Damage Sensing in CNT-Polypropylene Composites by Electrical Resistance Measurement for Automobile Applications

摘要

Polypropylene (PP) is suitable as a matrix polymer because of its low price and favorable properties such as good stiffness, lightweight, good weathering ability, design flexibility and good mechanical properties [1]. During their service life, damage initiates in the polymer matrix in the form of microcracks or delaminations [2]. The carbon nanotubes (CNTs) have attractive properties for producing conductive composites with a minimum of additional constituents. One of the advantages of CNTs as a reinforcement is their large surface area that can induce a better adhesion with the polymeric matrix, which is an important factor for an effective enhancement of the composite properties [3]. However, due to the strong intermolecular interactions among the nanotubes, which can lead to the formation of aggregates, it is very difficult to uniformly disperse CNT in a polymer matrix. Good dispersion of the CNTs in a polymer matrix is a prerequisite to optimize CNT as effective reinforcing filler for polymer composites [4]. The development of favorable thermoplastic-based matrices, while maintaining properties similar to those of thermosetting polymer composites, would be very advantageous for many industrial needs. Minimizing the filler percentage while retaining good polymer properties would reduces costs. The high aspect ratios of CNTs shows promise of significantly enhancing the mechanical properties of polymers at low filler concentrations [5]. The introduction of CNTs into the polymer matrix is a promising approach for damage monitoring. Generally, electrical resistance measurements are based on the principle that any change in the dimensions of the matrix affects the conductive paths within it, and it has been investigated as a nondestructive means of damage monitoring.