The performance and degradation of nonwoven mulches made from viscose, jute, hemp fibers, and their blends with PLA fibers, subjected to field conditions, are investigated. This research explores the ...possible substitution of traditional agricultural polyethylene mulching agro foil with environmentally friendly biodegradable nonwoven mulches produced from blends of jute, hemp, and viscose fibers along with PLA fibers. The nonwoven mulches underwent a ten-month exposure to field conditions, showing varied degradation. The jute and hemp nonwoven mulches degraded completely within the test period, whereas their blends with PLA fibers exhibited slowed degradation. This study indicated that PLA fibers in blends with jute, hemp, and viscose mulches slowed degradation, impacting their structural integrity and tensile properties. The tensile properties of nonwoven mulches blended with 20% of PLA fibers increased the breaking forces after field exposure. Observations on structural changes through microscopy highlighted the structure maintenance in jute and hemp blends due to the non-degraded PLA fibers, contrasting the complete degradation of 100% jute and hemp mulches. A microscopic analysis revealed alterations in the fiber structure and density changes, particularly in viscose mulches and their blends with PLA fibers. Soil temperature variations were observed under different mulches; e.g., agro foil consistently exhibited higher temperatures compared to nonwoven mulches. Notably, the hemp and jute/PLA blend mulches showed slightly elevated temperatures, while the viscose-based mulches consistently revealed the lowest temperatures. Regarding soil moisture, the nonwoven mulches generally maintained higher moisture levels compared to the control field and agro foil from June to October. These findings suggest that nonwoven mulches effectively preserved soil moisture during critical growth periods, potentially positively impacting plant growth. The weed suppression capabilities varied among mulches, with hemp mulch initially displaying the lowest suppression ability in the first six months. The addition of 20% of PLA fibers in mulch blends with viscose, jute, and hemp notably improved the weed control capabilities. Understanding the impacts of field conditions on newly produced nonwoven mulches is crucial for optimizing mulch selection in agricultural practices to enhance soil conditions and weed management.
This paper investigates the possibility of integrating the combination of nanofillers, titanium dioxide (TiO2) and carbon nanotubes (CNT) into the thermoplastic polymer matrix. This combination of ...fillers can possibly modify the physico-chemical properties of composites compared to the pure polymer matrix. The composites were blended using the extrusion method. The composite filament produced was used to manufacture static mixers on a 3D printer using the additive manufacturing technology fused filament fabrication (FFF). The aim of this work was to inspect the influence of the filler addition on the thermal and mechanical properties of glycol-modified polyethylene terephthalate (PET-G) polymer composites. The fillers were added to the PET-G polymer matrix in several ratios. Tensile test results showed an increase in the overall strength and decrease in the elongation at break of the material. Melt flow rate (MFR) showed a decrease in the viscosity with the initial filler addition and reaching a plateau after 2 wt% filler was added. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed minor changes in the thermal properties. Scanning electron microscope (SEM) results showed homogenous distribution of the filler in the matrix and strong filler–matrix adhesion. The results indicate suitable properties of new functional composites for the 3D printing of static mixers for application in tubular reactors.
The addition of static mixers within reactors leads to higher productivity of a process and an additional increase in mass and energy transfer. In this study, we developed millireactors with static ...mixers using stereolithography, an additive manufacturing technology. Computational fluid dynamics (CFD) simulations were conducted to study the flow, identify potential dead volumes, and optimize the design of the millireactors. We produced five millireactors with various static mixers and one tubular reactor without static mixers, which served as a reference. The Fenton reaction was performed as a model reaction to evaluate the performance of the millireactors. We observed that some of the reactors with static mixers had air plugs that created a significant dead volume but still exhibited higher conversions compared to the reference reactor. Our results demonstrate the potential of stereolithography for producing intricate millireactors with static mixers, which can enhance the productivity of chemical processes.
The flow regime inside the channel of 3D printed microreactors is defined by the surface properties of the channel walls. Polylactide (PLA) and acrylonitrile/butadiene/styrene (ABS) are two polymers ...that are the most common in additive manufacturing using fused filament fabrication, commonly known as “3D printing”. With the aim of developing new materials for the 3D printing of microreactors whose channel surface hydrophobicity could be modified, PLA and ABS were blended with cheaper and widely used polymers-high-density polyethylene (PE-HD) and low-density polyethylene (PE-LD). Polymer blend surfaces were treated with inductively coupled plasma (ICP) and coated by fluorocarbon-based material (CFx) plasma deposition treatment in order to modify surface hydrophobicity. It has been shown that the modification of surface morphology of PLA polymer blends can be achieved by ICP etching and CFx coating, while this was not possible for ABS polymer blends under the conducted treatment conditions. The treated surface of PLA/PE-HD 90/10 showed a contact angle of 121.6° which is 36° higher than the contact angle measured on the untreated surface. Surfaces that have achieved contact angles higher than 120° have an “island like” surface morphology. Samples with higher “islands” showed higher contact angles, that confirmed that the hydrophobicity also depends on the height of the “islands”. Furthermore, it has been found that etching time significantly impacts the contact angle values and surface morphology of the PLA polymer blends, while the CFx coating time does not have significant impact on the surface properties.
