Characterization of Some Functional Polymeric Composites in a Synergistic Regime of Protection at Electromagnetic Shielding and Electrostatic Transfer

The paper presents the characterization of 5 polymer composite materials with a poly-propylene (PP) matrix obtained with different (mass) concentrations of strontium ferrite (Fe12SrO19) reinforcement that have synergistic protective properties against electrostatic discharges (ESD) and electromagnetic impulses (EMI). These types of composites can be used to protect electronic equipment. To this purpose, suitable polymer composites were developed using SrFe12O19 type filler in two forms (powder and concentrate). The weight ratio of the PP/SrFe12O19 composites obtained by the extrusion process and injection from the melt is 75/25 and 70/30. The characterization of these composite materials consisted of carrying out some physico-chemical tests to determine the hydrostatic density and the resistance to the action of water, as well as FTIR, UV-Vis analyzes and dielectric, magnetic and functional tests to identify the simultaneous protection performance at electromagnetic shielding and electrostatic discharges, which can occur in the electro-technical, electronics and automotive industries. It is also found that all composite materials presented reflection shielding properties (SER) in the range: -71.5 dB...to -56.7 dB, indicating very low absorption shielding. The best performing material was the PP/SrFe12O19 powder composite with a weight ratio of 70/30. At the same time, EDS tests were also carried out on these materials. For these applications, the surface resistance Rs and the point-to-point resistance Rp were tested. Recommended composites for simultaneous EMI and sensitivity to electrostatic discharges (ESD) functionality, in order of their performance, are M2 (with 30% ferrite powder) and M1 (with 25% ferrite powder). M4 composite (with 30% ferrite powder concentrate) can also be used at the limit. Following the research carried out, the obtained results recommend the composite with promising simultaneous operations as M2 (with 30% ferrite powder). The element of originality consists of obtaining polymer composites with simultaneous properties of protection against electromagnetic impulses and electrostatic discharges.