Alessio Varesano - Profile on Academia.edu (original) (raw)

Papers by Alessio Varesano

... were arranged in an array spaced 1 cm apart in two rows parallel to the ... the collector, th... more ... were arranged in an array spaced 1 cm apart in two rows parallel to the ... the collector, the deposition zones, altogether, should cover the maximum width without cross-sectional gap ... but the process did not work as expected: some perturbations of the fibre-formation process are ...

FT-IR study of dopant-wool interactions during PPy deposition

Fibers and Polymers, 2006

Page 1. Fibers and Polymers 2006, Vol.7, No.2, 105-111 105 FT-IR Study of Dopant-wool Interaction... more Page 1. Fibers and Polymers 2006, Vol.7, No.2, 105-111 105 FT-IR Study of Dopant-wool Interactions During PPy Deposition Alessio Varesano, Annalisa Aluigi, Claudio Tonin*, and Franco Ferrero1 ... 11. VT Troung, BC Ennis, and M. Forsyth, Synthetic Metals, 69, 479 (1995). 12. ...

Carbohydrate Polymers, 2014

Communicable diseases can be transmitted by contaminated water. Water decontamination process is ... more Communicable diseases can be transmitted by contaminated water. Water decontamination process is fundamental to eliminate microorganisms. In this work, cotton gauzes were coated with chitosan using an UV-curing process or cationized by introduction of quaternary ammonium groups and tested, in static and dynamic conditions, as water filter for biological disinfection against both Gram-negative and Gram-positive bacteria. Both materials showed good antibacterial activity, in static assessment, instead in dynamic conditions, chitosan treated gauze showed a high antimicrobial efficiency in few seconds of contact time. This composite could be a good candidate for application as biological filter.

Small, 2007

In recent years, host-guest systems have raised much interest due to their very high emission eff... more In recent years, host-guest systems have raised much interest due to their very high emission efficiency and chemical stability that make them ideal systems for artificial antennae and color converters. Their properties derive from the fact that the host crystal imposes a specific spatial and geometrical organization to the emissive guest molecules, protecting them against photodegradation. Zeolite L crystals are inorganic hosts that are able to insert organic dyes into their parallel nanochannels, and to impose a specific orientation that depends on the size of the guest molecules. In these crystals, a large amount of emissive molecules are organized in such a way that the aggregation, inducing quenching effects, is avoided even at very high dye concentration. A further organization of the zeolite crystals at a macroscopic level offers the intriguing possibility to orient ensembles of emissive molecules through a hierarchical organization process. Zeolite organization has been pursued by the growth of ordered arrays of crystals onto aligned polyurethane films, while seeded-growth procedures allow zeolite structures to form membranes for organic vapor separation. Previously reported is the organization of dye-loaded zeolites on a substrate by preparing monolayers of oriented and densely packed crystals of which the nanochannels are well aligned perpendicularly to the substrate, and by obtaining two-dimensional hexagonal networks of crystals on elastomeric stamps via surface-tension driven processes. Zeolite embedding and organization into polymeric systems are relevant in exploiting their highly emissive properties in materials for optoelectronic devices.

Small, 2007

The cover picture shows composite nanofibers obtained by electrospinning a polymer doped with a b... more The cover picture shows composite nanofibers obtained by electrospinning a polymer doped with a blue-light-emitting dye, containing fluorescent zeolite L crystals. Even in small-diameter (150 nm) nanowires, zeolites of about 600-800 nm in diameter and 1 mm in length are well embedded into the fibers, with their crystal axis parallel to the fiber axis. Since zeolite L crystals impose a specific orientation on the organic dyes inserted into their parallel nanochannels, the reported procedure provides a simple method to hierarchically organize an ensemble of emissive molecules. Dye-loaded zeolites, integrated into fluorescent nanowires, form very bright nanometric light sources emitting polarized light in the visible region of the spectrum that can be exploited in advanced nanophotonic applications. For more information, please read the Communication, "Fluorescent Electrospun Nanofibers Embedding Dye-Loaded Zeolite Crystals" by C. Botta and co-workers on page 305.

