Low‐Temperature FT‐NIR Spectroscopy of Strain‐Induced Orientation and Crystallization in a Poly(dimethylsiloxane) Network

Summary: The mechanical properties, morphology, and orientation of a poly(dimethylsiloxane) (PDMS) network have been studied during cyclic elongation and recovery by simultaneous Fourier‐transform near‐infrared polarization spectroscopy at temperatures ranging from room temperature to −40 °C. Completely different orientation/recovery mechanisms and changes in the state of order of PDMS were detected as a consequence of cyclic loading/unloading with decreasing temperature. The differences observed at −20 °C compared to room temperature are explained in terms of conformationally regular chain segments, whereas the cooling to −40 °C leads to the formation of lamellar crystals. Stress/strain diagrams of the elongation/recovery‐cycles of the PDMS films. magnified image Stress/strain diagrams of the elongation/recovery‐cycles of the PDMS films.