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1.
Molecules ; 25(7)2020 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-32272751

RESUMO

Zinc oxide (ZnO) nanorods grown by chemical bath deposition (CBD) on the surface of polyetheresulfone (PES) electrospun fibers confer antimicrobial properties to the obtained hybrid inorganic-polymeric PES/ZnO mats. In particular, a decrement of bacteria colony forming units (CFU) is observed for both negative (Escherichia coli) and positive (Staphylococcus aureus and Staphylococcus epidermidis) Grams. Since antimicrobial action is strictly related to the quantity of ZnO present on surface, a CBD process optimization is performed to achieve the best results in terms of coverage uniformity and reproducibility. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) provide morphological and compositional analysis of PES/ZnO mats while thermogravimetric analysis (TGA) is useful to assess the best process conditions to guarantee the higher amount of ZnO with respect to PES scaffold. Biocidal action is associated to Zn2+ ion leaching in solution, easily indicated by UV-Vis measurement of metallation of free porphyrin layers deposited on glass.

2.
Polymers (Basel) ; 11(10)2019 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-31652651

RESUMO

The combination of functional polymers with inorganic nanostructured compounds has become a major area of research and technological development owing to the remarkable properties and multifunctionalities deriving from their nano and hybrid structures [...].

3.
Polymers (Basel) ; 11(9)2019 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-31505899

RESUMO

Two series of novel dumbbell-shaped polyhedral oligomeric silsesquioxanes (POSSs), fully functionalized with phenyl groups at the corner of the silicon cages, were used to prepare polystyrene (PS) nanocomposites through the method of in situ polymerization. The percentage of the molecular filler reinforcement was set as 5% w/w of POSS and was checked by 1H-NMR spectroscopy. The obtained nanocomposites were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Thermal and morphological properties were evaluated and compared among the nanocomposites obtained using the two different series of dumbbell-shaped POSSs and with the net PS. The thermal parameters for the prepared nanocomposites were very high when compared with those of neat PS, and they evidenced significant differences when an aliphatic or aromatic bridge was used to link the silicon cages. SEM analysis results allow us to hypothesize a justification for the different resistance to thermal degradation showed by the two series of molecular reinforcement.

4.
Materials (Basel) ; 12(18)2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31540351

RESUMO

The smart materials subclass of magnetorheological elastomer (MRE) composites is presented in this work, which aimed to investigate the influence of filler distribution on surface morphology. Iron particles with sizes ranging from 20 to 150 µm were incorporated into the elastomer matrix and a 30% volume fraction (V%) was chosen as the optimal quantity for the filler amount in the elastomer composite. The surface morphology of MRE composites was examined by 3D micro-computed tomography (µCT) and scanning electron microscopy (SEM) techniques. Isotropic and anisotropic distributions of the iron particles were estimated in the magnetorheological elastomer composites. The filler particle distribution at various heights of the MRE composites was examined. The isotropic distribution of filler particles was observed without any influence from the magnetic field during sample preparation. The anisotropic arrangement of iron fillers within the MRE composites was observed in the presence of a magnetic field during fabrication. It was shown that the linear arrangement of the iron particle chain induced magnetization within the composite. Simulation analysis was also performed to predict the particle distribution of magnetization in the MREs and make a comparison with the experimental observations.

5.
Materials (Basel) ; 12(1)2019 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-30621329

RESUMO

Implanted biomedical devices can induce adverse responses in the human body, which can cause failure of the implant-referred to as implant failure. Early implant failure is induced numerous factors, most importantly, infection and inflammation. Natural products are, today, one of the main sources of new drug molecules due to the development of pathogenic bacterial strains that possess resistance to more antibiotics used currently in various diseases. The aim of this work is the sol⁻gel synthesis of antibacterial biomedical implants. In the silica matrix, different percentages (6, 12, 24, 50 wt %) of polyethylene glycol (PEG) or poly(ε-caprolactone) (PCL) were embedded. Subsequently, the ethanol solutions with high amounts of chlorogenic acid (CGA 20 wt %) were slowly added to SiO2/PEG and SiO2/PCL sol. The interactions among different organic and inorganic phases in the hybrid materials was studied by Fourier transform infrared (FTIR) spectroscopy. Furthermore, the materials were soaked in simulated body fluid (SBF) for 21 days and the formation of a hydroxyapatite layer on their surface was evaluated by FTIR and XRD analysis. Finally, Escherichia coli and Pseudomonas aeruginosa were incubated with several hybrids, and the diameter of zone of inhibition was observed to assessment the potential antibacterial properties of the hybrids.

