# Application of Food Waste in Biodegradable Composites: An Ecological Alternative in Tribology

## TL;DR

This paper explores using food waste in biodegradable composites to reduce friction and wear in mechanical applications.

## Contribution

The study introduces food waste materials as fillers in biodegradable composites for tribological performance improvement.

## Key findings

- Cherry and plum stone fillers reduced friction in polypropylene and polylactic acid composites.
- Flaxseed pomace had inconsistent effects on tribological performance.
- Friction reduction was most significant at low concentrations and small particle sizes in polylactic acid.

## Abstract

Biodegradable composite materials enhanced with food waste for tribological applications are proposed in this article. Polymer materials used as matrices included polypropylene and polylactic acid, which, according to the manufacturers’ claims, were made entirely or partially from biodegradable raw materials. Additionally, the matrices were enhanced with three types of waste materials: powders derived from cherry and plum stones, and pomace extracted from flax seeds. The composites differed in the percentage content of filler (15 or 25 wt.%) and particle size (d < 400 µm or d > 400 µm). Thirty-minute block-on-ring friction tests were performed to determine frictional behaviour (when pairing with steel), and the wear mechanisms were analysed using optical microscopy and scanning electron microscopy, supplemented with Raman spectroscopy. A notable effect of cherry and plum stone fillers was observed as a reduction in motion resistance, as measured by the friction coefficient. This reduction was evident across all material configurations in polypropylene-based composites and was significant at the lowest concentrations and granulation in polylactic acid composites. The effect of flaxseed pomace filler was ambiguous for both composite bases.