Poly-l-Lactic Acid Scaffolds Additivated with Rosmarinic Acid: A Multi-Analytical Approach to Assess The Morphology, Thermal Behavior, and Hydrophilicity.

This study aims to demonstrate the possibility of incorporating a natural antioxidant biomolecule into polymeric porous scaffolds. To this end, Poly-l-Lactic Acid (PLLA) scaffolds were produced using the Thermally Induced Phase Separation (TIPS) technique and additivated with different amounts of rosmarinic acid (RA). The scaffolds, with a diameter of 4 mm and a thickness of 2 mm, were characterized with a multi-analytical approach. Specifically, Scanning Electron Microscopy analyses demonstrated the presence of an interconnected porous network, characterized by a layer of RA at the level of the pore's surfaces. Moreover, the presence of RA biomolecules increased the hydrophilic nature of the sample, as evidenced by the decrease in the contact angle with water from 128° to 76°. The structure of PLLA and PLLA containing RA molecules has been investigated through DSC and XRD analyses, and the obtained results suggest that the crystallinity decreases when increasing the RA content. This approach is cost-effective, and it can be customized with different biomolecules, offering the possibility of producing porous polymeric structures containing antioxidant molecules. These scaffolds meet the requirements of tissue engineering and could offer a potential solution to reduce inflammation associated with scaffold implantation, thus improving tissue regeneration.

Biodegradation of Polystyrene by Plastic-Eating Tenebrionidae Larvae.

Polystyrene (PS) is an extremely stable polymer with a relatively high molecular weight and a strong hydrophobic character that makes it highly resistant to biodegradation. In this study, PS was subjected to biodegradation tests by Tenebrio Molitor (T. Molitor) and Zophobas Morio (Z. Morio) larvae. Specifically, six different experimental diets were compared: (i) T. Molitor fed with bran; (ii) T. Molitor fed only PS; (iii) T. Molitor fed only PS treated with H2O2; (iv) Z. Morio fed with bran; (v) Z. Morio fed only PS; and (vi) Z. Morio fed only PS treated with H2O2. Therefore, the mass change of the larvae and the survival rate were measured periodically, while the frass collected after 15 and 30 days was analyzed by different analyses, such as spectroscopy (FTIR), spectrometry (molecular weight and polydispersity), thermal analysis (TGA) and microscopy (scanning electron microscopy observations). The obtained results suggest that in the case of T. Molitor larvae, larvae feeding on bran showed the highest survival rate of ~94% at 30 days, while in the case of the Z. Morio larvae, the highest survival rate was exhibited by larvae eating PS-H2O2. Although not strongly pronounced, the Mw and Mn of PS in the frass of both T. Molitor and Z. Morio larvae decreased over 30 days, suggesting PS biodegradation. Finally, the morphological analysis shows that PS samples isolated from the frass of T. Molitor and Z. Morio larvae showed completely different, rough and irregularly carved surface structures, in comparison to PS before biodegradation.

Understanding the Effects of Adding Metal Oxides to Polylactic Acid and Polylactic Acid Blends on Mechanical and Rheological Behaviour, Wettability, and Photo-Oxidation Resistance.

Biopolymers are of growing interest, but to improve some of their poor properties and performance, the formulation of bio-based blends and/or adding of nanoparticles is required. For this purpose, in this work, two different metal oxides, namely zinc oxide (ZnO) and titanium dioxide (TiO2), at different concentrations (0.5, 1, and 2%wt.) were added in polylactic acid (PLA) and polylactic acid/polyamide 11 (PLA/PA11) blends to establish their effects on solid-state properties, morphology, melt behaviour, and photo-oxidation resistance. It seems that the addition of ZnO in PLA leads to a significant reduction in its rigidity, probably due to an inefficient dispersion in the melt state, while the addition of TiO2 does not penalize PLA rigidity. Interestingly, the addition of both ZnO and TiO2 in the PLA/PA11 blend has a positive effect on the rigidity because of blend morphology refinement and leads to a slight increase in film hydrophobicity. The photo-oxidation resistance of the neat PLA and PLA/PA11 blend is significantly reduced due to the presence of both metal oxides, and this must be considered when designing potential applications. The last results suggest that both metal oxides could be considered photo-sensitive degradant agents for biopolymer and biopolymer blends.

