Novel Sustainable Composites Based on Poly(hydroxybutyrate-co-hydroxyvalerate) and Seagrass Beach-CAST Fibers: Performance and Degradability in Marine Environments

Abstract

In order to produce sustainable, bio-based and highly biodegradable materials, composites based on poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and fibers of Posidonia oceanica (PO), a dominant Mediterranean seagrass, were produced by simple melt mixing and characterized in terms of thermal stability, morphology and rheological/mechanical properties. In view of their potential application in marine environments, degradation of the developed composites was evaluated under simulated and real marine environmental conditions for 1 year. Using 10 wt % of acetyl tributyl citrate (ATBC) as a plasticizer, smooth processing was achieved for up to 30 wt % of PO fibers, despite the reduction of the melt fluidity observed with increasing fiber loading. The tensile modulus slightly increased (from 2 to 2.4 GPa) while the tensile strength and the elongation decreased (from 23.6 to 21.5 MPa and from 3.2 to 1.9%, respectively) by increasing the PO fiber content from 0 to 30 wt %. Interestingly, the impact resistance of the composites increased with the increasing of the PO content: the Charpy’s impact energy increased from 3.6 (without fiber) to 4.4 kJ/m2 for the composite with 30 wt %. The results of the aerobic biodegradation under simulated marine conditions showed that the presence of PO fibers favored the physical disintegration of the composite increasing the biodegradation rate of the polymeric matrix: after 216 days, the composite with 20 wt % PO fibers showed a biodegradability of about 30% compared to 20% of the composite without fibers. Under real marine conditions, the specimens containing PO fibers showed higher weight losses and deterioration of tensile properties compared to those without fibers. Presumably, biodegradation occurred after colonization of the specimen, and the specimens with 20 wt % PO fibers showed well-developed biofilm consisting of bacteria and fungi on the surface after only 3 months of incubation in marine sediments, unlike the no-fiber specimens. Consequently, the persistence of an adequate mechanical performance for a relatively long period (1 year), due to a moderate rate of biodegradation in the marine environment, make the developed PHBV/PO composites particularly suitable for the production of relatively low-cost and biodegradable items which are usable in the sea and/or sand dunes, increasing the market opportunities for biopolymers such as PHBV and, at the same time, finding an eco-sustainable valorization for the PO fibrous residues accumulated in large quantities on Mediterranean beaches, which represents a problem for coastal municipalities.

Cosmetic Packaging to Save the Environment: Future Perspectives

“…PHAs have also an excellent biodegradability, many aerobic and anaerobic microorganisms (bacteria, cyanobacteria, and fungi) may degrade PHAs in several environments: in soil, in industrial/domestic compost, in fresh water, and in various marine ecosystems both as raw material [55,56] than as polymeric matrix in bio-composites [57] These properties make the PHA-based materials very promising for being used in applications where environmental concern and biocompatibility are fundamental. However, there is not much work in literature about their durability and possible shelf life when used as packaging [58], thus research on these materials is still ongoing, and the positive perspective predicts their future application as packaging even for cosmetic products.…”

“…PHAs have also an excellent biodegradability, many aerobic and anaerobic microorganisms (bacteria, cyanobacteria, and fungi) may degrade PHAs in several environments: in soil, in industrial/domestic compost, in fresh water, and in various marine ecosystems both as raw material [55,56] than as polymeric matrix in bio-composites [57].…”

Skin-Compatible Biobased Beauty Masks Prepared by Extrusion

“…Among the biobased polymers already available on the market, poly(hydroxyalkanoates) (PHAs), a family of polymers obtained from bacteria [9], are suitable for this application because of their very high biocompatibility [10,11], lower greenhouse gas emissions [12] and both soil and marine compostability [13,14]. These properties make the PHA-based materials very promising to be used in applications where environmental concern and biocompatibility are both fundamental.…”

Preparation of Innovative Skin Compatible Films to Release Polysaccharides for Biobased Beauty Masks

“…From among biobased polymers already available on the market, poly(lactic acid) (PLA) as well as poly(3-hydroxybutyrate) (PHB) and poly(hydroxyalkanoates) (PHAs) in general are fully renewable [8,9]. Although PLA is produced on a higher scale and is currently less expensive than PHAs, some characteristics make PHAs more advantageous for this application: the very high biocompatibility [10,11], the lower Green House Gas emissions [12] and compostability both in soil and marine environment [13,14] of PHA. These properties make the PHA-based materials very promising for being used in applications where environmental concern and biocompatibility are fundamental.…”