Next Issue
Volume 7, April
Previous Issue
Volume 6, December
 
 

ChemEngineering, Volume 7, Issue 1 (February 2023) – 15 articles

Cover Story (view full-size image): Heterogeneous photocatalytic technology that uses biomass, sunlight and water offers a simple method to transform biomass waste into valuable chemicals and clean H2 fuel. The C3N4 organic polymer photocatalyst semiconductor and its composites are used to produce H2 at room temperature and atmospheric pressure in an efficient, low-cost and sustainable process. View this paper
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Select all
Export citation of selected articles as:
13 pages, 9951 KiB  
Article
Effects of Lithium Source and Content on the Properties of Li-Rich Layered Oxide Cathode Materials
by Yufan Wang, Marianna Hietaniemi, Juho Välikangas, Tao Hu, Pekka Tynjälä and Ulla Lassi
ChemEngineering 2023, 7(1), 15; https://doi.org/10.3390/chemengineering7010015 - 14 Feb 2023
Cited by 2 | Viewed by 2023
Abstract
Lithium-rich layered oxide (LLO) are considered high-capacity cathode materials for next-generation lithium-ion batteries. In this study, LLO cathode materials were synthesized via the hydroxide coprecipitation method followed by a two-step lithiation process using different lithium contents and lithium sources. The effects of lithium [...] Read more.
Lithium-rich layered oxide (LLO) are considered high-capacity cathode materials for next-generation lithium-ion batteries. In this study, LLO cathode materials were synthesized via the hydroxide coprecipitation method followed by a two-step lithiation process using different lithium contents and lithium sources. The effects of lithium content and lithium source on structure and electrochemical performance were investigated. This study demonstrated the clear impact of Li/TM ratio on electrochemical performance. Lower Li/TM ratio reduced the irreversible capacity loss in the first cycle and provided better cycling stability among all samples. The best results exhibited an initial discharge capacity of 279.65 mAh g−1 and reached a discharge capacity of 231.9 mAh g−1 (82.9% capacity retention) after 30 cycles. The sample using Li2CO3 as lithium source exhibits better electrochemical performance than the sample using LiOH as lithium source. Therefore, it is important to choose the appropriate lithium source and optimal lithium content for improving structural properties and electrochemical performance of LLO. Full article
Show Figures

Figure 1

11 pages, 2359 KiB  
Article
Extraction of Noble Metals from Pyrite Cinders
by Bagdaulet Kenzhaliyev, Tatiana Surkova, Dinara Yessimova, Zhazira Baltabekova, Yerkezhan Abikak, Bekzat Abdikerim and Zamzagul Dosymbayeva
ChemEngineering 2023, 7(1), 14; https://doi.org/10.3390/chemengineering7010014 - 14 Feb 2023
Cited by 3 | Viewed by 1964
Abstract
When obtaining sulfuric acid from pyrite concentrates, a significant amount of waste is generated in the form of pyrite cinders that require disposal. The methods used in processing this raw material are, as a rule, the pyrometallurgical processes of chlorination and chloride sublimation, [...] Read more.
When obtaining sulfuric acid from pyrite concentrates, a significant amount of waste is generated in the form of pyrite cinders that require disposal. The methods used in processing this raw material are, as a rule, the pyrometallurgical processes of chlorination and chloride sublimation, the disadvantages of which include increased energy consumption and a lack of complexity in the extraction of valuable components. Hydrometallurgical processes are in less demand due to their multi-stage nature and complexity of execution. The method of chemical activation developed at the JSC “Institute of Metallurgy and Ore Beneficiation” makes it possible to isolate iron and non-ferrous metals into separate, middling products and to concentrate noble metals in the cake at the first stage. Physical and chemical studies of the cake found that its basis comprises iron compounds. The silver in the cake is associated with pyrite, while the gold is associated with hematite; it is also possible to find gold in the form of AuCl3. The content of gold in the cake is 1.5 g/t, and the silver content is 17.7 g/t. Based on physical and chemical studies and data from the literature, various versions of the hydrochlorination method are proposed to open the cake. Full article
Show Figures

