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7870 KiB

Open AccessArticle

Preparation and Characterization of Polyvinyl Alcohol-Chitosan Composite Films Reinforced with Cellulose Nanofiber

by Kaiwen Choo, Yern Chee Ching, Cheng Hock Chuah, Sabariah Julai and Nai-Shang Liou

Materials 2016, 9(8), 644; https://doi.org/10.3390/ma9080644 - 29 Jul 2016

Cited by 250 | Viewed by 12056

In this study microcrystalline cellulose (MCC) was oxidized by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation. The treated cellulose slurry was mechanically homogenized to form a transparent dispersion which consisted of individual cellulose nanofibers with uniform widths of 3–4 nm. Bio-nanocomposite films were then prepared from [...] Read more.

In this study microcrystalline cellulose (MCC) was oxidized by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation. The treated cellulose slurry was mechanically homogenized to form a transparent dispersion which consisted of individual cellulose nanofibers with uniform widths of 3–4 nm. Bio-nanocomposite films were then prepared from a polyvinyl alcohol (PVA)-chitosan (CS) polymeric blend with different TEMPO-oxidized cellulose nanofiber (TOCN) contents (0, 0.5, 1.0 and 1.5 wt %) via the solution casting method. The characterizations of pure PVA/CS and PVA/CS/TOCN films were performed in terms of field emission scanning electron microscopy (FESEM), tensile tests, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results from FESEM analysis justified that low loading levels of TOCNs were dispersed uniformly and homogeneously in the PVA-CS blend matrix. The tensile strength and thermal stability of the films were increased with the increased loading levels of TOCNs to a maximum level. The thermal study indicated a slight improvement of the thermal stability upon the reinforcement of TOCNs. As evidenced by the FTIR and XRD, PVA and CS were considered miscible and compatible owing to hydrogen bonding interaction. These analyses also revealed the good dispersion of TOCNs within the PVA/CS polymer matrix. The improved properties due to the reinforcement of TOCNs can be highly beneficial in numerous applications. Full article

(This article belongs to the Special Issue Advances in Functionalization of Lignocellulosic Materials)

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4772 KiB

Open AccessFeature PaperArticle

Rapeseed and Raspberry Seed Cakes as Inexpensive Raw Materials in the Production of Activated Carbon by Physical Activation: Effect of Activation Conditions on Textural and Phenol Adsorption Characteristics

by Koen Smets, Mats De Jong, Iwona Lupul, Grazyna Gryglewicz, Sonja Schreurs, Robert Carleer and Jan Yperman

Materials 2016, 9(7), 565; https://doi.org/10.3390/ma9070565 - 12 Jul 2016

Cited by 20 | Viewed by 6004

Abstract

The production of activated carbons (ACs) from rapeseed cake and raspberry seed cake using slow pyrolysis followed by physical activation of the obtained solid residues is the topic of this study. The effect of activation temperature (850, 900 and 950 °C), activation time [...] Read more.

The production of activated carbons (ACs) from rapeseed cake and raspberry seed cake using slow pyrolysis followed by physical activation of the obtained solid residues is the topic of this study. The effect of activation temperature (850, 900 and 950 °C), activation time (30, 60, 90 and 120 min) and agent (steam and CO₂) on the textural characteristics of the ACs is investigated by N₂ adsorption. In general, higher activation temperatures and longer activation times increase the BET specific surface area and the porosity of the ACs, regardless of the activation agent or raw material. Steam is more reactive than CO₂ in terms of pore development, especially in the case of raspberry seed cake. The performance of the ACs in liquid adsorption is evaluated by batch phenol adsorption tests. Experimental data are best fitted by the Freundlich isotherm model. Based on total yield, textural characteristics and phenol adsorption, steam activation at 900 °C for 90 min and CO₂ activation at 900 °C for 120 min are found as the best activation conditions. Raspberry seed cake turns out to be a better raw material than rapeseed cake. Moreover, AC from raspberry seed cake produced by steam activation at 900 °C for 90 min performs as well as commercial AC (Norit GAC 1240) in phenol adsorption. The adsorption kinetics of the selected ACs are best fitted by the pseudo-second-order model. Full article

(This article belongs to the Special Issue Advances in Functionalization of Lignocellulosic Materials)

