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Giulio Malucelli - One of the best experts on this subject based on the ideXlab platform.
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cotton flame retardancy state of the art and future perspectives
RSC Advances, 2015Co-Authors: Jenny Alongi, Giulio MalucelliAbstract:As clearly reported in the scientific literature, the history of cotton flame retardancy is very old: this is easily attributable to the chemical and physical properties of this fibre that made it predominant during the 20th century; at present, it is only exceeded in volume by polyester. As a consequence, the huge number of papers published in the scientific literature so far covers an extended period and, sometimes, it could be easy to forget some of the knowledge already developed in the past and to focus the attention on the recent highlights only. Therefore, the present work is aimed to review the most significant scientific and technological results about the flame retardancy of cotton, merging the past experience and the current efforts, trying also to foresee a possible scenario for the next future. After a historical excursus on the achievements up to 2010, the review will summarize the recent developments reached in the so-called “era of nanotechnology” for cotton, as a consequence of the setup of new approaches like nanoparticle adsorption, Layer by Layer assembly and sol–gel Processes. Finally, a possible alternative development route indicated by the potential exploitation of bio-macromolecules as green flame retardant systems will be briefly discussed.
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sol gel derived architectures for enhancing cotton flame retardancy effect of pure and phosphorus doped silica phases
Polymer Degradation and Stability, 2014Co-Authors: Jenny Alongi, Claudio Colleoni, Giuseppe Rosace, Giulio MalucelliAbstract:Pure and phosphorus-doped silica phases derived from sol–gel Processes have been investigated, aiming to assess any enhancement of the thermal and fire stability of cotton fabrics. Indeed, it has already been shown that the combustion behaviour of cellulosic substrates can be strongly affected by the presence of a protective phosphorus-rich silica coating. Thus, in the present work, the performances of coatings consisting of pure silica and phosphorus-doped silica have been investigated and compared by using thermogravimetry and combustion tests (more specifically, resistance to an irradiative heat flux and to a flame application). The results show that the thermal and thermo-oxidative stability of cotton, as well its resistance to an irradiative heat flux of 35 kW/m2, have been enhanced by the deposited coating, irrespective of the presence of phosphorus. However, the best results have been achieved exploiting the joint effect of thermal shielding (exerted by the silica phase) and char-forming (as a consequence of the phosphoric acid source present in the alkoxysilane precursor). On the other hand, only pure silica coatings, despite their very low add-on, have proven to protect cotton from the application of a methane flame for 5 s, favouring the formation of a thermally stable residue.
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state of the art and perspectives on sol gel derived hybrid architectures for flame retardancy of textiles
Journal of Materials Chemistry, 2012Co-Authors: Jenny Alongi, Giulio MalucelliAbstract:Very recently, the exploitation of oxidic networks derived from sol–gel Processes for the surface modification of natural and/or synthetic fibres/fabrics has been successfully assessed, giving rise to novel “green” flame retardant systems. Indeed, inorganic, doped and hybrid organic–inorganic architectures can significantly improve the thermal stability and flame retardancy of the treated textile substrates, notwithstanding their functional (i.e. antimicrobial, self-cleaning, UV-protection, …) features. The present paper aims to describe the state of the art, the current academic efforts and the perspectives on the use of sol–gel derived hybrid architectures as effective flame retardant systems.
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hybrid phosphorus doped silica architectures derived from a multistep sol gel process for improving thermal stability and flame retardancy of cotton fabrics
Polymer Degradation and Stability, 2012Co-Authors: Jenny Alongi, Giulio Malucelli, Claudio Colleoni, Giuseppe RosaceAbstract:Abstract Hybrid phosphorus-doped silica architectures have been prepared through sol–gel Processes in order to enhance the thermal stability and flame retardancy of cotton. To this aim, diethylphosphatoethyltriethoxysilane has been used as a functional phosphate alkoxysilane in a multistep process, consisting of consecutive depositions for obtaining architectures with a different number of layers (namely, 1, 3 or 6 layers). The role of such architectures has been deeply investigated and correlated with the final properties of the treated fabrics. FT-IR ATR spectroscopy has been exploited for assessing the formation of the silica skeleton on the cotton surface and for evaluating the interactions between the cellulosic fibres and the doped film. The sol–gel treatments have proved to play a protective role on the degradation of the cotton fibres, hindering the formation of volatile species that fuel the further degradation and favouring the formation of char.