Figure 1

17 pages, 3821 KiB  
Article
Thermodynamics and Kinetics of the Reaction of Catalytic Dismutation of Chlorosilanes in the Vapor Phase in the Temperature Range of 353–393 K
by Georgy Mochalov, Yegor Stolmakov and Olesya Zhuchok
ChemEngineering 2023, 7(1), 13; https://doi.org/10.3390/chemengineering7010013 - 10 Feb 2023
Viewed by 1578
Abstract
Currently, the most common method of silane synthesis for electronics and photovoltaics is trichlorosilane (TS) dismutation. TS dismutation proceeds in the form of a reactions cascade, therefore its study is of both practical and scientific interest. The results of calculating the equilibrium composition [...] Read more.
Currently, the most common method of silane synthesis for electronics and photovoltaics is trichlorosilane (TS) dismutation. TS dismutation proceeds in the form of a reactions cascade, therefore its study is of both practical and scientific interest. The results of calculating the equilibrium composition of the reaction mixture in the vapor phase based on literature data from various sources were not reliable. Therefore, the dependence of the composition of the reaction mixture on the time of contact of the TS vapor with the catalyst under static conditions was experimentally investigated. The stationary composition of the mixture, close to equilibrium, was determined. A good agreement of the obtained results with the literature data in one of the sources was shown. The kinetics of the dismutation reaction of TS and dichlorosilane (DCS) was carried out by the flow method. As a result of regression analysis of experimental data, the rate constants of the direct and reverse dismutation reactions of TS, DCS, and monochlorosilane (MSC) were obtained. The rate constants were used to calculate the equilibrium composition of the reaction mixture. A good agreement between the calculated and experimental data was shown. Full article
Show Figures

Figure 1

10 pages, 465 KiB  
Communication
Rate Equations of Structure-Sensitive Catalytic Reactions with Arbitrary Kinetics
by Dmitry Yu. Murzin
ChemEngineering 2023, 7(1), 12; https://doi.org/10.3390/chemengineering7010012 - 08 Feb 2023
Viewed by 1221
Abstract
A general mathematical framework for the quantitative description of the cluster size dependence in heterogeneous catalytic reactions has been developed based on an analysis of the Gibbs energy of elementary reactions. The methodology was illustrated for a generic linear sequence of elementary reactions [...] Read more.
A general mathematical framework for the quantitative description of the cluster size dependence in heterogeneous catalytic reactions has been developed based on an analysis of the Gibbs energy of elementary reactions. The methodology was illustrated for a generic linear sequence of elementary reactions with three steps, a multi-step mechanism of ethanol oxidation comprising linear, nonlinear and quasi-equilibria steps and a network of parallel reactions in transformations of furfural. Full article
Show Figures

Figure 1

17 pages, 3128 KiB  
Review
Overview on Photoreforming of Biomass Aqueous Solutions to Generate H2 in the Presence of g-C3N4-Based Materials
by E. I. García-López, L. Palmisano and G. Marcì
ChemEngineering 2023, 7(1), 11; https://doi.org/10.3390/chemengineering7010011 - 03 Feb 2023
Cited by 7 | Viewed by 2196
Abstract
Photoreforming (PR) of biomass can be considered a viable technology under mild experimental conditions to produce hydrogen with a high reaction rate using compounds from renewable resources and waste materials. The application of biomass PR gives rise to both hydrogen generation and biomass [...] Read more.
Photoreforming (PR) of biomass can be considered a viable technology under mild experimental conditions to produce hydrogen with a high reaction rate using compounds from renewable resources and waste materials. The application of biomass PR gives rise to both hydrogen generation and biomass waste valorization. The process could be scaled up to obtain hydrogen under natural sunlight irradiation, and research on polymeric carbon nitride (g-C3N4)-based photocatalysts has been widely carried out in recent years. The non-metallic-based carbon nitride materials are economical and (photo)stable polymer semiconductors, and their physicochemical surface and electronic properties are optimal for obtaining H2, which can be considered a gas that does not cause major environmental problems. Some hindrances related to their structure, such as the low absorption of visible light and the relatively high recombination rate of electron-hole pairs, restrict the performance; therefore, it is necessary to improve their activity and the yield of the reaction by modifying them in various ways. Various types of solutions have been proposed in this regard, such as, for example, their coupling with other semiconductors to form composite materials. The current mini-review aims to overview the PR field, reporting some of the most interesting papers devoted to understanding the role of g-C3N4 in biomass PR. Information on many physico-chemical aspects related to the performance of the process and possible ways to obtain better results than those present up to now in the literature will be reported. Full article
(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)
Show Figures

