Characterization of Thermoplastic Starch Plasticized with Ternary Urea-Polyols Deep Eutectic Solvent with Two Selected Fillers: Microcrystalline Cellulose and Montmorillonite

The aim of the study was to prepare and characterize composite materials based on thermoplastic starch (TPS)/deep eutectic solvent (DES). Potato starch was plasticized with ternary DES: urea:glycerol:sorbitol and modified with the selected fillers: microcrystalline cellulose and sodium montmorillonite. Films were prepared via twin-screw extrusion and thermocompression of the extrudates. Then, the physicochemical properties of the TPS films were examined. The ternary DES effectively plasticized the polysaccharide leading to a highly amorphous structure of the TPS (confirmed via mechanical tests, DMTA and XRD analyses). An investigation of the behavior in water (swelling and dissolution degree) and water vapor transmission rate of the films was determined. The introduction of the two types of fillers resulted in higher tensile strength and better barrier properties of the composite TPS films. However, montmorillonite addition exhibited a higher impact than microcrystalline cellulose. Moreover, a cone calorimetry analysis of the TPS materials revealed that they showed better fire-retardant properties than TPS plasticized with a conventional plasticizer (glycerol)

Combustibility studies of unsaturated polyester resins modified by nanoparticles

Na bazie nienasyconej żywicy poliestrowej (UP) zsyntetyzowano kompozyty polimerowe zawierające nanocząstki w postaci: nanorurek węglowych, glinokrzemianów, poliedrycznego oligomerycznego silseskwioksanu oraz ditlenku tytanu. Przeprowadzono badania przy użyciu kalorymetru stożkowego i scharakteryzowano palność oraz dymotwórczość otrzymanych nanokompozytów. Stwierdzono, że charakteryzowały się one palnością zmniejszoną w stosunku do palności nienapełnionej żywicy poliestrowej. Zastosowane nanocząstki wykazywały różną skuteczność działania ograniczającego emisję dymów wydzielanych przez palące się nanokompozyty. Najkorzystniejszy wpływ uniepalniający wykazywał dodany do UP nanometryczny ditlenek tytanu.Unsaturated polyester resin (UP) – based polymer composites with selected nanoparticles, including carbon nanotubes, aluminosilicates, polyhedral oligomeric silsesquioxane, and titanium dioxide, were synthesized. The flammability and smoke emission of the resulting products were characterized using cone calorimetry. The reduction in flammability of the nanocomposites was observed when compared to the non-filled resin. Depending on the nanoparticle type, different effectiveness in reducing emission of fumes from the burning nanocomposites has been achieved. The most promising fire-retarding effect was observed in case of the UP modified by nanometric titanium dioxide

Chemical modification of biosorbents as a method of increasing the efficiency of zinc biosorption processes

Adsorbenty pochodzenia naturalnego, zwane biosorbentami, ze względu na niską cenę, łatwość pozyskiwania i brak właściwości toksycznych coraz powszechniej wykorzystywane są do usuwania metali ciężkich ze środowiska. W pracy analizowano możliwość chemicznego modyfikowania słomy, jako charakterystycznego dla Polski odpadu rolnego, w celu poprawy własności biosorbcyjnych, względem cynku. Stosowana w trakcie badań słoma jęczmienna była rozdrobniona do rozmiarów w zakresie 0,2-1,0 mm, a proces biosorpcji prowadzono dla wodnego roztworu cynku przy pH równym 5. Zastosowano dwie różne modyfikacje biosorbentu, tj. estryfikację przy pomocy metanolu oraz modyfikację kwasem cytrynowym w podwyższonej temperaturze. Uzyskane wyniki wskazują na wyraźną poprawę zdolności sorpcyjnych słomy poddanej modyfikacji z użyciem kwasu cytrynowego w porównaniu ze słomą niemodyfikowaną. W przypadku słomy modyfikowanej metanolem wykazano, że efektywność procesu biosorpcji cynku była nawet dwukrotnie niższa w stosunku do słomy niemodyfikowanej. Na podstawie uzyskanych wyników stwierdzono także, że usunięcie metali następowało przede wszystkim na drodze adsorpcji jonowymiennej, poprzez uwalnianie do roztworu, z powierzchni słomy, jonów wapnia i magnezu.Biosorbents are the natural origin adsorbents, which popularity in environmental engineering is steadily increasing due to their low price, ease of acquisition and lack of the toxic properties. Presented research aimed to analyse the possibility of chemical modification of the straw, which is a characteristic waste in the Polish agriculture, to improve its biosorption properties in respect to removal of selected metals from aqua solutions. Biosorbents used during the tests was a barley straw, that was shredded to a size in the range of 0.2-1.0 mm. The biosorption process was performed for aqueous solutions of zinc at a pH 5. Two different modifications of straw was analysed: esterification with methanol and modification using the citric acid at elevated temperature. The results, obtained during the research show a clear improvement in sorption capacity of the straw modified by the citric acid. In the case of straw modified with methanol it has been shown that the effectiveness of zinc biosorption process was even a twice lower with respect to the unmodified straw. Moreover it was concluded, that the removal of analysed metals was based mainly on the ion-exchange adsorption mechanism by releasing a calcium and magnesium ions from the straw surface to the solution

The Effect of Poly(Vinyl Chloride) Powder Addition on the Thermomechanical Properties of Epoxy Composites Reinforced with Basalt Fiber

