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

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

Recent advances in the design of water based-flame retardant coatings for polyester and polyester-cotton blends

Over the last ten years a new trend of research activities regarding the flame retardancy of polymeric materials has arisen. Indeed, the continuous search for new flame retardant systems able to replace the traditional approaches has encouraged alternative solutions, mainly centred on nanotechnology. In this context, the deposition of nanostructured coatings on fabrics appears to be the most appealing and performance suitable approach. To this aim, different strategies can be exploited: from the deposition of a single monolayer consisting of inorganic nanoparticles (single-step adsorption) to the building-up of more complex architectures derived from layer by layer assembly (multi-step adsorption). The present paper aims to review the application of such systems in the field of polyester and polyester-cotton blend fabrics. The results collated by the authors are discussed and compared with those published in the literature on the basis of the different deposition methods adopted. A critical analysis of the advantages and disadvantages exhibited by these approaches is also presented

Preparation of Fibres from Urginea indica Kunth (Jangli Pyaz) and it’s Microbial Properties

Urginea indica Kunth (Drimia indica), popularly known as Jangli Pyaz, is a rare, endangered, and threatened medicinal plant belonging to the Liliaceae family. It contains nutrients and beneficial compounds for your health. Onions have numerous papules in the bulbs that act as a defensive mechanism in addition to having a strong bitter flavour. Its mystical healing powers include cardiotonic, anti-carcinomic, anti-jaundice, anti-dropsy, anti-asthmatic, anti-epileptic, dermatological, and diuretic properties. It is also an abortifacient and has effects on the menstrual cycle. Insects, fungus, and rodents are all treated with it as a pesticide. There is a glaborous, bulbous plant known as Urginea indic. The Liliaceae family includes several therapeutic herb species. a Kunth in the forests of Maharashtra. Urginea indica Kunth bulb extracts' phytochemical analyses and antioxidant properties were evaluated. Bulbs are abundant in several primary and secondary metabolites, including sugars, alkaloids, vitamin C, vitamin E, flavonoids, phenols, glycosides, and saponins, according to phytochemical screening. An HPTL Catalysis method was developed for Urginea indica Kunth flavonoids' chemical fingerprinting. The method's accuracy, precision, and linearity were verified, and they were contrasted with those of the RP-HPLC-DAD method

Flammability behaviour of wood and a review of the methods for its reduction

Wood is one of the most sustainable, aesthetically pleasing and environmentally benign materials. Not only is wood often an integral part of structures, it is also the main source of furnishings found in homes, schools, and offices around the world. The often inevitable hazards of fire make wood a very desirable material for further investigation. As well as ignition resistance and a low heat release rate, timber products have long been required to resist burn-through and maintain structural integrity whilst continuing to provide protection when exposed to fire or heat. Various industry standard tests are thus required to ensure adequate protection from fire is provided. When heated, wood undergoes thermal degradation and combustion to produce gases, vapours, tars and char. In order to understand and alter the fire behaviour of wood, it is necessary to know in as much detail as possible about its processes of decomposition. Various thermal analysis and flammability assessment techniques are utilised for this purpose, including thermogravimetric analysis, cone calorimetry and the single burning item test. The results of such tests are often highly dependent on various parameters including changes to the gas composition, temperature, heating rate, and sample shape size. Potential approaches for fire retarding timber are reviewed, identifying two main approaches: char formation and isolating layers. Other potential approaches are recognised, including the use of inorganic minerals, such as sericrite, and metal foils in combination with intumescent products. Formulations containing silicon, nitrogen and phosphorus have been reported, and efforts to retain silicon in the wood have been successful using micro-layers of silicon dioxide. Nano-scale fire retardants, such as nanocomposite coatings, are considered to provide a new generation of fire retardants, and may have potential for wood. Expandable graphite is identified for use in polymers and has potential for wood provided coating applications are preferred

Flammability behaviour of wood and a review of the methods for its reduction

Wood is one of the most sustainable, aesthetically pleasing and environmentally benign materials. Not only is wood often an integral part of structures, it is also the main source of furnishings found in homes, schools, and offices around the world. The often inevitable hazards of fire make wood a very desirable material for further investigation. As well as ignition resistance and a low heat release rate, timber products have long been required to resist burn-through and maintain structural integrity whilst continuing to provide protection when exposed to fire or heat. Various industry standard tests are thus required to ensure adequate protection from fire is provided. When heated, wood undergoes thermal degradation and combustion to produce gases, vapours, tars and char. In order to understand and alter the fire behaviour of wood, it is necessary to know in as much detail as possible about its processes of decomposition. Various thermal analysis and flammability assessment techniques are utilised for this purpose, including thermogravimetric analysis, cone calorimetry and the single burning item test. The results of such tests are often highly dependent on various parameters including changes to the gas composition, temperature, heating rate, and sample shape size. Potential approaches for fire retarding timber are reviewed, identifying two main approaches: char formation and isolating layers. Other potential approaches are recognised, including the use of inorganic minerals, such as sericrite, and metal foils in combination with intumescent products. Formulations containing silicon, nitrogen and phosphorus have been reported, and efforts to retain silicon in the wood have been successful using micro-layers of silicon dioxide. Nano-scale fire retardants, such as nanocomposite coatings, are considered to provide a new generation of fire retardants, and may have potential for wood. Expandable graphite is identified for use in polymers and has potential for wood provided coating applications are preferred

