Agricultural Plastic Waste Management

- This article aims at describing both the studies and results implemented in the framework of the H2020-EU research project “RECOVER: New bio-recycling routes for food packaging and agricultural plastic waste” which deals with the sustainability of innovative biodegradation processes for plastic waste and production, in any environmental, social, economic and safety matters. In such a framework, the POLOG University Centre (Livorno, Italy), reconstructed and analyzed the actual farm plastic waste supply chain, as described in the following sections. The first section is introductive and it has been intended as a primer to the most common different types of plastic materials. The second section has deserved to be a state of the art on the most relevant issues raised in plastic waste management. The third section deals with suitable approaches to address the environmental side effects of rapidly growing plastics production, use, and disposal. Some of these approaches were listed, such as physical treatment of the polymeric components, plastic reduction use and employment as much as mechanical and/or chemical recycling and energy recovery. The fourth section shows how some of the above main issues, which raise coping with plastic reduction and recycling, are suited to be coped with from a logistics perspective. Such logistics belong to the basic needs due to tackling any plastic waste supply chain, i.e. collection and transport to intermediate stock and final delivery to recycling plants and/or brownfields, applying the set of methodologies and techniques drawn from the well-known field of pick-up-and delivery models. These last tasks become crucial when the main effort has addressed the enforcement of any feasible changes from the use of items made in old high environmental intrusive to their replacement with new agricultural and biodegradable plastics. The paper goes to end presenting shortly of a few suitable solutions that could be proposed and applied to the entire plastic waste supply chain. Finally, some concrete aspects of each phase of the supply chain were discussed and it was highlighted how much each of these can be best used in addressing the problem known throughout the world as the problem of the emergency of old plastic waste

Agricultural plastic waste management

This article aims at describing both the studies and results implemented in the framework of the H2020-EU research project “RECOVER: New bio-recycling routes for food packaging and agricultural plastic waste” which deals with the sustainability of innovative biodegradation processes for plastic waste and production, in any environmental, social, economic and safety matters. In such a framework, the POLOG University Centre (Livorno, Italy), reconstructed and analyzed the actual farm plastic waste supply chain, as described in the following sections. The first section is introductive and it has been intended as a primer to the most common different types of plastic materials. The second section has deserved to be a state of the art on the most relevant issues raised in plastic waste management. The third section deals with suitable approaches to address the environmental side effects of rapidly growing plastics production, use, and disposal. Some of these approaches were listed, such as physical treatment of the polymeric components, plastic reduction use and employment as much as mechanical and/or chemical recycling and energy recovery. The fourth section shows how some of the above main issues, which raise coping with plastic reduction and recycling, are suited to be coped with from a logistics perspective. Such logistics belong to the basic needs due to tackling any plastic waste supply chain, i.e. collection and transport to intermediate stock and final delivery to recycling plants and/or brownfields, applying the set of methodologies and techniques drawn from the well-known field of pick up-and-delivery models. These last tasks become crucial when the main effort has addressed the enforcement of any feasible changes from the use of items made in old high environmental intrusive to their replacement with new agricultural and biodegradable plastics. The paper goes to end presenting shortly of a few suitable solutions that could be proposed and applied to the entire plastic waste supply chain. Finally, some concrete aspects of each phase of the supply chain were discussed and it was highlighted how much each of these can be best used in addressing the problem known throughout the world as the problem of the emergency of old plastic waste

From Waste Vegetable Oil to a Green Compatibilizer for HDPE/PA6 Blends

When properly compatibilized, the blending of polyethylene (PE) and polyamide (PA) leads to materials that combine low prices, suitable processability, impact resistance, and attractive mechanical properties. Moreover, the possibility of using these polymers without prior separation may be a suitable opportunity for their recycling. In this work, the use of an epoxidized waste vegetable oil (EWVO) was investigated as a green compatibilizer precursor (CP) for the reactive blending of a high-density PE (HDPE) with a polyamide-6 (PA6). EWVO was synthesized from waste vegetable cooking oil (WVO) using ion-exchange resin (Amberlite) as a heterogeneous catalyst. HDPE/PA6 blends were produced with different weight ratios (25/75, 75/25, 85/15) and amounts of EWVO (1, 2, 5 phr). Samples with WVO or a commercial fossil-based CP were also prepared for comparison. All the blends were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), rheology, and mechanical tests. In the case of HDPE/PA6 75/25 and 85/15 blends, the addition of EWVO at 2 phr showed a satisfactory compatibilizing effect, thus yielding a material with improved mechanical properties with respect to the blend without compatibilizer. On the contrary, the HDPE/PA6 25/75 ratio yielded a material with a high degree of crosslinking that could not be further processed or characterized. In conclusion, the results showed that EWVO had a suitable compatibilizing effect in HDPE/PA6 blends with high HDPE content, while it resulted in unsuitable for blends with high content of PA6