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1383 KiB

Open AccessArticle

LCA of 1,4-Butanediol Produced via Direct Fermentation of Sugars from Wheat Straw Feedstock within a Territorial Biorefinery

by Annachiara Forte, Amalia Zucaro, Riccardo Basosi and Angelo Fierro

Materials 2016, 9(7), 563; https://doi.org/10.3390/ma9070563 - 12 Jul 2016

Cited by 52 | Viewed by 8886

Abstract

The bio-based industrial sector has been recognized by the European Union as a priority area toward sustainability, however, the environmental profile of bio-based products needs to be further addressed. This study investigated, through the Life Cycle Assessment (LCA) approach, the environmental performance of [...] Read more.

The bio-based industrial sector has been recognized by the European Union as a priority area toward sustainability, however, the environmental profile of bio-based products needs to be further addressed. This study investigated, through the Life Cycle Assessment (LCA) approach, the environmental performance of bio-based 1,4-butanediol (BDO) produced via direct fermentation of sugars from wheat straw, within a hypothetical regional biorefinery (Campania Region, Southern Italy). The aim was: (i) to identify the hotspots along the production chain; and (ii) to assess the potential environmental benefits of this bio-based polymer versus the reference conventional product (fossil-based BDO). Results identified the prevailing contribution to the total environmental load of bio-based BDO in the feedstock production and in the heat requirement at the biorefinery plant. The modeled industrial bio-based BDO supply chain, showed a general reduction of the environmental impacts compared to the fossil-based BDO. The lowest benefits were gained in terms of acidification and eutrophication, due to the environmental load of the crop phase for feedstock cultivation. Full article

(This article belongs to the Special Issue Advances in Functionalization of Lignocellulosic Materials)

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3863 KiB

Open AccessArticle

Enrichment of Cellulosic Waste Hemp (Cannabis sativa) Hurd into Non-Toxic Microfibres

by Reinu E. Abraham, Cynthia S. Wong and Munish Puri

Materials 2016, 9(7), 562; https://doi.org/10.3390/ma9070562 - 11 Jul 2016

Cited by 23 | Viewed by 7177

Abstract

In this study a largely available lignocellulose feedstock hemp (Cannabis sativa), obtained as an industrial waste, was used for cellulose extraction. The extraction of cellulose microfibres from hemp biomass was conducted by alkaline treatment and an acidification process. The extracted cellulose [...] Read more.

In this study a largely available lignocellulose feedstock hemp (Cannabis sativa), obtained as an industrial waste, was used for cellulose extraction. The extraction of cellulose microfibres from hemp biomass was conducted by alkaline treatment and an acidification process. The extracted cellulose microfibres were characterised using Fourier-transformed infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The viability of the study was determined by growing human fibroblasts on the preparation which resulted in being non-toxic; indicating its potential in preparing biological scaffolds. Upon enzymatic hydrolysis of the cellulose microfibre using cellulase from Trichoderma reesei, a maximum of 909 mg/g of reducing sugars were obtained, which endorses its suitability for biofuel production. Full article

(This article belongs to the Special Issue Advances in Functionalization of Lignocellulosic Materials)

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2174 KiB

Open AccessArticle

Physicochemical Characterization of Functional Lignin–Silica Hybrid Fillers for Potential Application in Abrasive Tools

by Beata Strzemiecka, Łukasz Klapiszewski, Artur Jamrozik, Tadeusz J. Szalaty, Danuta Matykiewicz, Tomasz Sterzyński, Adam Voelkel and Teofil Jesionowski

Materials 2016, 9(7), 517; https://doi.org/10.3390/ma9070517 - 25 Jun 2016

Cited by 39 | Viewed by 6419

Abstract

Functional lignin–SiO₂ hybrid fillers were prepared for potential application in binders for phenolic resins, and their chemical structure was characterized. The properties of these fillers and of composites obtained from them with phenolic resin were compared with those of systems with lignin [...] Read more.

