scholarly journals Preparation and characterization of lignin-containing nanofibrillated cellulose

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 4689-4698
Author(s):  
Tianqing Lan ◽  
Haoran Liu ◽  
Hui Li ◽  
Yuyue Qin ◽  
Guojun Yue
Keyword(s):  
Thermal Stability ◽  
Cellulose Nanofibrils ◽  
Nanofibrillated Cellulose ◽  
High Pressure Homogenization ◽  
Water Contact ◽  
X Ray ◽  
Thermal Gravimetric Analyzer ◽  
Uniform Dispersion ◽  
Pretreated Sugarcane Bagasse

Lignin-containing nanofibrillated cellulose (LNFC) were prepared from p-toluenesulfonic acid (p-TsOH) pretreated sugarcane bagasse (SCB) using either formic acid (FA) or hydrochloric acid (HCl) and high-pressure homogenization. The composition, morphology, dispersity, crystallinity, particle size, thermal stability, and hydrophobicity of LNFC treated with FA (F- LNFC) and HCl (H- LNFC) were compared via electron microscopy, an X-ray diffractometer (XRD), a thermal gravimetric analyzer (TGA), a Fourier transform infrared spectroscope (FTIR), and water contact angle (WCA) analysis. The results of morphology and dispersity testing showed that LNFC with uniform dispersion were successfully prepared using a homogeneous pressure of 30 MPa and the F- LNFC particles were more stable in an aqueous solution. The crystallinity of the LNFC was well maintained after homogenization. The TGA, FTIR, and WCA data indicated that F-LNFC had better thermal stability and were more hydrophobic than H-LNFC because FA could esterify cellulose. Improved dispersity and thermal stability and increased crystallinity and hydrophobicity of cellulose nanofibrils would enhance the performance of nanocomposite materials.

scholarly journals Improved Hydrophobicity of Macroalgae Biopolymer Film Incorporated with Kenaf Derived CNF Using Silane Coupling Agent

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2254
Author(s):  
Adeleke A. Oyekanmi ◽  
N. I. Saharudin ◽  
Che Mohamad Hazwan ◽  
Abdul Khalil H. P. S. ◽  
Niyi G. Olaiya ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Coupling Agent ◽  
Silane Coupling Agent ◽  
Cellulose Nanofibrils ◽  
Hydroxyl Groups ◽  
Water Contact ◽  
Silane Coupling ◽  
Cnf Films ◽  
Kenaf Bast ◽  
Thermal Stability Of

Hydrophilic behaviour of carrageenan macroalgae biopolymer, due to hydroxyl groups, has limited its applications, especially for packaging. In this study, macroalgae were reinforced with cellulose nanofibrils (CNFs) isolated from kenaf bast fibres. The macroalgae CNF film was after that treated with silane for hydrophobicity enhancement. The wettability and functional properties of unmodified macroalgae CNF films were compared with silane-modified macroalgae CNF films. Characterisation of the unmodified and modified biopolymers films was investigated. The atomic force microscope (AFM), SEM morphology, tensile properties, water contact angle, and thermal behaviour of the biofilms showed that the incorporation of Kenaf bast CNF remarkably increased the strength, moisture resistance, and thermal stability of the macroalgae biopolymer films. Moreover, the films’ modification using a silane coupling agent further enhanced the strength and thermal stability of the films apart from improved water-resistance of the biopolymer films compared to unmodified films. The morphology and AFM showed good interfacial interaction of the components of the biopolymer films. The modified biopolymer films exhibited significantly improved hydrophobic properties compared to the unmodified films due to the enhanced dispersion resulting from the silane treatment. The improved biopolymer films can potentially be utilised as packaging materials.

scholarly journals Acetylation improves thermal stability and transmittance in FOLED substrates based on nanocellulose films

RSC Advances ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 3619-3625 ◽  
Author(s):  
Shuang Yang ◽  
Qiuxia Xie ◽  
Xiuyu Liu ◽  
Min Wu ◽  
Shuangfei Wang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
High Pressure ◽  
Nanofibrillated Cellulose ◽  
High Pressure Homogenization ◽  
Mechanical Grinding ◽  
Homogenization Process ◽  
Softwood Pulp

Bleached softwood pulp was used to prepare nanofibrillated cellulose (NFC) by mechanical grinding and a high-pressure homogenization process.

scholarly journals AACVD Synthesis and Characterization of Iron and Copper Oxides Modified ZnO Structured Films

