scholarly journals Bio-based films/nanopapers of banana tree pseudostem: From lignocellulosic wastes to added-value micro/nanomaterials

2021 ◽  
Author(s):  
Barbara Maria Ribeiro Guimarães ◽  
Mário Vanoli Scatolino ◽  
Maria Alice Martins ◽  
Saulo Rocha Ferreira ◽  
Lourival Marin Mendes ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Raw Materials ◽  
Cellulose Nanofibrils ◽  
Dry Mass ◽  
Added Value ◽  
Light Transmittance ◽  
Transparent Films ◽  
Banana Tree ◽  
Lignocellulosic Wastes ◽  
Mechanical Fibrillation

Abstract The growing demand for products with lower environmental impact and the extensive applicability of cellulose nanofibrils (CNFs) have received attention in several fields of knowledge due to their attractive properties. In this study, bio-based films/nanopapers were produced with CNFs from banana tree pseudostem (BTPT) wastes and Eucalyptus kraft cellulose (EKC) and were evaluated by their properties, such as mechanical strength, biodegradability and light transmittance. The CNFs were produced by mechanical fibrillation (after 20 and 40 passages) from suspensions of BTPT (alkaline pre-treated) and EKC. Films/nanopapers were produced by casting from both suspensions with concentrations of 2% (based in dry mass of CNF). The BTPT films/nanopapers showed greater mechanical properties, with Young’s modulus and tensile strength around 2.42 GPa and 51 MPa (after 40 passages), respectively. On the other hand, the EKC samples showed lower disintegration in water after 24 h and biodegradability. The increase in the number of fibrillation cycles produced more transparent films/nanopapers and caused a significant reduction of water absorption for both raw materials. The permeability was similar for the films/nanopapers from BTPT and EKC. This study indicated that attractive mechanical properties and biodegradability could be achieved by bio-based nanomaterials, with potential for being applied as emulsifying agents and special membranes, enabling more efficient utilization of agricultural wastes.

The Property of Waterborne UV-Curable Polyurethane Based on Alkali Lignin of Wheat Straw

2013 ◽  
Vol 834-836 ◽  
pp. 199-202 ◽  
Author(s):  
Ji Lei Chao ◽  
Fu Qiang Chu ◽  
Chang Li Xu ◽  
Hui Wang ◽  
Yu Xin Liu
Keyword(s):  
Mechanical Properties ◽  
Optical Properties ◽  
Wheat Straw ◽  
Loss Factor ◽  
Loss Modulus ◽  
Added Value ◽  
Light Transmittance ◽  
Optical Performance ◽  
Uv Curable ◽  
Alkali Lignin

To improve the added value of lignin, the modified alkali lignin of wheat straw was used to prepare waterborne UV-curable polyurethane. The purpose of this paper is to discuss the properties of the cured films made from the above lignin-based polyurethane. The mechanical and optical properties of the cured films were investigated. Results showed that the tensile storage modulus, tensile loss modulus, and tensile loss factor of the cured film were influenced by the addition of the lignin, which indicated that proper dosage of the lignin could change the micro-phase separation structure and improve the mechanical properties of the product. The addition of the lignin also influenced the gloss and light transmittance of the cured film. On the whole, the lignin-based polyurethane exhibits good mechanical and optical performance if proper proportion of the lignin was added to the product. The study was beneficial for utilizing the lignin in high value products.

Production of Cement Blocks and New Ceramic Materials with High Content of Glass Waste

2015 ◽  
Vol 663 ◽  
pp. 34-41 ◽  
Author(s):  
Fernanda Andreola ◽  
Isabella Lancellotti ◽  
Rosa Taurino ◽  
Cristina Leonelli ◽  
Luisa Barbieri
Keyword(s):  
Mechanical Properties ◽  
Environmental Impact ◽  
Economic Burden ◽  
Raw Materials ◽  
Glass Melting ◽  
Physical And Mechanical Properties ◽  
Ceramic Materials ◽  
Raw Material ◽  
Added Value ◽  
Glass Waste

Virgin raw materials can be partially replaced by glass waste in order to reduce the environmental impact being its recycling a significant problem for municipalities worldwide. In Italy in 2013, approximately 1,600,000 tons of container glass have been collected but it was not possible to recycle all of them in the glass melting process.This work is focused on the valorization of glass waste as raw material in new cement and ceramic products, to convert it from an environmental and economic burden to a profitable, added-value resource in the formulation of new mixes. Several parameters, such as grinding, forming, firing, etc. have been studied.It has been optimized the grinding and the reclaiming step of waste to obtain an alternative raw material for hot and cold consolidation processes. Chemical, physical and mechanical properties of products were carried out. The results show new real possibilities to use high amounts of glass waste as an alternative raw material in products consolidated either by hot or cold techniques, reducing the management problems of the glass waste.