Small, 2007

The cover picture shows composite nanofibers obtained by electrospinning a polymer doped with a b... more The cover picture shows composite nanofibers obtained by electrospinning a polymer doped with a blue-light-emitting dye, containing fluorescent zeolite L crystals. Even in small-diameter (150 nm) nanowires, zeolites of about 600-800 nm in diameter and 1 mm in length are well embedded into the fibers, with their crystal axis parallel to the fiber axis. Since zeolite L crystals impose a specific orientation on the organic dyes inserted into their parallel nanochannels, the reported procedure provides a simple method to hierarchically organize an ensemble of emissive molecules. Dye-loaded zeolites, integrated into fluorescent nanowires, form very bright nanometric light sources emitting polarized light in the visible region of the spectrum that can be exploited in advanced nanophotonic applications. For more information, please read the Communication, "Fluorescent Electrospun Nanofibers Embedding Dye-Loaded Zeolite Crystals" by C. Botta and co-workers on page 305.

Small, 2007

In recent years, host-guest systems have raised much interest due to their very high emission eff... more In recent years, host-guest systems have raised much interest due to their very high emission efficiency and chemical stability that make them ideal systems for artificial antennae and color converters. Their properties derive from the fact that the host crystal imposes a specific spatial and geometrical organization to the emissive guest molecules, protecting them against photodegradation. Zeolite L crystals are inorganic hosts that are able to insert organic dyes into their parallel nanochannels, and to impose a specific orientation that depends on the size of the guest molecules. In these crystals, a large amount of emissive molecules are organized in such a way that the aggregation, inducing quenching effects, is avoided even at very high dye concentration. A further organization of the zeolite crystals at a macroscopic level offers the intriguing possibility to orient ensembles of emissive molecules through a hierarchical organization process. Zeolite organization has been pursued by the growth of ordered arrays of crystals onto aligned polyurethane films, while seeded-growth procedures allow zeolite structures to form membranes for organic vapor separation. Previously reported is the organization of dye-loaded zeolites on a substrate by preparing monolayers of oriented and densely packed crystals of which the nanochannels are well aligned perpendicularly to the substrate, and by obtaining two-dimensional hexagonal networks of crystals on elastomeric stamps via surface-tension driven processes. Zeolite embedding and organization into polymeric systems are relevant in exploiting their highly emissive properties in materials for optoelectronic devices.

Synthetic Metals, 2010

Solvent-based preliminary treatments were carried out on polyamide fabrics to be coated with a th... more Solvent-based preliminary treatments were carried out on polyamide fabrics to be coated with a thin layer of electrically conducting doped polypyrrole, with the aim of improving the adhesion of the conducting layer to the fibre substrate. Polyamide fabrics were treated with dilute formic acid, pure tetrachloroethylene and ethanol/water at different temperatures and times. After the treatments, the fabrics were coated with polypyrrole by in situ chemical oxidative polymerisation. The adhesion of the PPy layer was evaluated by means of surface resistivity measurements, SEM investigation and ATR FT-IR analysis after Martindale abrasion tests. The adhesion of PPy layer on the fibre surface was strongly improved by the solvent treatments, in particular with ethanol and tetrachloroethylene. The surface resistivity of the ethanol-treated fabrics did not change after more than 200 abrasion cycles and the PPy layer linked to the fibre surface was observed by SEM and ATR FT-IR also after 4000 abrasion cycles.

A study on the electrical conductivity decay of polypyrrole coated wool textiles

... rights reserved. Permissions & Reprints. A study on the electrical conductivity decay of ... more ... rights reserved. Permissions & Reprints. A study on the electrical conductivity decay of polypyrrole coated wool textiles. ... pyrrole. PPy coated wool fibres were spun andknitted using conventional industrial machinery. Electrical ...

Conducting textiles were prepared embedding polypyrrole in natural and man made cellulose-based f... more Conducting textiles were prepared embedding polypyrrole in natural and man made cellulose-based fibres, such as cotton, viscose, cupro and lyocell, by means of in situ polymerisation. Chemical vapour phase deposition of polypyrrole is a suitable process for producing electro-conductive composites in two steps: (a) fabric impregnation with an aqueous solution of oxidant and dopant and subsequent drying; (b) exposition to pyrrole vapour and polymerisation.