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 471 ◽  
Author(s):  
Martha Claros ◽  
Milena Setka ◽  
Yecid P. Jimenez ◽  
Stella Vallejos
Keyword(s):  
Contact Angle ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Contact Angles ◽  
Copper Oxides ◽  
Water Contact ◽  
X Ray ◽  
Hydrophobic Behavior

Non-modified (ZnO) and modified (Fe2O3@ZnO and CuO@ZnO) structured films are deposited via aerosol assisted chemical vapor deposition. The surface modification of ZnO with iron or copper oxides is achieved in a second aerosol assisted chemical vapor deposition step and the characterization of morphology, structure, and surface of these new structured films is discussed. X-ray photoelectron spectrometry and X-ray diffraction corroborate the formation of ZnO, Fe2O3, and CuO and the electron microscopy images show the morphological and crystalline characteristics of these structured films. Static water contact angle measurements for these structured films indicate hydrophobic behavior with the modified structures showing higher contact angles compared to the non-modified films. Overall, results show that the modification of ZnO with iron or copper oxides enhances the hydrophobic behavior of the surface, increasing the contact angle of the water drops at the non-modified ZnO structures from 122° to 135° and 145° for Fe2O3@ZnO and CuO@ZnO, respectively. This is attributed to the different surface properties of the films including the morphology and chemical composition.

Characterization of PET-Silver Nanocomposite Filaments

2018 ◽  
Vol 930 ◽  
pp. 224-229
Author(s):  
Marcos Antônio Guerra ◽  
Jeferson Prado Swerts ◽  
Mei Abe Funcia ◽  
Neide Aparecida Mariano ◽  
Maria Gabriela Nogueira Campos
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Scanning Electron Microscopy ◽  
Silver Nanoparticles ◽  
Addition Method ◽  
X Ray ◽  
Silver Nanocomposite ◽  
Thermal Stability Of ◽  
Scanning Electron

Polyethylene terephthalate (PET) fiber is a very versatile fiber that can be produced with different properties, such as antimicrobial activity. This study aims to synthesize antimicrobial PET filaments incorporated with silver nanoparticles immobilized in silica (NPAg-Si) by bulk additive method. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) characterized the obtained filaments at concentrations (w/w) of 0.008%, 0.016%, 0.032%, 0.047% and 0.063% NPAg-Si, in order to identify the nanoparticles and analyze their dispersion in the polymeric matrix. Moreover, thermogravimetric analysis (TGA) was carry out to confirm the presence and concentration of the silver nanoparticles in the filaments as well as the thermal stability of the nanocomposites. The bulk addition method was efficient to produce PET-Silver filaments with silver nanoparticles homogeneously dispersed in the PET matrix.

Synthesis and characterization of novel polysiloxane-grafted fluoropolymers

2005 ◽  
Vol 83 (6-7) ◽  
pp. 553-558 ◽  
Author(s):  
Bilal Baradie ◽  
Patricia HM Lai ◽  
Molly S Shoichet
Keyword(s):  
Carbon Dioxide ◽  
Thermal Stability ◽  
Supercritical Carbon Dioxide ◽  
Vinyl Acetate ◽  
Vinyl Alcohol ◽  
Contact Angles ◽  
Synthesis And Characterization ◽  
Water Contact ◽  
Degradation Temperature

Fluorosilicone polymers combine the properties of both fluorocarbons and siloxanes, yielding materials with unique properties. Novel crosslinked fluorosilicone polymers were synthesized by grafting diisocyanate-terminated polydimethylsiloxane (PDMS) to hydroxyl-functionalized fluoropolymers of poly(tetrafluoroethylene-co-vinyl acetate-co-vinyl alcohol) (PTFE-VAc-VA), as confirmed by elemental bulk and surface analysis. The fluorosilicone polymers containing 34 mol% of TFE were thermally stable with a degradation temperature of 267 °C. Fluorosilicone films were found to be more hydrophobic than the parent, non-grafted fluoropolymers; dynamic advancing and receding water contact angles for PTFE-co-VAc-co-VA-g-PDMS were 104° ± 1° and 61° ± 1°, respectively, whereas for PTFE-co-VAc they were 90° ± 2° and 59° ± 2°. The combined properties of thermal stability and hydrophobicity suggest that these fluorosilicones may be useful for coating and paint applications.Key words: fluoropolymers, fluorosilicone, polydimethylsiloxane, supercritical carbon dioxide.

