Giulia Ognibene

Photoactivity of hierarchically nanostructured ZnO–PES fibre mats for water treatments

A brush-like ZnO nanorods shell is grown by Chemical Bath Deposition on electrospun Zn(Ac)2 doped polyethersulfone fibres. The obtained mats are water resistant and photocatalytically active, thus resulting suitable for applications in water purification. The used procedure is simple, cost-effective and scalable to large volumes. The use of supported ZnO nanostructures onto fibrous mats paves the way to easily reusable photocatalyst that benefits the high surface area of nanostructures and limits the drawbacks associated to the use of nanoparticles and nanopowders (i.e. water turbidity, irradiation efficiency and photocatalyst recover), thus resulting suitable for use in membrane technology.

Comparison of Ultem 9085 Used in Fused Deposition Modelling (FDM) with Polytherimide Blends

Polyetherimide (PEI) blends modified by either polycarbonate (PC) or polyethylene terephthalate glycol-modified (PETG) were prepared. The latter modifier (PETG) was an industrial grade widely used for fused deposition modelling (FDM) printing. PEI blends were compared to Ultem 9085, which is the standard PEI grade for FDM printing in advanced applications. All the blends were thoroughly characterized in terms of their rheological, morphological, thermomechanical and tensile properties. Ultem 9085 showed improved rheology for processing over standard PEI. PEI/PC blends with 10 wt % of modifier developed here closely matched the viscosity behavior of Ultem 9085. On the other hand, the blends with low PC content (i.e., less than 20 wt %) outperformed Ultem 9085 in terms of thermal and tensile properties. When PETG was added, similar tensile properties to Ultem 9085 were found. The immiscibility for PC contents higher than 20 wt % deteriorated the tensile properties, making it less attractive for applications, although melt viscosity decreased further for increasing PC contents.

PES/POSS Soluble Veils as Advanced Modifiers for Multifunctional Fiber Reinforced Composites

Novel polyhedral oligomeric silsesquioxanes (POSS)-filled thermoplastic electrospun veils were used to tailor the properties of the interlaminar region of epoxy-based composites. The veils were designed to be soluble upon curing in the epoxy matrix, so that POSS could be released within the interlaminar region. Three different POSS contents, varying from 1 to 10 wt %, were tested while the percentage of coPolyethersulphone (coPES) dissolved in the epoxy resin was kept to a fixed value of 10 wt %. Good quality veils could be obtained at up to 10 wt % of POSS addition, with the nanofibers’ diameters varying from 861 nm for the coPES to 428 nm upon POSS addition. The feasibility of the soluble veils to disperse POSS in the interlaminar region was proved, and the effect of POSS on phase morphology and viscoelastic properties studied. POSS was demonstrated to significantly affect the morphology and viscoelastic properties of epoxy composites, especially for the percentages 1% and 5%, which enabled the composites to avoid POSS segregates occurring. A dynamic mechanical analysis showed a significant improvement to the storage modulus, and a shift of more than 30 °C due to the POSS cages hindering the motion of the molecular chains and network junctions.

Combined Approach To Remove and Fast Detect Heavy Metals in Water Based on PES–TiO2 Electrospun Mats and Porphyrin Chemosensors

Hybrid poly(ether sulfones) (PES)–TiO2 electrospun mats are used as selective filters to remove lead and zinc ions from water. Presence of TiO2 is functional to trigger fiber’s surface charge that allows for better performances in terms of ionic adsorption with respect to bare PES mats. Temperature increase promotes a speed up of ion removal. Ability of electrospun mats to retain adsorbed ions is proven by washing procedures, which confirm the lack of released Pb2+ in solution, even after sonication. To detect presence of metal ions in aqueous solutions, water-soluble porphyrins are used as chemosensors, which are able to provide fast, in-field, and real-time analysis. In particular, cationic H2T4 metalation, occurring both in solution or at transparent glass surface, allows for a straightforward spectrophotometric (UV–vis) detection of metal ions in solution.

Thermoplastic veils as advanced modifiers for multifunctional fiber reinforced composites

The present paper is focused on the development of a novel technique to obtain multifunctional fiber reinforced composites. The technique is based on the use of thermoplastic veils composed of nano and micro thermoplastic fibers which preferentially dissolve upon curing in the epoxy matrix. The technique allows to control the phase morphology in the inter- and intra-laminar region of the laminates. Moreover, the selective dissolution of the fibers allow to achieve tailored dispersion of different types of nanofillers in the composites to obtain a functional graded material.

