# Ecological Composite Materials Based on Polylactide (PLA) and Organic Fillers: Coffee Grounds and Hen Eggshells Produced by the FDM Method: Mechanical, Thermal Properties, Stress Relaxation and Creep

## TL;DR

This paper explores eco-friendly composites made from polylactide and organic fillers like coffee grounds and eggshells, showing reduced mechanical strength but increased environmental benefits.

## Contribution

The study introduces a novel ecological composite using coffee grounds and eggshells in FDM 3D printing, analyzing mechanical and thermal properties.

## Key findings

- Adding fillers reduced mechanical properties but increased environmental degradation potential.
- Using 10% coffee grounds lowered production temperature, time, and emissions.
- Voids in composites increased creep potential and reduced strength.

## Abstract

What are the main findings?

The use of organic substances in the production process of polymer composites can be recommended;

A deterioration in the strength properties of the produced composites can be achieved;

A reduction in the amount of environmental waste can be achieved.

What are the implications of the main findings?

Lower production costs, and reduced carbon dioxide emissions;

Increased potential for environmental degradation;

The use of waste for production can be recommended.

In this article, an ecological composite based on a neat polylactide with 50 and 75% degrees of coffee particles and eggshells as an infill and organic filler, was developed. It has been shown that the content of fillers used reduced the mechanical properties, increasing the possibility of environmental degradation and accelerating the biodegradation process. During the additive production of polylactide with 10% of coffee grounds as a filler, it was possible to reduce the additive manufacturing temperature, which reduced the process time, energy costs, carbon dioxide emissions and the amount of polymer that may affect the environment. The structure of polylactide enriched with hen eggshells is characterized by roan and irregular shapes, which can cause a high tendency to form a concentration of cracks in these areas. Based on the results obtained from the stress relaxation test, the Zener model was used to describe a creep model of the produced ecological composites. The polymer composition of coffee grounds and eggshells shows a tendency to creep faster than pure polylactide and with different degrees of infill. Voids reduce the strength of composite materials, which increases the creep potential of samples with incomplete degrees of infill.