scholarly journals Preparation and Characterization of Nanocellulose/Chitosan Aerogel Scaffolds Using Chemical-Free Approach

Gels ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 246
Author(s):  
Samsul Rizal ◽  
Esam Bashir Yahya ◽  
Abdul Khalil H.P.S. ◽  
C. K. Abdullah ◽  
Marwan Marwan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Water Uptake ◽  
High Surface ◽  
Cellulose Nanofibers ◽  
High Surface Area ◽  
Three Dimensional ◽  
High Water ◽  
Absorption Capacity ◽  
Mechanical And Thermal Properties ◽  
High Porosity

Biopolymer-based aerogels are open three-dimensional porous materials that are characterized by outstanding properties, such as a low density, high porosity and high surface area, in addition to their biocompatibility and non-cytotoxicity. Here we fabricated pure and binary blended aerogels from cellulose nanofibers (CNFs) and chitosan (CS), using a chemical-free approach that consists of high-pressure homogenization and freeze-drying. The prepared aerogels showed a different porosity and density, depending on the material and mixing ratio. The porosity and density of the aerogels ranged from 99.1 to 90.8% and from 0.0081 to 0.141 g/cm3, respectively. Pure CNFs aerogel had the highest porosity and lightest density, but it showed poor mechanical properties and a high water absorption capacity. Mixing CS with CNFs significantly enhance the mechanical properties and reduce its water uptake. The two investigated ratios of aerogel blends had superior mechanical and thermal properties over the single-material aerogels, in addition to reduced water uptake and 2-log antibacterial activity. This green fabrication and chemical-free approach could have great potential in the preparation of biopolymeric scaffolds for different biomedical applications, such as tissue-engineering scaffolds.

scholarly journals Porous Aerogels and Adsorption of Pollutants from Water and Air: A Review

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4440
Author(s):  
Paola Franco ◽  
Stefano Cardea ◽  
Antonio Tabernero ◽  
Iolanda De Marco
Keyword(s):  
Organic Dyes ◽  
High Surface ◽  
High Surface Area ◽  
Three Dimensional ◽  
Low Density ◽  
High Porosity ◽  
Future Developments ◽  
Oxygenated Volatile Organic Compounds ◽  
Volatile Organic ◽  
Harmful Substances

Aerogels are open, three-dimensional, porous materials characterized by outstanding properties, such as low density, high porosity, and high surface area. They have been used in various fields as adsorbents, catalysts, materials for thermal insulation, or matrices for drug delivery. Aerogels have been successfully used for environmental applications to eliminate toxic and harmful substances—such as metal ions or organic dyes—contained in wastewater, and pollutants—including aromatic or oxygenated volatile organic compounds (VOCs)—contained in the air. This updated review on the use of different aerogels—for instance, graphene oxide-, cellulose-, chitosan-, and silica-based aerogels—provides information on their various applications in removing pollutants, the results obtained, and potential future developments.

Size Effect of CaCO3 Filler on the Mechanical Properties of SMC Composites

2015 ◽  
Vol 365 ◽  
pp. 244-248 ◽  
Author(s):  
Y.J. Lee ◽  
Y. Kim ◽  
Soo Ryong Kim ◽  
Dong Geun Shin ◽  
Sea Cheon Oh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Calcium Carbonate ◽  
Size Effect ◽  
High Surface ◽  
High Surface Area ◽  
Mechanical And Thermal Properties ◽  
Calcium Carbonates ◽  
Surface Areas ◽  
High Thermal Resistance ◽  
Mineral Fillers

