# PLA/MWNTs Conductive Polymer Composites as Stress Sensors—The Role of Supramolecular Ordering

## TL;DR

This study explores how supramolecular ordering in PLA/MWNTs composites affects their performance as stress sensors, showing that low nanotube content can still yield effective sensors.

## Contribution

The study introduces a new approach to sensor development by linking supramolecular ordering in PLA to the electromechanical response of nanocomposites.

## Key findings

- PLA/MWNTs nanocomposites with low nanotube content show effective stress-sensing properties.
- Supramolecular ordering of the PLA matrix significantly influences the sensor's response to cyclic stress.
- A low percolation threshold of 0.2 wt.% was achieved using the precipitation method for filler dispersion.

## Abstract

What are the main findings?
Developing PLA-based nanocomposite stress sensor with low MWNTs content.Identifying the limits of applicability of PLA/MWNTs stress sensors based on stress-induced crystallization phenomenon.

Developing PLA-based nanocomposite stress sensor with low MWNTs content.

Identifying the limits of applicability of PLA/MWNTs stress sensors based on stress-induced crystallization phenomenon.

What is the implication of the main finding?
A new approach to the development of resistive sensors based on the supramolecular ordering of PLA matrix.Validation of the relationship between the quantity of nanoaditive, the supramolecular structure of the polymer matrix, and the stability of the nanocomposite in assessing its sensory response to cyclic stress.

A new approach to the development of resistive sensors based on the supramolecular ordering of PLA matrix.

Validation of the relationship between the quantity of nanoaditive, the supramolecular structure of the polymer matrix, and the stability of the nanocomposite in assessing its sensory response to cyclic stress.

The incorporation of carbon nanostructures into polymer composites is of significant importance for the development of novel sensor materials, due to the excellent mechanical strength and variable electrical conductivity that these structures provide. It is evident that the significance of polylactide (PLA) and carbon nanotube (CNT) systems is attributable to two key factors. Firstly, these systems are notable for their environmental sustainability. Secondly, they exhibit enhanced functional properties. Despite the fact that a considerable number of studies have been conducted on conductive PLA/CNT composites, there has been limited research focusing on the supramolecular ordering of the polymer matrix and its impact on electromechanical properties. This factor, however, has been demonstrated in this study to significantly influence their response to applied stress and, consequently, their potential application as stress sensors. The present study has demonstrated that the precipitation method is an effective means of producing conductive PLA/MWNTs nanocomposites. This method is effective in ensuring the uniform dispersion of the filler in the polymer matrix, which creates an interesting prospect for mechanical sensors. It is evident that the durability of the nanocomposites is a key factor in ensuring the ordering of the supramolecular structure of the PLA matrix into the α form. The materials obtained were found to have a low percolation threshold of 0.2 wt.%. Furthermore, the practical application of these sensors, in the form of resistive strain sensors, was demonstrated for materials containing 5 wt.% of carbon nanotubes. The results presented here demonstrate that this methodology provides a novel perspective on the production of sensor materials, with the supramolecular ordering of the PLA matrix being a key factor.