# Mechanical Properties of Surface-Treated Bamboo Strip-Reinforced Biobased Polyamide Composites

## TL;DR

This paper studies how treating bamboo strips affects the mechanical properties of biobased composites made with flame-retardant polyamide.

## Contribution

The study introduces a mercerization treatment to improve the performance of bamboo-reinforced bio-composites.

## Key findings

- Mercerization removes hemicellulose and amorphous cellulose while preserving crystalline cellulose.
- Composites with 1% NaOH-treated bamboo showed a 1.39 increase in glassy modulus and 1.3 in rubbery modulus.
- Moisture had minimal impact on the shear modulus at room temperature.

## Abstract

Fully bio-based composites were obtained from continuous bamboo strips and flame-retardant polyamide 11 (PA11-FR) matrix. A mercerization treatment was performed on the bamboo strips surface to optimize fiber-matrix interactions. Composites were obtained by thermocompression molding with two pressure plateaus. The influence of the concentration of NaOH solution treatment was analyzed. The thermogravimetric analysis highlighted that the mercerization treatment removes part of hemicellulose, low molecular weight lignin and amorphous cellulose, while crystalline cellulose is preserved. Dynamic mechanical analysis performed in the shear configuration revealed the level of interactions between bamboo strips and PA11-FR matrix. The glassy modulus was improved for the composites compared to the matrix and their rubbery modulus was increased by a factor 4.6. Composites with bamboo strips treated at 1% NaOH showed the highest shear modulus across the entire temperature range with an increase by a factor of 1.39 on the glassy plateau and 1.3 on the rubbery plateau, with the untreated bamboo strips/polyamide 11-FR composite as reference. Water uptake was analogous for composites and bamboo strips, so the shear modulus at room temperature was not impacted by moisture.