SMC composites consist of chopped glass fiber as a reinforcements, polyester and mineral fillers. Among them, filler is one of the important factors for improving mechanical and thermal properties of composites, but it has not drawn much attention for SMC composites. In this study, the size effect of calcium carbonate as mineral filler on mechanical properties of SMC composites was discussed using five different sizes of commercial calcium carbonates without chopped fiber reinforcement, to focus on the size effect itself. The SMC process was modified to be suitable for a laboratory scale composed of three steps. The mean sizes of the calcium carbonates were 3 – 20 μm, and the specific surface areas were calculated to be 1 – 5 m2/g by BET. Small size of calcium carbonate having high surface area up to 4 m2/g showed high thermal resistance, and showed higher strength comparing to the large fillers because it affected to form a dense packed microstructure.

scholarly journals Mechanical Properties of Hybrid Graphene Nanoplatelet-Nanosilica Filled Unidirectional Basalt Fibre Composites

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1468
Author(s):  
Ummu Raihanah Hashim ◽  
Aidah Jumahat ◽  
Mohammad Jawaid
Keyword(s):  
Mechanical Properties ◽  
Polymer Composites ◽  
Glass Fibre ◽  
Graphene Nanosheets ◽  
High Surface ◽  
High Surface Area ◽  
High Strength ◽  
Basalt Fibre ◽  
Graphene Nanoplatelet ◽  
Dispersion State

Basalt fibre (BF) is one of the most promising reinforcing natural materials for polymer composites that could replace the usage of glass fibre due to its comparable properties. The aim of adding nanofiller in polymer composites is to enhance the mechanical properties of the composites. In theory, the incorporation of high strength and stiffness nanofiller, namely graphene nanoplatelet (GNP), could create superior composite properties. However, the main challenges of incorporating this nanofiller are its poor dispersion state and aggregation in epoxy due to its high surface area and strong Van der Waals forces in between graphene sheets. In this study, we used one of the effective methods of functionalization to improve graphene’s dispersion and also introducing nanosilica filler to enhance platelets shear mechanism. The high dispersive silica nanospheres were introduced in the tactoids morphology of stacked graphene nanosheets in order to produce high shear forces during milling and exfoliate the GNP. The hybrid nanofiller modified epoxy polymers were impregnated into BF to evaluate the mechanical properties of the basalt fibre reinforced polymeric (BFRP) system under tensile, compression, flexural, and drop-weight impact tests. In response to the synergistic effect of zero-dimensional nanosilica and two-dimensional graphene nanoplatelets enhanced the mechanical properties of BFRP, especially in Basalt fibre + 0.2 wt% GNP/15 wt% NS (BF-H0.2) with the highest increment in modulus and strength to compare with unmodified BF. These findings also revealed that the incorporation of hybrid nanofiller contributed to the improvement in the mechanical properties of the composite. BF has huge potential as an alternative to the synthetic glass fibre for the fabrication of mechanical components and structures.

scholarly journals Exceptional Mechanical Properties and Heat Resistance of Photocurable Bismaleimide Ink for 3D Printing

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1708
Author(s):  
Wenqiang Hua ◽  
Qilang Lin ◽  
Bo Qu ◽  
Yanyu Zheng ◽  
Xiaoying Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Heat Resistance ◽  
Three Dimensional ◽  
Mechanical And Thermal Properties ◽  
Amino Group ◽  
Building Models ◽  
Fast Processing ◽  
Forming Precision ◽  
Complex Structural

Photosensitive resins used in three-dimensional (3D) printing are characterized by high forming precision and fast processing speed; however, they often possess poor mechanical properties and heat resistance. In this study, we report a photocurable bismaleimide ink with excellent comprehensive performance for stereolithography (SLA) 3D printing. First, the main chain of bismaleimide with an amino group (BDM) was synthesized, and then, the glycidyl methacrylate was grafted to the amino group to obtain the bismaleimide oligomer with an unsaturated double bond. The oligomers were combined with reaction diluents and photo-initiators to form photocurable inks that can be used for SLA 3D printing. The viscosity and curing behavior of the inks were studied, and the mechanical properties and heat resistance were tested. The tensile strength of 3D-printed samples based on BDM inks could reach 72.6 MPa (166% of that of commercial inks), glass transition temperature could reach 155 °C (205% of that of commercial inks), and energy storage modulus was 3625 MPa at 35 °C (327% of that of commercial inks). The maximum values of T-5%, T-50%, and Tmax of the 3D samples printed by BDM inks reached 351.5, 449.6, and 451.9 °C, respectively. These photocured BDM inks can be used to produce complex structural components and models with excellent mechanical and thermal properties, such as car parts, building models, and pipes.

