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Bio-Based Materials from Wood and Non-wood Fibers: Development, Properties and Design

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Biomaterials".

Deadline for manuscript submissions: closed (20 December 2022) | Viewed by 47866

Special Issue Editors


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Guest Editor
Latvian State Institute of Wood Chemistry, Dzerbenes str. 27, LV-1006 Riga, Latvia
Interests: mycelium biocomposites; biopolymers from natural fibres; microbial degradation of wood; microscopy of wood structure and microorganisms; fungal diversity in wooden constructions; biological durability of treated wood and wood based products
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Thünen Institute of Wood Research, Hamburg, Germany
Interests: wood quality; wood durability; wood modification; wood protection; service life prediction; structural health assessment; performance classification
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The use of wood and non-wood fibers from forestry and agricultural industries for the production of new end products has grown significantly in recent years. The most attractive factor of bio-based products is the possibility to exploit biological wastes and byproducts that are valorized to achieve the principles of circular economy.

Wood and non-wood fibers have received much attention for composite material applications. Another strategy to develop composites from alternative sources than plant-derived ones is the development of new materials based on fungal fibers (mycelium composites). Mycelium in composites is coupled with other materials originated from biological processes, such as wood and non-wood plant materials, to exploit the natural growth of the fungal organism on these substrates.

Composites from natural fibres have many advantages and are designed to be used in building, construction, furniture production, packaging, interior accessories. However, they should comply with a series of standards to achieve specified values of various properties.

The Special Issue aims to cover all the aspects related to recent innovations in composites from natural fibers such as wood, agro-fibers, plant biomass, grass and mycelium fibers. Development, physico-mechanical, chemical, biological properties and design of these materials are appreciated. Besides, contributions analyzing the effect of inclusion other natural biopolymers in composite materials are welcomed.

Finally, we would like to emphasize that this Special Issue is widely inclusive, so we expect a large number of works to fall within its scope. Therefore, it is our pleasure to invite you to submit a manuscript for this Special Issue. Full papers, communications, and reviews are all welcome.

Dr. Ilze Irbe
Prof. Dr. Christian Brischke
Prof. Dr. Miha Humar
Guest Editors

Manuscript Submission Information

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Keywords

  • biocomposites from natural fibres
  • mycelium composites
  • wood based composites
  • non-wood based composites
  • forestry byproducts
  • agricultural waste
  • renewable raw materials
  • biodegradability
  • biological durability
  • service life
  • life cycle assessment

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Published Papers (15 papers)

