研究目的
To develop quartz-enhanced conductance spectroscopy as an analytical tool for investigating dynamic nanomechanical behaviors of polymer wires to determine the glass transition temperature (Tg).
研究成果
The study successfully developed quartz-enhanced conductance spectroscopy as a fast and highly sensitive tool for measuring the glass transition temperature of polymer samples at the nanoscale. The technique is reversible and reproducible, with potential applications in dynamic mechanics investigation of polymer nanowires and blends.
研究不足
The error in Tg measurement is estimated at 62 (cid:2)C, mainly due to uncertainty in the actual temperature of the microwires and the broad maximum area of the loss modulus vs temperature curve. The acquisition time for resonance frequency and Q factor is approximately 1 min, which could be improved.
1：Experimental Design and Method Selection:
The study utilized quartz-enhanced conductance spectroscopy (QECS) to analyze the dynamic nanomechanical behaviors of a polymethyl methacrylate (PMMA) microwire. The resonance frequency and Q factor of the quartz tuning fork (QTF) modified with the PMMA microwire were measured through electrical conductance spectra.
2：Sample Selection and Data Sources:
A PMMA microwire with a diameter of 10 lm was bridged across the prongs of a QTF. The PMMA was prepared by heating the powder above its melting point and pulling a wire from the melt.
3：List of Experimental Equipment and Materials:
Quartz tuning forks (QTF), PMMA powder, resistive heater, tungsten tip, epoxy resin adhesive, optical microscope, function generator (Agilent 33210 A), lock-in amplifier (Stanford Research System model SR830), data acquisition card (DAQ), PT100 temperature sensor.
4：Experimental Procedures and Operational Workflow:
The PMMA microwire was glued across the QTF prongs and installed in a heating cell. The temperature was controlled from room temperature to 160 (cid:2)C. The resonance frequency and Q factor were measured by scanning the frequency of the external excitation source and analyzing the conductance spectra.
5：Data Analysis Methods:
The resonance frequency and Q factor were calculated from a Lorenz curve fitting to the square of the amplitude associated with the conductance spectra. The loss modulus was calculated to determine the Tg.
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