Bio-sourced Polymers Research Articles

Food applications of bioactive biomaterials based on gelatin and chitosan.

Food packaging must guarantee the products' quality during the different operations including packing and maintenance throughout transportation and storage until to consumption. Thus, it should satisfy, both, food freshness and quality preservation and consumers health safety. Natural bio-sourced polymers have been explored as safe edible materials for several packaging applications, being interestingly carrier of bioactive substances, once added to improve films' properties. Gelatin and chitosan are among the most studied biomaterials for the preparation of edible packaging films due to their excellent characteristics including biodegradability, compatibility and film-forming property. These polymers could be used alone or in combination with other polymers to produce composite films with the desired physicochemical and mechanical properties. When incorporated with bioactive substances (natural extracts, polyphenolic compounds, essential oils), chitosan/gelatin-based films acquired various biological properties, including antioxidant and antimicrobial activities. The emerging bioactive composite films with excellent physical attributes represent excellent packaging alternative to preserve different types of foodstuffs (fruits, meat, fish, dairy products, …) and have shown great achievements. This chapter provides the main techniques used to prepare gelatin- and chitosan- based films, showing some examples of bioactive compounds incorporated into the films' matrix. Also, it illustrates the outstanding advantages given by these biomaterials for food preservation, when used as coating and wrapping agents.

Water-soluble bio-sourced resist interactions with fluorinated etching plasmas during the photolithography process

Lithography is one of the key steps in micro/nanofabrication, which involves the use of oil-based resists, organic solvents, and toxic chemicals. Nowadays, environmental issues and regulation have raised the need for developing greener materials and processes. Therefore, efforts have been devoted to developing greener resists, in particular, resists based on water-soluble bio-sourced polymers. Among these biopolymers, polysaccharides have gained a strong interest. However, their interaction with silica etching plasmas, in particular, fluorinated plasmas, remains scarcely studied and contradictory results are found in the literature. The present contribution reports on the study of the interaction of two chitosans exhibiting different degrees of N-acetylation with SF6/Ar and CHF3 etching plasmas. The surface modifications and in-depth modifications were studied with x-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, infrared spectroscopy, water contact angle, and size-exclusion chromatography. The effect of neutrals, ions, and vacuum ultraviolet (VUV) was considered. Our results suggest that the chitosan selectivity is greatly influenced by the deposition of a fluorocarbon film and that VUV seems to be involved in scissions of the polymer chains. No significant difference between the two chitosans was observed.

Mechanical Recycling of Thermoplastics: A Review of Key Issues

During the last decade, the consumption of plastics has increased highly in parallel with plastic waste. The transition towards a circular economy is the only way to prevent the environment from landfilling and incineration. This review details the recycling techniques with a focus on mechanical recycling of polymers, which is the most known and developed technique in industries. The different steps of mechanical recycling have been highlighted, starting from sorting technologies to the different decontamination processes. This paper covers degradation mechanisms and ways to improve commodity polymers (Polyolefins), engineering polymers (PET, PA6), and bio-sourced polymers (PLA and PHB).

Alternative building blocks sources for poly (ethylene terephthalate): A short review with socio-economical points of view

