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Lignin: From Nature to Advanced Materials

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Materials Chemistry".

Deadline for manuscript submissions: closed (30 November 2022) | Viewed by 44234

Special Issue Editors


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Guest Editor
Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, PL-60965 Poznan, Poland
Interests: biopolymers; lignin chemistry; synthesis, characterization and applications of advanced functional materials; hybrid materials, biomaterials; polymer composites, biocomposites; chemical modification of synthetic and natural polymers; application of ligno-cellulosic materials in polymer chemistry; (bio)additives and eco-friendly fillers
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, PL-60965 Poznan, Poland
Interests: biopolymers; synthesis, characterization, and applications of advanced functional materials; functional fillers and polymer composites; (bio)additives and eco-friendly fillers; biomineralization-inspired syntheses and extreme biomimetics; biocomposites and biomaterials; removal of wastewater pollutants via adsorption; photocatalysis or precipitation methods; pigment composites; enzyme immobilization
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Lignin, a bio-based renewable compound that can be used to obtain valuable low-molecular-weight products or hybrid materials, has become one of the most important biopolymers obtained from biomass in the twenty-first century. The attractiveness of lignin is increasing due to the intensive development of low-waste technologies and methods of effective processing of bioavailable materials. The potential of this biopolymer, underappreciated for many years, is being rediscovered and utilized. Research is being done with the aim of defining the structure of lignin and characterizing the factors that determine it. This biopolymer has become a promising source for obtaining small-molecule organic compounds. The multiplicity of identified functional groups provides a basis for its use in adsorption. Furthermore, lignin is becoming a platform for obtaining highly advanced sensors and/or biosensors. The variety of applications of lignin means that it is currently one of the most intensively developed materials.
The number of studies which emphasize the importance of lignin for the development of related materials topic is still limited. Hence, it seems that the materials presented in the framework of the proposed Special Issue will be of interest for many scientists and will contribute to the intensification of scientific work in this field.
This Special Issue aims to cover recent progress and trends in the utilization of lignin or modified/de-polymerized lignin in chemical synthesis, design of functional materials and/or biomaterials, as polymer fillers, cement admixtures, and others.
Submissions are welcome but not limited to the topics listed below. Types of contributions to this Special Isssue can be full research articles, short communications, and reviews focusing on the utilization of lignin for chemicals and functional materials.

  • Chemical modification/depolymerization of lignin;
  • Combustion/co-combustion of lignin for energy;
  • Gasification of lignin for syngas/hydrogen;
  • Production of bio-aromatic chemicals from lignin;
  • Synthesis of bio-based polymeric materials from lignin (e.g., resins, polymer composites, cement admixtures);
  • Design of lignin-based hybrid materials;
  • Practical utylity of lignin and lignin-based materials.

Dr. Łukasz Klapiszewski
Prof. Teofil Jesionowski
Guest Editors

Manuscript Submission Information

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Keywords

  • Lignin and its derivatives
  • Green chemistry
  • Modification/activation/depolymerization of lignin
  • Chemical characterization of lignin
  • Biopolymers, biocomposites, renewable materials
  • Biobased hybrid materials
  • Polymer composites
  • Cement admixtures
  • Biosensors
  • Effective adsorbents
  • Lignin nanocontainers

Related Special Issue

Published Papers (13 papers)