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thermal stability flame retardancy and mechanical properties of cotton fabrics treated with inorganic coatings synthesized through sol gel Processes
Carbohydrate Polymers, 2012Co-Authors: Jenny Alongi, Mihaela Diana Ciobanu, Giulio MalucelliAbstract:Abstract Cotton was sol–gel treated employing several metal alkoxide precursors (namely, tetraethylortho-silicate, -titanate, -zirconate and aluminium isopropylate) in order to get inorganic phases able to improve the thermal stability and flame retardancy of the fabric, without changing its mechanical features. Indeed, after the sol–gel treatment the fibre/fabric surface was morphologically modified: a homogeneous and compact film located in the fibre interstices (warp and weft) and partially covering their walls was observed for all the systems investigated. These coatings turned out to be responsible of an overall enhancement of the thermal and fire stability of the fabrics preserving, at the same time, the original mechanical properties of the neat cotton in terms of tensile strength and deformation. In addition, such inorganic coatings increased the abrasion resistance of the cotton in a remarkable way.
Jenny Alongi - One of the best experts on this subject based on the ideXlab platform.
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cotton flame retardancy state of the art and future perspectives
RSC Advances, 2015Co-Authors: Jenny Alongi, Giulio MalucelliAbstract:As clearly reported in the scientific literature, the history of cotton flame retardancy is very old: this is easily attributable to the chemical and physical properties of this fibre that made it predominant during the 20th century; at present, it is only exceeded in volume by polyester. As a consequence, the huge number of papers published in the scientific literature so far covers an extended period and, sometimes, it could be easy to forget some of the knowledge already developed in the past and to focus the attention on the recent highlights only. Therefore, the present work is aimed to review the most significant scientific and technological results about the flame retardancy of cotton, merging the past experience and the current efforts, trying also to foresee a possible scenario for the next future. After a historical excursus on the achievements up to 2010, the review will summarize the recent developments reached in the so-called “era of nanotechnology” for cotton, as a consequence of the setup of new approaches like nanoparticle adsorption, Layer by Layer assembly and sol–gel Processes. Finally, a possible alternative development route indicated by the potential exploitation of bio-macromolecules as green flame retardant systems will be briefly discussed.
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sol gel derived architectures for enhancing cotton flame retardancy effect of pure and phosphorus doped silica phases
Polymer Degradation and Stability, 2014Co-Authors: Jenny Alongi, Claudio Colleoni, Giuseppe Rosace, Giulio MalucelliAbstract:Pure and phosphorus-doped silica phases derived from sol–gel Processes have been investigated, aiming to assess any enhancement of the thermal and fire stability of cotton fabrics. Indeed, it has already been shown that the combustion behaviour of cellulosic substrates can be strongly affected by the presence of a protective phosphorus-rich silica coating. Thus, in the present work, the performances of coatings consisting of pure silica and phosphorus-doped silica have been investigated and compared by using thermogravimetry and combustion tests (more specifically, resistance to an irradiative heat flux and to a flame application). The results show that the thermal and thermo-oxidative stability of cotton, as well its resistance to an irradiative heat flux of 35 kW/m2, have been enhanced by the deposited coating, irrespective of the presence of phosphorus. However, the best results have been achieved exploiting the joint effect of thermal shielding (exerted by the silica phase) and char-forming (as a consequence of the phosphoric acid source present in the alkoxysilane precursor). On the other hand, only pure silica coatings, despite their very low add-on, have proven to protect cotton from the application of a methane flame for 5 s, favouring the formation of a thermally stable residue.
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state of the art and perspectives on sol gel derived hybrid architectures for flame retardancy of textiles
Journal of Materials Chemistry, 2012Co-Authors: Jenny Alongi, Giulio MalucelliAbstract:Very recently, the exploitation of oxidic networks derived from sol–gel Processes for the surface modification of natural and/or synthetic fibres/fabrics has been successfully assessed, giving rise to novel “green” flame retardant systems. Indeed, inorganic, doped and hybrid organic–inorganic architectures can significantly improve the thermal stability and flame retardancy of the treated textile substrates, notwithstanding their functional (i.e. antimicrobial, self-cleaning, UV-protection, …) features. The present paper aims to describe the state of the art, the current academic efforts and the perspectives on the use of sol–gel derived hybrid architectures as effective flame retardant systems.