Nanofiber-coated fabrics have potential uses in filters and protective clothing. One major challe... more Nanofiber-coated fabrics have potential uses in filters and protective clothing. One major challenge is to ensure good adhesion of nanofibers to the fabrics achieving satisfactory durability against abrasion for practical use. This work is aimed to study adhesion mechanisms and their improvement between nanofibers and textile substrates; to achieve this goal cotton fabrics were treated with an alkali solution, while nylon fabrics were treated with ethanol. Adhesion of polyamide-6 electrospun nanofiber layer to fabrics was evaluated by means of a peeling test. Treated fabrics showed improved bonding towards nanofibers: adhesion energy was 0.58 J m 22 for both untreated fabrics, and after treatments increased to 0.93 and 0.86 J m 22 for cotton and nylon ones, respectively. Optical observations revealed that nanofibers deposited on fabrics are mainly linked to external protruding fibers (i.e., fabric hairiness). Therefore, surface hairiness seems to be the critical factor limiting adhesion.

Antibacterial water filtration by cationized or chitosan coated cotton gauze

Electrospun porous mats for high efficiency filtration

Submicron size fibers (so-called nanofibers) are easily produced with an electrospinning apparatu... more Submicron size fibers (so-called nanofibers) are easily produced with an electrospinning apparatus from polymer solutions of poly(ethylene oxide), poly(vinyl alcohol), and polyamide-6. Electrospinning seems the most powerful tool for fabricating polymer nanofibers. Fibers were directly deposited in the form of random fiber webs with high area-to-volume ratio and small porous size on ordinary nonwoven filters of PET microfibers. Morphology and

Improving Electrical Performances of Wool Textiles: Synthesis of Conducting Polypyrrole on the Fiber Surface

Textile Research Journal, 2008

Synthetic Metals, 2009

Electrically conductive fabrics were produced by deposition of a thin film of doped polypyrrole o... more Electrically conductive fabrics were produced by deposition of a thin film of doped polypyrrole on the surface of cotton fibres. In situ oxidative chemical polymerisation were carried out in aqueous solutions of pyrrole, oxidant and doping agents, at room temperature. Polypyrrole-coated fibres were characterized by Light Microscopy, SEM, EDX, FTIR and TGA. Moreover, fabric samples were also evaluated for moisture regain, electrical resistivity, heat generation and antibacterial activity. PPy alters the combustion process of cellulose fibres that maintain the fibrous shape after heating in air. Moreover, it seems that PPy is really an antibacterial agent, apart from the oxidant or dopant used. The results highlight potential applications as technical textiles with antistatic (low electrical resistance), heat generation, hygroscopy, antibacterial and high temperature resistance properties.

Journal of Thermal Analysis and Calorimetry, 2008

Electro-conducting doped polypyrrole was deposited by in situ oxidative polymerisation on PET non... more Electro-conducting doped polypyrrole was deposited by in situ oxidative polymerisation on PET non-wovens. Thermal properties were evaluated by means of DSC and TG in nitrogen and air. Flame resistance tests reveal that coated PET fibres resist to direct contact with fire. By thermal analysis, it was found that PPy reduces the temperature at which thermo-oxidative degradation of PET occurs. Polypyrrole-coated PET non-wovens were heated above the melting point of PET for 30 min. After the heating the fibres become brittle and frail, but SEM observations revealed that they maintained their fibrous shape. A loss of chlorine was found because of intense heating.

Thermal and structural characterization of poly(ethylene-oxide)/keratin blend films

Journal of Thermal Analysis and Calorimetry, 2007

ABSTRACT: The thermal properties and the crystalline structure of poly (methylenecyc1opentane) sa... more ABSTRACT: The thermal properties and the crystalline structure of poly (methylenecyc1opentane) samples with different microstructures are investigated. Similar disordered crystalline structures are formed, independently of the microstructure of the ...

Journal of Polymer Science Part B: Polymer Physics, 2008

Graessley's theory has been applied to keratin/PEO concentrated aqueous solutions giving qualitat... more Graessley's theory has been applied to keratin/PEO concentrated aqueous solutions giving qualitative insight to the rheology of these polymer blends in electrospinning. The shear rate dependent viscosity of different blends was compared with that of pure polymer solutions. The characteristic time s g was calculated by the minimum value of _ c at the beginning of the non-Newtonian viscosity behavior. Flow curves of PEO (at concentration from 1.0 to 7.0 wt %) reduce to a single curve by plotting g/g 0 against _ cs g . Moreover, PEO solutions exhibit a linear proportionality between zero-shear viscosity and the characteristic time g 0 ! s g . Keratin/PEO blend solutions follow the same proportionality at very high and low keratin content, whereas linearity drops when the keratin content range from 50 to 70%. The departure from the theory has been interpreted as a sign of some interaction between the macromolecules of keratin and PEO. It was supposed that keratin displaces solvent molecules and expands the PEO chain coils increasing the relaxation time of the polymer solution. This behavior was correlated with changes in the morphology of the nanofibres produced by electrospinning from these polymer blends. Finally, additive rules to zero-shear viscosity were applied to keratin and PEO solutions, indicating that the experimental g 0 values were higher than the theoretical ones for all the proportions of the blends, especially for high keratin amount.