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Research

14 pages, 4760 KiB  
Article
High Value Utilization of Waste Wood toward Porous and Lightweight Carbon Monolith with EMI Shielding, Heat Insulation and Mechanical Properties
by Xiaofan Ma, Xiaoshuai Han, Jiapeng Hu, Weisen Yang, Jingquan Han, Zhichao Lou, Chunmei Zhang and Shaohua Jiang
Molecules 2023, 28(6), 2482; https://doi.org/10.3390/molecules28062482 - 08 Mar 2023
Cited by 3 | Viewed by 1520
Abstract
With the increasing pollution of electromagnetic (EM) radiation, it is necessary to develop low-cost, renewable electromagnetic interference (EMI) shielding materials. Herein, wood-derived carbon (WC) materials for EMI shielding are prepared by one-step carbonization of renewable wood. With the increase in carbonization temperature, the [...] Read more.
With the increasing pollution of electromagnetic (EM) radiation, it is necessary to develop low-cost, renewable electromagnetic interference (EMI) shielding materials. Herein, wood-derived carbon (WC) materials for EMI shielding are prepared by one-step carbonization of renewable wood. With the increase in carbonization temperature, the conductivity and EMI performance of WC increase gradually. At the same carbonization temperature, the denser WC has better conductivity and higher EMI performance. In addition, due to the layered superimposed conductive channel structure, the WC in the vertical-section shows better EMI shielding performance than that in the cross-section. After excluding the influence of thickness and density, the specific EMI shielding effectiveness (SSE/t) value can be calculated to further optimize tree species. We further discuss the mechanism of the influence of the microstructure of WC on its EMI shielding properties. In addition, the lightweight WC EMI material also has good hydrophobicity and heat insulation properties, as well as good mechanical properties. Full article
(This article belongs to the Special Issue Lignin: From Nature to Advanced Materials)
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17 pages, 4021 KiB  
Article
Potential of Staphylea holocarpa Wood for Renewable Bioenergy
by Yiyang Li, Erdong Liu, Haiping Gu, Junwei Lou, Yafeng Yang, Longhai Ban, Wanxi Peng and Shengbo Ge
Molecules 2023, 28(1), 299; https://doi.org/10.3390/molecules28010299 - 30 Dec 2022
Viewed by 1337
Abstract
Energy is indispensable in human life and social development, but this has led to an overconsumption of non-renewable energy. Sustainable energy is needed to maintain the global energy balance. Lignocellulose from agriculture or forestry is often discarded or directly incinerated. It is abundantly [...] Read more.
Energy is indispensable in human life and social development, but this has led to an overconsumption of non-renewable energy. Sustainable energy is needed to maintain the global energy balance. Lignocellulose from agriculture or forestry is often discarded or directly incinerated. It is abundantly available to be discovered and studied as a biomass energy source. Therefore, this research uses Staphylea holocarpa wood as feedstock to evaluate its potential as energy source. We characterized Staphylea holocarpa wood by utilizing FT–IR, GC–MS, TGA, Py/GC–MS and NMR. The results showed that Staphylea holocarpa wood contained a large amount of oxygenated volatiles, indicating that it has the ability to act as biomass energy sources which can achieve green chemistry and sustainable development. Full article
(This article belongs to the Special Issue Lignin: From Nature to Advanced Materials)
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14 pages, 2926 KiB  
Article
Chemical and Mechanical Characterization of Licorice Root and Palm Leaf Waste Incorporated into Poly(urethane-acrylate) (PUA)
by Serena Gabrielli, Genny Pastore, Francesca Stella, Enrico Marcantoni, Fabrizio Sarasini, Jacopo Tirillò and Carlo Santulli
Molecules 2021, 26(24), 7682; https://doi.org/10.3390/molecules26247682 - 19 Dec 2021
Cited by 6 | Viewed by 2959
Abstract
A poly(urethane-acrylate) polymer (PUA) was synthesized, and a sufficiently high molecular weight starting from urethane-acrylate oligomer (UAO) was obtained. PUA was then loaded with two types of powdered ligno-cellulosic waste, namely from licorice root and palm leaf, in amounts of 1, 5 and [...] Read more.