scholarly journals Glucose/Graphene-Based Aerogels for Gas Adsorption and Electric Double Layer Capacitors

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 40 ◽  
Author(s):  
Kang-Kai Liu ◽  
Biao Jin ◽  
Long-Yue Meng
Keyword(s):  
Gas Adsorption ◽  
High Surface ◽  
Aqueous Media ◽  
High Surface Area ◽  
Three Dimensional ◽  
High Specific Capacitance ◽  
Mesopore Size Distribution ◽  
Excellent Electrochemical Performance ◽  
Double Layer Capacitors ◽  
Hydrothermal Reduction

In this study, three-dimensional glucose/graphene-based aerogels (G/GAs) were synthesized using the hydrothermal reduction and CO2 activation method. Graphene oxide (GO) was used as a matrix, and glucose was used as a binder for the orientation of the GO morphology in an aqueous media. We determined that G/GAs exhibited narrow mesopore size distribution, a high surface area (763 m2 g−1), and hierarchical macroporous and mesoporous structures. These features contributed to G/GAs being promising adsorbents for the removal of CO2 (76.5 mg g−1 at 298 K), CH4 (16.8 mg g−1 at 298 K), and H2 (12.1 mg g−1 at 77 K). G/GAs presented excellent electrochemical performance, featuring a high specific capacitance of 305.5 F g−1 at 1 A g−1, and good cyclic stability of 98.5% retention after 10,000 consecutive charge-discharge cycles at 10 A g−1. This study provided an efficient approach for preparing graphene aerogels exhibiting hierarchical porosity for gas adsorption and supercapacitors.

scholarly journals Complex Aerogels Generated from Nano-Polysaccharides and Its Derivatives for Oil–Water Separation

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1593 ◽  
Author(s):  
Hajo Yagoub ◽  
Liping Zhu ◽  
Mahmoud H. M. A. Shibraen ◽  
Ali A. Altam ◽  
Dafaalla M. D. Babiker ◽  
...  
Keyword(s):  
Guar Gum ◽  
Corn Oil ◽  
Cellulose Nanofibers ◽  
Aqueous Media ◽  
Three Dimensional ◽  
Absorption Capacity ◽  
Water Contact ◽  
Water Separation ◽  
Oil Water Separation ◽  
Oil Water

The complex aerogel generated from nano-polysaccharides, chitin nanocrystals (ChiNC) and TEMPO-oxidized cellulose nanofibers (TCNF), and its derivative cationic guar gum (CGG) is successfully prepared via a facile freeze-drying method with glutaraldehyde (GA) as cross-linkers. The complexation of ChiNC, TCNF, and CGG is shown to be helpful in creating a porous structure in the three-dimensional aerogel, which creates within the aerogel with large pore volume and excellent compressive properties. The ChiNC/TCNF/CGG aerogel is then modified with methyltrichlorosilane (MTCS) to obtain superhydrophobicity/superoleophilicity and used for oil–water separation. The successful modification is demonstrated through FTIR, XPS, and surface wettability studies. A water contact angle of 155° on the aerogel surface and 150° on the surface of the inside part of aerogel are obtained for the MTCS-modified ChiNC/TCNF/CGG aerogel, resulting in its effective absorption of corn oil and organic solvents (toluene, n-hexane, and trichloromethane) from both beneath and at the surface of water with excellent absorption capacity (i.e., 21.9 g/g for trichloromethane). More importantly, the modified aerogel can be used to continuously separate oil from water with the assistance of a vacuum setup and maintains a high absorption capacity after being used for 10 cycles. The as-prepared superhydrophobic/superoleophilic ChiNC/TCNF/CGG aerogel can be used as a promising absorbent material for the removal of oil from aqueous media.