Recovery of Rose Flower Waste to Formulate Eco-Friendly Biopolymer Packaging Films.

Considering the circular principles of materials and investigating the possibility to use waste materials before their final disposal, in this work, dry rose flower (DRF) and rose flower waste (RFW), after oil extraction, have been considered as suitable materials for the formulation of biopolymer packaging films. Both DRF and RFW particles have been characterized by spectroscopy analysis, and their radical scavenger ability has been investigated. Moreover, DRF and RFW particles have been added by melt mixing to PolyLactic Acid (PLA), and formulated PLA-based films have been studied through rheology analysis, mechanical test, differential scanning calorimetry, and microscopy observations. Finally, the influence of both DRF and RFW particles on the photo-oxidation behavior of PLA has been evaluated by subjecting thin films to UVB exposure, and the progress of degradation has been monitored following the accumulations of oxygen-containing groups in time. Obtained results suggest that both DRF and RFW have a beneficial effect on the photo-oxidation behavior of PLA, and they can slow down PLA degradation upon UVB exposure. Therefore, PLA-based composite materials could be considered a good candidate for applications as packaging films.

Sustainable Materials Containing Biochar Particles: A Review.

The conversion of polymer waste, food waste, and biomasses through thermochemical decomposition to fuels, syngas, and solid phase, named char/biochar particles, gives a second life to these waste materials, and this process has been widely investigated in the last two decades. The main thermochemical decomposition processes that have been explored are slow, fast, and flash pyrolysis, torrefaction, gasification, and hydrothermal liquefaction, which produce char/biochar particles that differ in their chemical and physical properties, i.e., their carbon-content, CHNOS compositions, porosity, and adsorption ability. Currently, the main proposed applications of the char/biochar particles are in the agricultural sector as fertilizers for soil retirement and water treatment, as well as use as high adsorption particles. Therefore, according to recently published papers, char/biochar particles could be successfully considered for the formulation of sustainable polymer and biopolymer-based composites. Additionally, in the last decade, these particles have also been proposed as suitable fillers for asphalts. Based on these findings, the current review gives a critical overview that highlights the advantages in using these novel particles as suitable additives and fillers, and at the same time, it shows some drawbacks in their use. Adding char/biochar particles in polymers and biopolymers significantly increases their elastic modulus, tensile strength, and flame and oxygen resistance, although composite ductility is significantly penalized. Unfortunately, due to the dark color of the char/biochar particles, all composites show brown-black coloration, and this issue limits the applications.

Recycling of Thermoset Materials and Thermoset-Based Composites: Challenge and Opportunity.

Thermoset materials and their composites are characterized by a long life cycle with their main applications in aircrafts, wind turbines and constructions as insulating materials. Considering the importance of recovery and valorization of these materials at their end-of-life, avoiding landfilling, the interest concerning their recycling grows continuously. The thermoset materials and their composites, to be successfully recovered and valorized, must degrade their three-dimensional structures and recover the mono-oligomers and/or fillers. The thermoset materials could successfully degrade through thermal treatment at different temperatures (for example, above 1000 °C for incineration, ca. 500 °C for oxidation/combustion of organic constituents, etc.), chemical degradation by catalyst, irradiation with or without the presence of water, alcohol, etc., and mechanical recycling, obtaining fine particles that are useful as filler and/or reinforcement additives. Among these recycling methods, this mini-review focuses on the formulation and recovery method of innovative thermoset with in-build recyclability, i.e., materials having chemical links that could be degraded on-demand or containing dynamic covalent bonds to have re-processable and/or recyclable thermoset. This issue could be considered the future perspective in developing novel thermoset materials. The aim of this review is to get an overview of the state of the art in thermoset recycling and of the most commonly used thermoset composites, recovering valuable reinforcing fibers. Additionally, in this work, we also report not only known recycling routes for thermoset and thermoset-based composites, but also new and novel formulating strategies for producing thermosets with built-in recyclability, i.e., containing chemical-triggered on-demand links. This mini-review is also a valuable guide for educational purposes for students and specialized technicians in polymer production and recycling.

