solubilizzazione e valorizzazione di biopolimeri tramite liquidi ionici

In questo lavoro di tesi è stata studiata la possibilità di valorizzare biopolimeri come cheratina e chitina (prodotti come scarto in grandi quantità, principalmente nell’industria alimentare e tessile). tramite la loro solubilizzazione in liquidi ionici (IL) o dotati di gruppi funzionali polimerizzabili (PIL). Questi ultimi possono essere copolimerizzati con un monomero neutro al fine di ottenere compositi polimero/biopolimero. Un composito cheratina/polimero o chitina/polimero potrebbe sfruttare i vantaggi delle naturali proprietà di fibre di cheratina (es. resistenza a bassa densità) per creare compositi rinnovabili, biodegradabili capaci di prendere il posto di materiali preparati da fonti non rinnovabili. Le sorgenti di cheratina utilizzate sono state lana di basso pregio e piume di tacchino mentre per la chitina sono stati utilizzati gusci di gamberi. È stata sintetizzata una serie di IL e PIL in scelti in base alla loro capacità di inserirsi nelle interazioni non covalenti (legami ad idrogeno, interazioni ione-ione, interazioni idrofobiche) interne ai biopolimeri presi in esame. In seguito all’esito delle prove di solubilità in essi dei biopolimeri si è deciso di concentrarsi sulla cheratina proveniente da piume. Su una serie di soluzioni contenenti grandi quantità di cheratina disciolta (fino al 60%). Sono state quindi eseguite copolimerizzazioni con stirene. I Compositi risultanti sono stati caratterizzati tramite tecniche spettroscopiche (FTIR e NMR) e termiche (TGA, DSC)

New eco-composites based on polyhydroxyalkanoates (PHA) for marine applications

Bio-based polymers have attracted increasing attention over the last two decades, predominantly due to their environmental friendly nature and no dependence on petroleum resources. This type of polymers has got a growing consideration which has been so far focused specifically on starch based products, PLA (Polylactic acid), PHA (Polyhydroxylalkanoates) in particular PHB (Polyhydroxyl butyrate), cellulose derived plastics, etc. The production of these materials is based on renewable agricultural and biomass feedstocks. The degradability of bio-based materials not just in compost but also in different natural environments is an important property for sustainability and reduction of plastic pollution. In this work, blends of PHA and PHB with Posidonia Oceanica fibres were investigated to assess the feasibility of producing materials biodegradable in marine environment, varying the fiber percentage from 10 to 30 wt%. The chemical composition of the Posidonia O. fiber is similar to that of other lignocellulosic materials. It consists mainly of cellulose, hemicellulose, and lignin. Thermal, rheological, mechanical and morphological characterization of the developed PHA/PHB-fibre blends has been conducted in order to investigate the effect of the fibres on their processability and tensile properties. Biodegradability of the produced composites has been investigated in sea water in view of their use in marine environment

Biopolyesters and bio based additives based blends and composites for application in packaging and agriculture

The utilization of “bio-polymers” for the production of “bio-plastic” is worldwide an assessed priority with the aim of reducing dependence from petro sources, and handle the concern for disposal of waste generated from not degradable plastics Biobased polyesters such as Polyhydroxyalkanoates (PHAs) and Polylactide (PLA) are promising biobased, compostable polymer suitable for replacing petro-derived polymer for several single use applications but are addressed even for durable materials requiring more demanding technical performances [1,2], in particular in terms of mechanical properties and stability. Consequently a better knowledge of the crystallization behavior of PLA [3] and PHAs, and its effects on the mechanical properties is crucial in order to extend bio polyesters industrial applications, and even for optimization of polymeric matrices to be further used for biocomposite or active packaging production. In the present study we have addressed the use of biobased biodegradable reactive plasticizers for production of PLA based films by blow moulding [4], and the production of biocomposites with either PLA or PHA based polymeric matrices and natural fibres such as wood, bran, and Posidonia oceanica [5]. Those studies were inserted in the activites of Regional project PHA (Project POR FESR 2014-2020) addressing production of pots and items degradable even in soil and marine water, and of the European Union’s Horizon2020, Project AGRIMAX GA: n° 720719, addressing valorization of agriculture biomass (tomato, olive, potato, bran) for different ranges of applications including biocomposites. Pla based films were produced by use of functional plasticizers derived from soy bean oils, or from cardanol, with properties comparable to polypropylene or high density polyethylene. Biocomposites were produced with either PLA or PHA polymeric matrices with up to 30% by weight of natural fibres