A poly(urethane-acrylate) polymer (PUA) was synthesized, and a sufficiently high molecular weight starting from urethane-acrylate oligomer (UAO) was obtained. PUA was then loaded with two types of powdered ligno-cellulosic waste, namely from licorice root and palm leaf, in amounts of 1, 5 and 10%, and the obtained composites were chemically and mechanically characterized. FTIR analysis of final PUA synthesized used for the composite production confirmed the new bonds formed during the polymerization process. The degradation temperatures of the two types of waste used were in line with what observed in most common natural fibers with an onset at 270 °C for licorice waste, and at 290 °C for palm leaf one. The former was more abundant in cellulose (44% vs. 12% lignin), whilst the latter was richer in lignin (30% vs. 26% cellulose). In the composites, only a limited reduction of degradation temperature was observed for palm leaf waste addition and some dispersion issues are observed for licorice root, leading to fluctuating results. Tensile performance of the composites indicates some reduction with respect to the pure polymer in terms of tensile strength, though stabilizing between data with 5 and 10% filler. In contrast, Shore A hardness of both composites slightly increases with higher filler content, while in stiffness-driven applications licorice-based composites showed potential due to an increase up to 50% compared to neat PUA. In general terms, the fracture surfaces tend to become rougher with filler introduction, which indicates the need for optimizing interfacial adhesion. Full article
(This article belongs to the Special Issue Lignin: From Nature to Advanced Materials)
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16 pages, 3085 KiB  
Article
Chemical Characterization of Kraft Lignin Prepared from Mixed Hardwoods
by Ji-Sun Mun, Justin Alfred Pe III and Sung-Phil Mun
Molecules 2021, 26(16), 4861; https://doi.org/10.3390/molecules26164861 - 11 Aug 2021
Cited by 16 | Viewed by 3189
Abstract
Chemical characterization of kraft lignin (KL) from mixed hardwoods (Acacia spp. from Vietnam and mixed hardwoods (mainly Quercus spp.) from Korea) was conducted for its future applications. To compare the structural changes that occurred in KL, two milled wood lignins (MWLs) were [...] Read more.
Chemical characterization of kraft lignin (KL) from mixed hardwoods (Acacia spp. from Vietnam and mixed hardwoods (mainly Quercus spp.) from Korea) was conducted for its future applications. To compare the structural changes that occurred in KL, two milled wood lignins (MWLs) were prepared from the same hardwood samples used in the production of KL. Elemental analysis showed that the MWL from acacia (MWL-aca) and mixed hardwood (MWL-mhw) had almost similar carbon content, methoxyl content, and C9 formula. KL had high carbon content but low oxygen and methoxyl contents compared to MWLs. The C9 formula of KL was determined to be C9H7.29O2.26N0.07S0.12(OCH3)1.24. The Mw of KL and MWLs was about 3000 Da and 12,000–13,000 Da, respectively. The structural features of KL and MWLs were investigated by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectrometry (1H, 13C NMR). The analyses indicated that KL underwent severe structural modifications, such as γ-carbon cleavage, demethylation, and polycondensation reactions during kraft pulping, which resulted in increased aromatic content and decreased aliphatic content. The main linkages in lignin, β-O-4 moieties, were hardly detected in the analysis as these linkages were extensively cleaved by nucleophilic attack of SH- and OH- during pulping. Full article
(This article belongs to the Special Issue Lignin: From Nature to Advanced Materials)
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18 pages, 6063 KiB  
Article
Lignin as a Partial Polyol Replacement in Polyurethane Flexible Foam
by Akash Gondaliya and Mojgan Nejad
Molecules 2021, 26(8), 2302; https://doi.org/10.3390/molecules26082302 - 15 Apr 2021
Cited by 25 | Viewed by 5563
Abstract
This study was focused on evaluating the suitability of a wide range of lignins, a natural polymer isolated from different plant sources and chemical extractions, in replacing 20 wt.% of petroleum-based polyol in the formulation of PU flexible foams. The main goal was [...] Read more.
