Quartz Enhanced Conductance Spectroscopy for Polymer Nano-Mechanical Thermal Analysis

Shangzhi Li,Biao Li,Zhijin Shang,Lei Dong,Bo Sun,Ruyue Cui,Hongpeng Wu

doi:10.3390/app10144954

Abstract

A fast and highly sensitive polymer nano-mechanical thermal analysis method for determining the melting temperature (Tm) of polymer microwires was proposed. In this method, a small-size, low-cost quartz tuning fork was used as a piezoelectric transducer to analyze the thermodynamics of polymer microwires at the nanogram level without changing its own properties. Due to the thin wire sample, which has a length of 1.2 mm and a diameter of ~5 µm, which is bridged across the prongs of the tuning fork, the nanogram-level sample greatly reduces the thermal equilibrium time for the measurement, resulting in a fast analysis for the melting temperature of the polymer sample. Compared with the traditional method, the analysis method based on the quartz enhanced conductivity spectrum (QECS) does not require annealing before measurement, which is an essential process for conventional thermal analysis to reduce the hardness, refine the grain, and eliminate the residual stress. In this work, the melting temperatures of three of the most commonly used polymers, namely polymers polymethyl methacrylate, high-density polyethylene, and disproportionated rosin, were obtained under the temperature from room temperature to >180 °C, proving the QECS method to be a useful tool for nano-mechanical thermal analysis.

Highlights

The nanomechanics of polymer materials has become increasingly significant for advanced technological applications including the field of optics, electricity, acoustics, mechanics, and biomedicine [1]
We proposed a fast and convenient method to determine the polymer Tm based on a quartz tuning fork (QTF), which was characterized by the features of small volume but femto-Newton level force sensing [23,24]
A fast and highly sensitive method for polymer nanomechanical thermal analysis was developed based on a commercially available QTF which costs less than one dollar

Summary

Introduction

The nanomechanics of polymer materials has become increasingly significant for advanced technological applications including the field of optics, electricity, acoustics, mechanics, and biomedicine [1]. Capillary melting point measurement is one of the conventional approaches to determine the Tm [14,15,16] In this method, the powder samples are placed in the capillary tube with a temperature increment of 1 ◦ C/min and the Tm corresponds to the temperature at which the powder samples in the tube begin to fall, and small droplets appear. Heating the samples at a constant temperature rise rate, the melting of the sample and the disappearance of the birefringence phenomenon determines the Tm. In this paper, we proposed a fast and convenient method to determine the polymer Tm based on a quartz tuning fork (QTF), which was characterized by the features of small volume but femto-Newton level force sensing [23,24]. The thermodynamics of three of the most commonly used polymers, namely, polymethyl methacrylate (PMMA), high-density polyethylene (HDPE), and disproportionated rosin (DPR) were analyzed in order to determine the Tm with the sample requirement of a few nanograms

Experimental Section

Photograph

10 System

Results

Conclusions