Functional lignin–SiO₂ hybrid fillers were prepared for potential application in binders for phenolic resins, and their chemical structure was characterized. The properties of these fillers and of composites obtained from them with phenolic resin were compared with those of systems with lignin or silica alone. The chemical structure of the materials was investigated by Fourier transform infrared spectroscopy (FT-IR) and carbon-13 nuclear magnetic resonance spectroscopy (¹³C CP MAS NMR). The thermal stability of the new functional fillers was examined by thermogravimetric analysis–mass spectrometry (TG-MS). Thermo-mechanical properties of the lignin–silica hybrids and resin systems were investigated by dynamic mechanical thermal analysis (DMTA). The DMTA results showed that abrasive composites with lignin–SiO₂ fillers have better thermo-mechanical properties than systems with silica alone. Thus, fillers based on lignin might provide new, promising properties for the abrasive industry, combining the good properties of lignin as a plasticizer and of silica as a filler improving mechanical properties. Full article

(This article belongs to the Special Issue Advances in Functionalization of Lignocellulosic Materials)

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3789 KiB

Open AccessArticle

Functionalization of Cellulose Nanocrystals in Choline Lactate Ionic Liquid

by Sarah Montes, Itxaso Azcune, Germán Cabañero, Hans-Jürgen Grande, Ibon Odriozola and Jalel Labidi

Materials 2016, 9(7), 499; https://doi.org/10.3390/ma9070499 - 23 Jun 2016

Cited by 18 | Viewed by 6220

Abstract

Cellulose nanocrystals (CNCs) are valuable nanomaterials obtained from renewable resources. Their properties make them suitable for a wide range of applications, including polymer reinforcement. However, due to their highly hydrophilic character, it is necessary to modify their surface with non-polar functional groups before [...] Read more.

Cellulose nanocrystals (CNCs) are valuable nanomaterials obtained from renewable resources. Their properties make them suitable for a wide range of applications, including polymer reinforcement. However, due to their highly hydrophilic character, it is necessary to modify their surface with non-polar functional groups before their incorporation into a hydrophobic polymer matrix. In this work, cellulose nanocrystals were modified using a silane coupling agent and choline lactate, an ionic liquid derived from renewable resources, as a reaction medium. Modified cellulose nanocrystals were characterized by infrared spectroscopy, showing new peaks associated to the modification performed. X-ray diffraction was used to analyze the crystalline structure of functionalized cellulose nanocrystals and to optimize the amount of silane for functionalization. Poly(lactic acid) (PLA) nanocomposites containing 1 wt % of functionalized cellulose nanocrystals were prepared. They were characterized by field-emission scanning electron microscopy (FE-SEM) and mechanical tests. The use of choline lactate as reaction media has been shown to be an alternative method for the dispersion and silanization of the cellulose nanocrystals without the addition of an external catalyst. Full article

(This article belongs to the Special Issue Advances in Functionalization of Lignocellulosic Materials)

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2219 KiB

Open AccessArticle

Water Uptake Behavior and Young Modulus Prediction of Composites Based on Treated Sisal Fibers and Poly(Lactic Acid)

by Ander Orue, Arantxa Eceiza, Cristina Peña-Rodriguez and Aitor Arbelaiz

Materials 2016, 9(5), 400; https://doi.org/10.3390/ma9050400 - 21 May 2016

Cited by 19 | Viewed by 5510

Abstract

The main aim of this work was to study the effect of sisal fiber surface treatments on water uptake behavior of composites based on untreated and treated fibers. For this purpose, sisal fibers were treated with different chemical treatments. All surface treatments delayed [...] Read more.

The main aim of this work was to study the effect of sisal fiber surface treatments on water uptake behavior of composites based on untreated and treated fibers. For this purpose, sisal fibers were treated with different chemical treatments. All surface treatments delayed the water absorption of fibers only for a short time of period. No significant differences were observed in water uptake profiles of composites based on fibers with different surface treatments. After water uptake period, tensile strength and Young modulus values of sisal fiber/poly(lactic acid) (PLA) composites were decreased. On the other hand, composites based on NaOH + silane treated fibers showed the lowest diffusion coefficient values, suggesting that this treatment seemed to be the most effective treatment to reduce water diffusion rate into the composites. Finally, Young modulus values of composites, before water uptake period, were predicted using different micromechanical models and were compared with experimental data. Full article

(This article belongs to the Special Issue Advances in Functionalization of Lignocellulosic Materials)

