Active Bilayer PE/PCL Films for Food Packaging Modified with Zinc Oxide and Casein

This paper studies the properties of active polymer food packaging bilayer polyethylene/polycaprolactone (PE/PCL) films. Such packaging material consists of primary PE layer coated with thin film of PCL coating modified with active component (zinc oxide or zinc oxide/casein complex) with intention to extend the shelf life of food and to maintain the quality and health safety. The influence of additives as active components on barrier, mechanical, thermal and antimicrobial properties of such materials was studied. The results show that, in comparison to the neat PE and PE/PCL films, some of PE/PCL bilayer films with additives exhibit improved barrier properties i.e. decreased water vapour permeability. Higher thermal stability of modified PE/PCL material is obtained due to a modified mechanism of thermal degradation. The samples with the additive nanoparticles homogeneously dispersed in the polymer matrix showed good mechanical properties. Addition of higher ZnO content contributes to the enhanced antibacterial activity of a material

Influence of Titanium Dioxide Preparation Method on Photocatalytic Degradation of Organic Dyes

Titanium catalysts (TiO2) were synthesized by three different methods. Their photocatalytic activity was validated through photodegradation of Reactive Red 45 (RR45) azo dye and Acid Blue 25 (AB25) anthraquinone dye in an aqueous solution under UV irradiation. TiO2 photocatalysts were characterized by FTIR, XRD and SEM. Photosensitivity and TiO2 activity range were characterized by UV/Vis spectroscopy. Photocatalytic validation has been made by way of determining the degree of RR45 and AB25 removal. TOC was determined as a measure of the mineralization of RR45 and AB25 by photocatalysis. The stability of TiO2 catalysts and a possibility of using them in consecutive photocatalysis cycles have also been studied. The results show that the photocatalytic efficiency depends on the crystal structure of TiO2. The size of crystallites depends on synthesis conditions. From the results of photocatalytic efficiency it is concluded that the chemical interaction between a catalyst and a dye strongly depends on the dye chemical structure

Applications of Advanced Polymer Materials

Sve intenzivniji razvoj naprednih polimernih materijala kao što su polimerne mješavine i (nano)kompoziti nude brojna inovativna rješenja za različitu upotrebu, što ima velik ekonomski značaj za plastičnu industriju i područja u kojima se primjenjuju. Napredne tehnike modificiranja polimera razvile su se gotovo do krajnjih granica, a znatno su poboljšale omjer troškova i svojstava nastalih modifikacijom strukture polimera. Miješanje različitih polimera, priprema (nano)kompozita te stvaranje višeslojnih materijala, laminata neke su od najznačajnijih tehnika modifikacije. Pri tome postoje sinergistička djelovanja između komponenti, kako bi se postigli izvrsni učinci koji su prilagođeni specifičnim primjenama, kao npr. antimikrobno djelovanje, blokiranje ultraljubičastog svjetla, smanjenje gorivosti, fotokatalitičko djelovanje, a u radu su prikazani rezultati ispitivanja polimernih nanokompozita s ciljem modifikacije navedenih svojstava. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.The intense development of advanced polymer materials, such as polymer blends and (nano)composites, offers a number of innovative solutions for different applications, which is of great economic importance for the plastics industry and the fields in which they are applied. Advanced polymer modification techniques have pushed the limit, and have significantly improved the cost/properties ratio engendered by manipulating the structure of polymers. Blending dissimilar polymers, preparing composites where polymer matrix is modified by fillers, and creating multilayer structures and laminates are some of the most significant polymer modification techniques. In such modification, synergistic effects between the components are required in order to achieve excellent performances tailored to specific applications, such as antimicrobial activity, blocking ultraviolet light, reducing flammability, photocatalytic activity. This paper presents the results of the research on polymer nanocomposites aimed at the modification of the aforementioned properties. This work is licensed under a Creative Commons Attribution 4.0 International License

The Influence of Different Hematite (α-Fe₂O₃) Particles on the Thermal, Optical, Mechanical, and Barrier Properties of LDPE/Hematite Composites

