Investigation of resistivity-strain sensitivity and electromagnetic wave shielding properties of carbon-filled flexible conductor polymer composites

The use of conductive polymer composites (CPCs) for strain sensing applications has attracted great interest recently. Flexible strain-sensitive CPCs have been playing an important role in various fields in recent years, especially in wearable electronics, healthcare equipment, and electronic coatings. A wide variety of materials are used in these applications; however, thermoplastic polyurethane (TPU) stands out due to its elastomer-like behavior, favorable flexibility, ease of processing, chemical stability, and ease of combination with various conductive materials. These properties of thermoplastic polyurethanes (TPU) provide better stretchability, higher sensitivity, and a wider detection range for flexible strain-sensitive CPCs. Carbon-based fillers find a place in elastic stress-sensitive CPCs due to their good mechanical and conductivity properties. Polymer composites with electromagnetic shielding properties have recently attracted the attention of researchers. In this thesis, TPU matrix conductive composites were preoduced using carbon-based conductive fillers. It was aimed to observe the effect of fillers with different geometries used in these prepared composites on the mechanical, morphological, conductivity, strain sensitivity and electromagnetic wave shielding properties of the composite. Carbon fiber and graphite were used as fillers in these CPCs. By using carbon-based conductive fillers of different geometries and sizes, the effects of these fillers on strain sensor sensitivity and electromagnetic shielding properties are discussed. While the morphological properties of the composites prepared in the study were determined by scanning electron microscopy (SEM), the mechanical properties and hardness results of the samples were evaluated with increasing filling ratio. The relationship between the filling ratio and conductivity of the prepared CPC's was observed. Additionally, the resistivity-strain behavior of CPC's was examined. Finally, the electromagnetic properties and electromagnetic shielding effectiveness of these composites were evaluated. As a result of this thesis study, the effect of carbon-based fillers of different geometries and sizes on strain sensor sensitivity and electromagnetic shielding effectiveness was discussed, and TPU matrix conductive polymer composites with optimum levels of both sensor sensitivity and electromagnetic shielding effectiveness were determined.