Polar Wax as Adhesion Promoter in Polymeric Blend Films for Durable Photovoltaic Encapsulants.

Technological developments in the solar photovoltaic field must guarantee the high performance and low deterioration of solar cells in order for solar power plants to be more efficient and competitive. The solar cell needs comprehensive protection offered by a polymeric encapsulant, which improves UV stability, reduces water and moisture absorption, reduces oxygen and vapor permeability and enhances mechanical resistance. Moreover, high transparency and adhesion yields improved the solar panel performance. The current work analyzes polymeric films based on poly(ethylene-co-vinyl acetate) (EVA) and polyolefin (PO) for photovoltaic encapsulant use (the high temperature resistance is improved by adding PO to EVA, as investigated and documented before). To enhance the mechanical resistance and optical properties of the investigated matrices, a crosslinking agent, an adhesion promoter and stabilizing agents have been incorporated in both EVA and EVA/PO systems. The adhesion promoter is a polar wax-silane-free agent; the absence of the silane function allows the integrity of the module to be maintained over time. All samples were characterized through mechanical and rheological analysis, and their long-term UV stability was investigated by accelerated ageing and by FTIR and UV-vis spectroscopy. The obtained results suggest that the presence of a crosslinking agent, an adhesion promoter and stabilizers in EVA/PO-based films allows for the achievement of the required features for the encapsulants, showing mechanical and rheological behavior similar to those of EVA containing the same additives.

Ecofriendly Biopolymer-Based Nanocomposite Films with Improved Photo-Oxidative Resistance.

The interest towards high performance biopolymer-based materials increases continuously and, to guarantee appropriately industrial applications, the photo-oxidative resistance and stability of these materials must be adequately addressed. In this study, innovative biopolymer-based nanocomposites, i.e., Polyamide 11 (PA11), containing ad-hoc modified Layered Double Hydroxides (LDH), were successfully formulated and characterized. Particularly, LDH were considered carriers for hindered amine light stabilizing molecules, so two different hindered amine moieties (HALS1 and HALS2) were anchored on LDH layered internal structures and/or outer surfaces. The presence of HALS1 and HALS2 in LDH were confirmed by X-ray diffraction, spectroscopy, and thermogravimetric analysis. Then, the novel LDH-HALS nanofillers (here named LDH-HALS1 and LDH-HALS2) were introduced into a PA11 matrix by melt mixing at 5 wt.%; the produced nanocomposites were characterized by differential scanning calorimetry, rheological, and morphological analysis. All obtained results suggest that the LDH-HALS1/HALS2 nanofillers were very well dispersed into the PA11 matrix. Additionally, the photo-oxidative resistance of the PA11-based nanocomposite films was evaluated by subjecting thin films to UVB exposure and the degradation process was monitored by spectroscopic analysis over time. The photo-oxidative resistance of the PA11/LDH-HALS1/HALS2 was compared to that of PA11-based nanocomposites containing unmodified LDH and the commercial hindered amine UV-stabilizer (Cyasorb® UV-3853). It was established that by anchoring the hindered amine moieties to the LDH, the PA11 nanocomposites were successfully protected against UVB exposure. This was because the hindered amine light stabilizing molecules were available to act at the critical zone where the degradation phenomena occur, which is at the interface between the matrix and the inorganic particles.

Biochar Particles Obtained from Agricultural Carob Waste as a Suitable Filler for Sustainable Biocomposite Formulations.