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Research

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18 pages, 4443 KiB  
Article
Properties of Sound Absorption Composite Materials Developed Using Flax Fiber, Sphagnum Moss, Vermiculite, and Sapropel
by Daira Sleinus, Maris Sinka, Aleksandrs Korjakins, Vaira Obuka, Vizma Nikolajeva, Raitis Brencis and Estere Savicka
Materials 2023, 16(3), 1060; https://doi.org/10.3390/ma16031060 - 25 Jan 2023
Cited by 6 | Viewed by 2213
Abstract
To address the need to reduce consumption and pollution in the industrial sector, composite materials were created using a new type of raw materials—organic lake sediments (sapropel) as a binder; sphagnum moss, flax fiber, and vermiculite as a filler. The main application of [...] Read more.
To address the need to reduce consumption and pollution in the industrial sector, composite materials were created using a new type of raw materials—organic lake sediments (sapropel) as a binder; sphagnum moss, flax fiber, and vermiculite as a filler. The main application of these composite materials is for sound absorption and moisture buffering, but since they contain bio-based binders and fillers, they also work as carbon storage. Within the framework of this work, a total of 100 samples of composite materials were created. Fungicides—a biocide quaternary ammonium compound and its natural substitute montmorillonite mineral material were also added to the materials to improve microbiological stability. The mechanical sound absorption and microbiological properties of materials were investigated and compared to similar environmentally friendly materials, such as hemp-lime concrete (FHL), hemp magnesium oxychloride composite (MOC), and hemp magnesium phosphate cement (MPC). The results showed that sound absorption and mechanical and microbial properties of the created composite materials are sufficient for their intended use, with flax fiber and vermiculite composites showing more stable mechanical, sound absorbing, and microbiological stability properties than materials containing flax fiber and moss. Full article
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12 pages, 2580 KiB  
Article
Biological Durability of Wood–Polymer Composites—The Role of Moisture and Aging
by Andreas Buschalsky, Christian Brischke, Kim Christian Klein, Thomas Kilian and Holger Militz
Materials 2022, 15(23), 8556; https://doi.org/10.3390/ma15238556 - 1 Dec 2022
Cited by 1 | Viewed by 1175
Abstract
Knowledge about the resistance of wood–polymer composites (WPCs) to biological attack is of high importance for purpose-oriented use in outdoor applications. To gain this knowledge, uniform test methods are essential. EN 15534-1 (2018) provides a general framework, including the recommendation of applying a [...] Read more.
Knowledge about the resistance of wood–polymer composites (WPCs) to biological attack is of high importance for purpose-oriented use in outdoor applications. To gain this knowledge, uniform test methods are essential. EN 15534-1 (2018) provides a general framework, including the recommendation of applying a pre-weathering procedure before the biological laboratory tests. However, the procedure’s manner is not specified, and its necessity assumes that a durability test without such pre-weathering will not produce the structural changes that occur during outdoor use. To verify this assumption, this study examined the influence of natural, ground-level pre-weathering on the material properties of different WPC variants, which were tested at intervals of six months in four durability tests under laboratory conditions in accordance with EN 15534-1 (2018). Weathering factors were calculated from determined characteristic values such as mass loss, and loss in moduli of elasticity (MOE) and rupture (MOR). The weathering factors based on mechanical properties tended to decrease with increasing weathering duration. The expected negative influence of pre-weathering on these material properties was thus not confirmed. The weathering factors based on mass loss were subject to high variation. No significant effect of pre-weathering on mass loss due to fungal attack became evident. Overall, the necessity of a pre-weathering step in biological durability tests shall be questioned based on the presented results. Full article
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14 pages, 5559 KiB  
Article
RIFT Process Analysis for the Production of Green Composites in Flax Fibers and Bio-Based Epoxy Resin
by Luca Sorrentino, Sandro Turchetta, Gianluca Parodo, Roberta Papa, Elisa Toto, Maria Gabriella Santonicola and Susanna Laurenzi
Materials 2022, 15(22), 8173; https://doi.org/10.3390/ma15228173 - 17 Nov 2022