The objectives of circularity are often focused on recycling, but combining use of alternative building blocks such as bio-sourced ones for virgin materials with ability for recycling seems to be a relevant challenge. Unfortunately, the volumes of rather new bio-based plastics, such as Poly (lactide) (PLA), seem be too low to allow the development of new recycling chains in the next years. Therefore, these bio-plastics are not likely to be recycled at large scale, reducing their interest when considering their whole life cycle. Nevertheless, continuing to produce petroleum-based plastics and searching for a way to recycle them seems not to be a self-sufficient solution. Indeed, in order to reconciliate recycling and bio-based plastics, a strategy is to focus on the production of conventional plastics, such as poly (ethylene terephthalate) (PET), from renewable resources while ensuring their recycling in existing chains. In this context, this review focuses on alternative building blocks sources to produce PET, for which recycling seems relevant and developed. Although still produced in small quantities, some alternative sources for building block production have been able to establish themselves in the industrial landscape. Nevertheless, there is still little industrialization and the synthons are often produced in small quantities. Most of the discoveries are still confined to laboratory studies with some pilot tests for part of them. It should be emphasized that, even if some synthons are already commercialized, research is active with the aim of improving yields, discovering cleaner catalysts, reducing energy consumption. The review describes alternative routes and sources for the production of PET, not only with technological but also socio-economical points of view with discussion on their potentials and limits. The different routes proposed display promising advantages to be improved by research studies. Nevertheless, producing bio-sourced polymers at a large-scale could lead to problems of access to resources. A more local economy involving smaller volumes of material and adapting to the resources of the territory could be an alternative. The review could help in orientating research contributing to a circular economy depending less on non renewable resources, considering technological and socio-economical points of view.

Wood-Sourced Polymers as Support for Catalysis by Group 10 Transition Metals

Despite providing interesting solutions to reduce the number of synthetic steps, to decrease energy consumption or to generate less waste, therefore contributing to a more sustainable way of producing important chemicals, the expansion of the use of homogeneous catalysis in industrial processes is hampered by several drawbacks. One of the most important is the difficulty to recycle the noble metals generating potential high costs and pollution of the synthesized products by metal traces detrimental to their applications. Supporting the metals on abundant and cheap biosourced polymers has recently appeared as an almost ideal solution: They are much easier to recover from the reaction medium and usually maintain high catalytic activity. The present bibliographical review focuses on the development of catalysts based on group 10 transition metals (nickel, palladium, platinum) supported on biopolymers obtained from wood, such as cellulose, hemicellulose, lignin, and their derivatives. The applications of these catalysts in organic synthesis or depollution are also addressed in this review with examples of C-C couplings, oxidation, or hydrogenation reactions.

The Use of Thermal Techniques in the Characterization of Bio-Sourced Polymers.

The public pressure about the problems derived from the environmental issues increasingly pushes the research areas, of both industrial and academic sectors, to design material architectures with more and more foundations and reinforcements derived from renewable sources. In these efforts, researchers make extensive and profound use of thermal analysis. Among the different techniques available, thermal analysis offers, in addition to high accuracy in the measurement, smartness of execution, allowing to obtain with a very limited quantity of material precious information regarding the property–structure correlation, essential not only in the production process, but overall, in the design one. Thus, techniques such as differential scanning calorimetry (DSC), differential thermal analysis (DTA), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were, are, and will be used in this transition from fossil feedstock to renewable ones, and in the development on new manufacturing processes such as those of additive manufacturing (AM). In this review, we report the state of the art of the last two years, as regards the use of thermal techniques in biopolymer design, polymer recycling, and the preparation of recyclable polymers as well as potential tools for biopolymer design in AM. For each study, we highlight how the most known thermal parameters, namely glass transition temperature (Tg), melting temperature (Tf), crystallization temperature (Tc) and percentage (%c), initial decomposition temperature (Ti), temperature at maximum mass loss rate (Tm), and tan δ, helped the researchers in understanding the characteristics of the investigated materials and the right way to the best design and preparation.

Hybrid Conversion of 5‐Hydroxymethylfurfural to 5‐Aminomethyl‐2‐furancarboxylic acid: Toward New Bio‐sourced Polymers

AbstractHybrid catalysis, which combines chemo‐ and biocatalytic benefits, is an efficient way to address green chemistry principles. 5‐Hydroxymethylfurfural (HMF) is a versatile building block in numerous industrial applications. To date, few studies have described the production of its amine derivatives and their polymers. Finding a good methodology to directly transform HMF to 5‐aminomethyl‐2‐furancarboxylic acid (AMFC) therefore represents an important challenge. After selecting the best oxidation catalyst for HMF conversion to 5‐aldehyde‐2‐furancarboxylic acid and immobilizing a transaminase onto a solid carrier, we implemented the first one‐pot/two‐steps hybrid catalytic process to produce AMFC (77 % yield); this is the most efficient AMFC catalytic production method from HMF reported to date. This process also produced 2,5‐furandicarboxylic acid (21 % yield) as a major secondary product that can be applied to polymer syntheses such as polyethylene furanoate. Herein, we report a novel way to access new biosourced polymers based on HMF oxidized and aminated derivatives.