Banana pseudostem sap and boric acid— A new green intumescent for making self- extinguishing cotton fabric

The flame retardant functionality has been imparted in cellulosic fabric using mixed formulation of banana pseudostem sap (BPS) and boric acid (BA). The extracted sap is mixed with different concentration of BA and applied onto the. pre-mordanted bleached and mercerized cotton fabrics at elevated temperature. It is found that BA acts as a strong afterglow and smoke arresting agent, when applied at the concentration of > 2% (w/v). Flame retardant characteristics of both the control and the treated fabrics have been analysed in terms of limiting oxygen index, vertical flammability and temperature generation profile during burning. The (BPS+3% BA) treated cotton fabric sample shows the LOI value of 42 and the specific char length of 14cm after vertical flammability test. The thermal degradation and pyrolysis mechanism are also studied, using both thermogravimetric analysis and fourier transform infrared spectroscopy. Besides, the charring morphology and mechanism of both the control and the treated fabric is analysed in detail by scanning electron microscopy and FTIR analysis. A char structure model and the mechanism of char formation have also been proposed in the paper

Enhancing the Thermal Stability of Carbon Nanomaterials with DNA

Single-walled carbon nanotubes (SWCNTs) have recently been utilized as fillers that reduce the flammability and enhance the strength and thermal conductivity of material composites. Enhancing the thermal stability of SWCNTs is crucial when these materials are applied to high temperature applications. In many instances, SWCNTs are applied to composites with surface coatings that are toxic to living organisms. Alternatively, single-stranded DNA, a naturally occurring biological polymer, has recently been utilized to form singly-dispersed hybrids with SWCNTs as well as suppress their known toxicological effects. These hybrids have shown unrivaled stabilities in both aqueous suspension or as a dried material. Furthermore, DNA has certain documented flame-retardant effects due to the creation of a protective char upon heating in the presence of oxygen. Herein, using various thermogravimetric analytical techniques, we find that single-stranded DNA has a significant flame-retardant effect on the SWCNTs, and effectively enhances their thermal stability. Hybridization with DNA results in the elevation of the thermal decomposition temperature of purified SWCNTs in excess of 200 °C. We translate this finding to other carbon nanomaterials including multi-walled carbon nanotubes (MWCNTs), reduced graphene oxide (RGO) and fullerene (C60), and show similar effects upon complexation with DNA. The rate of thermal decomposition of the SWCNTs was also explored and found to significantly depend upon the sequence of DNA that was used

Hybrid Silica‐Phytic Acid Coatings: Effect on the Thermal Stability and Flame Retardancy of Cotton

New hybrid sol–gel coatings based on tetraethoxysilane (TEOS) and phytic acid (PA) were designed and applied to cotton; the flame-retardant properties of the treated fabrics were thoroughly investigated by means of flame-spread and forced-combustion tests. The first goal was to identify the TEOS:PA weight ratio that allowed the achievement of the best flame-retardant properties, with the lowest final dry add-on on the fabrics. Therefore, different TEOS:PA sols were prepared and applied to cotton, and the resulting coated fabrics were thoroughly investigated. In particular, solid-state NMR pectroscopy was exploited for assessing the condensation degree during the sol–gel process, even for evaluating the occurrence of possible reactions between phytic acid and the cellulosic substrate or the alkoxy precursor. It was found that a total dry add-on of 16 wt. % together with 70:30 TEOS:PA weight ratio provided cotton with self-extinction, as clearly indicated by flame-spread tests. This formulation was further investigated in forced-combustion tests: a significant reduction of heat release rate (HRR), of the peak of HRR, and of total heat release (THR) was found, together with a remarkable increase of the residues after the test. Unfortunately, the treated fabrics were not resistant to washing cycles, as they significantly lost their flameretardant properties, consequently to the partial removal of the deposited hybrid coatings

All-natural and highly flame-resistant freeze-cast foams based on phosphorylated cellulose nanofibrils

Pure cellulosic foams suffer from low thermal stability and high flammability, limiting their fields of application

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

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