1. MOHAMMED ALZAYER CHRIS CLAY XINHANG SHEN CTE Measurements Using POM MAT E 453 11/11/14

2. Outline ◊Background History Theory ◊Procedures Microscope Temperature Controller Procedural Steps ◊Results Average CTE Standard Deviation ◊Discussion Advantages of POM Possible Improvements ◊Conclusions

3. Background: History ◊First OM: Who, Where, When? Zacharias and Hans Jansen, Netherlands, 16 th century. [1] ◊Modern OM: Who, Where, When? Robert Hooke, England, 1864. Only opaque and etched samples. [2] Fig 1. First OM. [1] Fig 2. Hooke’s OM. [1]

4. Background: Theory [2] ◊What OM does: Identifies phases. ◊How it works: Sends beam of light through the sample: 1.Condenser Lens: Focuses light on sample. 2.Objective Lens: Magnifies the beam (10X,50X….). 3.Projector Lens: Allows image to be viewed by observer. Fig 3. OM schematic. [2]

5. Background: Theory [2] ◊Polarizer: allows a permitted direction of vibration. ◊Advantage: Enhances contrast based on refractive indices in different directions. ◊Polymers: Amorphous regions appear opaque, crystalline regions appear light. Fig 4. Light polarization schematic. [2]

6. Background: Theory [2] ◊Coefficient of Thermal Expansion (α, CTE): “a property that indicates the extent to which a material expands upon heating.” ◊α: linear coefficient of thermal expansion. (µm/m °C) ◊dr: infinitesimal change in length. (µm) ◊dT: Temperature range over which the change occurs. ( °C) ◊r 0 : Original length of sample. (m)

7. Procedures: Microscope Eyepiece Objective Lens Polarizer Translational Thermal Stage Iris/Shutter Camera Objective Device Selection Slider Analyzer (Polarizer 2) Power Switch Fine Knob Coarse Knob Light Intensity Knob Fig 5. POM used. [2]

8. Procedures: T Controller Fig 6. Temperature controller.

9. ◊Sample: Ultem ® polyetherimide (PEI) film: 1 cm x 1 cm x 25 µm. ◊Equipment: Imaging program, camera, microscope, and temperature controller. Procedures Fig 7. Eyewear frame made of PEI. [3]

10. 1. PEI film slide put on heating stage. 2. Focused, adjusted light and polarization at 50x. 3. The temperature controller set to hold at 30, 40, 50, 60, 70, 80, and 100 °C for 4 minutes. 4. Heating rate of 10 °C/min between temps. 5. Images collected at each temperature. Procedures

11. ◊Origin Point ◊Five crystalline regions ◊Sample Calculation: Results: Method 1 Fig 8. Microscopic image of PEI film with five crystalline regions identified. Note: Conversion factor for 50X objective lens is 100 µm/484 pixels. [2]

12. ◊Average: 155 ppm/K ◊Standard Deviation: 1190 ppm/K Results: Method 1 Fig 9. Graph showing the calculated CTE values as a function of temperature.

13. Results: Method 2 Fig 10. Microscopic image of PEI film with five crystalline regions identified. ◊Five crystalline regions ◊Drew lines to x and y axis ◊Distance calculated using Pythagorean Theorem

14. ◊Average: 45 ppm/K ◊Standard Deviation: 27 ppm/K Results: Method 2 Fig 11. Graph showing the calculated CTE values as a function of temperature.

15. ◊TMA vs POM: Polarized Optical Microscopy is non- invasive, unlike TMA. ◊Further Improvements: 1. More data points could improve average and standard deviation. 2. Automated software could obtain more accurate results more easily. Discussion

16. ◊Both samples showed less deviation at higher temperatures. ◊Internal stress relief at higher temperatures. Discussion Fig 12. CTE vs T, Method 1.Fig 13. CTE vs T, Method 2.

17. ◊Method 1: Average CTE of 155 ppm/K ◊Method 2: Average CTE of 45 ppm/K ◊Literature: CTE of 45-56 ppm/K [4][5] Discussion

18. ◊Method 1: Sample moved in a circle. Possibly due to internal stress due to cutting of film with Exacto-knife. ◊Method 2: sample moved in one direction, more consistent with expectations. Discussion

19. Fig 14. Illustration of Method 1 ‘circle movement.’

20. Discussion Fig 15. Illustration of Method 2 normal movement.

21. 1.POM is a good method to determine CTE. 2.Method 2 agreed with literature CTE. 3.Method 1 had internal stresses causing faulty results. 4.Better results could be obtained by taking more data points. Conclusions

22. [1] “History of the Light Microscope.” History-of-the- Microscope.org. 2010. Web. 09 Nov. 2014. [2] De Leon, Jose. “Lab 9: Contact-free measurement of coefficient of thermal expansion using polarized optical microscopy.” Iowa State University. Web. 09 Nov. 2014. [3] “New Zoff SMART Eyewear Frames Using SABIC’s Ultem* Resin.” NieuwsBank, 2012. Web. 09 Nov. 2014. [4] "Thermal Expansion Coefficients - Plastics - Engineer's Handbook." Thermal Expansion Coefficients - Plastics. Engineer's Handbook, 2006. Web. 09 Nov. 2014. [5] Supplier Data - Polyetherimide ( PEI ) ( Goodfellow ). AZO Materials, 11 June 2013. Web. 09 Nov. 2014. References