Nanofibrillar green composites of polylactide/polyamide produced in situ due to shear induced crystallization

Nowadays, extensive efforts are devoted to develop efficient ways to prepare in-situ fibrillated polymer-polymer nanocomposites which are both strong and ductile. Using entirely bio-sourced polymers is essential to keep a green nature of the obtained nanocomposites. In current work, sustainable in-situ green nanocomposites of polylactide (PLA) and biosourced polyamide (PA) were obtained in one stage of extrusion through applying high shear rate. The critical role of a high shear rate in the possibility of implementing two simultaneous processes, namely, the transition from droplet to fibrillar morphology and the subsequent instantaneous stabilization of the formed fibrillar morphology via the shear induced crystallization of minor phase, is highlighted. It is shown that in the case of PLA/PA blend, both of these processes are activated at a shear rate of 300 s−1 and lead to the formation of nanofibers with nanosized scale (150–550 nm) and aspect ratios of 45. At a low concentration of PA, 5 wt%, this results in the formation of an effective nanofibrillar network, which leads to strong interfacial adhesion between the phases. The Young's modulus, strain at break and impact strength of in situ generated PLA/PA composite undergoes an enhancement nearly 7, 4500, and 90%, respectively, while its tensile strength retains high.

Acetylated lignin nanoparticles as a possible vehicle for photosensitizing molecules.

Lignins are underused and abundant bio-sourced polymers with various potential applications. An attractive one is the development of nanoparticles for bioactive compound delivery. Here, we optimized the synthesis of hydrodispersible nanoparticles of acetylated lignin by comparing different lignin sources, degrees of acetylation and preparation methods. The formation of acetylated lignin nanoparticles in various solvents was probed by both experiments and, for the first time, a molecular dynamics simulation. We showed that dialysis is more suitable to obtain these nanoparticles than anti-solvent addition. The encapsulation of hydrophobic photosensitizing porphyrin in these nanoparticles was also demonstrated and rationalized at the molecular level, together with experiments, docking and molecular dynamics simulations. As acetylated lignin has been demonstrated to exhibit photosensitizing activity, the encapsulation of bioactive compounds in lignin nanoparticles opens the doors to a broad range of potential applications.

A PROMISE ALBENDAZOLE DRUG DELIVERY SYSTEM BASED ON PHBV MICROSPHERES AND POROUS CORK MICROPARTICLES: INVESTIGATION OF ITS PHYSICOCHEMICAL PROPERTIES ANDIN VITRORELEASE BEHAVIOR

The association of biodegradable and biosourced polymers with biomass raw materials is a promising way for the preparation of new drug delivery systems (DDS). Cork as one of the typical biomass raw materials seems to be very interesting in the formulation of effective and reliable DDS. In this study, several formulations of DDS based on microspheres of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and different amounts of microparticles of cork (MPC) powder, containing albendazole, were successfully prepared by microencapsulation, using emulsification/solvent evaporation technique. The prepared formulations showed good production yields and encapsulation efficiencies exceeding 80%. The chemical compatibility between the drug and the DDS matrix was evaluated by Fourier transform infra-red spectroscopy (FTIR). The obtained results proved the lack of interactions. In term of morphology, scanning electron microscopy (SEM) revealed that DDS were composed of non-aggregated spherical shape PHBV microspheres and porous MPC capable of entrapping the drug and the PHBV microspheres. The evaluation of the drug dispersion state in the DDS matrix was conducted using thermogravimetric (TG) analysis, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) suggesting drug amorphization. The in vitro drug release experiments by UV-Visible spectrophotometery showed an initial burst followed by a sustained release. Compared with a commercial albendazole form no significant drug degradation was observed at low pH. Additionally, an improvement in the bioavailability of albendazole was obtained with increasing amounts of MPC in the DDS. In view of these results, the developed DDS appear to have great potential as carrier for a prospective delivery to colon.

