# Multi-Scale Tribo–Thermo–Viscoelastic Engineering of Sustainable Bio-Based Epoxy Through Hybrid Carbon Nano Architectures and Energy Partition Modeling

## TL;DR

This study shows that adding hybrid carbon nanofillers to a sustainable epoxy reduces wear and contact pressure under sliding conditions, making it more durable and eco-friendly.

## Contribution

The study introduces a novel interfacial energy-partition framework to link mechanical, thermal, and viscoelastic effects in sustainable bio-epoxy composites.

## Key findings

- GNP/ND hybrid fillers reduced wear volume by 64% and contact pressure by 54% compared to neat epoxy.
- Hybrid systems showed enhanced tribolayer stability with suppressed mid-cycle pressure spikes.
- Surface hardness increased from 0.18 GPa to 0.30 GPa with GNP/ND hybrids, improving wear resistance.

## Abstract

This study investigates the multi-scale tribo–thermo–viscoelastic performance of a sustainable bio-based FormuLITE epoxy reinforced with single and hybrid carbon nanofillers (0.1 wt.% total loading) under dry sliding up to 50 N. Pin-on-disk tests at 10, 30, and 50 N showed a consistent reduction in contact pressure and wear volume in the order: neat epoxy > 0.1 CNT > 0.1 GNP > 0.1 ND > 0.1 CNT/GNP > 0.1 CNT/ND > 0.1 GNP/ND. At 50 N and 1500 m sliding distance, neat epoxy exhibited a wear volume of 13.43 mm3 and contact pressure of 13.4 N/cm2, while the GNP/ND hybrid reduced wear to 4.86 mm3 and contact pressure to 6.2 N/cm2, corresponding to reductions of 64% and 54%, respectively. The accelerating wear coefficient decreased from 2.9 × 10−6 to 8.5 × 10−7, confirming slower damage accumulation in hybrid systems. Time-dependent contact pressure analysis revealed reduced asymptotic intensity and suppressed mid-cycle pressure spikes, indicating enhanced tribolayer stability. Effective surface hardness increased from 0.18 GPa (neat epoxy) to 0.30 GPa (GNP/ND), while normalized wear decreased from 1.00 to 0.36. Enhanced damping behavior and improved thermal conductivity in hybrid systems promoted stress redistribution and minimized flash-temperature localization. An interfacial energy-partition framework calibrated to experimental wear data quantitatively linked effective driving pressure, tribofilm stabilization, and surface hardness to material removal. The results demonstrate that wear mitigation in sustainable bio-epoxy systems is governed by coupled mechanical, viscoelastic, and thermal energy redistribution, with GNP/ND hybrids providing the most stable tribological interface under severe sliding. The findings contribute to the development of durable and sustainable bio-epoxy composite systems for engineering applications, supporting broader goals of responsible material utilization and sustainable industrial innovation aligned with the United Nations Sustainable Development Goals (SDG 9 and SDG 12).