Modelling Of Hydrothermal Aging Of Short Flax Fiber Reinforced Composites

TL;DR

This study develops a numerical model to predict the reversible effects of hydrothermal aging on short flax fiber reinforced PLA composites, aligning well with experimental data at lower temperatures.

Contribution

It introduces a simulation approach that captures water diffusion, swelling, and plasticizing effects in biocomposites during hydrothermal aging.

Findings

Model accurately predicts reversible aging behavior at 20°C and 35°C.

Deviations increase significantly at 50°C, indicating limits of the model.

Moisture impacts on flax fiber elastic modulus were quantified.

Abstract

As a contribution to the prediction of the evolutionary behavior of biocomposites in service conditions, this study focused on the simulation of the hydrothermal aging of short natural fiber reinforced composites made by extrusion/injection molding. We endeavored to model the reversible modifications of the behavior of PLA and PLA/flax composites when immersed in water at different temperatures (20, 35 and 50 {\textdegree}C). A numerical model accounting for the heterogeneous mechanisms involved during aging such as water diffusion and the resulting swelling and plasticizing of polymers was implemented. Simulated data proved to be in perfect accordance with experimental results as long as no irreversible mechanism was occurring. The deviations of the simulated data from experimental results were limited at 35{\textdegree}C but significant at 50{\textdegree}C. Finally, the influence of moisture on the local elastic modulus of flax fibers was inferred thanks to the Halpin-Kardos homogenization model.