Biodegradable PHB-Rubber Copolymer Toughened PLA Green Composites with Ultrahigh Extensibility

Abstract

The sustainable biopolymer, poly(lactide) (PLA), has been intensely researched over the past decades because of its excellent biodegradability, renewability, and sustainability. The boundless potential of this sustainable biopolymer could resolve the adverse negative impact caused by the petroleum-based polymers. However, the inherent drawback of PLA such as brittleness, low heat distortion temperature, and slow recrystallization rate narrowed the broad applications in biomedical, automotive, and structural fields. In this study, we successfully synthesized a PHB-based filler (PHB-di-rub) displaying synergetic functions of (1) effective nucleation and (2) extreme toughening of the PLA matrix at only 5% (1.5 wt % PHB content). Remarkably, the storage modulus improves by 15%; tensile elongation extends by 57-fold (300% strain) and toughness by 38-fold while maintaining its original strength and stiffness. Likewise, 10% of PHB-di-rub (3 wt % PHB content) has an even higher improvement with a storage modulus improvement by 32%, elongation by 128-fold (680% strain), and toughness by 84-fold, with a marginal change in strength and stiffness. NMR results confirmed the structure of PHB-di-rub, where PHB acts as the rigid core and the poly(lactide-cocaprolactone) (DLA-co-CL) random copolymer confers the flexibility. DSC, WAXD, and POM display the excellent nucleating ability of PHB-di-rub. SEM shows the morphology of elongated fibrils structure with strong matrix−filler interaction and homogeneous filler dispersion. SAXS, WAXS, and WAXD elucidate the extreme toughening mechanism to be a combination of rubber-induced crazing effect and highly orientated PLA matrix with PHB-di-rub. The Herman's orientation function further quantifies the extreme elongation (680%) owing to the perfect alignment. This highly biodegradable biocomposite with high strength and toughness shows potential in replacing the current petroleum-based polymers, which open up to broader prospects in the biomedical, automotive, and structural application.

The Effect of Antibacterial Particle Incorporation on the Mechanical Properties, Biodegradability, and Biocompatibility of PLA and PHBV Composites

“…Toughening effect of PHBV was also reported by Chee et al who showed that the addition of 10 wt% PHBV significantly improves the mechanical properties of PLA (storage modulus increase by 32%). [34] PHBV-based composites were characterized by more than twice lower elongation at break values compared with PLA composites, which significantly influenced on impact results. Composites based on PLA at +80 °C did not break in terms of the capabilities of the test machine, this effect was related to their T g , which was mentioned before.…”

Fully Green Poly(vinyl alcohol)/Tea Polyphenol Composites and Super Anti‐Ultraviolet and ‐Bacterial Properties

“…Facing to the growing problems in global environmental area, to use environmentally friendly fully biodegradable green composites is substantially increased and expected by various industries and families. [ 1 ] Aside from the traditional composites consisting of the nondegradable thermoplastic polymers, [ 2 ] e.g., polyethylene, polyesters, poly(methyl methacrylate), and the thermosetting polymers such as the epoxy and polyurethane, the fully biodegradable green composites composing of renewable and sustainable resources [ 3–7 ] are recently greatly reported elsewhere. [ 8–13 ]…”

“…Facing to the growing problems in global environmental area, to use environmentally friendly fully biodegradable green composites is substantially increased and expected by various industries and families. [1] Aside from the traditional composites consisting of the nondegradable thermoplastic polymers, [2] e.g., polyethylene, polyesters, poly(methyl methacrylate), and the thermosetting polymers such as the epoxy and polyurethane, the fully biodegradable green composites composing of renewable and sustainable resources [3][4][5][6][7] are recently greatly reported elsewhere. [8][9][10][11][12][13] As a natural and renewable material, the water-soluble tea polyphenols, TP, has been broadly applied as natural antioxidant to eliminate the free radicals in human body, to protect ultraviolet, UV, effect, as the resisting agent for treatment of the cancer, tumor, antiviral, anti-inflammatory and the deodorization.…”

Recent developments in the synthesis of poly(hydroxybutyrate) based biocomposites

“…For sustainable biocomposite development, correlation in structure-property-processing is important for specific end use. 53 From sustainable resources, proper combination of the polymers is used to develop biocomposites. 54 Specific requirements for sustainable biocomposites include renewable and recycled sources, 55 energy effective processing and modifications, 56 no toxicity should be observed at any stage, 54 and waste material should be easily disposed of.…”

“…Biocomposites importance in science and technology gives huge contribution to balance greenhouse gases, to preserve ecosystem and positive impact for whole life cycles. For sustainable biocomposite development, correlation in structure–property‐processing is important for specific end use . From sustainable resources, proper combination of the polymers is used to develop biocomposites .…”