Synthesis and Applications of Biopolymer Composites

This book, as a collection of 17 research articles, provides a selection of the most recent advances in the synthesis, characterization, and applications of environmentally friendly and biodegradable biopolymer composites and nanocomposites. Recently, the demand has been growing for a clean and pollution-free environment and an evident target regarding the minimization of fossil fuel usage. Therefore, much attention has been focused on research to replace petroleum-based commodity plastics by biodegradable materials arising from biological and renewable resources. Biopolymers—polymers produced from natural sources either chemically from a biological material or biosynthesized by living organisms—are suitable alternatives for addressing these issues due to their outstanding properties, including good barrier performance, biodegradation ability, and low weight. However, they generally possess poor mechanical properties, a short fatigue life, low chemical resistance, poor long-term durability, and limited processing capability. In order to overcome these deficiencies, biopolymers can be reinforced with fillers or nanofillers (with at least one of their dimensions in the nanometer range). Bionanocomposites are advantageous for a wide range of applications, such as in medicine, pharmaceutics, cosmetics, food packaging, agriculture, forestry, electronics, transport, construction, and many more

Thermoplastic Blends Based on Poly(Butylene Succinate- co -Adipate) and Different Collagen Hydrolysates from Tanning Industry: I—Processing and Thermo-mechanical Properties

AbstractIn this study, blends of a biodegradable thermoplastic polyester, poly (butylene succinate-co-adipate) (PBSA) with two different raw hydrolyzed collagens (HCs), derived from the tannery industry, were investigated in terms of processability, rheological, thermal and mechanical properties. HCs, obtained by alkaline (HCa) and enzymatic (HCe) hydrolysis of the solid wastes generated during the shaving of the tanned leather, were used in PBSA/HC blends, up to 20 wt% of HC, produced by melting extrusion and processed by injection molding. All the blends up to 20 wt% HCs resulted suitable for the injection molding obtaining flexible molded specimens with good tensile properties. The different secondary structure of the two HCs influenced the rheology, morphology and mechanical properties of the produced blends. In particular, HCa, due its higher content of oligopeptides and free amino-acids, showed a good compatibility with the polymeric matrix acting as a plasticizer with consequent reduction of melt viscosity with increasing its loading. The molded dog-bones specimens containing 20 wt% HCa showed a value of elongation at break of 810%. While, HCe, due its higher presence of b-sheet structures, behaved as organic filler, showing a poor interfacial interaction with PBSA with consequent decrease of the tensile properties with increasing its loading. The good processability and satisfactory mechanical properties obtained encourage the use of both investigated collagen hydrolysates in the production of thermoplastic blends and relative molded products for applications in agriculture and plant nurseries, such as pots or small containers with fertilizing properties, due the presence of HCs

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

Recyclability of PET/WPI/PE multilayer films by removal of whey protein isolate-based coatings with enzymatic detergents

Multilayer plastic films provide a range of properties, which cannot be obtained from monolayer films but, at present, their recyclability is an open issue and should be improved. Research to date has shown the possibility of using whey protein as a layer material with the property of acting as an excellent barrier against oxygen and moisture, replacing petrochemical non-recyclable materials. The innovative approach of the present research was to achieve the recyclability of the substrate films by separating them, with a simple process compatible with industrial procedures, in order to promote recycling processes leading to obtain high value products that will beneficially impact the packaging and food industries. Hence, polyethyleneterephthalate (PET)/polyethylene (PE) multi-layer film was prepared based on PET coated with a whey protein layer, and then the previous structure was laminated with PE. Whey proteins, constituting the coating, can be degraded by enzymes so that the coating films can be washed offfrom the plastic substrate layer. Enzyme types, dosage, time, and temperature optima, which are compatible with procedures adopted in industrial waste recycling, were determined for a highly-efficient process. The washing of samples based on PET/whey and PET/whey/PE were efficient when performed with enzymatic detergent containing protease enzymes, as an alternative to conventional detergents used in recycling facilities. Different types of enzymatic detergents tested presented positive results in removing the protein layer from the PET substrate and from the PET/whey/PE multilayer films at room temperature. These results attested to the possibility of organizing the pre-treatment of the whey-based multilayer film by washing with different available commercial enzymatic detergents in order to separate PET and PE, thus allowing a better recycling of the two different polymers. Mechanical properties of the plastic substrate, such as stress at yield, stress and elongation at break, evaluated by tensile testing on films before and after cleaning, were are not significantly affected by washing with enzymatic detergents

Optimizing the lignin based synthesis of flexible polyurethane foams employing reactive liquefying agents

The present work is focused on the optimization of a green process based on the employment of by-products obtained from wood treatments as raw materials for producing flexible polyurethane foams. More specifically, lignin was employed in flexible polyurethane foams in order to partially replace the usual fossil polyols; therefore glycerol (GLY) and glycerin polyglycidyl ether (EJ 300) were used as the polyol fraction for lignin liquefaction. Polypropylene glycol triol was used as a chain extender in different ratios with liquefaction solvents, and polymeric diphenylmethane diisocyanate as an isocyanate fraction. Liquefaction of lignin was performed by microwave irradiation, thus reducing the processing time and energy required compared to present industrial production processes. All the foams were produced in controlled expansion through the adoption of a one-shot' approach, using water as a blowing agent and with an isocyanate index (NCO/OH) of less than 100 to improve the flexibility of the foam. This approach allowed for the substitution of up to 12% of common petro derived polyol with commercial soda lignin. Finally, the foams were characterized, presenting properties that could be modulated as a function of lignin content, GLY/EJ 300 ratio and isocyanate index. The qualities of the foams were compatible with existing materials used for furniture and for the interiors of car seats and couches