scholarly journals Preparation of Transparent and Thick CNF/Epoxy Composites by Controlling the Properties of Cellulose Nanofibrils

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 625 ◽  
Author(s):  
Shin Young Park ◽  
Simyub Yook ◽  
Sooim Goo ◽  
Wanhee Im ◽  
Hye Jung Youn
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Cellulose Nanofibrils ◽  
High Light ◽  
Epoxy Composites ◽  
Light Transmittance ◽  
High Transparency ◽  
Preparation Conditions ◽  
Optically Transparent ◽  
Optical And Mechanical Properties

Cellulose nanofibrils (CNFs) have been used as reinforcing elements in optically transparent composites by combination with polymer matrices. In this study, strong, optically transparent, and thick CNF/epoxy composites were prepared by immersing two or four layers of CNF sheets in epoxy resin. The morphology of the CNF, the preparation conditions of the CNF sheet, and the grammage and layer numbers of the CNF sheets were controlled. The solvent-exchanged CNF sheets resulted in the production of a composite with high transparency and low haze. The CNF with smaller width and less aggregated fibrils, which are achieved by carboxymethylation, and a high number of grinding passes are beneficial in the production of optically transparent CNF/epoxy composites. Both the grammage and number of stacked layers of sheets in a composite affected the optical and mechanical properties of the composite. A composite with a thickness of 450–800 μm was prepared by stacking two or four layers of CNF sheets in epoxy resin. As the number of stacked sheets increased, light transmittance was reduced and the haze increased. The CNF/epoxy composites with two layers of low grammage (20 g/m2) sheets exhibited high light transmittance (>90%) and low haze (<5%). In addition, the composites with the low grammage sheet had higher tensile strength and elastic modulus compared with neat epoxy and those with high grammage sheets.

scholarly journals Production and Mechanical Characterisation of TEMPO-Oxidised Cellulose Nanofibrils/β-Cyclodextrin Films and Cryogels

Molecules ◽  
2020 ◽  
Vol 25 (10) ◽  
pp. 2381
Author(s):  
Bastien Michel ◽  
Julien Bras ◽  
Alain Dufresne ◽  
Ellinor B. Heggset ◽  
Kristin Syverud
Keyword(s):  
Mechanical Properties ◽  
Water Sorption ◽  
Biomedical Applications ◽  
Freeze Drying ◽  
Cellulose Nanofibrils ◽  
Added Value ◽  
Active Principle ◽  
Acidic Ph ◽  
Sorption Behaviour ◽  
The Impact

Wood-based TEMPO-oxidised cellulose nanofibrils (toCNF) are promising materials for biomedical applications. Cyclodextrins have ability to form inclusion complexes with hydrophobic molecules and are considered as a method to bring new functionalities to these materials. Water sorption and mechanical properties are also key properties for biomedical applications such as drug delivery and tissue engineering. In this work, we report the modification with β-cyclodextrin (βCD) of toCNF samples with different carboxyl contents viz. 756 ± 4 µmol/g and 1048 ± 32 µmol/g. The modification was carried out at neutral and acidic pH (2.5) to study the effect of dissociation of the carboxylic acid group. Films processed by casting/evaporation at 40 °C and cryogels processed by freeze-drying were prepared from βCD modified toCNF suspensions and compared with reference samples of unmodified toCNF. The impact of modification on water sorption and mechanical properties was assessed. It was shown that the water sorption behaviour for films is driven by adsorption, with a clear impact of the chemical makeup of the fibres (charge content, pH, and adsorption of cyclodextrin). Modified toCNF cryogels (acidic pH and addition of cyclodextrins) displayed lower mechanical properties linked to the modification of the cell wall porosity structure. Esterification between βCD and toCNF under acidic conditions was performed by freeze-drying, and such cryogels exhibited a lower decrease in mechanical properties in the swollen state. These results are promising for the development of scaffold and films with controlled mechanical properties and added value due to the ability of cyclodextrin to form an inclusion complex with active principle ingredient (API) or growth factor (GF) for biomedical applications.