The aim of the article was to determine the effect of the poly(vinyl chloride) additive (PVC) on the thermomechanical and fire properties of epoxy composites reinforced with basalt fabric. Ten-layered composites with 2.5, 5 and 10 wt.% of PVC powder were fabricated using hand lay-up. The following features were evaluated for composites: structure (by scanning electron microscopy, SEM), thermomechanical properties (by dynamical thermomechanical analysis, DMTA), mechanical properties (in bending, tensile and interlaminar shear strength tests), hardness (using the Barcol method), thermal stability (by thermogravimetry, TGA) and fire behavior (using a cone calorimeter). It was found that the introduction of micron PVC powder into the epoxy matrix improved the thermomechanical properties of composites, such as storage module, and mechanical properties, such as flexural strength and modulus, as well as hardness

An Approach to Testing Antivandal Composite Materials as a Function of Their Thickness and Striker Shape—A Case Study

Our research material comprised antivandal fire-retardant hybrid composites modified with inorganic and organic fillers intended for application in public transport vehicles. This paper presents an approach to studying their impact strength as a function of the composite thickness (3 to 6 mm) and striker shape (hemispherical, semicylindrical, wedge-shaped) used in the experimental stand. Group A composites, made of single fabric layers (n = 5), were thinner and their impact strength was lower by 73% than that for Group B composites made of double fabric layers. Study results show an almost threefold improvement in impact strength for a thickness increase of as little as 0.3 mm. Statistical analysis (the Shapiro–Wilk test, p > 0.05) did not show any significant differences in the quantitative evaluation of changes (n = 3) on the surface of the examined materials caused by impacts with strikers of different shapes. In turn, a linear correlation (Shapiro-Wilk test, W = 0.0857, p = 0.022) was found between impact strength and the thickness of the studied materials. It was observed that appropriate arrangement of fabrics and powder fillers can lead to a different distribution of forces and energy absorbed by the tested material. A lower impact strength was observed for the composite which had powder fillers in its composition, which caused the formation of microvoids in the structure of the material and thus led to a weakening in their strength properties. An effect of the placement of the glass fabric layer in the composite on the results was also observed. Moreover, SEM evaluation of the composites revealed their layered structure and the impregnation of woven fabrics with resin

The Effect of Silanes Treatments on Thermal and Mechanical Properties of Nettle Fibre/Bio Epoxy Composites

ABSTRACTObtaining suitable reinforcement of the polymer matrix depends largely on the appropriate connection at the fiber/polymer interface. Therefore, the main aim of the research was to assess the impact of silanization treatment of Himalayan nettle fibers on the properties of bio epoxy composites. Two types of silanes with different functional groups were used: 3-chloropropylmethyldimethoxysilane and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane at concentrations of 1 and 2%. The effectiveness of the fiber silanization process was confirmed using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). It was found that treatment with silane with amine groups provided more effective adhesion between the fiber and the epoxy matrix than treatment with silane with chlorine groups. In addition, the thermal stability, impact strength, bending strength, impact resistance, density and water absorption of the composites were determined. It should be emphasized that silane treatment had a positive effect on the impact strength, impact resistance and flexural modulus of the tested layered composites

Correction: Sałasińska et al. Burning Behaviour of Rigid Polyurethane Foams with Histidine and Modified Graphene Oxide. <i>Materials</i> 2021, <i>14</i>, 1184

In the original article [...

Moisture Resistance, Thermal Stability and Fire Behavior of Unsaturated Polyester Resin Modified with L-histidinium Dihydrogen Phosphate-Phosphoric Acid

In this paper, the fire behavior of unsaturated polyester resin (UP) modified with L-histidinium dihydrogen phosphate-phosphoric acid (LHP), being a novel intumescent fire retardant (IFR), was investigated. Thermal and thermomechanical properties of the UP with different amounts of LHP (from 10 to 30 wt. %) were determined by thermogravimetric analysis (TG) as well as dynamic mechanical thermal analysis (DMTA). Reaction to small flames was studied by horizontal burning (HB) test, while fire behavior and smoke emission were investigated with the cone calorimeter (CC) and smoke density chamber. Further, the analysis of volatile products was conducted (TGA/FT-IR). It was observed that the addition of LHP resulted in the formation of carbonaceous char inhibiting the thermal decomposition, burning rate and smoke emission. The most promising results were obtained for the UP containing 30 wt. % of LHP, for which the highest reduction in maximum values of heat release rate (200 kW/m2) and total smoke release (3535 m2/m2) compared to unmodified polymer (792 kW/m2 and 6895 m2/m2) were recorded. However, some important disadvantage with respect to water resistance was observed

Burning Behaviour of Rigid Polyurethane Foams with Histidine and Modified Graphene Oxide

Since rigid polyurethane (PU) foams are one of the most effective thermal insulation materials with widespread application, it is an urgent requirement to improve its fire retardancy and reduce the smoke emission. The current work assessed the fire behavior of PU foam with non-halogen fire retardants system, containing histidine (H) and modified graphene oxide (GOA). For investigated system, three loadings (10, 20, and 30 wt.%) were used. The Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis, cone calorimetry (CC) and smoke density chamber tests as well as pre- and post-burning morphological evaluation using scanning electron microscope (SEM) were performed. Moreover, TGA combined with FT-IR was conducted to determine the substances, which could be evolved during the thermal decomposition of the PU with fire retardant system. The results indicated a reduction in heat release rate (HRR), maximum average rate of heat emission (MAHRE), the total heat release (THR) as well as the total smoke release (TSR), and maximum specific optical density (Dsmax) compared to the polyurethane with commercial fire retardant, namely ammonium polyphosphate (APP). A significantly improvement, especially in smoke suppression, suggested that HGOA system may be a candidate as a fire retardant to reduce the flammability of PU foams