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

Ramie fibers in a comparison between chemical and microbiological retting proposed for application in biocomposites

Due to light weight, renewability, sustainability and generally moderate costs, natural fibers are addressed for the production of composites for application in packaging, automotive and other indus- tries. Several approaches are under investigation to improve compatibility with polymer matrices and improve mechanical performances of composites with natural fibers. The retting process is the major limitation to efficient and high-quality natural fiber production. The conventional retting is normally done chemically by treatment of decorticated fibers with hot alkaline solutions. Such a process requires high energy input and produces hazardous wastes. Microbiological and enzymatic methods represent a reliable replacement, however their application on ramie (Boehmeria nivea (L.) Gaud.) has not yet been optimized and tuned for use on a large scale. Consequently, the aim of this work was to evaluate the role of microbiological retting on the morphological, chemical and physical–mechanical properties of the derived ramie fibers for application in biocomposites. The decorticated ramie fibers, obtained by mature crop stands grown at the experimental station of the Department of Agriculture, Food and Environment (DAFE) of the University of Pisa, were subjected to a water based microbiological degumming performed with the use of two selected strains of Clostridium felsineum L. at 30◦C for 7 days. The results obtained with this method were compared with those recorded adopting the conventional chemical process with NaOH water solution at 100 ◦ C for 2 h. The morphological, chemical (hemicellulose, cellulose, lignin and ash) and physico-mechanical (tensile strength, elastic modulus and elongation at break) properties of retted ramie fibers were investigated. The fibers produced were evaluated for the production of compos- ites by using polyhydroxyalkanoates (PHAs) as polymeric matrix, as targeted in the EC running project OLI-PHA. Significant differences were observed between the two types of degumming in terms of yield and quality of the fibers. Even if the highest fiber yields were recorded with chemical retting, the perfor- mances of fibers modified by microbiological treatments were comparable with those of the composite prepared with fibers modified by chemical treatment. Scanning electron microscopy analysis revealed a good removal of non-cellulosic gummy material from the surface of ramie fibers. According to the mechanical properties, the ramie fibers obtained by both degumming processes, were suitable for use in PHAs composites

Microbiological valorisation of bio-composites based on polylactic acid and wood fibres

The use of wood fibres for production of bio-based composites has attracted interest in various application sectors ranging from packaging to automotive components and in other high value applications. In the course of the present research activity, several bio-based composites were developed using wood fibres with a compostable polymeric matrix such as polylactic acid (PLA) and a flexible biodegradable polymer such as poly(butylene adipate-co-terephthalate) (PBAT). The developed materials were used for the manufacture of several prototypes for food packaging (trays, boxes for refrigerated or frozen fish, egg box), agricultural applications (pots and yarns), automotive components (spoiler and seats) as well as containers for cosmetics and chemicals. Biodegradability and compostability are desired properties, allowing bio-recycling as end of life scenario, mainly for materials used in food packaging and agricultural applications. Thus, they may be recycled at the end of their life time service producing compost as a value-added by-product. Composting is the main option for bio-recycling but also other valuable pathways can be pursued. Because lignocellulose is one of the components of developed materials, several by-products such as enzymes, reducing sugars, proteins, amino acids, carbohydrates, organic acids, etc. may be obtained from the bio-composites produced. Alternatively, the bio-composites can be also used for the production of yeast biomass. This is important as another recyclability way of the new produced materials. In the present research the bio-composites produced were investigated as substrates for the production of the methylotrophic yeast Pichia pastoris, a potential source of single-cell protein (SCP), β-carotene, and Rhodotorula sp. as potential source of food and feed grade colorant. This is another more valuable alternative to the composting considering also that composting cannot be used to dispose of large quantities of bio-plastics, and in the future it will become more and more important to find alternative routes of valorisation for bio-plastics disposal

Cellulose Acetate Blends – Effect of Plasticizers on Properties and Biodegradability

Cellulose acetate (CDA) cannot be processed as raw material because it starts to decompose before melting. Triacetin and diacetin were tested to improve CDA processing versus conventional phthalate as environmentally sustainable plasticizers, because of their low toxicity and fast biodegradability. The addition of triacetin and diacetin allowed melt processing of CDA and the results of tensile tests outlined their effect as plasticizers. The values of mechanical properties were compatible with the requirements for applications in rigid packaging. From the results of biodegradation tests it can be concluded that for pure cellulose acetate, complete biodegradation was obtained within 200 days of testing after reinoculation. Incomplete biodegradation was observed for test items with 20% triacetin or with 30% phthalate. After 46 days of incubation, the test samples with 30% plasticizer based on triacetin or triacetin-diacetin were completely biodegraded. These formulations can be selected for the production of compostable blends and/or biocomposites