Figure 1

16 pages, 2178 KiB  
Article
Ultrasound-Assisted Encapsulation of Citronella Oil in Alginate/Carrageenan Beads: Characterization and Kinetic Models
by Aji Prasetyaningrum, Bangkit Suryo Wicaksono, Azafilmi Hakiim, Aulia Dwi Ashianti, Sadrakh Farel Christian Manalu, Nur Rokhati, Dani Puji Utomo and Mohammad Djaeni
ChemEngineering 2023, 7(1), 10; https://doi.org/10.3390/chemengineering7010010 - 02 Feb 2023
Cited by 3 | Viewed by 1763
Abstract
The objective of this research was to investigate the effect of ultrasonication on citronella oil encapsulation using alginate/carrageenan (Alg/Carr) in the presence of sodium dodecyl sulfate (SDS). The functional groups of microparticles were characterized using Fourier transform infrared spectroscopy (FTIR), and the beads’ [...] Read more.
The objective of this research was to investigate the effect of ultrasonication on citronella oil encapsulation using alginate/carrageenan (Alg/Carr) in the presence of sodium dodecyl sulfate (SDS). The functional groups of microparticles were characterized using Fourier transform infrared spectroscopy (FTIR), and the beads’ morphologies were observed using a scanning electron microscope (SEM). The FTIR results showed that the ultrasonication process caused the C-H bonds (1426 cm−1) to break down, resulting in polymer degradation. The SEM results showed that the ultrasonication caused the presence of cavities or pores in the cracked wall and a decrease in the beads’ size. In this study, the use of ultrasound during the encapsulation of citronella oil in Alg/Carr enhanced the encapsulation efficiency up to 95–97%. The kinetic evaluation of the oil release of the beads treated with ultrasound (UTS) showed a higher k1 value of the Ritger–Peppas model than that without ultrasonication (non-UTS), indicating that the oil release rate from the beads was faster. The R/F value from the Peppas–Sahlin model of the beads treated with UTS was smaller than that of the non-UTS model, revealing that the release of bioactive compounds from the UTS-treated beads was diffusion-controlled rather than due to a relaxation mechanism. This study suggests the potential utilization of UTS for controlling the bioactive compound release rate. Full article
Show Figures

Figure 1

3 pages, 264 KiB  
Editorial
Acknowledgment to the Reviewers of ChemEngineering in 2022
by ChemEngineering Editorial Office
ChemEngineering 2023, 7(1), 9; https://doi.org/10.3390/chemengineering7010009 - 18 Jan 2023
Viewed by 990
Abstract
High-quality academic publishing is built on rigorous peer review [...] Full article
11 pages, 2865 KiB  
Article
Renewable Polymers Derived from Limonene
by Roman Aleksandrovich Lyubushkin, Natalia Igorevna Cherkashina, Dar’ya Vasil’yevna Pushkarskaya, Dar’ya Sergeyevna Matveenko, Alexander Sergeevich Shcherbakov and Yuliya Sergeevna Ryzhkova
ChemEngineering 2023, 7(1), 8; https://doi.org/10.3390/chemengineering7010008 - 17 Jan 2023
Cited by 5 | Viewed by 2730
Abstract
Renewable natural and synthetic basic substances can be used to produce biodegradable polymers. Several methods of the polymerization of terpene limonene have been evaluated. The polymerization methods evaluated are radical polymerization, cationic polymerization and thiol-ene polymerization. The free-radical polymerization of limonene with azobisisobutyronitrile [...] Read more.
Renewable natural and synthetic basic substances can be used to produce biodegradable polymers. Several methods of the polymerization of terpene limonene have been evaluated. The polymerization methods evaluated are radical polymerization, cationic polymerization and thiol-ene polymerization. The free-radical polymerization of limonene with azobisisobutyronitrile (AIBN) as an initiator was carried out. The cationic polymerization of limonene was carried out using AlCl3 as a catalyst. The copolymerization of limonene with mercaptoethanol, 2-mercaptoethyl ether without an initiator and with an AIBN initiator was studied and it was also shown that polymerization can proceed spontaneously. The resulting compounds were investigated by NMR and FTIR spectroscopy. The values of the molecular weight characteristics of the samples obtained are presented, such as: number-average molecular weight, hydrodynamic radius and characteristic viscosity, depending on the method of production. The coefficients α (molecular shape) in the Mark–Kuhn–Houwink equation are determined according to the established values of the characteristic viscosity. According to the values obtained, the AC molecules in solution have parameters α 0.14 to 0.26, which corresponds to a good solvent and the molecular shape-dense coil. Full article
(This article belongs to the Topic Chemical and Biochemical Processes for Energy Sources)
Show Figures

