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THEORY AND APPLICATIONS OF ULTRASONIC SOFT MATERIALS AND
SURFACE ANALYZER (USMASA)
by
Wei Yang
________________________________________________________________________
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(CHEMICAL ENGINEERING)
August 2009
Copyright 2009 Wei Yang
Object Description
| Title | Theory and applications of ultrasonic soft materials and surface analyzer (USMASA) |
| Author | Yang, Wei |
| Author email | weiyang@usc.edu; ywhhzju@hotmail.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Chemical Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2009-06-25 |
| Date submitted | 2009 |
| Restricted until | Unrestricted |
| Date published | 2009-07-30 |
| Advisor (committee chair) | Chang, Wenji Victor |
| Advisor (committee member) |
Shing, Katherine S. Hogen-Esch, Thieo E. |
| Abstract | High-frequency linear viscoelastic properties of soft materials are essential for material designing and engineering applications. Traditionally, the high-frequency properties are estimated through the time-temperature superposition (WLF equation) of low-frequency data, which are questionable because the existence of multi-phase in elastomer compounds. Until now, no reliable data at high frequencies over MHz are available.; Ultrasonic measurement techniques are most cost-effective for measuring high-frequency properties. In order to fully characterize high-frequency mechanical properties of materials, both ultrasonic longitudinal and shear properties are necessary. Ultrasonic pulse echo method can measure longitudinal properties precisely, while shear properties can only be determined by ultrasonic impedance method due to high shear attenuation of soft materials. However, currently there are still some major difficulties in determination of high-frequency shear properties of soft materials using this technique.; One of the challenges for ultrasonic impedance technique is the requirement of high-precision ultrasonic data that are not feasible even a decade ago and currently are still limited to the sampling precision of A/D converter. Another more important factor is that the adhesion between the specimens and measurement device has never been perfect and repeatable, which is influenced by applied load, location, composition (carbon black loadings, etc.), and processing conditions, etc. However, at present, studies of high-frequency properties using ultrasonic impedance technique are almost based on the assumption of perfect contact. A new evaluation approach considering the effects of adhesion needs to be developed.; In this dissertation, a device of ultrasonic soft material and surface analyzer (USMASA) is established based on ultrasonic impedance technique. The device can determine both high frequency longitudinal and shear properties by one measurement. The reliability of USMASA is demonstrated through the characterization of water and sillyputty® that have almost perfect contact with the device.; USMASA is a valuable tool of monitoring adhesion dynamics. The adhesions between filled elastomers and fused silica plate, including the effects of pressure, specimen surface treatments with solvents, and composition of materials, were studied with USMASA.; Furthermore, a new evaluation scheme including adhesion effects is presented. The high-frequency shear properties of carbon black filled rubbers were characterized by USMASA. The effects of filler loading level, filler type, filler dispersion, base polymer, and temperature on high-frequency shear properties were discussed. The effects of different compound preparation techniques could be evaluated effectively by USMASA. |
| Keyword | elastomer; high frequency; rheology; shear properties; ultrasonic |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m2433 |
| Contributing entity | University of Southern California |
| Rights | Yang, Wei |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@dots.usc.edu |
| Filename | etd-Yang-3114 |
| Archival file | uscthesesreloadpub_Volume55/etd-Yang-3114.pdf |
Description
| Title | Page 1 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@dots.usc.edu |
| Full text | THEORY AND APPLICATIONS OF ULTRASONIC SOFT MATERIALS AND SURFACE ANALYZER (USMASA) by Wei Yang ________________________________________________________________________ A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (CHEMICAL ENGINEERING) August 2009 Copyright 2009 Wei Yang |