This study was focused on evaluating the suitability of a wide range of lignins, a natural polymer isolated from different plant sources and chemical extractions, in replacing 20 wt.% of petroleum-based polyol in the formulation of PU flexible foams. The main goal was to investigate the effect of unmodified lignin incorporation on the foam’s structural, mechanical, and thermal properties. The hydroxyl contents of the commercial lignins were measured using phosphorus nuclear magnetic resonance (31P NMR) spectroscopy, molar mass distributions with gel permeation chromatography (GPC), and thermal properties with differential scanning calorimetry (DSC) techniques. The results showed that incorporating 20 wt.% lignin increased tensile, compression, tear propagation strengths, thermal stability, and the support factor of the developed PU flexible foams. Additionally, statistical analysis of the results showed that foam properties such as density and compression force deflection were positively correlated with lignin’s total hydroxyl content. Studying correlations between lignin properties and the performance of the developed lignin-based PU foams showed that lignins with low hydroxyl content, high flexibility (low Tg), and high solubility in the co-polyol are better candidates for partially substituting petroleum-based polyols in the formulation of flexible PU foams intended for the automotive applications. Full article
(This article belongs to the Special Issue Lignin: From Nature to Advanced Materials)
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14 pages, 3063 KiB  
Article
Binderless, All-Lignin Briquette from Black Liquor Waste: Isolation, Purification, and Characterization
by Yati Mardiyati, Emia Yoseva Tarigan, Pandji Prawisudha, Silvia Mar’atus Shoimah, Raden Reza Rizkiansyah and Steven Steven
Molecules 2021, 26(3), 650; https://doi.org/10.3390/molecules26030650 - 27 Jan 2021
Cited by 6 | Viewed by 2901
Abstract
Lignin isolated from black liquor waste was studied in this research to be utilized as binderless, all-lignin briquette, with a calorific value in the range of 5670–5876 kcal/kg. Isolation of lignin from black liquor was conducted using the acid precipitation method. Sulfuric acid, [...] Read more.
Lignin isolated from black liquor waste was studied in this research to be utilized as binderless, all-lignin briquette, with a calorific value in the range of 5670–5876 kcal/kg. Isolation of lignin from black liquor was conducted using the acid precipitation method. Sulfuric acid, citric acid, and acetic acid were used to maintain the pH level, which varied from 5 to 2 for the precipitation process. The influence of these isolation conditions on the characteristic of lignin and the properties of the resulted briquette was evaluated through the Klasson method, proximate analysis, ultimate analysis, Fourier Transform Infrared (FTIR), adiabatic bomb calorimeter, density measurement, and Drop Shatter Index (DSI) testing. The finding showed that the lignin isolated using citric acid maintained to pH 3 resulted in briquette with 72% fixed carbon content, excellent 99.7% DSI, and a calorific value equivalent to coal-based briquette. Full article
(This article belongs to the Special Issue Lignin: From Nature to Advanced Materials)
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20 pages, 4062 KiB  
Article
Flammability Tests and Investigations of Properties of Lignin-Containing Polymer Composites Based on Acrylates
by Beata Podkościelna, Krystyna Wnuczek, Marta Goliszek, Tomasz Klepka and Kamil Dziuba
Molecules 2020, 25(24), 5947; https://doi.org/10.3390/molecules25245947 - 15 Dec 2020
Cited by 17 | Viewed by 2602
Abstract
In this paper flammability tests and detailed investigations of lignin-containing polymer composites’ properties are presented. Composites were obtained using bisphenol A glycerolate (1 glycerol/phenol) diacrylate (BPA.GDA), ethylene glycol dimethacrylate (EGDMA), and kraft lignin (lignin alkali, L) during UV curing. In order to evaluate [...] Read more.
In this paper flammability tests and detailed investigations of lignin-containing polymer composites’ properties are presented. Composites were obtained using bisphenol A glycerolate (1 glycerol/phenol) diacrylate (BPA.GDA), ethylene glycol dimethacrylate (EGDMA), and kraft lignin (lignin alkali, L) during UV curing. In order to evaluate the influence of lignin modification and the addition of flame retardant compounds on the thermal resistance of the obtained biocomposites, flammability tests have been conducted. After the modification with phosphoric acid (V) lignin, as well as diethyl vinylphosphonate, were used as flame retardant additives. The changes in the chemical structures (ATR-FTIR), as well as the influence of the different additives on the hardness, thermal (TG) and mechanical properties were discussed in detail. The samples after the flammability test were also studied to assess their thermal destruction. Full article
(This article belongs to the Special Issue Lignin: From Nature to Advanced Materials)
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25 pages, 4716 KiB  
Article
i-Propylammonium Lead Chloride Based Perovskite Photocatalysts for Depolymerization of Lignin Under UV Light
by Samia Kausar, Ataf Ali Altaf, Muhammad Hamayun, Nasir Rasool, Mahwish Hadait, Arusa Akhtar, Shabbir Muhammad, Amin Badshah, Syed Adnan Ali Shah and Zainul Amiruddin Zakaria
