Mitigating the Impact of Cellulose Particles on the Performance of Biopolyester-Based Composites by Gas-Phase Esterification

Abstract

Materials that are both biodegradable and bio-sourced are becoming serious candidates for substituting traditional petro-sourced plastics that accumulate in natural systems. New biocomposites have been produced by melt extrusion, using bacterial polyester (poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) as a matrix and cellulose particles as fillers. In this study, gas-phase esterified cellulose particles, with palmitoyl chloride, were used to improve filler-matrix compatibility and reduce moisture sensitivity. Structural analysis demonstrated that intrinsic properties of the polymer matrix (crystallinity, and molecular weight) were not more significantly affected by the incorporation of cellulose, either virgin or grafted. Only a little decrease in matrix thermal stability was noticed, this being limited by cellulose grafting. Gas-phase esterification of cellulose improved the filler’s dispersion state and filler/matrix interfacial adhesion, as shown by SEM cross-section observations, and limiting the degradation of tensile properties (stress and strain at break). Water vapor permeability, moisture, and liquid water uptake of biocomposites were increased compared to the neat matrix. The increase in thermodynamic parameters was limited in the case of grafted cellulose, principally ascribed to their increased hydrophobicity. However, no significant effect of grafting was noticed regarding diffusion parameters.

Upcycling of Vine Shoots: Production of Fillers for PHBV-Based Biocomposite Applications

“…virgin or grafted ViSh, the stress at break decreased with increasing filler content. Comparably, the addition of cellulose particles were shown to reduce the ultimate properties of the biocomposites [37]. However, it was shown that esterification of pure cellulose particles allowed to limit this negative impact while no significant impact was noticed in the present study in the case lignocellulosic particles.…”

“…However, it was shown that esterification of pure cellulose particles allowed to limit this negative impact while no significant impact was noticed in the present study in the case lignocellulosic particles. It is worth noting that the decrease in the stress and strain at break was lower in the case of ViSh particles as compared to cellulose or wheat straw particles [11,37]. The addition of ViSh fillers resulted in an increase of Young's modulus values, most probably due to the higher tensile of ViSh fillers than the PHBV matrix [10].…”

“…Most of these esterification treatments are implemented with solvents in homogeneous [32,33] or heterogeneous phase [34][35][36]. In a previous study on PHBV-based composites, a gas-phase esterification with palmitoyl chloride gave recently promising results on cellulose fillers [37]. This solvent-free treatment improved surface hydrophobicity significantly, resulting in a better affinity between cellulose particles and the PHBV matrix.…”

“…In addition, the gas-phase esterification was applied for the first time on lignocellulosic particles to attempt to improve interfacial adhesion with the matrix. It would allow the comparison with grafted cellulose from the previous study [37]. For the first time, the structure-properties relationships in PHBV/ViSh composites were studied.…”

Influence of Natural Fillers on Thermal and Mechanical Properties and Surface Morphology of Cellulose Acetate-Based Biocomposites

“…Le Digabel and Avérous [28] obtained similar results for aromatic copolyester matrix filled with wheat straw particles and report that the addition of lignocellulosic fillers did not change the matrix crystallinity but influenced the nucleation process. David et al [29] examined the influence of cellulosic filler particle addition on properties of biopolyester-based composites and revealed that intrinsic properties of polymeric matrix do not change significantly with the addition of cellulosic filler. Ni'mah et al [30] examined the effect of the particle size and crystallinity of the cellulose filler on mechanical and thermal properties of poly(L-lactic acid) acid-based biocomposites.…”