6.
Materials (Basel) ; 11(11)2018 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-30441749

RESUMO

The use of oral iron integration is commonly recommended for the treatment of iron deficiency, nevertheless the diagnosis and treatment of this disease could clearly be improved. The aim of this work was the synthesis of therapeutic systems, iron (II) based, by sol-gel method. In an SiO2 matrix, we embedded different weight percentages of polyethylene glycol (PEG6, 12, 24 wt%) and ferrous citrate (Fe(II)C5, 10, 15 wt%) for drug delivery applications. Fourier Transform Infrared (FTIR) spectroscopy was used to study the interactions among different components in the hybrid materials. Release kinetics in a simulated body fluid (SBF) were investigated and the amount of Fe2+ released was detected by Ultraviolet⁻Visible spectroscopy (UV-VIS) after reaction with ortho-phenantroline. Furthermore, the biological characterization was carried out. The bioactivity of the synthesized hybrid materials was evaluated by the formation of a layer of hydroxyapatite on the surface of samples soaked in SBF using FTIR spectroscopy. Finally, also, the potential antibacterial properties of the different materials against two different bacteria, E. coli and P. aeruginosa, were investigated.

7.
Materials (Basel) ; 11(8)2018 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-30096825

RESUMO

Polymers are a great and very important category of organic compounds that have changed our lifestyle. In the last eighty years, we have used them for the most varied applications, and from the first structural ones we began to investigate their durability, which can be fatal in the successful completion of the application for which the material was designed. Over the last thirty years, the environmental problems related to the disposal of polymers that have completed their lifecycle have begun to arise, and the need to foresee their end of life has become increasingly urgent. In this manuscript, the reliability of the lifetime predictions of polymeric materials is faced with comparing measurements obtained at low temperature with those carried out at high temperatures, in the molten state. The obtained data were treated by a well-established kinetics model and discrepancies were observed in the two different conditions (high and low temperatures), which led to a mismatching between expected and real data. A correction of the data extrapolated from measurements obtained at high temperatures, by using a novel equation which takes into account the induction period (IP) of the degradation process, is proposed. Considerations about the useful parameters, namely initial decomposition temperature (Ti), activation energy of degradation (Ea), and glass-transition temperature (Tg), to be used for making predictions, are also carried out.

8.
Materials (Basel) ; 11(7)2018 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-29997365

RESUMO

Three commercial filaments for Fused Deposition Modeling (FDM) were selected to study the influence of polymer formulation on the printing quality and mechanical properties of FDM specimens. The three filaments were all based on polylactic acid (PLA) as the matrix, and they are sold as PLA filaments. The printing quality was tested by printing one complex shape with overhang features. The marked shear thinning behavior for two filaments was observed by rheology. The filaments were also studied by scanning electron microscopy and thermogravimetric analysis (TGA) to unveil their composition. The filaments with the best printing quality showed the presence of mineral fillers, which explained the melt behavior observed by rheology. The tensile testing confirmed that the filled PLA was the best-performing filament both in terms of printing quality and thermomechanical performance, with a p-value = 0.106 for the tensile modulus, and a p-value = 0.615 for the ultimate tensile strength.

9.
Materials (Basel) ; 11(3)2018 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-29495571

RESUMO

An innovative recycling process for thermoset polymer composites developed by Connora Technologies (Hayward, CA, USA) was studied. The process efficacy has already been tested, and it is currently working at the plant level. The main aspect investigated in the present paper was the environmental impact by means of the Life Cycle Assessment (LCA) method. Because of the need to recycle and recover materials at their end of life, the Connora process creates a great innovation in the market of epoxy composites, as they are notoriously not recyclable. Connora Technologies developed a relatively gentle chemical recycling process that induces the conversion of thermosets into thermoplastics. The LCA demonstrated that low environmental burdens are associated with the process itself and, furthermore, impacts are avoided due to the recovery of the epoxy-composite constituents (fibres and matrix). A carbon fibre (CF) epoxy-composite panel was produced through Vacuum Resin Transfer Moulding (VRTM) and afterwards treated using the Connora recycling process. The LCA results of both the production and the recycling phases are reported.

10.
Materials (Basel) ; 11(2)2018 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-29439511

RESUMO

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.

