557 research outputs found

    Biodegradable Foams

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    Biodegradable foams are currently gathering a wide interest from both academia and industry for several reasons. Specifically, resins from crude oil or natural gas are becoming less attractive as the price of the raw materials is increasing substantially. This is stimulating the researchers toward the design and preparation of new products, which may represent a valuable alternative. Also, within the current circular economy concept, further attempts toward the reduction of waste—and consequently, of its environmental impact—are being carried out, aiming at developing polymer resins from renewable sources suitable for producing reliable polymeric foams. In this context, recyclability and/or biodegradability have become very important in modern society, in order to limit the landfill confinement of synthetic plastic waste or products at the end of their life. This also considers the significant growth of the world population and consequently the reduced available space for plastic confinement. These findings justify the potential of these biodegradable polymers (and in particular of biodegradable foams) for different industrial applications. This chapter aims to elucidate the materials, processes, and applications of biodegradable foams. Finally, some perspectives about their possible future development are considered

    Flame-Retardant systems based on chitosan and its derivatives: state of the art and perspectives.

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    During the last decade, the utilization of chitin, and in par0ticular its deacetylated form, i.e. chitosan, for flame retardant purposes, has represented quite a novel and interesting application, very far from the established uses of this bio-sourced material. In this context, chitosan is a carbon source that can be successfully exploited, often in combination with intumescent products, in order to provide different polymer systems (namely, bulky materials, fabrics and foams) with high flame retardant (FR) features. Besides, this specific use of chitosan in flame retardance is well suited to a green and sustainable approach. This review aims to summarize the recent advances concerning the utilization of chitosan as a key component in the design of efficient flame retardant systems for different polymeric materials

    How to reduce the flammability of plastics and textiles through surface treatments: recent advances

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    The high flammability of plastics, polymer composites, textiles, and foams represents a severe and stringent issue that significantly limits their use in all those sectors, where resistance to a flame or an irradiative heat flux is mandatory [...

    Surface engineered fire protective coatings for fabrics through sol-gel and layer-by-layer methods: an overview

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    Fabric flammability is a surface-confined phenomenon: in fact, the fabric surface represents the most critical region, through which the mass and heat transfers, responsible for fuelling the flame, are controlled and exchanged with the surroundings. More specifically, the heat, the fabric surface is exposed to, is transferred to the bulk, from which volatile products of thermal degradation diffuse toward the surface and the gas phase, hence feeding the flame. As a consequence, the chemical and physical characteristics of the fabric surface considerably affect the ignition and combustion processes, as the surface influences the flux of combustible volatile products toward the gas phase. In this context, it is possible to significantly modify (and improve) the fire performance of textile materials by “simply” tailoring their surface: one of the currently most effective approaches exploits the deposition of tailored coatings, able to slow down the heat and mass transfer phenomena occurring during the fire stages. This paper reviews the current state of the art related to the design of inorganic, hybrid or organic flame retardant coatings, suitable for the fire protection of different fabric substrates (particularly referring to cotton, polyester and their blends). More specifically, the use of sol-gel and layer-by-layer (LbL) methods is thoroughly discussed; then, some recent examples of flame retardant coatings are presented, showing their potential advances and their current limitations

    Biomacromolecules and Bio-Sourced Products for the Design of Flame Retarded Fabrics: Current State of the Art and Future Perspectives

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    The search for possible alternatives to traditional flame retardants (FRs) is pushing the academic and industrial communities towards the design of new products that exhibit low environmental impact and toxicity, notwithstanding high performances, when put in contact with a flame or exposed to an irradiative heat flux. In this context, in the last five to ten years, the suitability and eectiveness of some biomacromolecules and bio-sourced products with a specific chemical structure and composition as eective flame retardants for natural or synthetic textiles has been thoroughly explored at the lab-scale level. In particular, dierent proteins (such as whey proteins, caseins, and hydrophobins), nucleic acids and extracts from natural sources, even wastes and crops, have been selected and exploited for designing flame retardant finishing treatments for several fibers and fabrics. It was found that these biomacromolecules and bio-sourced products, which usually bear key elements (i.e., nitrogen, phosphorus, and sulphur) can be easily applied to textiles using standard impregnation/exhaustion methods or even the layer-by-layer technique; moreover, these “green” products are mostly responsible for the formation of a stable protective char (i.e., a carbonaceous residue), as a result of the exposure of the textile substrate to a heat flux or a flame. This review is aimed at summarizing the development and the recent progress concerning the utilization of biomacromolecules/bio-sourced products as eective flame retardants for dierent textile materials. Furthermore, the existing drawbacks and limitations of the proposed finishing approaches as well as some possible further advances will be considered