The formation and characterization of three-dimensional gold nanocrystal superlattices

2007 ◽  
Vol 222 (11/2007) ◽  
Author(s):  
Michael G. Constantinides ◽  
Heinrich M. Jaeger ◽  
Xuefa Li ◽  
Jin Wang ◽  
Xiao-Min Lin
Keyword(s):  
Thermal Stability ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Gold Nanocrystals ◽  
X Ray ◽  
X Ray Scattering ◽  
Drop Drying ◽  
Nanocrystal Superlattices ◽  
Gold Nanocrystal

Highly-ordered, three-dimensional superlattices were self-assembled from dodecanethiol-ligated gold nanocrystals using a simple drop-drying technique. The superlattices had the shape of truncated pyramids (frustums) and reached lateral dimensions of several micrometers. The formation and thermal stability were studied by grazing-incidence small-angle x-ray scattering. We found that the superlattice frustums adopt a

scholarly journals Biochemical and Structural Characterization of the Subclass B1 Metallo-β-Lactamase VIM-4

2010 ◽  
Vol 55 (3) ◽  
pp. 1248-1255 ◽  
Author(s):  
Patricia Lassaux ◽  
Daouda A. K. Traoré ◽  
Elodie Loisel ◽  
Adrien Favier ◽  
Jean-Denis Docquier ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Escherichia Coli ◽  
Thermal Stability ◽  
Pseudomonas Aeruginosa ◽  
Structural Characterization ◽  
Catalytic Efficiency ◽  
X Ray ◽  
Stabilizing Effect ◽  
Loop 2

ABSTRACTThe metallo-β-lactamase VIM-4, mainly found inPseudomonas aeruginosaorAcinetobacter baumannii, was produced inEscherichia coliand characterized by biochemical and X-ray techniques. A detailed kinetic study performed in the presence of Zn2+at concentrations ranging from 0.4 to 100 μM showed that VIM-4 exhibits a kinetic profile similar to the profiles of VIM-2 and VIM-1. However, VIM-4 is more active than VIM-1 against benzylpenicillin, cephalothin, nitrocefin, and imipenem and is less active than VIM-2 against ampicillin and meropenem. The crystal structure of the dizinc form of VIM-4 was solved at 1.9 Å. The sole difference between VIM-4 and VIM-1 is found at residue 228, which is Ser in VIM-1 and Arg in VIM-4. This substitution has a major impact on the VIM-4 catalytic efficiency compared to that of VIM-1. In contrast, the differences between VIM-2 and VIM-4 seem to be due to a different position of the flapping loop and two substitutions in loop 2. Study of the thermal stability and the activity of the holo- and apo-VIM-4 enzymes revealed that Zn2+ions have a pronounced stabilizing effect on the enzyme and are necessary for preserving the structure.

scholarly journals Synthesis and Characterization of Biodegradable Polyester/Polyether WPU As The Environmental Protection Coating

2021 ◽  
Author(s):  
Guangfeng Wu ◽  
Xin Song ◽  
ZhiHui Yang ◽  
Ying Chun Li ◽  
HuiXuan Zhang
Keyword(s):  
Thermal Stability ◽  
Contact Angle ◽  
Water Contact Angle ◽  
Degradation Rate ◽  
Soft Segment ◽  
Buffer Solution ◽  
Water Contact ◽  
Elongation At Break ◽  
Protection Coating

Abstract Polyester diol PCL and PBA, polyether diol PTMG and polycarbonate diol PCDL were used as components of WPU soft segment, respectively. Polyether PTMG-WPU has the worst hydrolytic property and the highest thermal stability. The maximum degradation rate temperature Tmax is 407.8°C, the water contact angle reaches 89.5°. Traditional polyester PCL-WPU shows the strongest hydrolysis performance, the smallest water contact angle, only 71.7°, the water absorption rate of 72 hours at room temperature is as high as 26.7%. However, the thermal stability of PCL-WPU is lower, the soft segment Tg is -52.3°C, and Tmax is only 333.7°C, but the mechanical propertie of which is the best, the tensile strength is 58.3 MPa, and the elongation at break reaches 857.9%. The most important thing is that the structure of polyester PCL-WPU is more easily destroyed by lipase and water molecules. The acidic products produced after hydrolysis will further promote the degradation of polyester. Therefore, compared with other WPUs, PCL -WPU has the best biodegradability and the most obvious degradation effect under the same conditions. The degradation rate of PTMG-WPU after 30 days of degradation in 0.6% lipase PBS buffer solution and soil was only 4.2% and 2.3%, while the highest degradation rate of traditional polyester PCL-WPU reached 41.7% and 32.0%, respectively. In addition, polycarbonate PCDL-WPU has the highest hardness, reaching 95.5 HD. But its other performances are lower than PCl-WPU.

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