Molecules 2020, 25(15), 3520; https://doi.org/10.3390/molecules25153520 - 31 Jul 2020
Cited by 12 | Viewed by 4361
Abstract
Lignin depolymerization for the purpose of synthesizing aromatic molecules is a growing focus of research to find alternative energy sources. In current studies, the photocatalytic depolymerization of lignin has been investigated by two new iso-propylamine-based lead chloride perovskite nanomaterials (SK9 and SK10 [...] Read more.
Lignin depolymerization for the purpose of synthesizing aromatic molecules is a growing focus of research to find alternative energy sources. In current studies, the photocatalytic depolymerization of lignin has been investigated by two new iso-propylamine-based lead chloride perovskite nanomaterials (SK9 and SK10), synthesized by the facile hydrothermal method. Characterization was done by Powder X-Ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), UV-Visible (UV-Vis), Photoluminescence (PL), and Fourier-Transform Infrared (FTIR) Spectroscopy and was used for the photocatalytic depolymerization of lignin under UV light. Lignin depolymerization was monitored by taking absorption spectra and catalytic paths studied by applying kinetic models. The %depolymerization was calculated for factors such as catalyst dose variation, initial concentration of lignin, and varying temperatures. Pseudo-second order was the best suited kinetic model, exhibiting a mechanism for lignin depolymerization that was chemically rate controlled. The activation energy (Ea) for the depolymerization reaction was found to be 15 kJ/mol, which is remarkably less than conventional depolymerization of the lignin, i.e., 59.75 kJ/mol, exhibiting significant catalytic efficiencies of synthesized perovskites. Products of lignin depolymerization obtained after photocatalytic activity at room temperature (20 °C) and at 90 °C were characterized by GC-MS analysis, indicating an increase in catalytic lignin depolymerization structural subunits into small monomeric functionalities at higher temperatures. Specifically, 2-methoxy-4-methylphenol (39%), benzene (17%), phenol (10%) and catechol (7%) were detected by GC-MS analysis of lignin depolymerization products. Full article
(This article belongs to the Special Issue Lignin: From Nature to Advanced Materials)
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17 pages, 2000 KiB  
Article
Epoxidation of Kraft Lignin as a Tool for Improving the Mechanical Properties of Epoxy Adhesive
by Julia R. Gouveia, Guilherme E. S. Garcia, Leonardo Dalseno Antonino, Lara B. Tavares and Demetrio J. dos Santos
Molecules 2020, 25(11), 2513; https://doi.org/10.3390/molecules25112513 - 28 May 2020
Cited by 49 | Viewed by 5019
Abstract
Owing to its chemical structure, wide availability and renewable nature, lignin is a promising candidate for the partial replacement of fossil-based raw material in the synthesis of epoxy resins. Its poor compatibility has been reported to be one of the main drawbacks in [...] Read more.
Owing to its chemical structure, wide availability and renewable nature, lignin is a promising candidate for the partial replacement of fossil-based raw material in the synthesis of epoxy resins. Its poor compatibility has been reported to be one of the main drawbacks in this domain. On the other hand, a well-established modification method for lignin epoxidation has been used for many years for the improvement of lignin compatibility. However, the extent of the effect of lignin epoxidation on the improvement of bio-based epoxy mechanical properties, applied as adhesives, is still an open question in the literature. In this context, a pristine and industrial grade kraft lignin (AKL) was reacted with epichlorohydrin to yield epoxidized lignin (E-AKL) in this work. Afterwards, AKL or E-AKL were separately blended with petroleum-based epoxy resin at 15 and 30 wt% and cured with a commercial amine. The adhesive curing kinetic was evaluated using a novel technique for thermal transition characterization, Temperature Modulated Optical Refractometry (TMOR); the results showed that the incorporation of AKL reduces the crosslinking rate, and that this effect is overcome by lignin modification. Mechanical tests revealed an improvement of impact and practical adhesion strength for samples containing 15 wt% of E-AKL. These results elucidate the effect of lignin epoxidation on the application of lignin-based epoxy adhesives, and might support the further development and application of these bio-based materials. Full article
(This article belongs to the Special Issue Lignin: From Nature to Advanced Materials)