Cited by 6 | Viewed by 1294
Abstract
In this work, a dual objective is carried out on composite materials in flax fiber and bio-based epoxy resin: to determine the process parameters and to develop a numerical model for highlighting the potential of and the limits in the production of “green” [...] Read more.
In this work, a dual objective is carried out on composite materials in flax fiber and bio-based epoxy resin: to determine the process parameters and to develop a numerical model for highlighting the potential of and the limits in the production of “green” laminates through a RIFT process (Resin Infusion under Flexible Tool). For these reasons, compressibility tests were performed in order to evaluate the behavior of commercial flax woven under the vacuum bag. Subsequently, permeability tests were performed in order to evaluate the permeability curves necessary for the numerical study of the infusion process. For the numerical analyses, the commercial software PAM-RTM was adopted and validated. In this work, vaseline oil was used as the injected resin for the validation, and a bio-based epoxy commercial system was used for the study of the infusion process in a simple case study. The results were compared with a petroleum-based epoxy system typically used for infusion processes, showing the potentiality and the critical use of bio-based resins for infusion processes. Full article
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16 pages, 3936 KiB  
Article
Utilizing and Valorizing Oat and Barley Straw as an Alternative Source of Lignocellulosic Fibers
by Marc Borrega, Ville Hinkka, Hanna Hörhammer, Kirsi Kataja, Eija Kenttä, Jukka A. Ketoja, Rosa Palmgren, Minna Salo, Henna Sundqvist-Andberg and Atsushi Tanaka
Materials 2022, 15(21), 7826; https://doi.org/10.3390/ma15217826 - 6 Nov 2022
Cited by 8 | Viewed by 2089
Abstract
The transition to sustainable, biodegradable, and recyclable materials requires new sources of cellulose fibers that are already used in large volumes by forest industries. Oat and barley straws provide interesting alternatives to wood fibers in lightweight material applications because of their similar chemical [...] Read more.
The transition to sustainable, biodegradable, and recyclable materials requires new sources of cellulose fibers that are already used in large volumes by forest industries. Oat and barley straws provide interesting alternatives to wood fibers in lightweight material applications because of their similar chemical composition. Here we investigate processing and material forming concepts, which would enable strong fiber network structures for various applications. The idea is to apply mild pretreatment processing that could be distributed locally so that the logistics of the raw material collection could be made efficient. The actual material production would then combine foam-forming and hot-pressing operations that allow using all fractions of fiber materials with minimal waste. We aimed to study the technical features of this type of processing on a laboratory scale. The homogeneity of the sheet samples was very much affected by whether the raw material was mechanically refined or not. Straw fibers did not form a bond spontaneously with one another after drying the sheets, but their effective bonding required a subsequent hot pressing operation. The mechanical properties of the formed materials were at a similar level as those of the conventional wood-fiber webs. In addition to the technical aspects of materials, we also discuss the business opportunities and system-level requirements of using straw as an alternative source of lignocellulosic fibers. Full article
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15 pages, 1577 KiB  
Article
Characterization of Self-Growing Biomaterials Made of Fungal Mycelium and Various Lignocellulose-Containing Ingredients
by Ilze Irbe, Gustavs Daniels Loris, Inese Filipova, Laura Andze and Marite Skute
Materials 2022, 15(21), 7608; https://doi.org/10.3390/ma15217608 - 29 Oct 2022
Cited by 8 | Viewed by 2216
Abstract
In this study, novel blends of mycelium biocomposites (MB) were developed. Various combinations of birch sawdust and hemp shives with birch bark (BB) and wheat bran (WB) additives were inoculated with basidiomycete Trametes versicolor to produce self-growing biomaterials. MB were characterized according to [...] Read more.