Piezoelectric Signals in Vascularized Bone Regeneration

The demand for bone substitutes is increasing in Western countries. Bone graft substitutes aim to provide reconstructive surgeons with off-the-shelf alternatives to the natural bone taken from humans or animal species. Under the tissue engineering paradigm, biomaterial scaffolds can be designed by incorporating bone stem cells to decrease the disadvantages of traditional tissue grafts. However, the effective clinical application of tissue-engineered bone is limited by insufficient neovascularization. As bone is a highly vascularized tissue, new strategies to promote both osteogenesis and vasculogenesis within the scaffolds need to be considered for a successful regeneration. It has been demonstrated that bone and blood vases are piezoelectric, namely, electric signals are locally produced upon mechanical stimulation of these tissues. The specific effects of electric charge generation on different cells are not fully understood, but a substantial amount of evidence has suggested their functional and physiological roles. This review summarizes the special contribution of piezoelectricity as a stimulatory signal for bone and vascular tissue regeneration, including osteogenesis, angiogenesis, vascular repair, and tissue engineering, by considering different stem cell sources entailed with osteogenic and angiogenic potential, aimed at collecting the key findings that may enable the development of successful vascularized bone replacements useful in orthopedic and otologic surgery

3D printed piezoelectric scaffolds based on polyhydroxybutyrate and barium titanate for bone tissue engineering

Bone defects resulting from trauma, disease or surgery are a significant health problem worldwide. The significant healthcare costs required to manage this problem are further aggravated by the long healing times experienced with current treatment practices. Novel treatment approaches in the tissue engineering field, is using biomaterial scaffolds to stimulate and guide the regeneration of damaged tissue that cannot heal spontaneously. Therefore, bone tissue engineering aims to induce new functional bone regeneration through the synergistic combination of biomaterials and cells. Scaffolds provide a three-dimensional network that mimics the extra cellular micro-environment supporting the viability, attachment, and growth of cells. In particular, the porosity of biomaterials plays an essential role in the context of osteointegration and osteoconduction. The purpose of this work is to prepare and characterize new stimuli-responsive porous scaffolds to provide electric bio-signals naturally present in bone and vascular tissues. Processing techniques, such as mixing and extrusion, were used to create nanocomposites made by polyhydroxybutyrate (PHB) as matrix, a green polymer, biobased, biodegradable, and biocompatible, and the barium titanate (BaTiO3) nanoparticles as fillers, a piezoelectric and biocompatible nanoceramic with antibacterial properties. Nanocomposites, containing different percentages of BaTiO3 (5, 10, 15, 20 wt%), were created to prove the change of the polymer properties once the filler has been added. Processed materials were characterized in terms of morphological, thermal, and mechanical properties. Scanning electron microscopy results showed that the increase in the extrusion number can enhance the nanoparticles dispersion within the polymer matrix. In terms of mechanical properties considerable increases in the Young’s modulus and compressive strength were observed with the increase of the BaTiO3 content. Once nanocomposites were characterized, 3D printing was used to create 3D porous cubic scaffolds. The application of piezoelectric ceramics as a biomaterial processed via additive manufacturing represents a promising and novel approach in biomaterial manufacturing. The processing of the PHB/BaTiO3 nanocomposites was possible and resulted in the fabrication of interconnected, porous scaffolds with an average pore size of about 1 mm. The scaffolds were successfully fabricated using 90° lay down pattern with a continuous contour filament to achieve interconnected porous reticular structure. Temperature and injection speed were changed during the printing process to obtain good mechanical stability. Results from compression tests showed that the porous structure decreased their compressive strength compared to a filled cube of the same material, but, thanks to porosity, scaffolds seem to be good candidates for stem cells loading. Besides the promising results, the study also demonstrates that the fabricated scaffolds exhibit high microporosity through weak mechanical properties. Future investigations will focus on eliminating these disadvantages by a deeper investigation of the microstructure and alteration of the material composition. In conclusion, the additive manufacturing of piezoelectric PHB/BaTiO3-based nanocomposites represents a promising approach to yield scaffolds of designed porosity, equipped with piezoelectric properties for enhanced bone regeneration. The scaffold purpose is not to achieve the same mechanical properties of the natural bone, but to ensure the piezoelectric properties, due to nanoceramic presence, needed for cells stimulation until complete bone regeneration once the polymer matrix is degraded

