Optimised use of dielectric spectroscopy at microwave frequencies for direct online monitoring of polymerisation reactions

SENSORS AND ACTUATORS B-CHEMICAL

卷:290

Article

Kalamiotis, Alexis¹  Ilchev, Alexander¹  Irvine, Derek J.¹  Dimitrakis, Georgios¹ 

[1] Univ Nottingham, Dept Chem & Environm Engn, Fac Engn, Nottingham NG7 2RD, England

关键词: Dielectric spectroscopy;    Coaxial sensors;    Online monitoring;    epsilon-caprolactone;    Ring opening polymerization;   

DOI  :  10.1016/j.snb.2019.03.120

来源: Elsevier

【 摘 要 】

This study reports the first use of dielectric spectroscopy over at a wide frequency range to monitor, in real time, the progress of a ring opening polymerisation. An open-ended coaxial line sensor was placed directly into the reaction medium of a polymerisation of e-caprolactone and used to characterise the dielectric properties of the polymerisation mixture both 'in-situ' and with time at microwave frequencies. In addition to measurements obtained by the sensor, samples of the medium were extracted at various time points for off-line analysis, to confirm the level of conversion and polymer molecular weights that had been achieved. The results demonstrated that the dielectric properties values exhibited by the reaction medium with time could be correlated directly to the progress of the reaction. Thus, the experimental data allowed the construction of a calibration curve which could be used to predict the conversion of monomer to polymer at any given point of the reaction. The dielectric data permitted also the identification of key reaction parameters, such as the optimum point of termination for the reaction. Furthermore, the analysis of the dielectric data over a wide frequency spectrum enabled the identification of the most suitable frequencies for the practical operation of the sensor, in terms of linearity and sensitivity. This will enable the development of suitable instrumentation and an improved strategy for the online monitoring and control of a broad range of polymerisation reactions.

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