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hybrid phosphorus doped silica architectures derived from a multistep sol gel process for improving thermal stability and flame retardancy of cotton fabrics
Polymer Degradation and Stability, 2012Co-Authors: Jenny Alongi, Giulio Malucelli, Claudio Colleoni, Giuseppe RosaceAbstract:Abstract Hybrid phosphorus-doped silica architectures have been prepared through sol–gel Processes in order to enhance the thermal stability and flame retardancy of cotton. To this aim, diethylphosphatoethyltriethoxysilane has been used as a functional phosphate alkoxysilane in a multistep process, consisting of consecutive depositions for obtaining architectures with a different number of layers (namely, 1, 3 or 6 layers). The role of such architectures has been deeply investigated and correlated with the final properties of the treated fabrics. FT-IR ATR spectroscopy has been exploited for assessing the formation of the silica skeleton on the cotton surface and for evaluating the interactions between the cellulosic fibres and the doped film. The sol–gel treatments have proved to play a protective role on the degradation of the cotton fibres, hindering the formation of volatile species that fuel the further degradation and favouring the formation of char.
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thermal stability flame retardancy and mechanical properties of cotton fabrics treated with inorganic coatings synthesized through sol gel Processes
Carbohydrate Polymers, 2012Co-Authors: Jenny Alongi, Mihaela Diana Ciobanu, Giulio MalucelliAbstract:Abstract Cotton was sol–gel treated employing several metal alkoxide precursors (namely, tetraethylortho-silicate, -titanate, -zirconate and aluminium isopropylate) in order to get inorganic phases able to improve the thermal stability and flame retardancy of the fabric, without changing its mechanical features. Indeed, after the sol–gel treatment the fibre/fabric surface was morphologically modified: a homogeneous and compact film located in the fibre interstices (warp and weft) and partially covering their walls was observed for all the systems investigated. These coatings turned out to be responsible of an overall enhancement of the thermal and fire stability of the fabrics preserving, at the same time, the original mechanical properties of the neat cotton in terms of tensile strength and deformation. In addition, such inorganic coatings increased the abrasion resistance of the cotton in a remarkable way.
Ramona Iseppi - One of the best experts on this subject based on the ideXlab platform.
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antibacterial activity of plastics coated with silver doped organic inorganic hybrid coatings prepared by sol gel Processes
Biomacromolecules, 2007Co-Authors: Michele Marini, N De Niederhausern, Ramona IseppiAbstract:Silver-doped organic−inorganic hybrid coatings were prepared starting from tetraethoxysilane- and triethoxysilane-terminated poly(ethylene glycol)-block-polyethylene by the sol−gel process. They were applied as a thin layer (0.6−1.1 μm) to polyethylene (PE) and poly(vinyl chloride) (PVC) films and the antibacterial activity of the coated films was tested against Gram-negative (Escherichia coli ATCC 25922) and Gram-positive (Staphylococcus aureus ATCC 6538) bacteria. The effect of several factors (such as organic−inorganic ratio, type of catalyst, time of post-curing, silver ion concentration, etc.) was investigated. Measurements at different contact times showed a rapid decrease of the viable count for both tested strains. The highest antibacterial activity [more than 6 log reduction within 6 h starting from 106 colony-forming units (cfu) mL-1] was obtained for samples with an organic−inorganic weight ratio of 80:20 and 5 wt % silver salt with respect to the coating. For the coatings prepared by an acid-c...