Thermal behavior of PEI/PETG blends for the application in fused deposition modelling (FDM)

This manuscript represents an experimental investigation about the thermal properties of polymeric Polyetherimide (PEI) / Polyethyleneterephthalate-glycol (PEG) blends, with the aim to improve the processability of pristine PEI without an excessive decrease of its properties, thus obtaining a suitable material to feed machines for rapid prototyping, in particular for the fusion deposition modelling (FDM) production technique. Mixtures with 5 and 10% of PETG were obtained applying the melt blending technique using a batch mixer. The materials obtained from the latter were subjected to a thermomechanical process in order to obtain pellets, used as feed for an injection-moulding machine, thus suitable to be employed for the various characterizations. The blends were characterized through thermal (TGA and DSC) and morphological (SEM) analysis.This manuscript represents an experimental investigation about the thermal properties of polymeric Polyetherimide (PEI) / Polyethyleneterephthalate-glycol (PEG) blends, with the aim to improve the processability of pristine PEI without an excessive decrease of its properties, thus obtaining a suitable material to feed machines for rapid prototyping, in particular for the fusion deposition modelling (FDM) production technique. Mixtures with 5 and 10% of PETG were obtained applying the melt blending technique using a batch mixer. The materials obtained from the latter were subjected to a thermomechanical process in order to obtain pellets, used as feed for an injection-moulding machine, thus suitable to be employed for the various characterizations. The blends were characterized through thermal (TGA and DSC) and morphological (SEM) analysis.

Novel poly(ethersulphone)s bearing pendant carboxylic acid groups for membranes: Structure and thermal properties

Poly(ethersulfone)s (PES) with active carboxylic acid groups, as branch in the main chain, were prepared in order to obtain membranes, by solution polymerization via nucleophilic displacement polycondensation reaction between various amounts of 4,4’-bis (4-hydroxyphenyl) valeric acid (DPA) and 4,4’-sulfonyldiphenol (DHDPS) with 4,4’-dichlorodiphenyl sulfone (DCDPS). The novel synthetic route developed here let to obtain structures with tailored thermal properties, which were investigated by the means of dynamic mechanical analysis (DMA). In addition to that, preliminary testing have showed that these polymers can be used in membranes for removing heavy metals from water.Poly(ethersulfone)s (PES) with active carboxylic acid groups, as branch in the main chain, were prepared in order to obtain membranes, by solution polymerization via nucleophilic displacement polycondensation reaction between various amounts of 4,4’-bis (4-hydroxyphenyl) valeric acid (DPA) and 4,4’-sulfonyldiphenol (DHDPS) with 4,4’-dichlorodiphenyl sulfone (DCDPS). The novel synthetic route developed here let to obtain structures with tailored thermal properties, which were investigated by the means of dynamic mechanical analysis (DMA). In addition to that, preliminary testing have showed that these polymers can be used in membranes for removing heavy metals from water.

Trifunctional Epoxy Resin Composites Modified by Soluble Electrospun Veils: Effect on the Viscoelastic and Morphological Properties

Electrospun veils from copolyethersulfones (coPES) were prepared as soluble interlaminar veils for carbon fiber/epoxy composites. Neat, resin samples were impregnated into coPES veils with unmodified resin, while dry carbon fabrics were covered with electrospun veils and then infused with the unmodified epoxy resin to prepare reinforced laminates. The thermoplastic content varied from 10 wt% to 20 wt%. TGAP epoxy monomer showed improved and fast dissolution for all the temperatures tested. The unreinforced samples were cured first at 180 °C for 2 h and then were post-cured at 220 °C for 3 h. These sample showed a high dependence on the curing cycle. Carbon reinforced samples showed significant differences compared to the neat resin samples in terms of both viscoelastic and morphological properties.

Functional electrospun membranes

In this study we combined electrospun PES nanofibers with ZnO nanostructures in order to obtain a hierarchical nanostructured hybrid material to be use for active water filtration membranes. It benefits of flexibility and high surface area of the polymeric nanofibers as well as of additional functionalities of ZnOnanostructures. First, randomly oriented nanofibers with diameters of 716nm ±365 nm were electrospun on a glass fibers substrate from a solution of PES and DMF-TOL(1:1). ZnO nanorods were grown onto the surface of electrospun PES fibers by a Chemical Bath Deposition (CBD) process. It was preceed by a seeding process necessary to form nucleation sites for the subsequent radially aligned growth of ZnO nanowires. The morfology of the fibers and the effect of the seeding time have been analysed by SEM. The amount of ZnO nanowires grown over electrospun nanofibers was determined as 45% by weight. The high purity and crystallinity of the asobtained products are confirmed by XRD since all reflection pea...

Poly-paper: a sustainable material for packaging, based on recycled paper and recyclable with paper

Background Until now, environmental sustainability issues are almost entirely unsolved for packaging materials. With the final aim of finding materials with a single recycling channel, cellulose fiber/poly(vinyl)alcohol composites were investigated. Methods After extrusion and injection molding, samples of composite with different cellulose fiber content (30%, 50% and 70% w/w) were tested. Results Tensile mechanical tests exhibited an improvement in composite stiffness when the reinforcement content was increased together with a decrease in composite elongation. Solubility tests performed at room temperature and 45°C showed different behavior depending on the water-resistant film applied on the composite (50% cellulose fiber content). In particular, the uncoated composite showed complete solubility after 2 hours, whereas at the same time point, no solubility occurred when a non-water-soluble varnish was used. Conclusions The proposed composites, named Poly-paper, appear to warrant further investigation as highly sustainable packaging.