Valorization of Municipal Biowaste into Electrospun Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Biopapers for Food Packaging Applications

Abstract

The present study reports on the production and characterization of a new biopackaging material made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) derived from municipal biowaste (MBW) and produced by the mixed bacterial culture technology. After purification and extraction, the MBW-derived PHBV was processed by electrospinning to yield defect-free ultrathin fibers, which were thermally post-treated. Annealing at 130 °C, well below the biopolymer's melting temperature (Tm), successfully yielded a continuous film resulting from coalescence of the electrospun fibrillar morphology, the so-called biopaper, exhibiting enhanced optical and color properties compared to traditional melt compounding routes. The crystallinity and crystalline morphology were comprehensively studied as a function of temperature by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and combined time-resolved synchrotron small-and wide-angle X-ray scattering (SAXS and WAXS) experiments, which clearly indicated that the molecular order within the copolyester was improved up to a maximum at 130 °C, and then it decreased at the biopolymer's Tm. It was hypothesized that by annealing at the temperature at which the thermally induced molecular order is maximized, the fibers generated sufficient mobility to align alongside, hence reducing surface energy and porosity. The data suggest that this material shows a good balance between enhanced mechanical and improved barrier properties to vapors and gases in comparison to traditional paper and other currently used petroleum-derived polymers, thus presenting significant potential to be part of innovative food biopackaging designs for the protection and preservation of foods in a circular bioeconomy scenario.

Development and Characterization of Electrospun Fiber-Based Poly(ethylene-co-vinyl Alcohol) Films of Application Interest as High-Gas-Barrier Interlayers in Food Packaging

“…Many FTIR bands in polymers are conformationally sensitive, being the sharper peaks associated to ordered chain segments along the backbone, arising mostly from within crystals. When the relative intensity of conformationally sensitive bands rises upon heating, they typically sharpen, shifting in position and become narrower [ 57 ]. From Figure 8 , a progressive increase in the intensity of many bands was initially observed, associated to classical crystal perfecting, followed by a leveling-off of these and a subsequent decrease up to around 160 °C.…”

“…Moreover, the electrospun mats can be, thereafter, post-treated at temperatures below the T m of the polymer, forming fiber-based continuous films with eliminated porosity. These materials are also called “biopapers” when made of biopolymers [ 56 , 57 ] due to their biofiber-based morphology and improved properties compared to traditional cellulosic papers. Thus, these materials can be produced after using minimal thermal exposure and they show good optical as well as mechanical and barrier properties, potentially offering high value in food packaging applications [ 58 ].…”

Characterization of Polyhydroxyalkanoates Produced at Pilot Scale From Different Organic Wastes

“…Preliminary results showed that it is possible to obtain biodegradable films (for agricultural purposes) with acceptable mechanical and permeability properties through melt compounding and blown extrusion, starting from mixtures at different PHA content. Also packaging applications have been explored by Melendez-Rodriguez et al (2020) on PHA from Treviso, carrying out a wide characterization on fiber-based continuous films obtained starting from electrospun PHA. The combination of electrospinning and a mild annealing postprocessing below the biopolymer’s T m was able to yield unique biomaterials with balanced mechanical, thermal and barrier properties ( Melendez-Rodriguez et al, 2020 ).…”

“…Also packaging applications have been explored by Melendez-Rodriguez et al (2020) on PHA from Treviso, carrying out a wide characterization on fiber-based continuous films obtained starting from electrospun PHA. The combination of electrospinning and a mild annealing postprocessing below the biopolymer’s T m was able to yield unique biomaterials with balanced mechanical, thermal and barrier properties ( Melendez-Rodriguez et al, 2020 ). Furthermore, one of the main concerns relating to the use of waste as feedstock is the content of pollutants that can migrate from the waste, through the technology chain, and into the end-products.…”

Development of Active Barrier Multilayer Films Based on Electrospun Antimicrobial Hot-Tack Food Waste Derived Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Cellulose Nanocrystal Interlayers

“…Similarly, Cherpinski et al [42] developed multilayer films based on PHB nanopapers, showing that the multilayers presented a similar continuous structure and strong interlayer adhesion, which was attributed to the coalescence process at the fiber interphase. This annealing process, performed at temperatures well below the polymer's melting point, has been recently described and better understood by Melendez-Rodriguez et al [43] Nanomaterials 2020, 10, x FOR PEER REVIEW 10 of 24…”