Micromechanical String Resonators: Analytical Tool for Thermal Characterization of Polymers

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• 作者：Sanjukta Bose ; Silvan Schmid ; Tom Larsen ; Stephan S. Keller ; Peter Sommer-Larsen ; Anja Boisen ; Kristoffer Almdal
• 刊名：ACS Macro Letters
• 出版年：2014
• 出版时间：January 21, 2014
• 年：2014
• 卷：3
• 期：1
• 页码：55-58
• 全文大小：279K
• ISSN：2161-1653

文摘

Resonant microstrings show promise as a new analytical tool for thermal characterization of polymers with only few nanograms of sample. The detection of the glass transition temperature (T_g) of an amorphous poly(d,l-lactide) (PDLLA) and a semicrystalline poly(l-lactide) (PLLA) is investigated. The polymers are spray coated on one side of the resonating microstrings. The resonance frequency and quality factor (Q) are measured simultaneously as a function of temperature. Change in the resonance frequency reflects a change in static tensile stress, which yields information about the Young鈥檚 modulus of the polymer, and a change in Q reflects the change in damping of the polymer-coated string. The frequency response of the microstring is validated with an analytical model. From the frequency independent tensile stress change, static T_g values of 40.6 and 57.6 掳C were measured for PDLLA and PLLA, respectively. The frequency-dependent damping from Q indicates higher T_g values of 62.6 and 88.8 掳C for PDLLA and PLLA, respectively, at 10⁵ Hz. Resonant microstrings facilitate thermal analysis of nanogram polymer samples measuring the static and a dynamic glass transition temperature simultaneously.