An innovative microwave cavity sensor for non-destructive characterisation of polymers

This paper investigates the feasibility of using an innovative microwave sensing technology to characterise and study various properties of polymer material such as difference between various polymer types, particle size and particle size distribution, contamination and pigmentation. A microwave sensor designed previously has been utilised to carry out this initial study to analyse the capability of microwave techniques to carry out the analysis. The curves obtained from material response to microwaves are distinguishable showing the shift to the lower frequency end with the insertion of polymer material. S11 measurements have shown distinctive peaks for each size and type of the sample tested. The results are quantifiable in terms of various polymer properties under consideration. In terms of S21 measurements, microwave sensor clearly distinguishes between coarse and fine polymer samples in terms of particle size. The effect of air voids in the sample and the particle size distribution has also been studied. The results are promising and justifies a thorough design and development of a dedicated microwave sensor unit for the characterisation of polymers. The sensor will have a significant industrial benefit in terms of costs associated with the industrial analysis, increase in the efficiency of manufacturing and production operation as well as material quality, control and validation.