# Influence of Filler in the Form of Waste Wood Flour and Microcellulose on the Mechanical, Thermal, and Morphological Characteristics of Hierarchical Epoxy Composites

## TL;DR

This study explores how waste wood flour and microcellulose, when added to epoxy composites, affect their mechanical, thermal, and morphological properties.

## Contribution

The study introduces a two-stage silanization process to improve the interaction between natural fillers and epoxy matrices.

## Key findings

- Silanization of waste wood flour significantly improved its interaction with the epoxy matrix, enhancing mechanical properties.
- Composites with silanized wood flour showed better flexural and compressive strength compared to unmodified and unfilled composites.
- Cellulosic additives improved impact properties of the epoxy composites.

## Abstract

In response to growing interest in green additives derived from natural raw materials or post-production waste of natural origin, epoxy compositions containing the additive in the form of waste wood flour and microcellulose were prepared. The research involved the chemical modification of the additive through a two-stage silanization process using 3-aminopropyltriethoxysilane. Followed by filler’s characterization using Fourier Transformed Infrared Spectroscopy (FT-IR) to analyze the modification in chemical structure, Wide Angle X-Ray Diffraction (WAXD) to detect differences in crystal structure, and Scanning Electron Microscopy (SEM) to observe morphological changes. Next, waste oak flour (WF) and microcrystalline cellulose (MCC) were used in unmodified and silanized form (sil-WF and sil-MCC, respectively) to prepare epoxy composites, followed by testing their influence on the mechanical (hardness, tensile strength, flexural strength, compressive strength, and impact strength), thermal, and morphological characteristics of epoxy composites based on Epidian 6. Comparing the effect of modification on the properties of the analyzed additives, it was found that silanization had a larger impact on increasing the interaction of the waste wood flour with the epoxy matrix than silanization of MCC due to a lesser tendency of the sil-WF than the sil-MCC to agglomerate. An enhanced interaction of sil-WF with the polymer resulted in improved mechanical properties. Composite EP/sil-WF (cured epoxy composite based on low-molecular-weight epoxy resin Epidian 6 filled with 5 wt.% of silanized wood flour) was characterized by improved flexural (61.97 MPa) and compressive properties (69.1 MPa) compared to both EP/WF (cured epoxy composite based on low-molecular-weight epoxy resin Epidian 6 filled with 5 wt.% of unmodified wood flour) (42.39 MPa and 61.0 MPa) and the unfilled reference composition (54.55 MPa and 67.4 MPa, respectively). Moreover, compositions containing a cellulosic additive were characterized by better impact properties than the reference composition.