Study on Electromagnetic Properties of Sendust/MWCNTs/Polymer Composites

Abstract

This dissertation is about a study of making an electromagnetic wave absorption material that has high permeability and high permittivity. As a first step to make a hybrid composite that satisfy these two properties, a magnetic absorber (mixing Sendust with polymer) and a dielectric absorber (mixing MWCNTs with polymer) was made through melt mixing and solution mixing process. And to measure the permeability and permittivity of each absorber, vector network analyzer was used as a measurement tool. The measurement results showed that the complex permeability and the electromagnetic wave absorption ability of a magnetic absorber increased in two conditions: when more amount of Sendsut was mixed and by using flake shape Sendust instead of bulk shape. While the complex permittivity and the electromagnetic wave absorption ability of a dielectric absorber proportionated to the weight ratio of MWCNTs. Sendust/MWCNTs/polymer composites were created in order to make an electromagnetic wave absorption material as initially planned. We challenged to make the best hybrid composite that could gratify the conditions of preserving high permeability and high permittivity by changing the proportion of filler. In order to get a fixed permeability value contain of Sudust was fixed to 100 phr and 3 composites were made by adjusting the amount of MWCNTs to 5 phr, 10 phr and 15 phr. The result showed that the complex permittivity and the power loss increases as more filler was mixed but this was not promising because there was great reduction of reflection loss. The most realistic and effective hybrid composite was the composite with 5 phr of MWCNTs which was lighter and had excellent electromagnetic wave absorption with only 16 dB at a 4.6 GHz frequency.