Figure 1

18 pages, 13438 KiB  
Article
Multivariable Model Predictive Control to Control Bio-H2 Production from Biomass
by Muhammad Adjisetya and Abdul Wahid
ChemEngineering 2023, 7(1), 7; https://doi.org/10.3390/chemengineering7010007 - 13 Jan 2023
Cited by 2 | Viewed by 1453
Abstract
Two significant units in biomass-based hydrogen plants are the compressor and steam reformer. The compressor works to achieve high pressure for further operations, while the steam reformer produces H2 gas. For the units to operate well against disturbances that may occur (regulatory [...] Read more.
Two significant units in biomass-based hydrogen plants are the compressor and steam reformer. The compressor works to achieve high pressure for further operations, while the steam reformer produces H2 gas. For the units to operate well against disturbances that may occur (regulatory control) or changes in the set point (servo control), as well as the interactions between the relevant process variables, a Multivariable Model Predictive Control (MMPC) is considered as a controller. The determination of MMPC parameters, including the sampling time (T), prediction horizon (P), and control horizon (M), is crucial for achieving such objectives. Therefore, in this study, MMPC parameter adjustment was performed. The Integral of Absolute Error (IAE) and Integral of Square Error (ISE) were used as control performance indicators. For comparison, we considered the IAE and ISE from the Single-Input Single-Output (SISO)-based Model Predictive Control (MPC) from previous research. As a result, the optimum MMPC parameters were found to be T = 1, P = 341, and M = 121 for the compressor unit, and T = 1, P = 45, and M = 21 for the steam reformer unit. The average increases in control performance (IAE and ISE), compared to the MPC (SISO) used in previous research, were 85.84% for compressor unit 1, 61.39% for compressor unit 2, 94.57% for compressor unit 3, and 73.35% for compressor unit 4. Meanwhile, in the steam reformer unit, the increases in control performance were 63.34% for the heater and 80.16% for the combustor. Full article
Show Figures

Figure 1

13 pages, 970 KiB  
Article
Optimization of Adsorption Parameters for Removal of Cationic Dyes on Lignocellulosic Agricultural Waste Modified by Citric Acid: Central Composite Design
by Liudmyla Soldatkina and Marianna Yanar
ChemEngineering 2023, 7(1), 6; https://doi.org/10.3390/chemengineering7010006 - 13 Jan 2023
Cited by 5 | Viewed by 1443
Abstract
Barley straw (BS-C) and corn stalks (CS-C) modified by citric acid are hopeful adsorbents for the removal of cationic dyes from aqueous solutions. Optimization of adsorption factors to improve removal of methylene blue (MB) and malachite green (MG) on BC-C and CS-C was [...] Read more.
Barley straw (BS-C) and corn stalks (CS-C) modified by citric acid are hopeful adsorbents for the removal of cationic dyes from aqueous solutions. Optimization of adsorption factors to improve removal of methylene blue (MB) and malachite green (MG) on BC-C and CS-C was carried out by response surface methodology with central composite design. The effect of pH, time, dye concentration, and adsorbent dose on the removal efficiency of cationic dyes was investigated. The experimental data were in good agreement with the predicted data obtained by mathematical models. Accordingly, the maximum MB removal efficiency on BS-C of 97% was achieved with a pH of 6.4, time of 50 min, an adsorbent dose of 11 g L−1, and an initial MB concentration of 26 mg L−1; the maximum MG removal efficiency on BS-C of 95% was achieved with a pH of 7.2, time of 60 min, an adsorbent dose of 14 g L−1, and an initial MG concentration of 24 mg L−1; the maximum MB removal efficiency on CS-C of 97% was achieved with a pH of 6.5, time of 45 min, an adsorbent dose of 11 g L−1, and an initial MB concentration of 20 mg L−1; the maximum MG removal efficiency on CS-C of 94% was achieved with a pH of 6.6, time of 50 min, an adsorbent dose of 12 g L−1, and an initial MG concentration of 24 mg L−1. Full article
Show Figures

