The Influence of Additives and Environment on Biodegradation of PHBV Biocomposites

Abstract

The biodegradation of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) ternary biocomposites containing nature-based plasticizer acetyl tributyl citrate (ATBC), heterogeneous nucleation agents—calcium carbonate (CaCO3) and spray-dried lignin-coated cellulose nanocrystals (L-CNC)—in vermicomposting, freshwater biotope, and thermophilic composting have been studied. The degree of disintegration, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and the evaluation of surface images taken by scanning electron microscopy (SEM) were conducted for the determination influence of different environments and additives on the biodegradation of PHBV. Furthermore, the method adapted from ISO 14855-1 standard was used for thermophilic composting. It is a method based on the measurement of the amount of carbon dioxide evolved during microbial degradation. The highest biodegradation rate was observed in the thermophilic condition of composting. The biodegradation level of all PHBV-based samples was, after 90 days, higher than 90%. Different mechanisms of degradation and consequently different degradation rate were evaluated in vermicomposting and freshwater biotope. The surface enzymatic degradation, observed during the vermicomposting process, showed slightly higher biodegradation potential than the hydrolytic attack of freshwater biotope. The application of ATBC plasticizers in the PHBV matrix caused an increase in biodegradation rate in all environments. However, the highest biodegradation rate was achieved for ternary PHBV biocomposites containing 10 wt. % of ATBC and 10 wt. % of CaCO3. A considerable increase in the degree of disintegration was evaluated, even in freshwater biotope. Furthermore, the slight inhibition effect of L-CNC on the biodegradation process of ternary PHBV/ATBC/L-CNC could be stated.

Boosting Degradation of Biodegradable Polymers

“…However, the presence of a plasticizer could create some restrictions for food packaging applications in terms of toxicity and/or rapid migration from the polymer matrix. [ 59 ]…”

“…However, the presence of a plasticizer could create some restrictions for food packaging applications in terms of toxicity and/or rapid migration from the polymer matrix. [59] The incorporation of fillers (at the micro and nano scale) could potentially provide two main functions: first, a reinforcement of mechanical and/or barrier properties during the service life of the plastic; and second, an incentive for water diffusion, swelling, and breaking of the polymer bulk (Figure 6). [88] It has been shown that hydrolysis of PLA nanocomposites is affected by the type of composite or filler, degradation and dispersion of the composite, and the polymer structure.…”

In-soil degradation of polymer materials waste – A survey of different approaches in relation with environmental impact

“…The presence of other pollutants and additives may impact biodegradation by affecting the surface properties of polymers, as well as the soil texture, moisture content, pH, and biota (Maddela et al 2022;Sajjad et al 2022). Plastics themselves frequently contain various amounts and types of substances added to improve the resilience and practical performances of native polymer chains, which could significantly alter the biological degradative response (Allen and Edge 2020;Brdlik et al 2022;Hahladakis et al 2018;Hermabessiere et al 2022;Sridharan et al 2022). The shape of plastic debris could be a relevant factor as well (Lehmann et al 2021).…”

“…There are slower degradation rates for polylactic acid PLA and polybutylene succinate PBS, and also the rate is sluggish in the case of polyethylene terephthalate PET (Al Hosni et al 2019;Larrañaga and Lizundia 2019;Qi et al 2022). Polyester biodegradation could be improved by copolymerization, as is the case of polybutylene adipate terephthalate PBAT, insertion of natural polyols, adipate and succinate diols in polyurethanes, or by mixing with additives or other biodegradable polymers like modified celluloses and PLA in blends or composites (Brdlik et al 2022;Erdal and Hakkarainen 2022;Schöpfer et al 2022).…”

Physical, Mechanical, and Structural Properties of the Polylactide and Polybutylene Adipate Terephthalate (PBAT)-Based Biodegradable Polymer during Compost Storage

“…The most promising materials are polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polyhydroxyalkanoate (PHA), polybutylene adipate terephthalate (PBAT), polyhydroxybutyrate-co-hydroxyvalerate (PHBV), and their compounds [ 12 , 13 , 14 , 15 ]. The biodegradation rate greatly depends on the ambient temperature and humidity [ 8 ].…”