Nanofibrillar Green Composites of Polylactide/Polyhydroxyalkanoate Produced in Situ Due to Shear Induced Crystallization.

This study addresses the new concept of in situ inducing fibrillar morphology (micro or nanofibrils) of a minority component based on the simultaneous occurrence of orientation and shear induced crystallization of polymer fibers directly at the stage of extrusion in a single step. This possibility is demonstrated by using two entirely bio-sourced polymers: polylactide (PLA) and polyhydroxyalkanoate (PHA) as components. The shear induced crystallization allowed crystallization of PHA nanofibers immediately after applying high shear rate and elongation strain, avoiding subsequent cooling to initiate crystallization. Shearing of PHA increased non-isothermal crystallization temperature by 50 °C and decreased the temperature range in which the transition from a molten state to a crystallized one occurs by 17 °C. SEM observations demonstrate the successful transformation of the dispersed PHA phase into nanofibrils with diameters of nearly 200 nm. The transition from the droplets of PHA to fibers causes the brittle-to-ductile transition of the PLA matrix at a low concentration of PHA and contributes to the simultaneous increase of its rigidity and strength.

Capability of PN3-type Cobalt Complexes toward Selective (Co-)Polymerization of Myrcene, Butadiene, and Isoprene: Access to Biosourced Polymers

In this manuscript, cobalt complexes Co1, Co2, and Co3 supported by PN3-type of ligand have been prepared, characterized, and applied in polymerization of myrcene (My), butadiene (Bd), and isoprene (Ip). The type of catalyst, cocatalyst, and temperature variation have little influence on polymer microstructure. We also have reported the preparation of novel isoprene–myrcene copolymers in the presence of complex Co1. Isoprene and myrcene are found to be randomly copolymerized at various monomer feeding, with typical myrcene incorporation of 7.6–57.6%. The copolymer has cis-1,4 microstructure of 69.4–73.4% and 79.4–83.4% for polyisoprene and polymyrcene segments, respectively, and Tg = ca. −41.7 to 51.1 °C. The reactivity ratios obtained from the Fineman–Ross plot of r1 = 0.74 and r2 = 1.67 (r1 = kmymy/kmyip and r2 = kipip/kipmy) indicate that isoprene has the privilege of getting into the macromolecules during the polymerization by this catalyst system.

Measurement of the thermal conductivity of flexible biosourced polymers using the 3-omega method

The thermal conductivity of flexible biosourced polymers was measured by the 3-omega method. Two biopolymers were investigated: the polylactic acid (PLA), a widely used commercial biodegradable one, and the cellulose palmitate (CP), a hydrophobic biosourced material developed in the laboratory, that could be used in electronic or microfluidic applications. The 3-omega method is based-on the use of a metal element as both heating device to thermally disturb the system and temperature sensor. A stencil lithography technique was applied to obtain metallic lines, since biopolymers are not compatible with classical photolithography method. Thermal conductivities of 0.19 and 0.30 W/m.K are obtained respectively for PLA and CP thick films, and 0.12 and 0.22 W/m.K for respectively PLA and CP thin films. These values are close to those measured for petro-sourced substrates or films and so give the possibility to address the applications mentioned.

