An undergraduate laboratory experiment on nucleation and growth via polarizing optical microscopy of semicrystalline polymers.

The article focuses on an instructional laboratory experiment designed for undergraduate students to study nucleation and growth in semicrystalline polymers, specifically polyethylene oxide (PEO), using polarizing optical microscopy (POM) and the concept of birefringence. The experiment demonstrates how the microstructure of PEO, characterized by birefringent spherulites visible as Maltese cross extinction patterns under crossed polars, varies with transformation temperature and undercooling, showing increased spherulite areal density at larger undercoolings. Real-time video microscopy of solidification at room temperature allows students to analyze the kinetics of phase transformation, which aligns well with the Avrami nucleation and growth model. This low-cost experiment integrates principles from materials science, optics, and thermodynamics, providing experiential learning that reinforces theoretical concepts related to phase transformations and polymer microstructures.