Development of a Dielectric Nonresonant Spectral Hole Burning Capability

Shankar Kollengodu-Subramanian

Studying the Viscoleastic Properties of Glassy Polymers in the Vicinity of Glass Transition Temperature Using Time Domain Dielectric Spectroscopy

Kollengodu-Subramanian, Shankar

Dielectric spectroscopy is a novel technique which can be used to probe dynamics in the range of 10-6 to 106 in time or frequency. It has been used with great success to explain the dynamic heterogeneity in small molecules and polymers (1, 2, 3). However, there is only limited work available in the literature to study responses such as the memory effect in glassy polymers (4, 5) that has been widely discussed in mechanical measurements. Here, we have set up a custom built dielectric spectrometer for the purpose of studying these properties of glassy polymers in the vicinity of the glass transition temperature. This technique will also be used to explain the anomalous differences observed in structural recovery and physical aging experiments after plasticizer and temperature jumps to the same final condition in polymeric glasses that has been previously observed using mechanical and volumetric measurements in our lab (6, 7).

Preliminary results for Poly(Vinyl acetate) (PVAc) subjected to isothermal scans are shown in Figure 1. Modified KWW fit (solid lines) has been used to capture the full range of the data including the Dc conductivity. Figure 2 is the master curve of the data of Figure 1. The horizontal shift factors are shown in Figure 3 are in reasonable agreement with the literature. The memory effect observed using pulse probe technique is shown in Figure 4.

Figure 1: Isothermal scan of PVAc
Figure 2: Time temperature superposition of Figure 1

Figure 3: Horizontal Shift factor of Figure 1
Figure 4: Pulsed probe data of PVAc at different time interval

References

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Funding

• • National Science Foundation