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Antibacterial activity of plastics coated with silver-doped organic-inorganic hybrid coatings prepared by Sol-Gel Processes
Biomacromolecules, 2007Co-Authors: Michele Marini, Ramona Iseppi, Carla Sabia, Simona De Niederhausern, Maurizio Toselli, Michela Bondì, Francesco PilatiAbstract:Silver-doped organic-inorganic hybrid coatings were prepared starting from tetraethoxysilane- and triethoxysilane-terminated poly(ethylene glycol)-block-polyethylene by the Sol-Gel process. They were applied as a thin layer (0.6-1.1 μm) to polyethylene (PE) and poly(vinyl chloride) (PVC) films and the antibacterial activity of the coated films was tested against Gram-negative (Escherichia coli ATCC 25922) and Gram-positive (Staphylococcus aureus ATCC 6538) bacteria. The effect of several factors (such as organic-inorganic ratio, type of catalyst, time of post-curing, silver ion concentration, etc.) was investigated. Measurements at different contact times showed a rapid decrease of the viable count for both tested strains. The highest antibacterial activity [more than 6 log reduction within 6 h starting from 106 colony-forming units (cfu) mL-1] was obtained for samples with an organic-inorganic weight ratio of 80:20 and 5 wt % silver salt with respect to the coating. For the coatings prepared by an acid-catalyzed process, a high level of permanence of the antibacterial activity of the coated films was demonstrated by repeatedly washing the samples in warm water or by immersion in physiological saline solution at 37°C for 3 days. The release of silver ions per square meter of coating is very similar to that previously observed for polyamides filled with metallic silver nanoparticles; however, when compared on the basis of Ag content, the concentration of silver ions released from the coating is much higher than that released from 1 mm thick specimens of polyamide (PA) filled with silver nanoparticles. Transparency and good adhesion of the coating to PE and PVC plastic substrates without any previous surface treatment are further interesting features. © 2007 American Chemical Society.
Francesco Pilati - One of the best experts on this subject based on the ideXlab platform.
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structure dynamics and interactions of complex sol gel hybrid materials through ssnmr and dsc part i binary systems based on pe peg block copolymer phs and silica
Polymer, 2011Co-Authors: Francesca Martini, Francesco Pilati, Silvia Borsacchi, Marco Geppi, Maurizio ToselliAbstract:Abstract This paper is the first part of a combined DSC and solid-state NMR study aimed at understanding the dynamic, morphological and interaction properties of three-component organic–inorganic hybrid coatings exhibiting interesting barrier properties against oxygen diffusion, obtained by sol–gel Processes starting from triethoxysilane terminated polyethylene- b -poly(ethylene glycol) copolymer (PE-PEGSi), poly(4-hydroxystyrene) (PHS), and tetraethoxysilane (TEOS). This paper reports the results of the study of the corresponding simpler two-component hybrids, which, beside the interest of these systems by themselves, was necessary for unravelling the characterization of the complex three-component systems. The phase, dynamic and interaction properties of binary systems PE-PEG/SiO 2 , PHS/SiO 2 , and PE-PEG/PHS have been here investigated and compared with those of the single components. Evidences of the occurrence of hydrogen bonds between PHS and both silica and PEG have been obtained. The interaction with silica and PHS seems to strongly inhibit the crystallization of PEG segments but to not prevent PE from segregating into crystalline domains. Moreover a noticeable mobility of amorphous PEG segments and the presence of mobile isolated or loosely packed PE segments in all- trans conformations have been highlighted in PE-PEG/SiO 2 hybrids. The structural and phase behaviour of PHS results to be strongly affected by the presence of either silica or PEG. In PHS/SiO 2 hybrids a two-state model with PHS chains either tightly- or loosely bound to silica domains has been proposed, while in PE-PEG/PHS blends the presence of a PEG-PHS miscible amorphous phase has been observed.