Journal of Materials Processing Technology, 2009

Multi-jet electrospinning systems can be designed to increase both productivity and cover area fo... more Multi-jet electrospinning systems can be designed to increase both productivity and cover area for largescale nanofibre production. In this work several multi-jet electrospinning setups were tested. A solution of 7 wt% PEO was electrospun varying the number of nozzles between 2 and 16. Tests showed that the divergence angle between jets can be reduced employing a secondary electrode. The standard configuration consisting of a charged solution and a grounded collector plate was used, as was the opposite case of a charged collector and a grounded solution. These configurations were, respectively, tested with positive and negative polarity. Process operating conditions were varied in order to obtain nanofibres without defects. Samples collected were examined with SEM; it was demonstrated that multi-jet electrospinning works with standard and reverse configurations both applying positive and negative polarity. Good quality nanofibres were obtained in both cases.

Journal of Applied Polymer Science, 2007

Research on the electrospinning of nanofibers has increased in recent years because of the number... more Research on the electrospinning of nanofibers has increased in recent years because of the number of potential applications in different areas, ranging from technical textiles (e.g., filters, composite reinforcements, and protective fabrics) to biomedical commodities and devices such as bandages, membranes, bioactive surfaces, and porous substrates for tissue engineering, for which biocompatible polymers play an essential role. In this work, wool keratin/poly(ethylene oxide) nanofibers were electrospun from aqueous solutions of polymer blends under different operating conditions. The filaments were characterized with scanning electron microscopy, Fourier transform infrared, and differential scanning calorimetry analyses and compared with films of the same materials produced via casting with the aim of investigating structural changes due to the electrospinning process.

... were arranged in an array spaced 1 cm apart in two rows parallel to the ... the collector, th... more ... were arranged in an array spaced 1 cm apart in two rows parallel to the ... the collector, the deposition zones, altogether, should cover the maximum width without cross-sectional gap ... but the process did not work as expected: some perturbations of the fibre-formation process are ...

FT-IR study of dopant-wool interactions during PPy deposition

Fibers and Polymers, 2006

Page 1. Fibers and Polymers 2006, Vol.7, No.2, 105-111 105 FT-IR Study of Dopant-wool Interaction... more Page 1. Fibers and Polymers 2006, Vol.7, No.2, 105-111 105 FT-IR Study of Dopant-wool Interactions During PPy Deposition Alessio Varesano, Annalisa Aluigi, Claudio Tonin*, and Franco Ferrero1 ... 11. VT Troung, BC Ennis, and M. Forsyth, Synthetic Metals, 69, 479 (1995). 12. ...

Carbohydrate Polymers, 2014

Communicable diseases can be transmitted by contaminated water. Water decontamination process is ... more Communicable diseases can be transmitted by contaminated water. Water decontamination process is fundamental to eliminate microorganisms. In this work, cotton gauzes were coated with chitosan using an UV-curing process or cationized by introduction of quaternary ammonium groups and tested, in static and dynamic conditions, as water filter for biological disinfection against both Gram-negative and Gram-positive bacteria. Both materials showed good antibacterial activity, in static assessment, instead in dynamic conditions, chitosan treated gauze showed a high antimicrobial efficiency in few seconds of contact time. This composite could be a good candidate for application as biological filter.