Hierarchical Nano/Micro-structured Surfaces with High Surface Area/Volume Ratios

2021 ◽  
pp. 1-36
Author(s):  
Ketki Lichade ◽  
Yizhou Jiang ◽  
Yayue Pan
Keyword(s):  
Surface Structure ◽  
Surface Area ◽  
Light Trapping ◽  
High Surface ◽  
High Surface Area ◽  
Three Dimensional ◽  
Structure Design ◽  
Surface Structures ◽  
Structured Surfaces ◽  
Design And Manufacture

Abstract Recently, many studies have investigated additive manufacturing of hierarchical surfaces with high surface area/volume (SA/V) ratios, and their performance has been characterized for applications in next-generation functional devices. Despite recent advances, it remains challenging to design and manufacture high SA/V ratio structures with desired functionalities. In this study, we established the complex correlations among the SA/V ratio, surface structure geometry, functionality, and manufacturability in the Two-Photon Polymerization (TPP) process. Inspired by numerous natural structures, we proposed a 3-level hierarchical structure design along with the mathematical modeling of the SA/V ratio. Geometric and manufacturing constraints were modeled to create well-defined three-dimensional hierarchically structured surfaces with a high accuracy. A process flowchart was developed to design the proposed surface structures to achieve the target functionality, SA/V ratio, and geometric accuracy. Surfaces with varied SA/V ratios and hierarchy levels were designed and printed. The wettability and antireflection properties of the fabricated surfaces were characterized. It was observed that the wetting and antireflection properties of the 3-level design could be easily tailored by adjusting the design parameter settings and hierarchy levels. Furthermore, the proposed surface structure could change a naturally-hydrophilic surface to near-superhydrophobic. Geometrical light trapping effects were enabled and the antireflection property could be significantly enhanced (>80% less reflection) by the proposed hierarchical surface structures. Experimental results implied the great potential of the proposed surface structures for various applications such as microfluidics, optics, energy, and interfaces.

Highly stable metal-organic framework UiO-66-NH2 for high-performance triboelectric nanogenerators

2021 ◽  
Author(s):  
Yong-Mei Wang ◽  
Xinxin Zhang ◽  
Dingyi Yang ◽  
Liting Wu ◽  
Jiaojiao Zhang ◽  
...  
Keyword(s):  
High Performance ◽  
Metal Organic Framework ◽  
High Surface ◽  
High Surface Area ◽  
Triboelectric Nanogenerator ◽  
High Porosity ◽  
Chemically Modified ◽  
Metal Organic ◽  
Triboelectric Nanogenerators ◽  
Organic Framework

Abstract The high porosity, controllable size, high surface area, and chemical versatility of a metal-organic framework (MOF) enable it a good material for a triboelectric nanogenerator (TENG), and some MOFs have been incorporated in the fabrication of TENGs. However, the understanding of effects of MOFs on the energy conversion of a TENG is still lacking, which inhibits the improvement of the performance of MOF-based TENGs. Here, UiO-66-NH2 MOFs were found to significantly increase the power of a TENG and the mechanism was carefully examined. The electron-withdrawing ability of Zr-based UiO-66-family MOFs was enhanced by designing the amino functionalized 1,4-terephthalic acid (1,4-BDC) as ligand. The chemically modified UiO-66-NH2 was found to increase the surface roughness and surface potential of a composite film with MOFs embedded in polydimethylsiloxane (PDMS) matrix. Thus the total charges due to the contact electrification increased significantly. The composite-based TENG was found to be very durable and its output voltage and current were 4 times and 60 times higher than that of a PDMS-based TENG. This work revealed an effective strategy to design MOFs with excellent electron-withdrawing abilities for high-performance TENGs.

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