Influence of supercritical debinding and processing parameters on final properties of injection-moulded Inconel 718

In the metal injection-moulding process, the thermoplastic polymer binder plays an essential role as it provides fluidity to the high-loaded feedstock and strength to maintain the moulded shape. The purpose of this study is to develop an environmentally friendly feedstock loaded with a super-alloy Inconel 718 powder. Different binder formulations based on polyethylene glycol (PEG), for its water solubility, and bio-sourced polymers were investigated. Poly(lactic acid)/(polyhydroxybutyrate-valerate) was investigated as a bio-sourced polymer because its miscibility with the PEG. The results are compared to a standard formulation using polypropylene and PEG developed by our research group. A micro powder of Inconel 718 (nickel-based super-alloy) was chosen to elaborate the feedstock. The chemical and rheological behaviour of the feedstock during the mixing, injection, and debinding processes were investigated, with tight control of each process. The comparative impacts of the two different debinding processes and optimum sintering parameters were investigated: one by water and one by CO2 in supercritical state. The supercritical debinding caused no damage to the components for all types of feedstock and decreased the time to remove the PEG from 48 h to 4 h. Finally, the density, microstructure, and hardness of the different samples after final heat treatment were compared. The microstructure was clearly optimized, as the γ″ phases were promoted inside the grains. The results show that the well-adapted binder and debinding process produces an Inconel 718 component with high mechanical properties (Vickers hardness of 341 ± 19 HV). Moreover, this approach can be used with other formulations, powders, and binder systems.

Stability of gold nanocatalysts supported on mesoporous silica for the oxidation of 5-hydroxymethyl furfural to furan-2,5-dicarboxylic acid

The synthesis of furan-2,5-dicarboxylic acid via catalytic oxidation of 5-hydroxymethyl furfural is an important step for the production of bio-sourced polymers. We report on the activity of SiO2-supported Au catalysts for this reaction. These catalysts reached 74% furan-2,5-dicarboxylic acid yield at 90 °C in 5 h when 5-hydroxymethyl furfural to Au molar ratio was 72. We also investigated the influence of the morphologies of the silica supports on the growth of Au nanoparticles under reaction conditions. Pronounced growth of Au nanoparticles occurred on Aerosil, SiO2 with a disordered porosity and 50 nm average pore diameter: Au nanoparticles grew from 2.4 to 10.1 nm. However, by using ordered mesoporous supports, the growth of the gold nanoparticles was successfully minimized. Also the reaction conditions influenced the particle growth; for instance using HCO3− as a base led to more pronounced particle growth than using NaOH. Particle diffusion in solution, and subsequent coalescence and agglomeration was proposed to be the dominant particle growth mechanism. Our results show the importance of support morphology in mitigation of Au particle growth in liquid phase oxidation reactions.

Development and characterisation of a biosourced feedstock of superalloy in metal injection moulding process

ABSTRACTIn the metal injection moulding process the binder plays the most important role. It provides fluidity of the feedstock and strength to keep the moulded shape. The goal of this study is to develop an environmentally friendly feedstock of superalloy Inconel 718. For this different binders formulations based on polyethylene glycol and biosourced polymers were studied. Polylactic acid was investigated as biosourced polymer due to his miscibility with the PEG. The results are compared to a standard formulation using polypropylene. The chemical and rheological behaviour of the binder formulation during mixing, injection and debinding process were investigated. Moreover, a powder of superalloy Inconel 718 was chosen to produce a feedstock. The feedstock was characterised like the binders and the interactions between the powder and the binders was also studied. The results show the well adapted formulation of polymer binder to produce a superalloy Inconel 718 feedstock.This paper is part of a special issue on the Advances in Materials and Processing Technologies (AMPT) 2015 and has subsequently been revised and extended before publication in Powder Metallurgy.

Oxidized Xanthan Gum and Chitosan as Natural Adhesives for Cork.

Natural cork stopper manufacturing produces a significant amount of cork waste, which is granulated and combined with synthetic glues for use in a wide range of applications. There is a high demand for using biosourced polymers in these composite materials. In this study, xanthan gum (XG) and chitosan (CS) were investigated as possible natural binders for cork. Xanthan gum was oxidized at two different aldehyde contents as a strategy to improve its water resistance. This modification was studied in detail by 1H and 13C nuclear magnetic resonance (NMR), and the degree of oxidation was determined by the hydroxylamine hydrochloride titration method. The performance of the adhesives was studied by tensile tests and total soluble matter (TSM) determinations. Xanthan gum showed no water resistance, contrary to oxidized xanthan gum and chitosan. It is hypothesized that the good performance of oxidized xanthan gum is due to the reaction of aldehyde groups—formed in the oxidation process—with hydroxyl groups on the cork surface during the high temperature drying. Combining oxidized xanthan gum with chitosan did not yield significant improvements.