Small, 2007

In recent years, host-guest systems have raised much interest due to their very high emission eff... more In recent years, host-guest systems have raised much interest due to their very high emission efficiency and chemical stability that make them ideal systems for artificial antennae and color converters. Their properties derive from the fact that the host crystal imposes a specific spatial and geometrical organization to the emissive guest molecules, protecting them against photodegradation. Zeolite L crystals are inorganic hosts that are able to insert organic dyes into their parallel nanochannels, and to impose a specific orientation that depends on the size of the guest molecules. In these crystals, a large amount of emissive molecules are organized in such a way that the aggregation, inducing quenching effects, is avoided even at very high dye concentration. A further organization of the zeolite crystals at a macroscopic level offers the intriguing possibility to orient ensembles of emissive molecules through a hierarchical organization process. Zeolite organization has been pursued by the growth of ordered arrays of crystals onto aligned polyurethane films, while seeded-growth procedures allow zeolite structures to form membranes for organic vapor separation. Previously reported is the organization of dye-loaded zeolites on a substrate by preparing monolayers of oriented and densely packed crystals of which the nanochannels are well aligned perpendicularly to the substrate, and by obtaining two-dimensional hexagonal networks of crystals on elastomeric stamps via surface-tension driven processes. Zeolite embedding and organization into polymeric systems are relevant in exploiting their highly emissive properties in materials for optoelectronic devices.

Small, 2007

The cover picture shows composite nanofibers obtained by electrospinning a polymer doped with a b... more The cover picture shows composite nanofibers obtained by electrospinning a polymer doped with a blue-light-emitting dye, containing fluorescent zeolite L crystals. Even in small-diameter (150 nm) nanowires, zeolites of about 600-800 nm in diameter and 1 mm in length are well embedded into the fibers, with their crystal axis parallel to the fiber axis. Since zeolite L crystals impose a specific orientation on the organic dyes inserted into their parallel nanochannels, the reported procedure provides a simple method to hierarchically organize an ensemble of emissive molecules. Dye-loaded zeolites, integrated into fluorescent nanowires, form very bright nanometric light sources emitting polarized light in the visible region of the spectrum that can be exploited in advanced nanophotonic applications. For more information, please read the Communication, "Fluorescent Electrospun Nanofibers Embedding Dye-Loaded Zeolite Crystals" by C. Botta and co-workers on page 305.

Small, 2007

The cover picture shows composite nanofibers obtained by electrospinning a polymer doped with a b... more The cover picture shows composite nanofibers obtained by electrospinning a polymer doped with a blue-light-emitting dye, containing fluorescent zeolite L crystals. Even in small-diameter (150 nm) nanowires, zeolites of about 600-800 nm in diameter and 1 mm in length are well embedded into the fibers, with their crystal axis parallel to the fiber axis. Since zeolite L crystals impose a specific orientation on the organic dyes inserted into their parallel nanochannels, the reported procedure provides a simple method to hierarchically organize an ensemble of emissive molecules. Dye-loaded zeolites, integrated into fluorescent nanowires, form very bright nanometric light sources emitting polarized light in the visible region of the spectrum that can be exploited in advanced nanophotonic applications. For more information, please read the Communication, "Fluorescent Electrospun Nanofibers Embedding Dye-Loaded Zeolite Crystals" by C. Botta and co-workers on page 305.

Small, 2007

In recent years, host-guest systems have raised much interest due to their very high emission eff... more In recent years, host-guest systems have raised much interest due to their very high emission efficiency and chemical stability that make them ideal systems for artificial antennae and color converters. Their properties derive from the fact that the host crystal imposes a specific spatial and geometrical organization to the emissive guest molecules, protecting them against photodegradation. Zeolite L crystals are inorganic hosts that are able to insert organic dyes into their parallel nanochannels, and to impose a specific orientation that depends on the size of the guest molecules. In these crystals, a large amount of emissive molecules are organized in such a way that the aggregation, inducing quenching effects, is avoided even at very high dye concentration. A further organization of the zeolite crystals at a macroscopic level offers the intriguing possibility to orient ensembles of emissive molecules through a hierarchical organization process. Zeolite organization has been pursued by the growth of ordered arrays of crystals onto aligned polyurethane films, while seeded-growth procedures allow zeolite structures to form membranes for organic vapor separation. Previously reported is the organization of dye-loaded zeolites on a substrate by preparing monolayers of oriented and densely packed crystals of which the nanochannels are well aligned perpendicularly to the substrate, and by obtaining two-dimensional hexagonal networks of crystals on elastomeric stamps via surface-tension driven processes. Zeolite embedding and organization into polymeric systems are relevant in exploiting their highly emissive properties in materials for optoelectronic devices.

