טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentStauber Uri
SubjectMechanical Properties of polyetherimide (ULTEM 1000R)
DepartmentDepartment of Mechanical Engineering
Supervisors Professor Daniel Rittel
Dr. Nitzan Link
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

The mechanical properties of materials change with environmental conditions, such as temperature , pressure and acidity. In order to incorporate a certain material in the industry, properties and life span should be estimated. The present study reports the static and dynamic mechanical properties of ULTEM? (polyetherimide - PEI) ,a polymer frequently used for medical and chemical instrumentation, for which very little data is available mostly in the high strain-rate regime . In our research the influence of humidity, strain rate, load direction and hydrostatic pressure on the material were tested, as these parameters were found to influence the mechanical properties of other polymers as well. To better understand the influence of the hydrostatic pressure, finite element simulations were carried out . Among the main results of this work, we observed a lack of symmetry between the tensile and compressive properties of ULTEM?, a fact that indicates its sensitivity to hydrostatic pressure. A linear relation was identified between the peak stress and the applied hydrostatic pressure on it , while an exponential relation was identified between the peak stress and the strain rate. The pressure sensitivity of this polymer was determined to be twice as high as that previously determined for glassy commercial polymers such as PMMA and polycarbonate. However, unlike for these two polymers, it was also observed that the pressure sensitivity is influenced by the strain rate. This study reveals that moisture absorption within limits similar to those encountered in real life had no significant influence on the mechanical properties of ULTEM?. The above-mentioned results were cast into a simple constitutive relation at the high strain rate regime that can be implemented into numerical simulations .