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. 2019 May 29;11(6):933.
doi: 10.3390/polym11060933.

Influence of Epoxidized Canola Oil (eCO) and Cellulose Nanocrystals (CNCs) on the Mechanical and Thermal Properties of Polyhydroxybutyrate (PHB)-Poly(lactic acid) (PLA) Blends

Adrián Lopera-Valle  1 , Joseph V Caputo  2 , Rosineide Leão  3 , Dominic Sauvageau  4 , Sandra Maria Luz  5   6 , Anastasia Elias  7
Affiliations

Influence of Epoxidized Canola Oil (eCO) and Cellulose Nanocrystals (CNCs) on the Mechanical and Thermal Properties of Polyhydroxybutyrate (PHB)-Poly(lactic acid) (PLA) Blends

Adrián Lopera-Valle et al. Polymers (Basel). .

Abstract

Two major obstacles to utilizing polyhydroxybutyrate (PHB)-a biodegradable and biocompatible polymer-in commercial applications are its low tensile yield strength (<10 MPa) and elongation at break (~5%). In this work, we investigated the modification of the mechanical properties of PHB through the use of a variety of bio-derived additives. Poly(lactic acid) (PLA) and sugarcane-sourced cellulose nanocrystals (CNCs) were proposed as mechanical reinforcing elements, and epoxidized canola oil (eCO) was utilized as a green plasticizer. Zinc acetate was added to PHB and PLA blends in order to improve blending. Composites were mixed in a micro-extruder, and the resulting filaments were molded into 2-mm sheets utilizing a hot-press prior to characterization. The inclusion of the various additives was found to influence the crystallization process of PHB without affecting thermal stability. In general, the addition of PLA and, to a lesser degree, CNCs, resulted in an increase in the Young's modulus of the material, while the addition of eCO improved the strain at break. Overall, samples containing eCO and PLA (at concentrations of 10 wt %, and 25 wt %, respectively) demonstrated the best mechanical properties in terms of Young's modulus, tensile strength and strain at break.

Keywords: cellulose nanocrystals (CNCs); epoxidized canola oil (eCO); mechanical properties; poly(lactic acid) (PLA); polyhydroxyalkanoate (PHA); polyhydroxybutyrate (PHB); thermal properties.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
SEM micrographs of failure surfaces for (a) neat PHB, (b) PHB/10eCO, (c) PHB/PLA, (d) high magnification of poly(lactide acid) (PLA) phase in PHB/PLA composition, (e) PHB/5CNC, and (f) high magnification of cellulose nanocrystals (CNCs) in PHB/5CNC composition.
Figure 2
Figure 2
(a) Stress-strain curves as well as (b) E, (c) yield stress, (d) strain at yield, (e) σUTS, and (f) εb values for neat polyhydroxybutyrate (PHB), neat poly(lactic acid) (PLA) and seven eCO/CNC plasticized PHB samples.
Figure 3
Figure 3
Behavior of E’ over temperature of (a) polyhydroxybutyrate (PHB)-based, and (b) PHB/PLA-based polymer blends.
Figure 4
Figure 4
DSC (a) Heating and (b) cooling cycles curves for different polyhydroxybutyrate (PHB), poly(lactic acid) (PLA), and PHB/PLA polymer composites (aged 7 days).
Figure 5
Figure 5
TGA curves showing the influence of additives on weight loss for polyhydroxybutyrate (PHB) and PHB/PLA composites.
See this image and copyright information in PMC

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