Development of Poly (butylene adipate-co-terephthalate) Filled with Montmorillonite-Polypyrrole for Pressure Sensor Applications

Abstract

A novel pressure sensing material composed of poly (butylene adipate-co-terephthalate) (PBAT) and montmorillonite-polypyrrole (Mt-PPy) was prepared using melt mixing and injection molding. The structure and properties of the PBAT/Mt-PPy composites were evaluated and compared with those of the PBAT/PPy blends. The PBAT/Mt-PPy displays a very sharp insulator-conductor transition and its percolation threshold was reached at 6.5 wt% of Mt-PPy, which was lower than that for PBAT/ PPy (11.0 wt% of PPy). The transmission electron microscopy analysis shows that Mt-PPy displays a high aspect ratio and was better distributed and dispersed into PBAT compared to PPy. PBAT/Mt-PPy exhibits a decrease in the electrical resistivity with an applied compressive stress due to the formation of new conducting pathways. The electromechanical response was dependent on Mt-PPy and the maximum sensitivity was observed for the composite containing 10 wt% of Mt-PPy. In this system, the electrical resistivity drops from 9 x 10 6 to 2 x 10 6 Ω cm when a compressive stress of 0.25 MPa was applied. The electrical resistivity changes with applied compressive stress, the reproducibility and the reversibility makes PBAT/Mt-PPy a suitable material for the development of pressure sensors.

Fabrication and characterization of piezoresistive flexible pressure sensors based on poly(vinylidene fluoride)/thermoplastic polyurethane filled with carbon black‐polypyrrole

“…However, when the compressive force is released, the composite returns to its undeformed shape and the initial electrical conductivity is restored. 2,3,8,[11][12][13] Nevertheless, during the cyclic loading the conductive network of the filler can be irreversibly modified and hysteresis effects might be observed after repeated loading-unloading cycles, which is also related to the polymers viscoelasticity and interaction between components of the mixture. 3,6,9,14 The main challenge in the development of sensors based on CPCs is achieving good responses at minimum filler concentration to maintain the mechanical properties and processability of the matrix.…”

Pressure Sensibility of Conductive Rubber Based on NBR- and Polypyrrole-Designed Materials

“…Pressure sensors are quite interesting materials to be used in areas such as medical and computer science (Job et al, 2003;Rosa et al, 2019). Conductive rubber is a composite material of an elastomeric matrix and conductive particles as a dispersed phase.…”

“…Typically, the conductive particles are carbon composites and/or intrinsically conducting polymers (ICP) (Ali and Abo-Hashem, 1997;Cho et al, 1998;Sombatsompop et al, 2000;Das et al, 2002;Knite et al, 2004;Bing et al, 2010). This last class has attracted the attention of a wide academic and technological field since they combine electrical properties, similar to metals, and mechanical properties and processability inherent to conventional polymers (Mattoso, 1996;Job et al, 2003;Swart et al, 2017;Sethi et al, 2018;Rosa et al, 2019). The addition of ICP in elastomers can combine the electrical and mechanical properties of these two classes of polymer in one (Hussain et al, 2001;Soto-Oviedo et al, 2006;Tran et al, 2018), allowing its application on technological fields such as pressure sensors, electric wires and cables coating, electrical contacts, carpet with antistatic properties, and others (Mravčáková et al, 2006;Bing et al, 2010).…”

“…The electrical conductivity of conductive rubber depends on factors such as the nature of the elastomeric matrix and the type, size, structure, surface, and dispersion of the conductive particles as well as the test conditions, such as temperature and pressure (Ali and Abo-Hashem, 1997;Sombatsompop et al, 2000;Job et al, 2003;Bing et al, 2010). The conductor path is created by the different sizes and shapes of conducting particles homogeneously distributed and closer to each other (Hussain et al, 2001;Rosa et al, 2019). At the percolation threshold, the contact between the particles produces a conductive network that can be improved during the compression.…”

“…Then, the use of an inorganic matrix [e.g., organomontmorillonite clay (OMt)] as a template for ICP synthesis is interesting to improve the compatibility of the conductive polymer and the elastomeric matrix, affording a material with superior mechanical properties (Baldissera and Ferreira, 2017). In addition, ICP produced in a confined environment, such as clays, produces a material with superior polymer chain organization and, consequently, higher electrical conductivity and thermal stability, which enables melt processing without degradation and/or electrical properties loss (Mravčáková et al, 2006;Soto-Oviedo et al, 2006;Rosa et al, 2019). Furthermore, the combination of silver nanoparticles with ICP improves the conductivity of the polymer (Wei et al, 2010) and opens the opportunity to use humidity and chemoreceptive sensors (Jlassi et al, 2013).…”