In this study, novel blends of mycelium biocomposites (MB) were developed. Various combinations of birch sawdust and hemp shives with birch bark (BB) and wheat bran (WB) additives were inoculated with basidiomycete Trametes versicolor to produce self-growing biomaterials. MB were characterized according to mycelial biomass increment in final samples, changes in chemical composition, elemental (C, H, N) analyses, granulometry of substrates, water-related and mechanical properties, as well as mold resistance and biodegradability. The mycelial biomass in manufactured MB increased by ~100% and ~50% in hemp and sawdust substrates, respectively. The lignocellulose ingredients during fungal growth were degraded as follows: cellulose up to 7% and 28% in sawdust and hemp substrates, respectively, and lignin in the range of 13% in both substrates. A larger granulometric fraction in hemp MB ensured higher strength property but weakened water absorption (600–880%) performance. Perspective MB combinations regarding strength performance were hemp/BB and pure hemp MB (σ10 0.19–0.20 MPa; E 2.9 MPa), as well as sawdust/WB combination (σ10 0.23 MPa; E 2.9 MPa). WB positively affected fungal biomass yield, but elevated water absorption ability. WB improved compressive strength in the sawdust samples but decreased it in the hemp samples. BB supplement reduced water absorption by more than 100% and increased the density of sawdust and hemp samples. All MB samples were susceptible to mold contamination after full water immersion, with identified fungal genera Rhizopus, Trichoderma and Achremonium. The MB exhibited high biodegradability after 12 weeks’ exposure in compost, and are therefore competitive with non-biodegradable synthetic foam materials. Full article
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10 pages, 2270 KiB  
Article
Loofah Sandwich Panels: The Effect of Adhesive Content on Mechanical and Physical Properties
by Robert Köhler, Marvin Jurisch, Aaron Kilian Mayer, Carsten Mai and Wolfgang Viöl
Materials 2022, 15(20), 7129; https://doi.org/10.3390/ma15207129 - 13 Oct 2022
Cited by 2 | Viewed by 1871
Abstract
In the development of new materials, the focus nowadays is increasingly on their relevance with regard to lightweight construction or environmental compatibility. The idea of a lightweight sandwich panel was inspired by an increasing number of cosmetic accessories that use the fibers of [...] Read more.
In the development of new materials, the focus nowadays is increasingly on their relevance with regard to lightweight construction or environmental compatibility. The idea of a lightweight sandwich panel was inspired by an increasing number of cosmetic accessories that use the fibers of the loofah plant, a rapidly renewable, light, fibrous raw material. The aim of the study was to develop a fiber composite panel based on the fibers of the loofah plant (Luffa cylindrica) as core material and wooden veneer as the skin layer to be used in areas of lead construction. Three different panel variations were produced for the tests, with a fiber–adhesive ratio between 1:1.05, 1:0.8, and 1:0.5. The mechanical strength (flexural strength and internal bond) and the physical properties (density and thickness swelling) were determined as a function of the fiber–adhesive composition. The results show that the flexural strength increased by approx. 400% and the thickness swelling was reduced by 10% with increasing adhesive quantity. Full article
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17 pages, 2781 KiB  
Article
Seagrass Leaves: An Alternative Resource for the Production of Insulation Materials
by Aldi Kuqo and Carsten Mai
Materials 2022, 15(19), 6933; https://doi.org/10.3390/ma15196933 - 6 Oct 2022
Cited by 7 | Viewed by 3275
Abstract
Seagrass wracks, the remains of dead leaves accumulated on seashores, are important ecosystems and beneficial for the marine environment. Their presence on the touristic beaches, however, is a problem for the tourism industry due to the lack of aesthetics and safety reasons. At [...] Read more.
Seagrass wracks, the remains of dead leaves accumulated on seashores, are important ecosystems and beneficial for the marine environment. Their presence on the touristic beaches, however, is a problem for the tourism industry due to the lack of aesthetics and safety reasons. At the present time, seagrass leaves are landfilled, although this is not considered an ecological waste management practice. Among other proposed practices for more sustainable and environmentally friendly management, such as composting and biogas or energy generation, in this study we aim to use seagrass leaves for the production of insulation materials. Insulation boards from two types of seagrass leaves (Posidonia oceanica and Zostera marina) at densities varying from 80 to 200 kg m−3 were prepared and their physical and mechanical properties were examined and compared to those of wood fiber insulation boards. The thermal conductivity of seagrass-based insulation boards varied from 0.042 to 0.050 W m−1 K−1, which was up to 12% lower compared to the latter. The cone calorimetry analysis revealed that seagrass-based insulation boards are more fire resistant than those from wood fibers, as they release very low amounts of heat during combustion and do not ignite when exposed to a single flame (Bunsen burner). A simplified cost analysis showed that insulation boards made from seagrass leaves can be up to 30% cheaper compared to those made from wood fibers. After their end of life, seagrass leaves can again be considered a valuable resource and be further utilized by adopting other management strategies. Full article