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6830 KiB

Open AccessArticle

Immobilization of Trypsin in Lignocellulosic Waste Material to Produce Peptides with Bioactive Potential from Whey Protein

by Juliana Cristina Bassan, Thaís Milena De Souza Bezerra, Guilherme Peixoto, Clariana Zanutto Paulino Da Cruz, Julián Paul Martínez Galán, Aline Buda dos Santos Vaz, Saulo Santesso Garrido, Marco Filice and Rubens Monti

Materials 2016, 9(5), 357; https://doi.org/10.3390/ma9050357 - 12 May 2016

Cited by 27 | Viewed by 6282

Abstract

In this study, trypsin (Enzyme Comission 3.4.21.4) was immobilized in a low cost, lignocellulosic support (corn cob powder—CCP) with the goal of obtaining peptides with bioactive potential from cheese whey. The pretreated support was activated with glyoxyl groups, glutaraldehyde and IDA-glyoxyl. The immobilization [...] Read more.

In this study, trypsin (Enzyme Comission 3.4.21.4) was immobilized in a low cost, lignocellulosic support (corn cob powder—CCP) with the goal of obtaining peptides with bioactive potential from cheese whey. The pretreated support was activated with glyoxyl groups, glutaraldehyde and IDA-glyoxyl. The immobilization yields of the derivatives were higher than 83%, and the retention of catalytic activity was higher than 74%. The trypsin-glyoxyl-CCP derivative was thermally stable at 65 °C, a value that was 1090-fold higher than that obtained with the free enzyme. The trypsin-IDA-glyoxyl-CCP and trypsin-glutaraldehyde-CCP derivatives had thermal stabilities that were 883- and five-fold higher, respectively, then those obtained with the free enzyme. In the batch experiments, trypsin-IDA-glyoxyl-CCP retained 91% of its activity and had a degree of hydrolysis of 12.49%, while the values for trypsin-glyoxyl-CCP were 87% and 15.46%, respectively. The stabilized derivative trypsin-glyoxyl-CCP was also tested in an upflow packed-bed reactor. The hydrodynamic characterization of this reactor was a plug flow pattern, and the kinetics of this system provided a relative activity of 3.04 ± 0.01 U·g⁻¹ and an average degree of hydrolysis of 23%, which were suitable for the production of potentially bioactive peptides. Full article

(This article belongs to the Special Issue Advances in Functionalization of Lignocellulosic Materials)

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4776 KiB

Open AccessReview

Plant Fibre: Molecular Structure and Biomechanical Properties, of a Complex Living Material, Influencing Its Deconstruction towards a Biobased Composite

by Mathias Sorieul, Alan Dickson, Stefan J. Hill and Hamish Pearson

Materials 2016, 9(8), 618; https://doi.org/10.3390/ma9080618 - 26 Jul 2016

Cited by 131 | Viewed by 16367

Abstract

Plant cell walls form an organic complex composite material that fulfils various functions. The hierarchical structure of this material is generated from the integration of its elementary components. This review provides an overview of wood as a composite material followed by its deconstruction [...] Read more.

Plant cell walls form an organic complex composite material that fulfils various functions. The hierarchical structure of this material is generated from the integration of its elementary components. This review provides an overview of wood as a composite material followed by its deconstruction into fibres that can then be incorporated into biobased composites. Firstly, the fibres are defined, and their various origins are discussed. Then, the organisation of cell walls and their components are described. The emphasis is on the molecular interactions of the cellulose microfibrils, lignin and hemicelluloses in planta. Hemicelluloses of diverse species and cell walls are described. Details of their organisation in the primary cell wall are provided, as understanding of the role of hemicellulose has recently evolved and is likely to affect our perception and future study of their secondary cell wall homologs. The importance of the presence of water on wood mechanical properties is also discussed. These sections provide the basis for understanding the molecular arrangements and interactions of the components and how they influence changes in fibre properties once isolated. A range of pulping processes can be used to individualise wood fibres, but these can cause damage to the fibres. Therefore, issues relating to fibre production are discussed along with the dispersion of wood fibres during extrusion. The final section explores various ways to improve fibres obtained from wood. Full article

(This article belongs to the Special Issue Advances in Functionalization of Lignocellulosic Materials)

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