Thermo-Mechanical Properties of PLA/Short Flax Fiber Biocomposites

Laura Aliotta,Andrea Lazzeri,Patrizia Cinelli,Vito Gigante,Maria-Beatrice Coltelli,Maurizia Seggiani

doi:10.3390/app9183797

Abstract

In this work, biocomposites based on poly(lactic acid) (PLA) and short flax fibers (10–40 wt.%) were produced by extrusion and characterized in terms of thermal, mechanical, morphological, and thermo-mechanical properties. Analytical models were adopted to predict the tensile properties (stress at break and elastic modulus) of the composites, and to assess the matrix/fiber interface adhesion. The resulting composites were easily processable by extrusion and injection molding up to 40 wt.% of flax fibers. It was observed that despite any superficial treatment of fibers, the matrix/fiber adhesion was found to be sufficiently strong to ensure an efficient load transfer between the two components obtaining composites with good mechanical properties. The best mechanical performance, in terms of break stress (66 MPa), was obtained with 20 wt.% of flax fibers. The flax fiber acted also as nucleating agent for PLA, leading to an increment of the composite stiffness and, at 40 wt.% of flax fibers, improving the elastic modulus decay near the PLA glass transition temperature.

Highlights

The development of biocomposites, produced using a biopolymer matrix and a reinforcement from renewable resources, is currently an extensive research area due to the promising mechanical properties, recyclability after service [1], and biodegradability [2] of these materials
The possibility to use conventional melt processes is a very important for industrial use of these bio-composites. In this case poly(lactic acid) (PLA)/flax fiber composites did not show any difficulties during the extrusion followed by injection molding
These results are in accordance with the findings of Oksman et al [30] who did not experience any difficulties in the extrusion and compression molding processes of PLA/long flax fiber composites up to 40 wt.% fibers

Summary

Introduction

The development of biocomposites, produced using a biopolymer matrix and a reinforcement from renewable resources, is currently an extensive research area due to the promising mechanical properties, recyclability after service [1], and biodegradability [2] of these materials. These composites have potential applications in different fields such as automotive, packaging, and household goods [3]. They can be formed into light composites leading to weight reductions and, especially in automotive field, to fuel saving [5]. Lignocellulosic fibers are investigated as promising substitutes of the synthetic fibers in polymeric composites and several studies have examined drawbacks and advantages of the most significant lignocellulosic fibers and their related polymeric composites [6,7,8,9]

Methods

Results

Conclusion