In the context of sustainable and circular economy, the recovery of biowaste for sustainable biocomposites formulation is a challenging issue. The aim of this work is to give a new life to agricultural carob waste after glucose extraction carried out by a local factory for carob candy production. A pyrolysis process was carried out on bio-waste to produce biofuel and, later, the solid residual fraction of pyrolysis process was used as interesting filler for biocomposites production. In this work, biochar particles (BC) as a pyrolysis product, after fuels recovery of organic biowaste, specifically, pyrolyzed carobs after glucose extraction, were added on poly(butylene-adipate-co-terephthalate), (PBAT), at two different concentrations, i.e., 10 and 20 wt%. The BC have been produced using three pyrolysis processing temperatures (i.e., 280, 340 and 400 °C) to optimize the compositions of produced solid fractions and biofuels. The resulting particles from the pyrolysis process (BC280, BC340 and BC400) were considered as suitable fillers for PBAT. Firstly, the BC particles properties were characterized by elemental composition and spectroscopy analysis, particle size measurements and evaluation of radical scavenging activity and efficiency. Moreover, PBAT/BC composites were subjected to analysis of their rheological and thermal behavior, morphologies and mechanical properties. In addition, accelerated weathering, monitored by both tensile test and spectroscopic analysis, was carried out, and obtained results show that the biochar particles can exert a beneficial effect on photo-oxidation delay of PBAT matrix.

Recycled (Bio)Plastics and (Bio)Plastic Composites: A Trade Opportunity in a Green Future.

Today's world is at the point where almost everyone realizes the usefulness of going green. Due to so-called global warming, there is an urgent need to find solutions to help the Earth and move towards a green future. Many worldwide events are focusing on the global technologies in plastics, bioplastic production, the recycling industry, and waste management where the goal is to turn plastic waste into a trade opportunity among the industrialists and manufacturers. The present work aims to review the recycling process via analyzing the recycling of thermoplastic, thermoset polymers, biopolymers, and their complex composite systems, such as fiber-reinforced polymers and nanocomposites. Moreover, it will be highlighted how the frame of the waste management, increasing the materials specificity, cleanliness, and a low level of collected material contamination will increase the potential recycling of plastics and bioplastics-based materials. At the same time, to have a real and approachable trade opportunity in recycling, it needs to implement an integrated single market for secondary raw materials.

Durability and Performance of Encapsulant Films for Bifacial Heterojunction Photovoltaic Modules.

Energy recovery from renewable sources is a very attractive, and sometimes, challenging issue. To recover solar energy, the production of photovoltaic (PV) modules becomes a prosperous industrial certainty. An important material in PV modules production and correct functioning is the encapsulant material and it must have a good performance and durability. In this work, accurate characterizations of performance and durability, in terms of photo- and thermo-oxidation resistance, of encapsulants based on PolyEthylene Vinyl Acetate (EVA) and PolyOlefin Elastomer (POE), containing appropriate additives, before (pre-) and after (post-) lamination process have been carried out. To simulate industrial lamination processing conditions, both EVApre-lam and POEpre-lam sheets have been subjected to prolonged thermal treatment upon high pressure. To carry out an accurate characterization, differential scanning calorimetry, rheological and mechanical analysis, FTIR and UV-visible spectroscopy analyses have been performed on pre- and post-laminated EVA and POE. The durability, in terms of photo- and thermo-oxidation resistance, of pre-laminated and post-laminated EVA and POE sheets has been evaluated upon UVB exposure and prolonged thermal treatment, and the progress of degradation has been monitored by spectroscopy analysis. All obtained results agree that the lamination process has a beneficial effect on 3D-structuration of both EVA and POE sheets, and after lamination, the POE shows enhanced rigidity and appropriate ductility. Finally, although both EVA and POE can be considered good candidates as encapsulants for bifacial PV modules, it seems that the POE sheets show a better resistance to oxidation than the EVA sheets.

Matrix and Filler Recycling of Carbon and Glass Fiber-Reinforced Polymer Composites: A Review.