New Bio-Composites Based on Polyhydroxyalkanoates and Posidonia oceanica Fibres for Applications in a Marine Environment

Bio-composites based on polyhydroxyalkanoates (PHAs) and fibres of Posidonia oceanica (PO) were investigated to assess their processability by extrusion, mechanical properties, and potential biodegradability in a natural marine environment. PHAs were successfully compounded with PO fibres up to 20 wt%while, at 30 wt%of fibres, the addition of 10 wt%of polyethylene glycol (PEG 400) was necessary to improve their processability. Thermal, rheological, mechanical, and morphological characterizations of the developed composites were conducted and the degradation of composite films in a natural marine habitat was evaluated in a mesocosm by weight loss measure during an incubation period of six months. The addition of PO fibres led to an increase in stiffness of the composites with tensile modulus values about 80% higher for composites with 30 wt % fibre (2.3 GPa) compared to unfilled material (1.24 GPa). Furthermore, the impact energy markedly increased with the addition of the PO fibres, from 1.63 (unfilled material) to 3.8 kJ/m2 for the composites with 30 wt % PO. The rate of degradation was markedly influenced by seawater temperature and significantly promoted by the presence of PO fibres leading to the total degradation of the film with 30 wt % PO in less than six months. The obtained results showed that the developed composites can be suitable to manufacture items usable in marine environments, for example, in natural engineering interventions, and represent an interesting valorisation of the PO fibrous wastes accumulated in large amounts on coastal beaches

Biocomposites Based on Polyhydroxyalkanoates and Natural Fibres from Renewable Byproducts

Background and Objective: The use of biopolyesters and natural fibres or fillers for production of biobased composites has attracted interest of various application sectors ranging from packaging to automotive components and other high value applications in agreement with a bioeconomy approach. In the present paper biobased composites were produced by using compostable polymers degradable even in soil and marine water such as polyhydroxyalkanoates with natural fibres or fillers derived by food wastes (legumes by-products) and by wood industry.Material and Methods: Polyhydroxyalkanoates were processed with a biobased, biodegradable plasticizer such as acetyltributylcitrate and calcium carbonate as inorganic filler. The selected polymeric matrix was used for the production of composites with variable amounts of natural fibres. Green composites were manufactured by extrusion and injection moulding. Thermal, rheological, mechanical and morphological characterizations of the developed composites were performed.Results and Conclusion: The bio composites properties match the requirements for production of rigid food packaging or other single use items where the market is looking for more sustainable solutions versus the products actually used and hardly recyclable, opening a route for valorization of food residue. Pukanzsky’s model predicts with good accuracy the tensile behavior of the composites showing a medium intensity adhesion between fibres and polymer matrix in both cases analyzed.Conflict of interest: The authors declare no conflict of interest.

Biocomposites based on PHBs and natural fibers for commodity applications in different environments: processing, performance in soil, compost and sea water

Composites based on poly(3-hydroxybutyrate) (PHB) and natural fibres such as fibres of Posidonia oceanica (PO), wood saw dust (WSD) and bran were produced by extrusion in presence of appropriate amounts of plasticizer (Acetyl Tri-n- Butyl Citrate, ATBC) and filler (calcium carbonate). Thermal, rheological, mechanical and morphological characterizations of the developed composites were conducted in order to optimize formulations in terms of processability and mechanical performance. The biodegradability of the optimized composites was investigated under controlled composting conditions in accordance with standard methods (ASTM D5338-98, ISO 20200-2004) and in soil for the PHB/WSD composites, because their expected fate is to be treated in composting plants or used for applications in agriculture; in simulated and natural marine sediments in mesocosms and dune habitat for the PHB/PO composites, because their potential applications are in marine environment, such as natural engineering interventions (restoration of seagrass habitats). The optimized PHB/WSD compounds were used for the production of pots for terrestrial plants, PHB/PO compounds for pots and other items usable in the sea and sand dunes, such as transplanting tools and structures for restoration or protection of coastal habitats, and the PHB/bran fibres for the production of food contact containers. The results showed that the industrial processing by extrusion of the composites did not show any difficulty up to 20 wt. % fibres and the presence of the fibres (PO or WSD) facilitated the disintegration of the PHB matrix and, consequently, accelerated its biodegradation both in compost, soil, sea water and dune. The PHB/WSD composites resulted no-phytotoxic by using cress (Lepidium sativum L.) germination test, compostable in accordance with EN 13427:2000, biodegradable in soil at controlled degradation rate. The PHB/PO composites showed a good controlled biodegradation rate in marine sediments and were suitable to manufacture items usable, for example, in natural engineering interventions and represent an interesting valorisation of the PO fibrous wastes accumulated in large amounts on coastal beaches

