Nanocomposites and nanomaterials

Piezoresistive polymer nanocomposites with segregated structure
Maruzhenko O.V.1, Mamunya Ye.P.1, Pruvost S.2, Boiteux G.3
1 Institute of Macromolecular Chemistry of NAS of Ukraine
48, Kharkivske shose, Kyiv, 02160, Ukraine
E-mail: ymamunya@ukr.net
2 Université de Lyon, INSA Lyon, Ingénierie des Matériaux Polymères;
UMR CNRS 5223, 69 621 Villeurbanne Cedex, France
3 Université de Lyon, Université Lyon 1, Ingénierie des Matériaux Polymères;
UMR CNRS 5223, 69 622 Villeurbanne Cedex, France

Modern technologies require novel polymer composites with coupled properties. In particular, composites having a piezoresistive effect are of great interest for the development of sensors having a direct electrical response to the action of mechanical loads.
The investigated polymer nanocomposites had a segregated structure, which means the creation of a filler-ordered structure as a framework in the polymer matrix. The local concentration of filler in the framework is much higher than the average filler concentration at its statistical distribution in the entire volume of the composite. This distribution of fillers inside the polymer matrix leads to high electrical conductivity at low filler concentration. Ground rubber with a particle size of 250 m was selected as the elastic, mechanically-sensitive matrix. The composites were processed by hot compacting method. Before compacting the rubber, the particles were covered by adhesive polymer filled with hybrid carbon filler, CB/CNT, which creates a conductive framework structure localized at the boundary between the rubber grains.
The piezoresistive effect was investigated by cyclic loading (10 cycles) of the samples with the change of force in a range of 0.1-1.0-0.1 N (it corresponds to an interval 0.014-0.141 MPa) and recording the electrical response, namely the current I (mA) with the applied constant voltage U = 2 V. The samples were characterized at different loading frequencies in the range of 0.1-0.001 Hz.
The results of the experiments demonstrated the high sensitivity of the composites to the action of low loads, which is explained by the high elasticity of the polymer matrix. The electrical response (current) corresponded to the applied force and remained unchanged as the loading frequency changed. The systems under study also highlighted the stability of the results during long cycle tests, indicating their durability.