle sizes increases toner flowability improves. The data also indicate that toner flow properties are improved by the addition of fumed silica as a post-additive. The addition of this post-additive appeared to lower the toner powder surface charge (tribo-electrical charge) raising questions about potential print quality problems. Print quality issues attributed to the lowering of surface charge include poor line development and decreased image fusibility.