Fiber-reinforced polymers (FRPs) are low-density, high-performance composite materials, which find important applications in the automotive, aerospace, and energy industry, to only cite a few. With the increasing concerns about sustainability and environment risks, the problem of the recycling of such complex composite systems has been emerging in politics, industry, and academia. The issue is exacerbated by the increased use of FRPs in the automotive industry and by the expected decommissioning of airplanes and wind turbines amounting to thousands of metric tons of composite materials. Currently, the recycling of FRPs downcycles the entire composite to some form of reinforcement material (typically for cements) or degrades the polymer matrix to recover the fibers. Following the principles of sustainability, the reuse and recycling of the whole composite-fiber and polymer-should be promoted. In this review paper, we report on recent research works that achieve the recycling of both the fiber and matrix phase of FRP composites, with the polymer being either directly recovered or converted to value-added monomers and oligomers.

End-of-life and waste management of disposable beverage cups.

Different human activities have caused and currently cause catastrophic environmental phenomena, and unfortunately, a significant negative contribution to these catastrophic phenomena can be attributed to uncontrolled plastic production, use and release everywhere. On the other hand, the plastics offer numerous comforts and advantages, and for this reason, the modern life is unthinkable without plastic. Currently, numerous scientific papers and large audience advertisings, related to the production and use of polymers made by natural sources, i.e. bio-based polymers, as a valid alternative to the petroleum-based counterparts, have been published. Therefore, for production of daily disposables and usages, the choice of petroleum-based polymers, coming from fossil-based resources, or bio-based polymers, coming from renewable resources, can be correctly understood and evaluated taking into account different issues concerning resources supplying, production technology and costs, application properties and performance, and finally, waste management. Current paper is focused on a reflection point related to waste management through burning/incineration (i.e. oxidation) of disposable beverage cups (volume 200 ml). The simple calculations of oxidation process of petrol-based or bio-based materials, which is the theoretical basis of waste management through burning/incineration, highlights that none of cup materials, can be considered better than the others to produce daily disposables and usages.

Environmentally Friendly Eutectogels Comprising l-amino Acids and Deep Eutectic Solvents: Efficient Materials for Wastewater Treatment.

Current concerns for sustainability and the environment make low-impact materials desirable for environmental remediation and, in particular wastewater treatment. We obtained supramolecular gels of l-amino acids in the deep eutectic solvent formed by choline chloride and phenylacetic acid. After gel characterization, and investigating gel-sol transition temperatures, gelation kinetics, rheological properties, and morphology, the gels were applied as sorbents to remove cationic dyes from aqueous solutions. The effects of the pH, dye nature, volume, and concentration of wastewater were analyzed, and the best result was obtained with a l-phenylalanine-based eutectogel. It can be reused for at least 9 times without losing efficiency, also with dye mixtures. Interestingly, this gel can be loaded onto columns to decolorize flowing solutions, achieving 85 % of removal efficiency in only 10 minutes and allowing its reuse for at least 4 cycles. In terms of adsorption capacity, this eutectogel is competitive with efficient gel-based dye sorbent systems, with a value 1930 mg/g reached at a high concentration of rhodamine B 479 mg/L.

Ionic liquid gels and antioxidant carbon nanotubes: Hybrid soft materials with improved radical scavenging activity.

HYPOTHESIS: Performances of materials are frequently affected by the action of radicals that can induce their degradation. To overcome the above issue, natural antioxidants (AOs) can be added during manufacturing. Considering the high instability of AOs, they have been adsorbed on carbon nanomaterials surface. However, the inclusion of functionalized carbon nanomaterials into gel matrix could enhance the antioxidant efficiency and represent an easy way to disperse and handle the active species. EXPERIMENTS: Carboxypropyl functionalized carbon nanotubes (f-CNT), pure or with physically adsorbed α-tocopherol (f-CNT-VE) and quercetin (f-CNT-Q), were incorporated in some ionic liquid gels (ILGs) formed by 1,3-didodecylimidazolium-based salts. Temperature of gel-sol transition, morphology, response to external stimuli and rheology of hybrid ILGs (HILGs) were investigated before their use as radical scavengers. To this purpose a free radical test was performed on gels. FINDINGS: The properties of HILGs significantly differ from the ones of pure ILGs, as CNTs appreciably improved gel rheological response. Besides, the gel network is able to enhance radical scavenging activity of both natural AOs and f-CNTs, achieving a complete radical reduction in less than 1 h. Furthermore, the activity is also preserved in thin films obtained from HILGs, opening the way to the application of these systems as material coatings.

