Matching Items (2)
Description
The wettability of powders is an important characteristic for both industry and academia and is often described by the powder’s contact angle with a certain liquid. While there exist many ways to measure contact angle, it is a portion of the powder technology field that is not fully understood and requires more investigation and research. This study investigates two methods for measuring contact angle, the sessile drop method and the Washburn method, and looks to compare results to determine which method offers the most reliable data in terms of accuracy and repeatability. Two powders - microcrystalline cellulose and aluminum oxide - and three liquids - water, 50 cSt silicone oil, and 350 cSt silicone oil - were used to study the differences between the two measurement techniques as well as the effects of varying fluid viscosity on the measurements. It was found that the sessile drop method proved to be an ineffective method for measuring contact angle when liquid penetration into the powder occurred, as the contact angle changed while the drop penetrated. Initial results showed the contact angle for silicone oil on the powders to be greater than 90°, indicating nonwetting of the surface which was inconsistent with observations. The results from the Washburn method align better with other values in similar studies, but more study is needed to confirm the results gathered in this research.
ContributorsSmith, Bryan Alexander (Author) / Emady, Heather (Thesis director) / Rykaczewski, Konrad (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Direct Ink Deposition is a type of 3D printing that utilizes a nozzle to coat thin films onto substrates. Electrospray deposition is a subcategory of Direct Ink Deposition wherein a very strong electric field is applied between the nozzle exit and the substrate, which results in the precursor polymer ink to be sprayed onto the substrate in the form of micro- or nano-droplets. As of today, its applications are limited to producing small area polymer solar cells or for biomedical applications, particularly in laboratories, but in the future, with optimization of electrospray deposition, this method can be further expanded to 3D printing components that can be used in the aerospace, automotive, and other such large-scale industries. The objective of this research is to see how application of ultrasonic vibrations during, and post deposition affects the morphology, electrical conductivity, and the respective surface properties of the thin Poly(3,4 – Ethylenedioxythipohene)-Poly(Styrenesulfonate) (PEDOT:PSS) film printed via electrospray deposition. The printing setup was previously designed and constructed, wherein the syringe was loaded with the PEDOT:PSS and Isopropyl Alcohol (IPA) solution which was then printed onto thin and small sized Indium Tin Oxide (ITO) substrates under the application of a high voltage. The distance of the nozzle from the substrate was appropriately adjusted via the vertical linear movable stage before printing, as well as the voltage supply. Deposition time was set using an Arduino code that controlled the horizontal movement of the shutter attached to the bottom of the vertical linear aluminum frame. Horizontally and vertically induced vibrations were turned on during and post deposition to analyze the effect of both on the films’ properties through an ultrasonic transducer. The electrical sheet resistance of the PEDOT:PSS films was measured using a 4-point probe device and the surface contact angle of water on the PEDOT:PSS was measured using a contact angle meter. From the results obtained, it was concluded that the application ultrasonic vibrations improved wettability compared to the films printed without any vibrations. Furthermore, the electrical sheet resistance and contact angle of pure ITO was measured as a reference.
ContributorsRavishekar, Rohan (Author) / Li, Xiangjia (Thesis advisor) / Alford, Terry L (Thesis advisor) / Pathikonda, Gokul (Committee member) / Arizona State University (Publisher)
Created2023