The Sintering Behaviour and Mechanical Properties of Hydroxyapatite - Based Composites for Bone Tissue Regeneration

2018 ◽  
Vol 69 (5) ◽  
pp. 1272-1275 ◽  
Author(s):  
Camelia Tecu ◽  
Aurora Antoniac ◽  
Gultekin Goller ◽  
Mustafa Guven Gok ◽  
Marius Manole ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tricalcium Phosphate ◽  
Cosmetic Surgery ◽  
Mechanical Stability ◽  
Raw Materials ◽  
Oyster Shell ◽  
Bone Tissue Regeneration ◽  
Sintering Behavior ◽  
Bovine Bone ◽  
Human Teeth

Bone reconstruction is a complex process which involves an osteoconductive matrix, osteoinductive signaling, osteogenic cells, vascularization and mechanical stability. Lately, to improve the healing of the bone defects and to accelerate the bone fusion and bone augmentation, bioceramic composite materials have been used as bone substitutes in the field of orthopedics and dentistry, as well as in cosmetic surgery. Of all types of bioceramics, the most used is hydroxyapatite, because of its similar properties to those of the human bone and better mechanical properties compared to b-tricalcium phosphate [1]. Currently, the most used raw materials sources for obtaining the hydroxyapatite are: bovine bone, seashells, corals, oyster shell, eggshells and human teeth. There are two common ways to obtain hydroxyapatite: synthetically and naturally. Generally, for the improvement of the mechanical properties and the structural one, hydroxyapatite is subjected to the sintering process. Considering the disadvantages of hydroxyapatite such as poor biodegradation rate, b-TCP has been developed, which has some disadvantages too, such as brittleness. For this reason, the aim of this study is to look into the effect of adding magnesium oxide on the sintering behavior, the structure and the mechanical properties of the hydroxyapatite-tricalcium phosphate composites.

Cellulose Nanofibrils-based Hydrogels for Biomedical Applications: Progresses and Challenges

2020 ◽  
Vol 27 (28) ◽  
pp. 4622-4646 ◽  
Author(s):  
Huayu Liu ◽  
Kun Liu ◽  
Xiao Han ◽  
Hongxiang Xie ◽  
Chuanling Si ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Metal Ion ◽  
Biomedical Applications ◽  
Biomedical Application ◽  
Cellulose Nanofibrils ◽  
Wound Dressings ◽  
Preparation Methods ◽  
Tissue Scaffold ◽  
Surface Areas ◽  
Mechanical Methods

Background: Cellulose Nanofibrils (CNFs) are natural nanomaterials with nanometer dimensions. Compared with ordinary cellulose, CNFs own good mechanical properties, large specific surface areas, high Young's modulus, strong hydrophilicity and other distinguishing characteristics, which make them widely used in many fields. This review aims to introduce the preparation of CNFs-based hydrogels and their recent biomedical application advances. Methods: By searching the recent literatures, we have summarized the preparation methods of CNFs, including mechanical methods and chemical mechanical methods, and also introduced the fabrication methods of CNFs-based hydrogels, including CNFs cross-linked with metal ion and with polymers. In addition, we have summarized the biomedical applications of CNFs-based hydrogels, including scaffold materials and wound dressings. Results: CNFs-based hydrogels are new types of materials that are non-toxic and display a certain mechanical strength. In the tissue scaffold application, they can provide a micro-environment for the damaged tissue to repair and regenerate it. In wound dressing applications, it can fit the wound surface and protect the wound from the external environment, thereby effectively promoting the healing of skin tissue. Conclusion: By summarizing the preparation and application of CNFs-based hydrogels, we have analyzed and forecasted their development trends. At present, the research of CNFs-based hydrogels is still in the laboratory stage. It needs further exploration to be applied in practice. The development of medical hydrogels with high mechanical properties and biocompatibility still poses significant challenges.

scholarly journals Understanding ion-induced assembly of cellulose nanofibrilllar gels through shear-free mixing and in situ scanning-SAXS

2021 ◽  
Author(s):  
Tomas Rosén ◽  
Ruifu Wang ◽  
HongRui He ◽  
Chengbo Zhan ◽  
Shirish Chodankar ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Building Block ◽  
Cellulose Nanofibrils ◽  
Advanced Materials ◽  
The Past

During the past decade, cellulose nanofibrils (CNFs) have shown tremendous potential as a building block to fabricate new advanced materials that are both biocompatible and biodegradable. The excellent mechanical properties...

scholarly journals Effect of Sintering Temperature on Microstructure and Mechanical Properties of Hot-Pressed Fe/FeAl2O4 Composite