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19 pages, 3185 KiB  
Article
Sustainable Process for the Depolymerization/Oxidation of Softwood and Hardwood Kraft Lignins Using Hydrogen Peroxide under Ambient Conditions
by Zaid Ahmad, Waleed Wafa Al Dajani, Michael Paleologou and Chunbao (Charles) Xu
Molecules 2020, 25(10), 2329; https://doi.org/10.3390/molecules25102329 - 16 May 2020
Cited by 32 | Viewed by 4179
Abstract
The present study demonstrated a sustainable and cost-effective approach to depolymerize/oxidize softwood (SW) and hardwood (HW) kraft lignins using concentrated hydrogen peroxide at temperatures ranging from 25 to 35 °C, in the absence of catalysts or organic solvents. The degree of lignin depolymerization [...] Read more.
The present study demonstrated a sustainable and cost-effective approach to depolymerize/oxidize softwood (SW) and hardwood (HW) kraft lignins using concentrated hydrogen peroxide at temperatures ranging from 25 to 35 °C, in the absence of catalysts or organic solvents. The degree of lignin depolymerization could be simply controlled by reaction time, and no further separation process was needed at the completion of the treatment. The obtained depolymerized lignin products were comprehensively characterized by GPC–UV, FTIR, 31P-NMR, TGA, Py-GC/MS and elemental analysis. The weight-average molecular weights (Mw) of the depolymerized lignins obtained from SW or HW lignin at a lignin/H2O2 mass ratio of 1:1 after treatment for 120 h at room temperature (≈25 °C) were approximately 1420 Da. The contents of carboxylic acid groups in the obtained depolymerized lignins were found to significantly increase compared with those of the untreated raw lignins. Moreover, the depolymerized lignin products had lower thermal decomposition temperatures than those of the raw lignins, as expected, owing to the greatly reduced Mw. These findings represent a novel solution to lignin depolymerization for the production of chemicals that can be utilized as a bio-substitute for petroleum-based polyols in polyurethane production. Full article
(This article belongs to the Special Issue Lignin: From Nature to Advanced Materials)
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16 pages, 7053 KiB  
Article
Effect of Solvents on Fe–Lignin Precursors for Production Graphene-Based Nanostructures
by Qiangu Yan and Zhiyong Cai
Molecules 2020, 25(9), 2167; https://doi.org/10.3390/molecules25092167 - 06 May 2020
Cited by 14 | Viewed by 3115
Abstract
Kraft lignin was catalytically graphitized to graphene-based nanostructures at high temperature under non-oxidative atmospheres. To obtain the best catalytic performance, a uniform catalyst–lignin mixture must be made by bonding transitional metal (M) ions to oxygen (O), sulfur (S) or nitrogen (N)-containing functional groups [...] Read more.
Kraft lignin was catalytically graphitized to graphene-based nanostructures at high temperature under non-oxidative atmospheres. To obtain the best catalytic performance, a uniform catalyst–lignin mixture must be made by bonding transitional metal (M) ions to oxygen (O), sulfur (S) or nitrogen (N)-containing functional groups in kraft lignin. One of the strategies is to dissolve or disperse kraft lignin in a suitable solvent, whereby the polymer chains in the condensed lignin molecules will be detangled and stretched out while the functional groups are solvated, and when mixing lignin solution with catalyst metal solution, the solvated metal ions in an aqueous solution can diffuse and migrate onto lignin chains to form M-O, M-S, or M-N bonds during the mixing process. Therefore, solvent effects are important in preparing M–lignin mixture for production of graphene-based nanostructures. Fe–lignin precursors were prepared by dissolving lignin with different solvents, including water, methanol, acetone, and tetrahydrofuran (THF). Solvent effects on the catalytic performance, size and morphology of graphene-based nanostructures were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM), and nitrogen sorption measurements. The sizes, morphologies, and catalytic properties of the products obtained from Fe–lignin precursors are greatly influenced by the solvents used. It was found that Fe–lignin (THF) had the highest iron dispersion and the smallest iron particle size. Furthermore, Fe–lignin (THF) exhibited the best catalytic performance for graphitization of kraft lignin while the graphitization degree decreased in the order: Fe–lignin(THF) > Fe–lignin(Acetone) > Fe–lignin(methanol) > Fe–lignin(water). Full article
(This article belongs to the Special Issue Lignin: From Nature to Advanced Materials)
