# Composites Based on Eucalyptus Nitens Leaves and Natural Rubber as a Valuable Alternative for the Development of Elastomeric Materials with Low Microbiological Impact

## TL;DR

This paper explores using Eucalyptus nitens leaves in natural rubber to improve mechanical properties and reduce antibacterial effects, offering a sustainable alternative from forestry by-products.

## Contribution

The study introduces a novel use of Eucalyptus nitens leaves as a filler in natural rubber, enhancing mechanical properties and altering microbiological impact.

## Key findings

- Natural rubber with Eucalyptus nitens leaves achieved 9.45 MPa tensile strength and 649% elongation at break.
- The leaf filler reduced antibacterial effects against multiple bacteria like Staphylococcus aureus and Escherichia coli.
- This approach adds value to forestry by-products while promoting sustainable material development.

## Abstract

The forest industry produces several low-value by-products, such as bark, sawdust, limbs, and leaves, that are not ultimately disposed of and remain in the forests and sawmill facilities. Among these by-products are leaves, which contain not only cellulose fibers and lignin but also essential oils such as terpenes. These are biosynthesized in a similar way as cis-1,4-polyisoprene. In this context, this work evaluates the use of screened and unscreened dried Eucalyptus nitens leaves in natural rubber. Among the most relevant results of this work is a significant increase in mechanical properties, such as tensile strength and elongation at break, reaching values of 9.45 MPa and 649% of tensile strength and elongation at break, respectively, for a sample of natural rubber containing sieved dried leaves of Eucalyptus nitens. In addition, it is observed that the content of this vegetable filler allows for inhibiting the antibacterial effect of vulcanized rubber against several bacteria, such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli K 12, Escherichia coli FT 17 and Pseudomonas fluorescens. These results are promising because they not only add value to a by-product of the forestry industry, improving the mechanical properties of natural rubber from a sustainable approach but also increase the affinity of rubber with bacterial microorganisms that may play a role in certain ecosystems.