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Antibacterial activity of plastics coated with silver-doped organic-inorganic hybrid coatings prepared by Sol-Gel Processes
Biomacromolecules, 2007Co-Authors: Michele Marini, Ramona Iseppi, Carla Sabia, Simona De Niederhausern, Maurizio Toselli, Michela Bondì, Francesco PilatiAbstract:Silver-doped organic-inorganic hybrid coatings were prepared starting from tetraethoxysilane- and triethoxysilane-terminated poly(ethylene glycol)-block-polyethylene by the Sol-Gel process. They were applied as a thin layer (0.6-1.1 μm) to polyethylene (PE) and poly(vinyl chloride) (PVC) films and the antibacterial activity of the coated films was tested against Gram-negative (Escherichia coli ATCC 25922) and Gram-positive (Staphylococcus aureus ATCC 6538) bacteria. The effect of several factors (such as organic-inorganic ratio, type of catalyst, time of post-curing, silver ion concentration, etc.) was investigated. Measurements at different contact times showed a rapid decrease of the viable count for both tested strains. The highest antibacterial activity [more than 6 log reduction within 6 h starting from 106 colony-forming units (cfu) mL-1] was obtained for samples with an organic-inorganic weight ratio of 80:20 and 5 wt % silver salt with respect to the coating. For the coatings prepared by an acid-catalyzed process, a high level of permanence of the antibacterial activity of the coated films was demonstrated by repeatedly washing the samples in warm water or by immersion in physiological saline solution at 37°C for 3 days. The release of silver ions per square meter of coating is very similar to that previously observed for polyamides filled with metallic silver nanoparticles; however, when compared on the basis of Ag content, the concentration of silver ions released from the coating is much higher than that released from 1 mm thick specimens of polyamide (PA) filled with silver nanoparticles. Transparency and good adhesion of the coating to PE and PVC plastic substrates without any previous surface treatment are further interesting features. © 2007 American Chemical Society.
Michele Marini - One of the best experts on this subject based on the ideXlab platform.
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antibacterial activity of plastics coated with silver doped organic inorganic hybrid coatings prepared by sol gel Processes
Biomacromolecules, 2007Co-Authors: Michele Marini, N De Niederhausern, Ramona IseppiAbstract:Silver-doped organic−inorganic hybrid coatings were prepared starting from tetraethoxysilane- and triethoxysilane-terminated poly(ethylene glycol)-block-polyethylene by the sol−gel process. They were applied as a thin layer (0.6−1.1 μm) to polyethylene (PE) and poly(vinyl chloride) (PVC) films and the antibacterial activity of the coated films was tested against Gram-negative (Escherichia coli ATCC 25922) and Gram-positive (Staphylococcus aureus ATCC 6538) bacteria. The effect of several factors (such as organic−inorganic ratio, type of catalyst, time of post-curing, silver ion concentration, etc.) was investigated. Measurements at different contact times showed a rapid decrease of the viable count for both tested strains. The highest antibacterial activity [more than 6 log reduction within 6 h starting from 106 colony-forming units (cfu) mL-1] was obtained for samples with an organic−inorganic weight ratio of 80:20 and 5 wt % silver salt with respect to the coating. For the coatings prepared by an acid-c...
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Antibacterial activity of plastics coated with silver-doped organic-inorganic hybrid coatings prepared by Sol-Gel Processes
Biomacromolecules, 2007Co-Authors: Michele Marini, Ramona Iseppi, Carla Sabia, Simona De Niederhausern, Maurizio Toselli, Michela Bondì, Francesco PilatiAbstract:Silver-doped organic-inorganic hybrid coatings were prepared starting from tetraethoxysilane- and triethoxysilane-terminated poly(ethylene glycol)-block-polyethylene by the Sol-Gel process. They were applied as a thin layer (0.6-1.1 μm) to polyethylene (PE) and poly(vinyl chloride) (PVC) films and the antibacterial activity of the coated films was tested against Gram-negative (Escherichia coli ATCC 25922) and Gram-positive (Staphylococcus aureus ATCC 6538) bacteria. The effect of several factors (such as organic-inorganic ratio, type of catalyst, time of post-curing, silver ion concentration, etc.) was investigated. Measurements at different contact times showed a rapid decrease of the viable count for both tested strains. The highest antibacterial activity [more than 6 log reduction within 6 h starting from 106 colony-forming units (cfu) mL-1] was obtained for samples with an organic-inorganic weight ratio of 80:20 and 5 wt % silver salt with respect to the coating. For the coatings prepared by an acid-catalyzed process, a high level of permanence of the antibacterial activity of the coated films was demonstrated by repeatedly washing the samples in warm water or by immersion in physiological saline solution at 37°C for 3 days. The release of silver ions per square meter of coating is very similar to that previously observed for polyamides filled with metallic silver nanoparticles; however, when compared on the basis of Ag content, the concentration of silver ions released from the coating is much higher than that released from 1 mm thick specimens of polyamide (PA) filled with silver nanoparticles. Transparency and good adhesion of the coating to PE and PVC plastic substrates without any previous surface treatment are further interesting features. © 2007 American Chemical Society.