Evaluation of the activity of natural phenolic antioxidants, extracted from industrial coffee residues, on the stability of poly(1,4‐butylene succinate) formulations

In this work, the evaluation of the antioxidant activity of natural phenolic compounds is performed and compared to that of a conventional antioxidative agent. Phenolic molecules, extracted from industrial processing coffee residues, are added to a matrix of poly(1,4-butylene succinate) (PBS). The apparent activation energy (Ea) of the thermo-oxidative degradation is calculated by employing different methods like Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa and Friedman. The results are compared with the antioxidant activity evaluation obtained through the ABTS radical scavenging assay. From the average activation energies, it is observed that the addition of the natural antioxidants led to an increase in the activation energy of the degradation process as a function of the phenolic compound content. This trend is confirmed by the results of the ABTS assay. Hence, this study proves that the active molecules extracted from agri-food waste could be employed to improve the antioxidant capacity of the biopolymer, even if the composition of the extract must be evaluated in order to mitigate the effects of other components

Development of biodegradable blends and composites from natural resources

The massive globalization of food plastic packaging has considerably increased the volume of plastic waste in cities, beaches, maritime transport and industries. When these debris end up in marine environment this translates into 13 billion $ of annual losses, caused by damage to marine ecosystems, fisheries and tourism. Plastics and synthetic polymers are usually produced from petrochemical sources and their derived products cannot be biodegraded. For this reason, the production of plastics based on bio based and biodegradable and / or recyclable biopolymers are taking off, and can be proposed in different sectors due to their low environmental impact and independence on fossil resources. In this study, we developed blends and composites based on PLA and PHA adding natural fibres (nano chitin-lignocellulosic fibres) from renewable resources. One of the main limitations in the application of PHAs and PLA is their relatively high cost 7–12 €/kg and 3-4 €/kg respectively, compared to other biopolymers, restricting their use to high-value applications, such as those in medical and pharmaceutical sectors. In this thesis several materials with technical properties sound for different applications, such as in packaging, agriculture, etc have been developed and produced to replace the conventional petro-plastic derivatives, not biodegradable and hardly recyclable, with something valuable in terms of performances, sustainability and final cost. A study of the effect of different polymeric matrices on final performance of the material has been conducted as well as investigation of the effect of different additives on properties including degradability. Finally for some products the sustainability has also been considered by Life Cycle Assessment studies

Photofermentative poly-3-hydroxybutyrate production by Rhodopseudomonas sp. S16-VOGS3 in a novel outdoor 70-L photobioreactor

In the present study, the performance of a 70 L photobioreactor, operating outdoors, was investigated using a purple bacterial strain as Rhodopseudomonas sp. S16-VOGS3 for producing poly-3-hydroxybutyrate (PHB). The novel photobioreactor was equipped with 5 rows L-shaped; the bottom of every row was placed in a stainless-steel tank containing water with controlled temperature. The photofermentation trials were carried out under fed-batch mode and under a semi-continuous regimen using lactic acid as the carbon source. The effect of the irradiance and the carbon/nitrogen ratio on the PHB accumulation was investigated, in order to evaluate the optimal bacterial growth. The results showed the feasibility of the prototype photobioreactor for the production of PHB by Rhodopseudomonas sp. S16-VOGS3 under the natural light/dark cycle. During the fed-batch growth (144 h long), the cumulative PHB increased quickly reaching a maximum value of 377 mg/L and decreased to 255 mg/L during the semi-continuous regimen (336 h long)

Processability and degradability of PHA-based composites in terrestrial environments

In this work, composites based on poly(3-hydroxybutyrate-3-hydroxyvalerate) (PHB-HV) and waste wood sawdust (SD) fibers, a byproduct of the wood industry, were produced by melt extrusion and characterized in terms of processability, thermal stability, morphology, and mechanical properties in order to discriminate the formulations suitable for injection molding. Given their application in agriculture and/or plant nursery, the biodegradability of the optimized composites was investigated under controlled composting conditions in accordance with standard methods (ASTM D5338-98 and ISO 20200-2004). The optimized PHB-HV/SD composites were used for the production of pots by injection molding and their performance was qualitatively monitored in a plant nursery and underground for 14 months. This study presents a sustainable option of valuation of wood factory residues and lowering the production cost of PHB-HV-based compounds without affecting their mechanical properties, improving their impact resistance and biodegradability rates in terrestrial environments