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 422
Author(s):  
Kuai Zhang ◽  
Yungang Li ◽  
Hongyan Yan ◽  
Chuang Wang ◽  
Hui Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Hot Press ◽  
Microstructure And Mechanical Properties ◽  
Powder Particles ◽  
Hot Press Sintering ◽  
Sintering Method

An Fe/FeAl2O4 composite was prepared with Fe-Fe2O3-Al2O3 powder by a hot press sintering method. The mass ratio was 6:1:2, sintering pressure was 30 MPa, and holding time was 120 min. The raw materials for the powder particles were respectively 1 µm (Fe), 0.5 µm (Fe2O3), and 1 µm (Al2O3) in diameter. The effect of sintering temperature on the microstructure and mechanical properties of Fe/FeAl2O4 composite was studied. The results showed that Fe/FeAl2O4 composite was formed by in situ reaction at 1300 °C–1500 °C. With the increased sintering temperature, the microstructure and mechanical properties of the Fe/FeAl2O4 composite showed a change law that initially became better and then became worse. The best microstructure and optimal mechanical properties were obtained at 1400 °C. At this temperature, the grain size of Fe and FeAl2O4 phases in Fe/FeAl2O4 composite was uniform, the relative density was 96.7%, and the Vickers hardness and bending strength were 1.88 GPa and 280.0 MPa, respectively. The wettability between Fe and FeAl2O4 was enhanced with increased sintering temperature. And then the densification process was accelerated. Finally, the microstructure and mechanical properties of the Fe/FeAl2O4 composite were improved.

scholarly journals Comparative Study of High-Performance Concrete Characteristics and Loading Test of Pretensioned Experimental Beams

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 427
Author(s):  
Pavlina Mateckova ◽  
Vlastimil Bilek ◽  
Oldrich Sucharda
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
High Performance Concrete ◽  
Raw Materials ◽  
Load Capacity ◽  
Materials Testing ◽  
Loading Test ◽  
Conventional Concrete ◽  
Concrete Mechanical Properties ◽  
Normal Strength

High-performance concrete (HPC) is subjected to wide attention in current research. Many research tasks are focused on laboratory testing of concrete mechanical properties with specific raw materials, where a mixture is prepared in a relatively small amount in ideal conditions. The wider utilization of HPC is connected, among other things, with its utilization in the construction industry. The paper presents two variants of HPC which were developed by modification of ordinary concrete used by a precast company for pretensioned bridge beams. The presented variants were produced in industrial conditions using common raw materials. Testing and comparison of basic mechanical properties are complemented with specialized tests of the resistance to chloride penetration. Tentative expenses for normal strength concrete (NSC) and HPC are compared. The research program was accomplished with a loading test of model experimental pretensioned beams with a length of 7 m made of ordinarily used concrete and one variant of HPC. The aim of the loading test was to determine the load–deformation diagrams and verify the design code load capacity calculation method. Overall, the article summarizes the possible benefits of using HPC compared to conventional concrete.

scholarly journals Ecofriendly Preparation and Characterization of a Cassava Starch/Polybutylene Adipate Terephthalate Film

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 329
Author(s):  
Tan Yi ◽  
Minghui Qi ◽  
Qi Mo ◽  
Lijie Huang ◽  
Hanyu Zhao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Contact Angle ◽  
Water Vapor ◽  
Composite Film ◽  
Water Absorption ◽  
Composite Films ◽  
Thermoplastic Starch ◽  
Light Transmittance ◽  
Infrared Spectrometry ◽  
Nano Zno

Composite films of polybutylene adipate terephthalate (PBAT) were prepared by adding thermoplastic starch (TPS) (TPS/PBAT) and nano-zinc oxide (nano-ZnO) (TPS/PBAT/nano-ZnO). The changes of surface morphology, thermal properties, crystal types and functional groups of starch during plasticization were analyzed by scanning electron microscopy, synchronous thermal analysis, X-ray diffraction, infrared spectrometry, mechanical property tests, and contact Angle and transmittance tests. The relationship between the addition of TPS and the tensile strength, transmittance, contact angle, water absorption, and water vapor barrier of the composite film, and the influence of nano-ZnO on the mechanical properties and contact angle of the 10% TPS/PBAT composite film. Experimental results show that, after plasticizing, the crystalline form of starch changed from A-type to V-type, the functional group changed and the lipophilicity increased; the increase of TPS content, the light transmittance and mechanical properties of the composite membrane decreased, while the water vapor transmittance and water absorption increased. The mechanical properties of the composite can be significantly improved by adding nano-ZnO at a lower concentration (optimum content is 1 wt%).

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