Date of Award
Master of Engineering Science
Mechanical and Materials Engineering
Dr. D. M. Shinozaki
Recently, Polydimethylsiloxane (PDMS) has attracted much attention as a useful polymer in various fields due to its excellent properties. On the contrary poor mechanical properties are the major drawbacks of PDMS which has led to many researches to overcome this deficiency.
One way to enhance the mechanical properties and broaden the applications is preparation of nanocomposite of PDMS and clay along with probing the mechanical properties. Among the mechanical characterization methods, indentation technique is known as a useful method to examine the local mechanical properties of PDMS and PDMS-clay nanocomposites.
In this study, flat indentation test is carried out on bulk PDMS and PDMS-clay nanocomposites. Validity of the Sneddon’s theory proposed for flat cylindrical indenter is approved in terms of both elastic deformations under the flat tip and indentation load- displacement behavior for filled and unfilled PDMS. Moreover effect of clay and cross linker amount on the stress fields and indentation load-displacement curves is discussed. Stress distributions along radial distance by finite element analysis (FEA) are examined to investigate the reason of radial crack initiation during indentation test.
Indentation test of thin films of PDMS and PDMS-clay filled nanocomposite adhering to the rigid substrate was also conducted. Distribution of the radial and shear stresses near the interface regime is examined by FEA to assess the validity of Dehm et al.’s model. The result showed a good agreement with Dehm’s model which was used to compute the critical interfacial shear strength leading failure in the interface of thin film and substrate.
Nazari, Amir Mohammad, "Flat Indentation of Filled and Unfilled PDMS" (2011). Digitized Theses. 3369.