Figure 1

23 pages, 4769 KiB  
Article
Removal of Ammonium Ions from Aqueous Solutions Using Alkali-Activated Analcime as Sorbent
by Hanna Runtti, Elavarasi Sundhararasu, Janne Pesonen, Sari Tuomikoski, Tao Hu, Ulla Lassi and Teija Kangas
ChemEngineering 2023, 7(1), 5; https://doi.org/10.3390/chemengineering7010005 - 12 Jan 2023
Cited by 3 | Viewed by 2152
Abstract
Five alkali-activated analcime (ANA) sorbents (ANA-MK 1, ANA 2, ANA 3, ANA-MK 4, and ANA-MK 5) were developed for ammonium (NH4+) ion removal. Acid treatment and calcination were used as pre-treatments for analcime, and metakaolin (MK) was used as a [...] Read more.
Five alkali-activated analcime (ANA) sorbents (ANA-MK 1, ANA 2, ANA 3, ANA-MK 4, and ANA-MK 5) were developed for ammonium (NH4+) ion removal. Acid treatment and calcination were used as pre-treatments for analcime, and metakaolin (MK) was used as a blending agent in three sorbents. Sorption experiments were performed to evaluate the effects of sorbent dosage (1–20 g L−1), initial NH4+ ion concentration (5–1000 g L−1), and contact time (1 min–24 h). ANA-MK 1, ANA 2, and ANA-MK 4 were the most efficient sorbents for NH4+ ion removal, with a maximum experimental sorption uptake of 29.79, 26.00, and 22.24 mg g−1, respectively. ANA 3 and ANA-MK 5 demonstrated lower sorption capacities at 7.18 and 12.65 mg g−1, respectively. The results for the sorption of NH4+ ions onto the alkali-activated analcime surfaces were modeled using several isotherms. The Langmuir, Freundlich, Sips, and Bi-Langmuir isotherms were the best isotherm models to represent the studied systems. The results of the kinetic studies showed the maximum NH4+ ion removal percentage of the sorbents was ~80%, except for ANA-MK 5, which had a ~70% removal. Moreover, the pseudo-first-order, pseudo-second-order, and Elovich models were applied to the experimental data. The results showed that the sorption process for ANA-MK 1, ANA 2, ANA 3, and ANA-MK 4 followed the Elovich model, whereas the pseudo-second-order model provided the best correlation for ANA-MK 5. Full article
(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
Show Figures

Figure 1

13 pages, 3040 KiB  
Article
Polyaniline/Bi12TiO20 Hybrid System for Cefixime Removal by Combining Adsorption and Photocatalytic Degradation
by Oussama Baaloudj, Noureddine Nasrallah, Hamza Kenfoud, Khaled Wassim Bourkeb and Ahmad K. Badawi
ChemEngineering 2023, 7(1), 4; https://doi.org/10.3390/chemengineering7010004 - 10 Jan 2023
Cited by 27 | Viewed by 2250
Abstract
Sillenite catalysts have shown efficient photocatalytic activity for the removal of various pollutants from water in previous studies, thus enhancing their activity by combining them with other materials will be very promising for environmental applications. In this context, an interesting hybrid system containing [...] Read more.
Sillenite catalysts have shown efficient photocatalytic activity for the removal of various pollutants from water in previous studies, thus enhancing their activity by combining them with other materials will be very promising for environmental applications. In this context, an interesting hybrid system containing Polyaniline (PANI) as an adsorbent and Bi12TiO20 (BTO) sillenite as a catalyst was proposed in this work. Cefixime (CFX) has been selected as a pollutant for this study, and its removal was evaluated using PANI (adsorption), PANI and BTO (combined system) and the hybrid system Bi12TiO20/Polyaniline (BTO/PANI). First, the impact of PANI adsorption was investigated on its own; after that, the solution was filtered to separate the adsorbent from the liquid in order to re-treat the solution using photocatalysis (combining adsorption with photocatalysis). At the same time, a similar technique was used involving the hybrid system BTO/PANI. The results show that the hybrid system can remove a very high Cefixime concentration of 30 mg/L, almost 100%, within only 2 h, and this is better than previous investigations. These results indicate that it is possible to combine photocatalysis and adsorption processes to control water pollution. Full article
Show Figures

