Potential of Cellulose Microfibers for PHA and PLA Biopolymers Reinforcement

Abstract

Cellulose nanocrystals (CNC) have attracted the attention of many engineering fields and offered excellent mechanical and physical properties as polymer reinforcement. However, their application in composite products with high material demand is complex due to the current production costs. This work explores the use of cellulose microfibers (MF) obtained by a straightforward water dispersion of kraft paper to reinforce polyhydroxyalkanoate (PHA) and polylactic acid (PLA) films. To assess the influence of this type of filler material on the properties of biopolymers, films were cast and reinforced at different scales, with both CNC and MF separately, to compare their effectiveness. Regarding mechanical properties, CNC has a better reinforcing effect on the tensile strength of PLA samples, though up to 20 wt.% of MF may also lead to stronger PLA films. Moreover, PHA films reinforced with MF are 23% stronger than neat PHA samples. This gain in strength is accompanied by an increment of the stiffness of the material. Additionally, the addition of MF leads to an increase in the crystallinity of PHA that can be controlled by heat treatment followed by quenching. This change in the crystallinity of PHA affects the hygroscopicity of PHA samples, allowing the modification of the water barrier properties according to the required features. The addition of MF to both types of polymers also increases the surface roughness of the films, which may contribute to obtaining better interlaminar bonding in multi-layer composite applications. Due to the partial lignin content in MF from kraft paper, samples reinforced with MF present a UV blocking effect. Therefore, MF from kraft paper may be explored as a way to introduce high fiber concentrations (up to 20 wt.%) from other sources of recycled paper into biocomposite manufacturing with economic and technical benefits.

Development of bio-based membranes for building envelope applications from poly(lactic acid) and cellulose microfibers

“…It might be due to the poor intermolecular interaction between PLA and untreated CMF. Previous studies also reported the agglomeration of cellulose fibers in the PLA matrix (Fortunati et al 2013;Lu et al 2014;Mármol et al 2020). (Sheth et al 1997;Mohapatra et al 2014).…”

One-Step Synthesis of Eu3+-Modified Cellulose Acetate Film and Light Conversion Mechanism

“…The average light transmittance of CA-Eu light conversion film with a thickness of 10 µm could reach the maximum exceeding 90%. Compared with the previously work, the light conversion films present the high transmittance in the visible range [34][35][36][37]. Mechanical properties include tensile strength that represents the strength, and elongation at breaking that reflects flexibility and elasticity of the films.…”

Volatile Fatty Acids as Carbon Sources for Polyhydroxyalkanoates Production

“…PLA has gained much attention as the effective polymer for biomedical and packing composites. Nonetheless, due to fragility, reduced impact strength, and low thermal stability, PLA has become a hurdle for the application in engineering purposes [2]. Additionally, PHAs are attracting attention as the next generation of environmentally friendly materials and have become an alternative to synthetic polymers because they are completely biodegradable, biocompatible and can be produced from renewable sources [3].…”