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16 pages, 2796 KiB  
Article
Electrical and Optical Properties of Silicon Oxide Lignin Polylactide (SiO2-L-PLA)
by Jacek Fal, Katarzyna Bulanda, Julian Traciak, Jolanta Sobczak, Rafał Kuzioła, Katarzyna Maria Grąz, Grzegorz Budzik, Mariusz Oleksy and Gaweł Żyła
Molecules 2020, 25(6), 1354; https://doi.org/10.3390/molecules25061354 - 16 Mar 2020
Cited by 5 | Viewed by 3236
Abstract
This paper presents a study on the electrical properties of new polylactide-based nanocomposites with the addition of silicon-dioxide–lignin nanoparticles and glycerine as a plasticizer. Four samples were prepared with nanoparticle mass fractions ranging between 0.01 to 0.15 (0.01, 0.05, 0.10, and 0.15), and [...] Read more.
This paper presents a study on the electrical properties of new polylactide-based nanocomposites with the addition of silicon-dioxide–lignin nanoparticles and glycerine as a plasticizer. Four samples were prepared with nanoparticle mass fractions ranging between 0.01 to 0.15 (0.01, 0.05, 0.10, and 0.15), and three samples were prepared without nanoparticle filler—unfilled and unprocessed polylactide, unfilled and processed polylactide, and polylactide with Fusabond and glycerine. All samples were manufactured using the melt mixing extrusion technique and injection molding. Only the unfilled and unprocessed PLA sample was directly prepared by injection molding. Dielectric properties were studied with broadband spectroscopy in a frequency range from 0.1 Hz to 1 MHz in 55 steps designed on a logarithmic scale and a temperature range from 293.15 to 333.15 K with a 5 K step. Optical properties of nanocomposites were measured with UV-VIS spectroscopy at wavelengths from 190 to 1100 nm. The experimental data show that the addition of silicon-dioxide–lignin and glycerine significantly affected the electrical properties of the studied nanocomposites based on polylactide. Permittivity and electrical conductivity show a significant increase with an increasing concentration of nanoparticle filler. The optical properties are also affected by nanofiller and cause an increase in absorbance as the number of silicon-dioxide–lignin nanoparticles increase. Full article
(This article belongs to the Special Issue Lignin: From Nature to Advanced Materials)
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16 pages, 2878 KiB  
Article
Functional MgO–Lignin Hybrids and Their Application as Fillers for Polypropylene Composites
by Aleksandra Grząbka-Zasadzińska, Łukasz Klapiszewski, Teofil Jesionowski and Sławomir Borysiak
Molecules 2020, 25(4), 864; https://doi.org/10.3390/molecules25040864 - 16 Feb 2020
Cited by 14 | Viewed by 2883
Abstract
Inorganic–organic hybrids are a group of materials that have recently become the subject of intense scientific research. They exhibit some of the specific properties of both highly durable inorganic materials (e.g., titanium dioxide, zinc) and organic products with divergent physicochemical traits (e.g., lignin, [...] Read more.
Inorganic–organic hybrids are a group of materials that have recently become the subject of intense scientific research. They exhibit some of the specific properties of both highly durable inorganic materials (e.g., titanium dioxide, zinc) and organic products with divergent physicochemical traits (e.g., lignin, chitin). This combination results in improved physicochemical, thermal or mechanical properties. Hybrids with defined characteristics can be used as fillers for polymer composites. In this study, three types of filler with different MgO/lignin ratio were used as fillers for polypropylene (PP). The effectiveness of MgO-lignin binding was confirmed using Fourier transform infrared spectroscopy. The fillers were also tested in terms of thermal stability, dispersive-morphological properties as well as porous structure. Polymer composites containing 3 wt.% of each filler were subjected to wide angle X-ray diffraction tests, differential scanning calorimetry and microscopic studies to define their structure, morphology and thermal properties. Additionally, tensile tests of the composites were performed. It was established that the composition of the filler has a significant influence on the crystallization of polypropylene—either spherulites or transcrystalline layers were formed. The value of Young’s modulus and tensile strength remained unaffected by filler type. However, composites with hybrid fillers exhibited lower elongation at break than unfilled polypropylene. Full article
(This article belongs to the Special Issue Lignin: From Nature to Advanced Materials)
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