Following the trend of transport decarbonization, biodiesel has become a promising alternative fuel option. Its production includes multiple steps, all of which can be time-consuming and energy ...intensive. Improving any of these steps could bring considerable environmental and economic benefits. The utilization of deep eutectic solvents (DESs) for glycerol extraction from crude biodiesel has predominantly been explored as a batch process. This work provides insight into continuous column extraction. Different waste cooking oils were used to produce biodiesel via transesterification with methanol, and the selective solvent for purification was DES choline chloride–ethylene glycol (1:2.5, mol.). A laboratory Karr column at different pulsation frequencies and DES to biodiesel mass ratio was used for extraction. Plate material (steel and 3D printed PETG) and geometry influence on the efficiency of extraction were investigated. Contact angle measurement was used to measure the surface free energy of steel and PETG and the spreading ability of biodiesel and DESs on both materials. Extraction efficiency was analyzed by several analytical techniques. Higher efficiency was observed with steel plates of a triangular pitch hole arrangement. Increasing the mixing intensity and DES to biodiesel mass ratio further increased the efficiency of extraction.
Aditivnom proizvodnjom moguće je izraditi proizvode složene geometrije koje konvencionalnim tehnikama poput tokarenja i glodanja nije moguće izraditi. Primjenom proizvodnje rastaljenim filamentom – ...FFF (engl. Fused Filament Fabrication) i stereolitografije – SLA (engl. Stereolithography) moguće je izraditi složene unutarnje strukture, tankostijene dijelove (milikanale) kao i dijelove unutar dijelova (pregrade).
Cilj ovoga rada bio je ispitati mogućnosti 3D ispisa na uređajima Zortrax M200 (FFF) i Formlabs Form 2 (SLA) u svrhu izrade funkcionalnih milireaktora s unutarnjim pregradama.
Kako bi se istražio utjecaj dimenzija milikanala na reakciju, ali i demonstrirala funkcionalnost cijelog sustava, u milireaktorima s pregradama je provedena sinteza FAME-a (engl. Fatty Acid Methyl Esters) transesterifikacijom suncokretovog ulja pomoću metanola uz dodatak baznog katalizatora KOH.
Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna .
In this study, spray drying was used as a technological solution for the valorization of
extract into carboxymethyl cellulose-based delivery systems (CMC), individually or in combination with ...collagen, guar gum, gum arabic, and kappa-carrageenan. The results showed that the process yield and morphological properties were positively influenced by the introduction of CMC binary blends. The employment of CMC resulted in a high encapsulation efficiency (77-96%) for all phenylethanoid glycosides (PGs) analyzed. Due to the low wettability of the microparticles, a relatively gradual in vitro release of the PGs was achieved. Infusion of the filling with hydrophilic
extract encapsulated in microparticles with high hydrophobic surface area proved to be a practical route for significant confectionery fortification (5-9 mg PGs per dw serving), ensuring prolonged interaction between the food matrix used and the extract under simulated gastrointestinal conditions. Based on sensory evaluation, the introduction of kudzu starch into the jelly matrix has shown a texture-modifying potential.
Materijali za izradu mikroreaktora Hajdari Gretić, Zana; Rahelić, Tin; Vrsaljko, Domagoj
Kemija u industriji; časopis kemičara i tehnologa Jugoslavije,
11/2017, Letnik:
66, Številka:
11-12
Journal Article
Recenzirano
Odprti dostop
Mikroreaktori su reaktorski sustavi izvedeni u mikroskopskom mjerilu, a zbog svoje velike međufazne površine imaju prednosti u odnosu na klasične – makroreaktorske sustave. Odabir materijala za ...izradu mikroreaktora ovisi o vrsti reakcije koja se provodi u sustavu, kompatibilnosti otapala i materijala, mehaničkim zahtjevima te o cijeni i dostupnosti na tržištu. Materijali koji se najčešće upotrebljavaju za izradu su različite vrste stakla, keramike, metali te polimerni materijali. Ovisno o materijalu odabiru se postupci izrade, a najčešći postupci su jetkanje, litografija, pjeskarenje, strojna obrada, injekcijsko prešanje te aditivni postupci izrade.
Cilj ovog rada je predstaviti najčešće materijale i postupke izrade mikroreaktora.
Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna .
Intense pulsed light was investigated for partial photoreduction of AgCl in a poly(vinyl butyral) matrix to obtain a Ag/AgCl reference membrane. The membrane was deposited on both glassy carbon and ...inkjet‐printed silver electrodes giving all‐solid‐state reference electrodes. Regardless of the electrode material, a sufficient potential stability was obtained in a broad concentration range of various salt solutions. Long‐term potential stability was significantly improved with inkjet‐printed silver electrical contacts. The electroanalytical performance of inkjet‐printed electrodes was successfully demonstrated in potentiometric and amperometric systems.
Insulating liquids (transformer oils) are dielectrics used in a wide range of electrical equipment and provide a medium for both insulation and cooling. During equipment operation, liquids are ...subjected to electrical and thermal stresses. With continued use, they chemically degrade and produce degradation products and aging markers. In this study, models based on Fourier-transform infrared spectroscopic (FTIR) measurements of liquids are proposed for estimating insulating liquid properties (acidity, interfacial tension (IFT), and density) using only a single measurement combined with spectral data analysis. Estimation models based on artificial neural networks (ANN) and partial least squares (PLS) were developed through training and validation on approximately 850 samples of mineral insulating liquids. The proposed models provide an effective means for estimating the acidity, IFT, and density of mineral insulating liquids. The models provide estimation results comparable in reproducibility to standardized laboratory analyses, provide the means for a rapid and accurate assessment of the condition of the insulating liquid, as well as allow the design of dedicated sensors to perform these analyses online.
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