There is an increasing need to develop new polymer composites with improved properties compared to conventional pure polymer materials. This work aims to develop composites of low-density polyethylene (LDPE) and iron oxide hematite particles. For this purpose, different types of hematite particles with well-defined shapes and narrow size distributions were synthesized: HC2 sample with pseudocubic hematite particles of an average diameter of 1020 nm, HE1 sample with ellipsoidal hematite particles of an average diameter of 533 nm, and HS1 sample with spherical hematite particles of an average diameter of 168 nm. The mass fractions of hematite in the composites were 0.25%, 0.5%, and 1%. Prepared LDPE/hematite composites were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and diffuse reflectance ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. The mechanical and barrier properties were also studied. The obtained results showed that all prepared composites have improved properties compared to the pure LDPE, especially the composites with pseudocubic hematite particles of well-defined shapes. The results of this study indicate that LDPE/hematite composites can be promising materials for a wide range of applications, especially as packaging materials where improved thermal and mechanical properties as well as resistance to ultraviolet (UV) irradiation are required

Polymer Composites of Low-Density Polyethylene (LDPE) with Elongated Hematite (α-Fe₂O₃) Particles of Different Shapes

Due to the intensive search for new types of advanced polymer materials for targeted applications, this work offers insight into the properties of low-density polyethylene/hematite composites. The specific feature of this study lies in the use of elongated hematite particles of different shapes. Uniform ellipsoid-, peanut- and rod-shaped hematite particles were hydrothermally synthesized and incorporated into the polymer matrix of low-density polyethylene (LDPE). LDPE/hematite composites are prepared by melt mixing. Hematite particles are characterized by scanning electron microscopy (SEM) and powder X-ray diffraction (PXRD). The pure LDPE polymer and LDPE/hematite composites were studied by FT-IR and UV-Vis-NIR spectroscopy and by thermogravimetric analysis (TGA). The determination of the mechanical and barrier properties was also carried out. The obtained results indicate the influence of the elongated particles on the improvement of LDPE properties. An increase in thermal stability and UV-absorption was observed as well as the improvement of mechanical and barrier properties. The improvement of the composites’ properties in comparison to the pure LDPE is especially visible in the composites prepared with low content of hematite (0.25%). LDPE/hematite composites have promising characteristics for application as packaging materials with enhanced mechanical, thermal and barrier properties as well as UV-protective materials

Efficiency of TiO2 catalyst supported by modified waste fly ash during photodegradation of RR45 dye

The waste fly ash (FA) material was subjected to chemical treatment with HCl at elevated temperature for a different time to modify its porosity. Modified FA particles with highest surface area and pore volume were further used as a support for TiO2 catalyst during FA/TiO2 nanocomposite preparation. The nanocomposite photocatalysts were obtained by in situ sol–gel synthesis of titanium dioxide in the presence of FA particles. To perform accurate characterization of modified FA and FA/TiO2 nanocomposite photocatalysts, gas adsorption-desorption analysis, X-ray diffraction, scanning electron microscopy, UV/Vis and Infrared spectroscopy were used. Efficiency evaluation of the synthesized FA/TiO2 nanocomposites was performed by following the removal of Reactive Red 45 (RR45) azo dye during photocatalytic treatment under the UV-A irradiation. Photocatalysis has been carried out up to five cycles with the same catalysts to investigate their stability and the possible reuse. The FA/TiO2 photocatalyst showed very good photocatalytic activity and stability even after the fifth cycles. The obtained results show that successfully modified waste fly ash can be used as very good TiO2 support

Study of Fire Retardancy and Thermal and Mechanical Properties of HDPE-Wood Composites

<div><p>This article reports a study of flame retardancy and thermal and mechanical properties of wood-plastic composites (WPCs) based on high-density polyethylene and pine flour. The study shows that sample composition plays an important role in WPCs' properties. The influence of additives like fillers (SiO₂ or CaCO₃) and flame retardants ammonium polyphosphate (APP) and pentaerythritol (PER) on WPCs' properties has been considered. The best properties are shown in samples using SiO₂ as filler and treated with the intumescent fire retardant APP/PER. Such samples have excellent fire retardancy with V-0 rating (UL-94 test) and imply that APP/PER fire retardant ensures effective fire retardancy for WPCs.</p></div

