The properties of a material depend strongly on the microstructure, which is in turn influenced by the processing the material has undergone. In this lab, students investigate how the crystallization temperature affects the growth rate of polymer crystals, and also the size of the resulting microstructural features. Using the heating stage and an optical microscope, students can watch and record in real time how polyethylene oxide crystals (spherulites) form from the melt as the liquid polymer is quickly cooled down. Differential Scanning Calorimetry (DSC) is also used to measure the latent heat of fusion and melting temperature, in order to compare the experimental growth rate to the theoretical model.
PROCEDURE – POLYMER CRYSTALLIZATION
Equipment Used
- Optical microscopes (Nikon and Olympus)
- Linkam hot-stage and controller (PE 94 or PE 95), with Linksys 32 software where appropriate
- Crossed polarizing filters
- Digital camera with Infinity Analyze for image capture
- Clean silicon wafers
- Spin coater
- PerkinElmer DSC (Jade and DSC 4000 models) with Pyris Manager software
- Al DSC pans and lids
- Crimper for DSC pans
Material Tested
- Poly(ethylene oxide) in acetonitrile solution
- Powdered poly(ethylene oxide) for DSC trial