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15 pages, 3585 KiB  
Article
Lignocellulosic Biomass of C3 and C4 Perennial Grasses as a Valuable Feedstock for Particleboard Manufacture
by Dominika Janiszewska, Grzegorz Żurek, Danuta Martyniak and Wojciech Bałęczny
Materials 2022, 15(18), 6384; https://doi.org/10.3390/ma15186384 - 14 Sep 2022
Cited by 5 | Viewed by 1361
Abstract
Looking for new alternative raw materials is one of the key issues in line with a bioeconomy approach, particularly for particleboard manufacturing. In this framework, this paper presents a comparison of some physico-mechanical properties and the formaldehyde contents of particleboards made with 30% [...] Read more.
Looking for new alternative raw materials is one of the key issues in line with a bioeconomy approach, particularly for particleboard manufacturing. In this framework, this paper presents a comparison of some physico-mechanical properties and the formaldehyde contents of particleboards made with 30% substitution of grass biomass from six perennial grass species. Our studies indicate relatively high values of mechanical properties for particleboards made with the addition of biomass from grasses with the C4 photosynthetic pathway: Miscanthus x giganteus and switchgrass (Panicum virgatum). Boards made with the addition of biomass from grasses with the C3 photosynthetic pathway—tall wheatgrass (Elymus elongatus), tall fescue (Festuca arundinacea), and perennial ryegrass (Lolium perenne)—gave lower values of mechanical properties. The opposite results were obtained in the case of the formaldehyde content: the lowest value was measured for particleboards made with the addition of tall fescue biomass (0.1% less than the control), and the highest for switchgrass (0.9% greater than the control) and cordgrass (3.2% greater than the control). Future research should address the optimization of the manufacturing process of particleboards from perennial grasses, taking into account the needs and technical possibilities of the wood industry sector. Full article
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11 pages, 3198 KiB  
Article
Thermomechanical and Alkaline Peroxide Mechanical Pulping of Lignocellulose Residue Obtained from the 2-Furaldehyde Production Process
by Maris Puke, Daniela Godina, Prans Brazdausks, Janis Rizikovs and Velta Fridrihsone
Materials 2022, 15(17), 5872; https://doi.org/10.3390/ma15175872 - 25 Aug 2022
Cited by 2 | Viewed by 1344
Abstract
The necessity for the reduction in greenhouse gas emissions, the growing demand for the improvement of biorefinery technologies, and the development of new biorefining concepts oblige us as a society, and particularly us, as scientists, to develop novel biorefinery approaches. The purpose of [...] Read more.
The necessity for the reduction in greenhouse gas emissions, the growing demand for the improvement of biorefinery technologies, and the development of new biorefining concepts oblige us as a society, and particularly us, as scientists, to develop novel biorefinery approaches. The purpose of this study is to thoroughly evaluate the leftover lignocellulosic (LC) biomass obtained after the manufacture of 2-furaldehyde, with the intention of further valorizing this resource. This study demonstrates that by using thermomechanical and alkaline peroxide mechanical pulping techniques, birch wood chips can be used in the new biorefinery processing chain for the production of 2-furaraldehyde, acetic acid, and cellulose pulp. In addition, the obtained lignocellulosic residue is also characterized. To produce a lignocellulosic material without pentoses and with the greatest amount of cellulose fiber preserved for future use, a novel bench-scale reactor technology is used. Studies were conducted utilizing orthophosphoric acid as a catalyst to deacetylate and dehydrate pentose monosaccharides found in birch wood, converting them to 2-furaldehyde and acetic acid. The results showed that, with the least amount of admixtures, the yields