Carbon Nanomaterial Doped Ionic Liquid Gels for the Removal of Pharmaceutically Active Compounds from Water.

Due to large drug consumption, pharmaceutically active compounds (PhACs) can be found as water contaminants. The removal of PhACs is a significant issue, as they can easily overtake traditional purification methods. Because of their surface properties, carbon nanomaterials are among the most efficient materials able to adsorb PhACs. However, their limitation is their recovery after use and their possible leakage into the aquatic system. Consequently, new hybrid supramolecular ionic liquid gels (HILGs) have been designed for the adsorption of some antibiotic drugs (ciprofloxacin and nalidixic acid) from water. The chemical-physical properties of gels, such as the temperature of the gel-sol transition, morphology, and rheology, have been studied for their use as sorbents. These properties influence the gel removal efficiency of PhAC, i.e., the best system is the gel that presents weaker colloidal forces. A fast removal (RE = 51%) is obtained in 3 h for ciprofloxacin, while a slower adsorption process is observed for nalidixic acid (RE = 88% in 24 h). HILGs can be recycled up to seven cycles and regenerated. In addition, they can be used with higher concentrations or volumes of PhAC and in a realistic apparatus like dialysis membranes. These peculiarities suggest that HILGs can be competitive with more complex sorbent systems.

Supramolecular Hydro- and Ionogels: A Study of Their Properties and Antibacterial Activity.

Diimidazolium-based organic salts, bearing peptides or amino acids as anions have been synthesised and tested for their gelling ability in biocompatible solvents. These low molecular weight salts were successfully used as gelators in phosphate buffered saline (PBS) solution and ionic liquids. Then, the properties of the obtained soft materials were analysed in terms of melting temperature and gel strength as accounted for by rheological investigations. The gel-phase formation was studied by using UV/Vis and resonance light scattering measurements, whereas the morphology of the soft materials was analysed by using polarised optical microscopy and scanning electron microscopy. To get information about the organisation of the gelator in the gelatinous matrix, X-ray diffraction measurements were performed both on the neat gelators and their gels. The results collected show that the properties of the gel phases, like the thermal stability, the self-repairing ability, the resistance to flow as well as the morphology, are dependent on the nature of the anion. Furthermore, bioassays revealed that the obtained diimidazolium organic salts possessed antimicrobial activity, against gram-negative and gram-positive tester strains. In particular and noteworthy, the diimidazolium organic salts exert a bactericidal capability, which was retained even if they are included in the gel phase. Thus, a novel kind of bioactive soft material was obtained that could be fruitfully employed as a non-covalent coating exerting antibacterial capability.

Grafting of Hindered Phenol Groups onto Ethylene/α-Olefin Copolymer by Nitroxide Radical Coupling.

The covalent immobilization of hindered phenol groups, with potential antioxidant activity, onto an ethylene/α-olefin (EOC) copolymer was carried out by the nitroxide radical coupling (NRC) reaction performed in the melt with a peroxide and the 3,5-di-tert-butyl-4-hydroxybenzoyl-2,2,6,6-tetramethylpiperidine-1-oxyl radical (BHB-T). Functionalized EOC (EOC-g-(BHB-T)) was exposed to photo- and thermo-oxidation. By comparison with some model compounds bearing the (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) moiety or the hindered phenol unit, it was observed that the grafted BHB-T could effectively help the stabilization of the polymer matrix both under photo- and thermo-oxidation. In addition, the immobilization of BHB-T can effectively increase the service life of the functionalized polymers when polymer films were put in contact with ethanol solution thus simulating a possible application of the modified polymer.