    UV-curable acrylic coatings containing biomacromolecules: A new fire retardant strategy for ethylene-vinyl acetate copolymers

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    Abstract This work aims at demonstrating the suitability of selected biomacromolecules, namely caseins and deoxyribonucleic acids, as low environmental impact flame retardant additives for UV-curable coatings. To this aim, Bisphenol A hydroxyl ethyl diacrylate was utilized as UV-curable system, in the presence of a suitable photoinitiator (i.e. 2-hydroxy-2-methyl-1-phenylpropan-1-one), for coating ethylene-vinyl acetate copolymer thick plates. The flame retardant features of the coatings were evaluated in the presence of caseins or deoxyribonucleic acids – DNA – (at 10 and 15 wt.% loading) or a mixture of the two biomacromolecules (15 wt.% total loading) embedded in the UV-curable coating system, by means of forced combustion (i.e. cone calorimetry) tests. The coatings containing the biomacromolecules (namely 10 wt.% of DNA or 15 wt.% of casein) showed a decrease of peak of heat release rate and an increase of the time to peak as compared to the unfilled UV-cured counterparts. The proposed strategy may represent a possible starting point for the development of green and durable alternatives to the use of standard and more environmental impacting flame retarded coatings

    Consolidation of Stone Materials by Organic and Hybrid Polymers: An Overview

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    Historic stone buildings and monuments undergo a gradual, unstoppable, and episodic deterioration due to environmental or climatic impact, biological or mechanical deterioration, or, in the case of better-preserved structures, inadequate maintenance. Water infiltration, freezing and thawing, carbonation, wind erosion, acid rain, and graffiti/vandalism are the key “environmental” issues that strongly impact cultural heritage and therefore must be limited or even prevented. This interaction leads to the occurrence of different phenomena, possibly involving blistering phenomena on the stone surface, its gradual weather away, leaving a sound surface behind, or the dropping away of the bulk material, because of prolonged weathering, in a single event. It is noteworthy that, quite often, the stone may appear perfectly intact to the naked eye, though it is losing its cohesion beneath its surface. Therefore, it becomes necessary to either efficiently protect the stone substrates to prolong their life, or to fix the damage that already occurred by means of effective, reliable, and long-lasting consolidation/restoration strategies. This work aims at summarizing the current state-of-the-art referring to the use of monomeric/oligomeric or polymeric consolidants, providing the reader with some perspectives for the next future

    UV-LED curable acrylic films containing phosphate glass powder: effect of the filler loading on the thermal, optical, mechanical and flame retardant properties

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    In this work, we thoroughly investigate the effects of the incorporation of a phosphate glass micrometric powder on the morphology, as well as on the thermal, optical, mechanical and flame retardant properties of UV-LED curable acrylic films. To this aim, the filler loading was changed within 10 and 50 wt.%. UV-LED initiated curing was selected as a fast and reliable system, as the standard UV-curing process was not suitable because of the presence of the glass powder that decreased the quantum efficiency during the UV exposure, hence preventing the transformation of the liquid system into a solid network. The glass powder slightly increased the glass transition temperature of the acrylic network, hence showing a limited effect on the chain segments mobility; besides, increasing filler loadings were responsible for a progressive decrease of the transparency of films, irrespective of a marginal effect on their refractive index. Conversely, the presence of increasing amounts of phosphate glass improved the thermal and thermo-oxidative stability of the cured products. Besides, phosphate glass was capable of remarkably enhancing the flame retardance of the acrylic network at 50 wt.% loading, which achieved self-extinction in vertical flame spread tests (and was V-0 rated). This formulation, as assessed by forced-combustion tests, also displayed a remarkable decrease of peak of Heat Release Rate and Total Heat Release (by 44 and 33%, respectively) and of Total Smoke Release and Specific Extinction Area (by 53 and 56%, respectively). Further, the filler promoted an increase of the stiffness and surface hardness of the films, at the expense of a decrease in ductility. All these findings may justify the potential use of these composite films as flame retardant coatings for different flammable substrates
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