of the initial feedstock’s oven-dried mass (o.d.m.) of 2-furaldehyde, acetic acid, and lignocellulose residue ranged from 0.04 to 10.84%, 0.51 to 6.50%, and 68.13 to 98.07%, respectively, depending on the pretreatment conditions utilized. The ideal 2-furaldehyde production conditions with reference to the purity and usability of cellulose in residual lignocellulosic material were also discovered through experimental testing. The experiment that produced the best results in terms of 2-furaldehyde yield and purity of residual lignocellulose used a catalyst concentration of 70%, a catalyst quantity of 4%, a reaction temperature of 175 °C, and a treatment period of 60 min. It was possible to create pulp with a tensile index similar to standard printing paper by mechanically pulping the necessary LC residue with alkaline peroxide, proving that stepwise 2-furaldehyde production may be carried out with subsequent pulping to provide a variety of value-added goods. Full article
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13 pages, 2059 KiB  
Article
Qualitative Differences and Emission Persistence of Volatile Organic Compounds from Bio-Based Particleboards
by Ramunas Tupciauskas, Kristine Meile, Daniela Godina, Janis Rizhikovs, Michail Syrpas and Petras Rimantas Venskutonis
Materials 2022, 15(15), 5278; https://doi.org/10.3390/ma15155278 - 30 Jul 2022
Cited by 3 | Viewed by 1479
Abstract
An attempt to reduce, replace, or even eliminate the synthetic resins from wood-based panels alongside broadening the array of raw lignocellulosics is still essential and attractive. Many pretreatments of lignocellulosics have been studied, among which steam explosion (SE) resulted in superior physical-mechanical properties [...] Read more.
An attempt to reduce, replace, or even eliminate the synthetic resins from wood-based panels alongside broadening the array of raw lignocellulosics is still essential and attractive. Many pretreatments of lignocellulosics have been studied, among which steam explosion (SE) resulted in superior physical-mechanical properties of the obtained binder-less boards. However, the SE pretreatment leads to a relatively strong odor, which is even emitted from the obtained binder-less boards independent of the raw lignocellulosic, raising concern about the use of the boards. Emissions of volatile organic compounds (VOCs) were investigated in the framework of the study from binder-less boards obtained from different SE raw lignocellulosics and SE-untreated suberinic acids-bonded particleboard. VOCs were collected by headspace solid-phase microextraction (HS-SPME) and analyzed by gas chromatography–mass spectrometry (GC–MS) for 28 days with an interval of 2 weeks. The results showed that the number of detected VOCs and their chromatographic peak area varied significantly depending on the raw lignocellulosic, board density, and post-treatment (overlayering), decreasing over time. The lowest area of detected VOCs was demonstrated by the suberinic acids-bonded particleboard, while the highest area was detected from the high-density binder-less board obtained from SE hemp shives with the main compound of furfural (up to 70%) in all board types. Full article
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19 pages, 3492 KiB  
Article
Eco-Friendly Adhesives Based on the Oligomeric Condensed Tannins-Rich Extract from Alder Bark for Particleboard and Plywood Production
by Sarmite Janceva, Anna Andersone, Uldis Spulle, Ramunas Tupciauskas, Electra Papadopoulou, Oskars Bikovens, Martins Andzs, Natalija Zaharova, Gints Rieksts and Galina Telysheva
Materials 2022, 15(11), 3894; https://doi.org/10.3390/ma15113894 - 30 May 2022
Cited by 11 | Viewed by 3194
Abstract
Toxic formaldehyde emissions, and the necessity to reduce the consumption of petrochemicals, stimulates the development of environmentally friendly adhesives. The aim of this research was to study, for the first time, the possibility of using condensed tannins (CTs)-rich extracts from grey alder ( [...] Read more.