Figure 1

2 pages, 201 KiB  
Editorial
Advanced Heat Exchangers for Waste Heat Recovery Applications
by Hussam Jouhara
ChemEngineering 2023, 7(1), 3; https://doi.org/10.3390/chemengineering7010003 - 09 Jan 2023
Viewed by 1418
Abstract
The incentive for industrial waste heat recovery, which has attracted much research interest in recent years, has been twofold: the obligation to reduce greenhouse gas emissions in line with climate change targets and the need for processes to reduce overall energy consumption in [...] Read more.
The incentive for industrial waste heat recovery, which has attracted much research interest in recent years, has been twofold: the obligation to reduce greenhouse gas emissions in line with climate change targets and the need for processes to reduce overall energy consumption in order to remain commercially competitive [...] Full article
(This article belongs to the Special Issue Advanced Heat Exchangers for Waste Heat Recovery Applications)
19 pages, 4253 KiB  
Systematic Review
Bibliometric Analysis of Fourth Industrial Revolution Applied to Material Sciences Based on Web of Science and Scopus Databases from 2017 to 2021
by Anibal Alviz-Meza, Juan Orozco-Agamez, Diana C. P. Quinayá and Antistio Alviz-Amador
ChemEngineering 2023, 7(1), 2; https://doi.org/10.3390/chemengineering7010002 - 05 Jan 2023
Cited by 8 | Viewed by 2176
Abstract
Material science is a broad discipline focused on subjects such as metals, ceramics, polymers, electronics, and composite materials. Each of these fields covers areas associated with designing, synthesizing, and manufacturing, materials. These are tasks in which the use of technology may constitute paramount [...] Read more.
Material science is a broad discipline focused on subjects such as metals, ceramics, polymers, electronics, and composite materials. Each of these fields covers areas associated with designing, synthesizing, and manufacturing, materials. These are tasks in which the use of technology may constitute paramount importance, reducing cost and time to develop new materials and substituting try-and-error standard procedures. This study aimed to analyze, quantify and map the scientific production of research on the fourth industrial revolution linked to material science studies in Scopus and Web of Science databases from 2017 to 2021. For this bibliometric analysis, the Biblioshiny software from RStudio was employed to categorize and evaluate the contribution of authors, countries, institutions, and journals. VOSviewer was used to visualize their collaboration networks. As a result, we found that artificial intelligence represents a hotspot technology used in material science, which has become usual in molecular simulations and manufacturing industries. Recent studies aim to provide possible avenues in the discovery and design of new high-entropy alloys as well as to detect and classify corrosion in the industrial sector. This bibliometric analysis releases an updated perspective on the implementations of technologies in material science as a possible guideline for future worldwide research. Full article
Show Figures

Figure 1

13 pages, 1840 KiB  
Article
Predicting the Printability of Poly(Lactide) Acid Filaments in Fused Deposition Modeling (FDM) Technology: Rheological Measurements and Experimental Evidence
by Antonella Patti, Stefano Acierno, Gianluca Cicala and Domenico Acierno
ChemEngineering 2023, 7(1), 1; https://doi.org/10.3390/chemengineering7010001 - 23 Dec 2022
Cited by 6 | Viewed by 2068
Abstract
In this work, the authors aimed to identify a potential correlation between the printability and crucial rheological characteristics of materials involved in fused deposition modeling (FDM) technology. In this regard, three different poly(lactide) acid (PLA)-based filaments (two commercially available (here called V-PLA and [...] Read more.
In this work, the authors aimed to identify a potential correlation between the printability and crucial rheological characteristics of materials involved in fused deposition modeling (FDM) technology. In this regard, three different poly(lactide) acid (PLA)-based filaments (two commercially available (here called V-PLA and R-PLA) and one processed in a lab-scale extruder (here called L-PLA)) have been considered. Dynamic rheological testing, in terms of frequency sweep at five different temperatures (130, 150, 170, 190, and 210 °C), was performed. Rheological properties expressed in terms of viscoelastic moduli and complex viscosity curves vs. frequency, characteristic relaxation times, activation energy (Ea), zero shear viscosity (η0) and shear thinning index (n) were derived for each material. A characteristic relaxation time of around 0.243 s was found for V-PLA, a similar value (0.295 s) was calculated for R-PLA filaments, and a lower value of about an order of magnitude was calculated for L-PLA filament (~0.0303 s). The activation energy and shear thinning index resulted to be very comparable for all the filaments. On the contrary, V-PLA and R-PLA possessed a zero-shear viscosity (~104 Pa*s at 170 °C) much higher than L-PLA (~103 Pa*s). All the filaments were processed in a 3D printer, by attesting the effect of nozzle temperature (180, 190, and 210 °C, respectively) on printing process, and macroscopic shaping defects in printed objects. Final considerations allowed us to conclude that polymer relaxation time, zero-shear viscosity, and melt viscosity (affected by printing temperature) were critical parameters affecting the printing quality. Full article
Show Figures

Figure 1

Previous Issue
Next Issue
Back to TopTop