Synthetic Metals, 2010

Solvent-based preliminary treatments were carried out on polyamide fabrics to be coated with a th... more Solvent-based preliminary treatments were carried out on polyamide fabrics to be coated with a thin layer of electrically conducting doped polypyrrole, with the aim of improving the adhesion of the conducting layer to the fibre substrate. Polyamide fabrics were treated with dilute formic acid, pure tetrachloroethylene and ethanol/water at different temperatures and times. After the treatments, the fabrics were coated with polypyrrole by in situ chemical oxidative polymerisation. The adhesion of the PPy layer was evaluated by means of surface resistivity measurements, SEM investigation and ATR FT-IR analysis after Martindale abrasion tests. The adhesion of PPy layer on the fibre surface was strongly improved by the solvent treatments, in particular with ethanol and tetrachloroethylene. The surface resistivity of the ethanol-treated fabrics did not change after more than 200 abrasion cycles and the PPy layer linked to the fibre surface was observed by SEM and ATR FT-IR also after 4000 abrasion cycles.

A study on the electrical conductivity decay of polypyrrole coated wool textiles

... rights reserved. Permissions & Reprints. A study on the electrical conductivity decay of ... more ... rights reserved. Permissions & Reprints. A study on the electrical conductivity decay of polypyrrole coated wool textiles. ... pyrrole. PPy coated wool fibres were spun andknitted using conventional industrial machinery. Electrical ...

Conducting textiles were prepared embedding polypyrrole in natural and man made cellulose-based f... more Conducting textiles were prepared embedding polypyrrole in natural and man made cellulose-based fibres, such as cotton, viscose, cupro and lyocell, by means of in situ polymerisation. Chemical vapour phase deposition of polypyrrole is a suitable process for producing electro-conductive composites in two steps: (a) fabric impregnation with an aqueous solution of oxidant and dopant and subsequent drying; (b) exposition to pyrrole vapour and polymerisation.

Nanofiber-coated fabrics have potential uses in filters and protective clothing. One major challe... more Nanofiber-coated fabrics have potential uses in filters and protective clothing. One major challenge is to ensure good adhesion of nanofibers to the fabrics achieving satisfactory durability against abrasion for practical use. This work is aimed to study adhesion mechanisms and their improvement between nanofibers and textile substrates; to achieve this goal cotton fabrics were treated with an alkali solution, while nylon fabrics were treated with ethanol. Adhesion of polyamide-6 electrospun nanofiber layer to fabrics was evaluated by means of a peeling test. Treated fabrics showed improved bonding towards nanofibers: adhesion energy was 0.58 J m 22 for both untreated fabrics, and after treatments increased to 0.93 and 0.86 J m 22 for cotton and nylon ones, respectively. Optical observations revealed that nanofibers deposited on fabrics are mainly linked to external protruding fibers (i.e., fabric hairiness). Therefore, surface hairiness seems to be the critical factor limiting adhesion.

Antibacterial water filtration by cationized or chitosan coated cotton gauze

Electrospun porous mats for high efficiency filtration

Submicron size fibers (so-called nanofibers) are easily produced with an electrospinning apparatu... more Submicron size fibers (so-called nanofibers) are easily produced with an electrospinning apparatus from polymer solutions of poly(ethylene oxide), poly(vinyl alcohol), and polyamide-6. Electrospinning seems the most powerful tool for fabricating polymer nanofibers. Fibers were directly deposited in the form of random fiber webs with high area-to-volume ratio and small porous size on ordinary nonwoven filters of PET microfibers. Morphology and

Improving Electrical Performances of Wool Textiles: Synthesis of Conducting Polypyrrole on the Fiber Surface

Textile Research Journal, 2008

Synthetic Metals, 2009

Electrically conductive fabrics were produced by deposition of a thin film of doped polypyrrole o... more Electrically conductive fabrics were produced by deposition of a thin film of doped polypyrrole on the surface of cotton fibres. In situ oxidative chemical polymerisation were carried out in aqueous solutions of pyrrole, oxidant and doping agents, at room temperature. Polypyrrole-coated fibres were characterized by Light Microscopy, SEM, EDX, FTIR and TGA. Moreover, fabric samples were also evaluated for moisture regain, electrical resistivity, heat generation and antibacterial activity. PPy alters the combustion process of cellulose fibres that maintain the fibrous shape after heating in air. Moreover, it seems that PPy is really an antibacterial agent, apart from the oxidant or dopant used. The results highlight potential applications as technical textiles with antistatic (low electrical resistance), heat generation, hygroscopy, antibacterial and high temperature resistance properties.