Toxic formaldehyde emissions, and the necessity to reduce the consumption of petrochemicals, stimulates the development of environmentally friendly adhesives. The aim of this research was to study, for the first time, the possibility of using condensed tannins (CTs)-rich extracts from grey alder (Alnus incana) and black alder (Alnus glutinosa) bark in the production of particleboards and plywood adhesives. The chemical structure, composition, and molecular weight of the CTs were identified by a 13C-NMR and TOF-MS analysis. Three innovative adhesive systems were studied: CTs-phenol-formaldehyde (CTs-PF) resin; a CTs-polyethyleneimine (PEI) adhesive system; and CTs–PEI combined with an ultra-low emitting formaldehyde resin (ULEFR)—CTs–PEI–ULEFR. The results showed that CTs-PF resin has properties close to commercial PF resin, and the formaldehyde emission was twice lower. CTs–PEI bonded particleboards corresponded to the requirements of the EN 312:2010 standard for particleboards in dry conditions (Type P2). CTs–PEI–ULEFR, with a 40–60% substitution of ULEFR by CTs–PEI, had adhesive properties very close to ULEFR; the plywood shear strength fit the requirements of the EN 314-2:1993 standard for application in internal and external system conditions. The introduction of extracted alder bark residues microparticles into the composition of the adhesive system showed their positive potential for application as a filler. Full article
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23 pages, 6547 KiB  
Article
Influence of Manufacturing Conditions on Binder-Less Boards from Steam-Exploded Hemp Shives and Wheat Straw
by Ramunas Tupciauskas, Janis Rizhikovs, Martins Andzs and Oskars Bikovens
Materials 2022, 15(9), 3141; https://doi.org/10.3390/ma15093141 - 26 Apr 2022
Cited by 5 | Viewed by 1843
Abstract
In the current decade, based on the European Green Deal, new challenges of the wood-based panel industry have arisen, seeking for formaldehyde-free bio-based adhesives and broadening raw lignocellulosics. In order to contribute to the potential solution to the challenges, binder-less boards of steam-exploded [...] Read more.
In the current decade, based on the European Green Deal, new challenges of the wood-based panel industry have arisen, seeking for formaldehyde-free bio-based adhesives and broadening raw lignocellulosics. In order to contribute to the potential solution to the challenges, binder-less boards of steam-exploded (SE 220 °C/2 min) hemp shives and wheat straw were investigated. The objective of this study was to find out the optimal hot-pressing conditions in terms of temperature (150–200 °C) and time (5–16 min) for the boards with three density levels (800–1000–1200 kg·m−3). An experimental design was created and the influence of the variables on binder-less panels were evaluated using a randomized central composite design of the response surface methodology. Water absorption (WA) and thickness swelling (TS) during 24 h, modulus of elasticity (MOE), and modulus of rupture (MOR) in bending test, internal bonding (IB), and Fourier-transform infrared spectroscopy were determined for the obtained boards. Each detected physical-mechanical property of the obtained boards was described by statistical models being different at each density level. The optimal conditions of the obtained binder-less boards were different depending on the raw material and density. For example, the optimal conditions of the boards from SE wheat straw with a density of 800 kg m−3 were found at T = 220 °C and t = 15 min, with the achieved properties of WA = 53%, TS = 4%, MOE = 2750 N mm−2, MOR = 15.5 N mm−2, and IB = 0.64 N mm−2. Based on the achieved properties at the optimal conditions, the boards meet the requirements of the conventional particleboard Type P3 according to EN 312. Full article
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16 pages, 1638 KiB  
Article
Effect of Biochar Addition on Mechanical Properties, Thermal Stability, and Water Resistance of Hemp-Polylactic Acid (PLA) Composites
by Mariem Zouari, David B. Devallance and Laetitia Marrot
Materials 2022, 15(6), 2271; https://doi.org/10.3390/ma15062271 - 19 Mar 2022
Cited by 21 | Viewed by 3754
Abstract
The present study investigated the effect of biochar (BC) addition on mechanical, thermal, and water resistance properties of PLA and hemp-PLA-based composites. BC was combined with variable concentration to PLA (5 wt%, 10 wt%, and 20 wt%) and hemp (30 wt%)-PLA (5 wt% [...] Read more.
The present study investigated the effect of biochar (BC) addition on mechanical, thermal, and water resistance properties of PLA and hemp-PLA-based composites. BC was combined with variable concentration to PLA (5 wt%, 10 wt%, and 20 wt%) and hemp (30 wt%)-PLA (5 wt% and 10 wt%); then, composites were blended and injection molded. Samples were characterized by color measurements, tensile tests, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and water contact angle analysis. Experimental results showed that adding 5 wt% of BC enhanced the composite’s tensile modulus of elasticity and strength. Hence, the use of optimized loading of BC improved the mechanical strength of the composites. However, after BC addition, thermal stability slightly decreased compared with that of neat PLA due to the catalytic effect of BC particles. Moreover, the water-repelling ability decreased as BC content increased due to the specific hydrophilic characteristics of the BC used and its great porosity. Full article