Effect of Ru3+ ions on the formation, structural, magnetic and optical properties of hematite (α-Fe2O3) nanorods

Nanosized hematite (α-Fe2O3) is a widely investigated material due to its favourable properties (chemically stable, environmentally safe, inexpensive) and very good performance in several advanced applications. Properties and performance of hematite nanoparticles can be adjusted and improved by modification of particle size and shape, as well as by substitution of Fe3+ ions in the crystal structure of hematite with other metal ions. Ru3+ ions are potentially suitable metal ions for the substitution of Fe3+ ions in hematite because of the same charge and similar ionic radii. In the present work, the effects of Ru3+ ions on the formation and properties of hematite nanorods prepared by combination of hydrothermal precipitation and calcination were investigated. The influence of the molar fraction of Ru3+ ions in the hydrothermal precipitation system on the formation and properties of iron oxide phases was studied. Single-phase goethite (α-FeOOH) nanorods containing incorporated Ru3+ ions were formed in the presence of low levels of Ru3+ ions (<3 mol%), while at higher levels (4 and 5 mol% Ru) hematite nanocylinders, consisting of self-assembled and fused nanoparticles, were obtained. The mechanism of the formation of these iron oxide nanostructures in the presence of Ru3+ ions was explained and compared with the effect of other metal cations reported in the literature. Ru-doped hematite nanorods were formed after calcination of Ru-doped goethite nanorods at 500 °C. A gradual elongation of hematite nanorods with increased Ru doping to highly elongated Ru-doped hematite nanoneedles at 2 mol% Ru was observed and explained. The influence of the Ru doping level on the magnetic properties of hematite nanorods was investigated using Mössbauer spectroscopy and magnetic measurements. Temperature of the transition between antiferromagnetic (AFM) and weakly ferromagnetic (WFM) spin ordering state (Morin transition) gradually rose with increasing Ru3+-for-Fe3+ substitution in hematite. Besides, magnetization of the WFM hematite gradually decreased with Ru doping which was attributed to the reduced canting of two almost antiparallel spin sublattices in this phase. The optical band gap in hematite nanorods was found to get gradually narrower with increased Ru doping due to the modified electronic structure.Supplementary material: [https://cherry.chem.bg.ac.rs/handle/123456789/4817

Influence of Fe(III) doping on the crystal structure and properties of hydrothermally prepared β-Ni(OH) 2 nanostructures

This paper systematically examines the influence of the level of Fe(III) doping on the crystal structure and other properties of Ni(OH)(2). Reference beta-Ni(OH)(2) and Fe-doped Ni(OH)(2) samples were synthesized by hydrothermal precipitation of mixed Ni(II) and Fe(III) nitrate aqueous solutions in a highly alkaline medium. The samples were investigated using X-ray powder diffraction (XRPD), scanning and transmission electron microscopy (FE-SEM and TEM), energy dispersive X-ray spectroscopy (EDS), Mossbauer spectroscopy, magnetic measurements, Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy, thermogravimetric analysis (TGA) and electrochemical measurements. Incorporation of Fe in beta-Ni(OH)(2) by cation substitution was confirmed from the shifts in position of XRPD lines due to the difference in the ionic radius of Fe3+ and Ni-2. The Fe-3-for-Ni2+ substitution in beta-Ni(OH)(2) caused formation of an interstratifled structure with beta-Ni(OH)(2) and alpha-Ni(OH)(2) structural units interconnected within the same structural layers and crystallites. Mossbauer spectra revealed the presence of Fe3+ ions in highly distorted octahedral sites, presumably at the boundary between the alpha-Ni(OH)(2) and beta-Ni(OH)(2) structural units within the same structural layer. Electrochemical measurements showed significant increase in oxygen evolution reaction (OER) catalytic activity of Fe-doped Ni(OH)(2) compared to pure phase. (C) 2018 Elsevier B.V. All rights reserved