11.
Polymers (Basel) ; 10(7)2018 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-30960680

RESUMO

One of the historical problems of medicine is that often, diagnosis and therapy do not interface, at best. Moreover, especially in some areas, such as oncology, the stress for the organism during the two phases (diagnosis and therapy) can become excessive, and be fatal to the success of the treatment. The extraordinary progress of nanotechnology in the last 25 years has offered the opportunity to build a nanoplatform able to ferry drugs, and loads onto them both imaging and therapeutic functions, thus creating nanosystems capable of diagnosis, drug delivery, and monitoring of therapeutic response. The purpose of this unusual, and up to recent times, unimaginable, marriage between diagnosis and therapeutics is the reaching of protocols more specific to individuals. The dual use of particles/device lead to a personalized medicine. Due to their biocompatibility, versatility, physical and chemical resistance, and ability to be functionalized, silica nanoparticles and polysiloxanes are the heart and the shield of this nanoplatform, respectively. In this short review, I analyze the applications of these silicon-based materials in the field of controlled drug delivery.

12.
Polymers (Basel) ; 10(8)2018 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-30960829

RESUMO

The use of polyhedral oligomeric silsesquioxanes (POSSs) for making polymer composites has grown exponentially since the last few years of the 20th century. In comparison with the other most commonly used fillers, POSSs possess the advantage of being molecules. Thus, this allows us to combine their nano-sized cage structures, which have dimensions that are similar to those of most polymer segments and produce a particular and exclusive chemical composition. These characteristics linked with their hybrid (inorganic⁻organic) nature allow researchers to modify POSS according to particular needs or original ideas, before incorporating them into polymers. In this present study, we first start with a brief introduction about the reasons for the rediscovery of these nanoparticles over the last 25 years. Starting from the form of POSS that is most widely used in literature (octaisobutyl POSS), this present study aims to evaluate how the reduction of symmetry through the introduction of organic groups favors their dispersion in polystyrene matrix without compromising their solubility.

13.
Materials (Basel) ; 10(9)2017 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-28846607

RESUMO

Green composites from polypropylene and lignin-based natural material were manufactured using a melt extrusion process. The lignin-based material used was the so called "liquid wood". The PP/"Liquid Wood" blends were extruded with "liquid wood" content varying from 20 wt % to 80 wt %. The blends were thoroughly characterized by flexural, impact, and dynamic mechanical testing. The addition of the Liquid Wood resulted in a great improvement in terms of both the flexural modulus and strength but, on the other hand, a reduction of the impact strength was observed. For one blend composition, the composites reinforced with hemp fibers were also studied. The addition of hemp allowed us to further improve the mechanical properties. The composite with 20 wt % of hemp, subjected to up to three recycling cycles, showed good mechanical property retention and thermal stability after recycling.

14.
Polymers (Basel) ; 9(7)2017 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-30970959

RESUMO

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.

15.
J Food Sci ; 77(10): E264-72, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22946743

RESUMO

UNLABELLED: This work reports an experimental study on the permeability and thermal behavior of commercial polypropylene (PP) film used for fresh-cut potatoes packaging. The permeability was tested using oxygen, carbon dioxide, nitrogen, mix of these 3 gases, normally used for modified atmosphere packaging (MAP) and Air, to understand if it would be possible to extend the shelf life of this food product designed for the catering field in respect to the packaging behavior. The temperature influence on permeability data, from 5 to 40 °C, was analyzed, before and after 4, 8, 12, 15, and 20 d of food contact, pointing out the dependence between temperature and gas transmission rate (GTR), solubility (S), diffusion coefficient (D), and time lag (t(L)) parameters. The activation energies (E) of the permeation process were determined with the different gases used in the experiments. The thermal behavior of PP film was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) to well understand its thermal stability. Fourier transformed-infrared with attenuated total reflectance (FT-IR/ATR) spectroscopy was also performed in order to study the influence of the food contact on the chemical characteristics of the polymer film. The results obtained were discussed and compared each other. Studied samples showed, for all investigated gases, an increase of gas permeability and S values at higher temperature. Heat resistance classification among the sample as it is and stored in modified atmospheres was made. Finally all performed experiments have showed good polymer stability for the shelf-life storage potatoes under study. PRACTICAL APPLICATION: Study of packaging material was performed in a range of temperature, which can simulate the service condition to assess the suitability of a commercial polymer film for modified atmosphere packaging of fresh-cut potatoes minimally processed designed for catering purpose.


Assuntos
Embalagem de Alimentos/métodos , Gases/metabolismo , Polipropilenos/metabolismo , Solanum tuberosum/química , Atmosfera , Varredura Diferencial de Calorimetria , Dióxido de Carbono/metabolismo , Conservação de Alimentos/métodos , Armazenamento de Alimentos , Nitrogênio/metabolismo , Oxigênio/metabolismo , Permeabilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Termogravimetria
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