Seawater Biodegradable Poly(butylene succinate-<i>co</i>-adipate)—Wheat Bran Biocomposites

The present work focused on the development and characterization of biocomposites based on a fully bio-based polyester, poly(butylene succinate-co-butylene adipate) (PBSA), and wheat bran derived by flour milling. PBSA-bran composites containing 5, 10, 15, and 20 wt.% of wheat bran were produced via melt extrusion and processed by injection molding. Their thermal, rheological, morphological, and tensile properties were investigated. In addition, a biodegradation test in a natural marine environment was conducted on composite dog-bones to assess the capacity of the used filler to increase the PBSA biodegradation rate. The composites maintained similar melt processability and mechanical properties to virgin PBSA with up to 15 wt.% bran content. This result was also supported by morphological investigation, which showed good filler dispersion within the polymer matrix at low-mid bran content, whereas poor polymer-filler dispersion occurred at higher concentrations. Furthermore, the biodegradation tests showed bran’s capacity to improve the PBSA biodegradation rate, probably due to the hygroscopic bran swelling, which induced the fragmentation of the dog-bone with a consequent increase in the polymeric matrix–seawater interfacial area, accelerating the degradation mechanisms. These results encourage the use of wheat bran, an abundant and low-cost agri-food by-product, as a filler in PBSA-based composites to develop products with good processability, mechanical properties, and controlled biodegradability in marine environments

Innovative Biotic Symbiosis for Plastic Biodegradation to Solve their End-of-Life Challenges in the Agriculture and Food Industries

At present just about 30% of the waste plastic collected is efficiently recycled, while the rest is incinerated, disposed in landfills, or can end up in compost and be released in the environment, inducing a very negative effect on safety and health of flora and fauna. Sustainable management of hardly recyclable plastic waste generated by light weight single use packaging and agricultural films can be improved by applying biotechnological approaches, combining microorganisms, new enzymes, earthworms, and insects to work collaboratively, not only to promote the degradation of these plastics but also to obtain, by-products of the biodegradation process to be valorized as fertilizers, functional polysaccharides, etc. In order to develop a feasible process, mapping and characterization of the most diffused agri-food waste plastic were conducted isolating the main types of plastic involved. Plastic waste in agriculture is mainly constituted by polyethylene (PE) both linear low density (LLDPE) and high density (HDPE), polypropylene (PP) and polystyrene (PS), whereas in food packaging polyethylene is still present together with a large presence of polypropylene, polystyrene and polyethylene terephthalate (PET). Combining plastic presence and availability of organisms for their degradability, representative samples of plastics (PE, PET, PS) were selected for analysis of deterioration and potential subsequent biodegradation by enzymes and organisms. To monitor the plastic degradability by enzymes, and larvae, methods for the plastic analysis were set, outlining some differences in virgin and post consumer plastic in particular after use in agriculture, assessing the possibility to monitor the degradability of plastic with time and different treatments, in particular, some evidence of polyethylene degradability from larvae of Tenebrio molitor was observed

3D Printed Piezoelectric BaTiO₃/Polyhydroxybutyrate Nanocomposite Scaffolds for Bone Tissue Engineering

Bone defects are a significant health problem worldwide. Novel treatment approaches in the tissue engineering field rely on the use of biomaterial scaffolds to stimulate and guide the regeneration of damaged tissue that cannot repair or regrow spontaneously. This work aimed at developing and characterizing new piezoelectric scaffolds to provide electric bio-signals naturally present in bone and vascular tissues. Mixing and extrusion were used to obtain nanocomposites made of polyhydroxybutyrate (PHB) as a matrix and barium titanate (BaTiO3) nanoparticles as a filler, at BaTiO3/PHB compositions of 5/95, 10/90, 15/85 and 20/80 (w/w%). The morphological, thermal, mechanical and piezoelectric properties of the nanocomposites were studied. Scanning electron microscopy analysis showed good nanoparticle dispersion within the polymer matrix. Considerable increases in the Young’s modulus, compressive strength and the piezoelectric coefficient d31 were observed with increasing BaTiO3 content, with d31 = 37 pm/V in 20/80 (w/w%) BaTiO3/PHB. 3D printing was used to produce porous cubic-shaped scaffolds using a 90° lay-down pattern, with pore size ranging in 0.60–0.77 mm and good mechanical stability. Biodegradation tests conducted for 8 weeks in saline solution at 37 °C showed low mass loss (∼4%) for 3D printed scaffolds. The results obtained in terms of piezoelectric, mechanical and chemical properties of the nanocomposite provide a new promising strategy for vascularized bone tissue engineering