Journal of Thermal Analysis and Calorimetry, 2008

Electro-conducting doped polypyrrole was deposited by in situ oxidative polymerisation on PET non... more Electro-conducting doped polypyrrole was deposited by in situ oxidative polymerisation on PET non-wovens. Thermal properties were evaluated by means of DSC and TG in nitrogen and air. Flame resistance tests reveal that coated PET fibres resist to direct contact with fire. By thermal analysis, it was found that PPy reduces the temperature at which thermo-oxidative degradation of PET occurs. Polypyrrole-coated PET non-wovens were heated above the melting point of PET for 30 min. After the heating the fibres become brittle and frail, but SEM observations revealed that they maintained their fibrous shape. A loss of chlorine was found because of intense heating.

Thermal and structural characterization of poly(ethylene-oxide)/keratin blend films

Journal of Thermal Analysis and Calorimetry, 2007

ABSTRACT: The thermal properties and the crystalline structure of poly (methylenecyc1opentane) sa... more ABSTRACT: The thermal properties and the crystalline structure of poly (methylenecyc1opentane) samples with different microstructures are investigated. Similar disordered crystalline structures are formed, independently of the microstructure of the ...

Journal of Polymer Science Part B: Polymer Physics, 2008

Graessley's theory has been applied to keratin/PEO concentrated aqueous solutions giving qualitat... more Graessley's theory has been applied to keratin/PEO concentrated aqueous solutions giving qualitative insight to the rheology of these polymer blends in electrospinning. The shear rate dependent viscosity of different blends was compared with that of pure polymer solutions. The characteristic time s g was calculated by the minimum value of _ c at the beginning of the non-Newtonian viscosity behavior. Flow curves of PEO (at concentration from 1.0 to 7.0 wt %) reduce to a single curve by plotting g/g 0 against _ cs g . Moreover, PEO solutions exhibit a linear proportionality between zero-shear viscosity and the characteristic time g 0 ! s g . Keratin/PEO blend solutions follow the same proportionality at very high and low keratin content, whereas linearity drops when the keratin content range from 50 to 70%. The departure from the theory has been interpreted as a sign of some interaction between the macromolecules of keratin and PEO. It was supposed that keratin displaces solvent molecules and expands the PEO chain coils increasing the relaxation time of the polymer solution. This behavior was correlated with changes in the morphology of the nanofibres produced by electrospinning from these polymer blends. Finally, additive rules to zero-shear viscosity were applied to keratin and PEO solutions, indicating that the experimental g 0 values were higher than the theoretical ones for all the proportions of the blends, especially for high keratin amount.

Journal of Materials Processing Technology, 2009

Multi-jet electrospinning systems can be designed to increase both productivity and cover area fo... more Multi-jet electrospinning systems can be designed to increase both productivity and cover area for largescale nanofibre production. In this work several multi-jet electrospinning setups were tested. A solution of 7 wt% PEO was electrospun varying the number of nozzles between 2 and 16. Tests showed that the divergence angle between jets can be reduced employing a secondary electrode. The standard configuration consisting of a charged solution and a grounded collector plate was used, as was the opposite case of a charged collector and a grounded solution. These configurations were, respectively, tested with positive and negative polarity. Process operating conditions were varied in order to obtain nanofibres without defects. Samples collected were examined with SEM; it was demonstrated that multi-jet electrospinning works with standard and reverse configurations both applying positive and negative polarity. Good quality nanofibres were obtained in both cases.

Journal of Applied Polymer Science, 2007

Research on the electrospinning of nanofibers has increased in recent years because of the number... more Research on the electrospinning of nanofibers has increased in recent years because of the number of potential applications in different areas, ranging from technical textiles (e.g., filters, composite reinforcements, and protective fabrics) to biomedical commodities and devices such as bandages, membranes, bioactive surfaces, and porous substrates for tissue engineering, for which biocompatible polymers play an essential role. In this work, wool keratin/poly(ethylene oxide) nanofibers were electrospun from aqueous solutions of polymer blends under different operating conditions. The filaments were characterized with scanning electron microscopy, Fourier transform infrared, and differential scanning calorimetry analyses and compared with films of the same materials produced via casting with the aim of investigating structural changes due to the electrospinning process.