Development and Characterization of a Metal Injection Molding Bio Sourced Inconel 718 Feedstock Based on Polyhydroxyalkanoates

The binder plays the most important role in the metal injection molding (MIM) process. It provides fluidity of the feedstock mixture and adhesion of the powder to keep the molded shape during injection molding. The binder must provide strength and cohesion for the molded part and must be easy to remove from the molded part. Moreover, it must be recyclable, environmentally friendly and economical. Also, the miscibility between polymers affects the homogeneity of the injected parts. The goal of this study is to develop a feedstock of superalloy Inconel 718 that is environmentally friendly. For these different binders, formulations based on polyethylene glycol (PEG), because of his water solubility property, and bio sourced polymers were studied. Polyhydroxyalkanoates (PHA) were investigated as a bio sourced polymer due to its miscibility with the PEG. The result is compared to a standard formulation using polypropylene (PP). The chemical and rheological behavior of the binder formulation during mixing, injection and debinding process were investigated. The feedstock was characterized in the same way as the binders and the interactions between the powder and the binders were also studied. The results show the well adapted formulation of polymer binder to produce a superalloy Inconel 718 feedstock.

Metallic Pollutant Removal in Leachates Extracted from Sediment by Geotextiles Based on Crosslinked Bio-Sourced Polymers

The aim of this study was to prepare ion exchange textiles (IET) by grafting carboxylic functions onto the surface of polyethylene terephthalate (PET) nonwoven fabrics in order to capture metals in leachates extracted from dredged sediment samples, taken from Dunkerque seaport. A pad/dry/cure coating process, based on the in situ polymerization of a mixture consisting of maltodextrin and a polycarboxylic acid on the textile structure, was applied. We used either citric acid (CTR) or 1,2,3,4-butanetetracarboxylic acid (BTCA) as polycarboxylic acids. The amount of ion exchange functions on the geotextiles was first measured and we evaluated their adsorption capacities towards metal cations. To reach that purpose, a first test was carried out on solutions prepared with lead (Pb) in the absence or presence of NaCl, to mimic seawater saline conditions. The presence of NaCl led to a moderate reduction of 25% in lead removal by the IET. The second test was carried out on a sediment leachate. This leachate being weakly contaminated, we artificially doped it with cadmium, copper, lead and zinc in order to evaluate the potential utility of the geotextile treatment. The functionalized textiles adsorbed more than 60% of the lead and zinc. A complete removal of copper was reached for CTR-based IET and the textiles showed less efficiency towards cadmium in the considered mixture.

Capillary rheometry of a binary mixture polymer/CO2 in a single screw extruder

Processing bio-sourced polymers with supercritical fluids is a promising route towards new green engineering processes. Supercritical carbon dioxide (sc-CO2), is soluble in large quantities in molten polymers, where it acts as plasticizer and swelling agent. It is used, in blending or foaming of polymers, particle formation and polymerisation process.The process of hot-melt extrusion assisted by sc-CO2 allowed the development of an on-line viscosity measurement based on capillary rheometry. Applied to a bio-sourced polyamide, it was validated by comparison with a classic capillary rheometer. Both data sets were in good agreement.A pseudoplastic fluid behaviour was observed with a 30 % viscosity decrease from 46 to 32Pas at 5000s−1 and 220°C, upon addition of CO2. However, viscosity decreased to a plateau before reaching the thermodynamic solubility. The comparison with a model coupling solubility and flow allowed to identify the method limitations, which were attributed to the kinetics of dissolution and mixing. The higher the shear stress, the higher the amount of CO2 at which the viscosity plateau is reached. These measurements may quantify the impact of the CO2 on the rheology of the system but also of the efficiency of the mixing process in our experimental setup.