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34 pages, 3824 KiB  
Review
Fungi in Mycelium-Based Composites: Usage and Recommendations
by Maciej Sydor, Grzegorz Cofta, Beata Doczekalska and Agata Bonenberg
Materials 2022, 15(18), 6283; https://doi.org/10.3390/ma15186283 - 9 Sep 2022
Cited by 39 | Viewed by 9351
Abstract
Mycelium-Based Composites (MBCs) are innovative engineering materials made from lignocellulosic by-products bonded with fungal mycelium. While some performance characteristics of MBCs are inferior to those of currently used engineering materials, these composites nevertheless prove to be superior in ecological aspects. Improving the properties [...] Read more.
Mycelium-Based Composites (MBCs) are innovative engineering materials made from lignocellulosic by-products bonded with fungal mycelium. While some performance characteristics of MBCs are inferior to those of currently used engineering materials, these composites nevertheless prove to be superior in ecological aspects. Improving the properties of MBCs may be achieved using an adequate substrate type, fungus species, and manufacturing technology. This article presents scientifically verified guiding principles for choosing a fungus species to obtain the desired effect. This aim was realized based on analyses of scientific articles concerning MBCs, mycological literature, and patent documents. Based on these analyses, over 70 fungi species used to manufacture MBC have been identified and the most commonly used combinations of fungi species-substrate-manufacturing technology are presented. The main result of this review was to demonstrate the characteristics of the fungi considered optimal in terms of the resulting engineering material properties. Thus, a list of the 11 main fungus characteristics that increase the effectiveness in the engineering material formation include: rapid hyphae growth, high virulence, dimitic or trimitic hyphal system, white rot decay type, high versatility in nutrition, high tolerance to a substrate, environmental parameters, susceptibility to readily controlled factors, easy to deactivate, saprophytic, non-mycotoxic, and capability to biosynthesize natural active substances. An additional analysis result is a list of the names of fungus species, the types of substrates used, the applications of the material produced, and the main findings reported in the scientific literature. Full article
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33 pages, 6613 KiB  
Review
Nettle, a Long-Known Fiber Plant with New Perspectives
by Chloé Viotti, Katharina Albrecht, Stefano Amaducci, Paul Bardos, Coralie Bertheau, Damien Blaudez, Lea Bothe, David Cazaux, Andrea Ferrarini, Jason Govilas, Hans-Jörg Gusovius, Thomas Jeannin, Carsten Lühr, Jörg Müssig, Marcello Pilla, Vincent Placet, Markus Puschenreiter, Alice Tognacchini, Loïc Yung and Michel Chalot
Materials 2022, 15(12), 4288; https://doi.org/10.3390/ma15124288 - 17 Jun 2022
Cited by 12 | Viewed by 9256
Abstract
The stinging nettle Urticadioica L. is a perennial crop with low fertilizer and pesticide requirements, well adapted to a wide range of environmental conditions. It has been successfully grown in most European climatic zones while also promoting local flora and fauna diversity. [...] Read more.
The stinging nettle Urticadioica L. is a perennial crop with low fertilizer and pesticide requirements, well adapted to a wide range of environmental conditions. It has been successfully grown in most European climatic zones while also promoting local flora and fauna diversity. The cultivation of nettle could help meet the strong increase in demand for raw materials based on plant fibers as a substitute for artificial fibers in sectors as diverse as the textile and automotive industries. In the present review, we present a historical perspective of selection, harvest, and fiber processing features where the state of the art of nettle varietal selection is detailed. A synthesis of the general knowledge about its biology, adaptability, and genetics constituents, highlighting gaps in our current knowledge on interactions with other organisms, is provided. We further addressed cultivation and processing features, putting a special emphasis on harvesting systems and fiber extraction processes to improve fiber yield and quality. Various uses in industrial processes and notably for the restoration of marginal lands and avenues of future research on this high-value multi-use plant for the global fiber market are described. Full article
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