scholarly journals Contribution of Different Pretreatments to the Thermal Stability and UV Resistance Performance of Cellulose Nanofiber Films

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 247
Author(s):  
Lianxin Luo ◽  
Xuchong Wang ◽  
Sheng Zhang ◽  
Xiaojun Yuan ◽  
Mingfu Li ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Cellulose Nanofibers ◽  
Hot Water ◽  
Sodium Chlorite ◽  
Uv Resistance ◽  
Green Liquor ◽  
Ultraviolet Resistance ◽  
Cnf Films ◽  
Resistance Performance ◽  
Thermal Stability Of

Hot water (HW), green liquor (GL), and sodium chlorite (SC) pretreatments were used to pretreat sugarcane bagasse (SCB) and spruce (SP) and then to prepare cellulose nanofibers (CNFs) through high-pressure homogenization to explore the effect of physicochemical properties on the thermal stability and ultraviolet (UV) resistance performance of CNF films. The results indicated that the lignin content of HW-pretreated CNFs was higher than that of GL- and SC-pretreated CNFs, and the hemicellulose content of HW-pretreated CNFs was lower than that of GL- and SC-pretreated CNFs. The synergy of lignin and hemicellulose impacted the thermal stability of CNF films. The thermal stability of all the SP CNF films was higher than that of all the SCB CNF films. Hot water pretreatment improved the thermal stability of CNF films, and green liquor and sodium chlorite pretreatment decreased the thermal stability of CNF films. The highest thermal stability of SP-HW CNF films reached 392 °C, which was 5.4% higher than that of SP-SC CNF films. Furthermore, the ultraviolet resistance properties of different CNF films were as follows: SCB-HW > SCB-GL > SCB-SC and SP-HW > SP-GL > SP-SC. Green liquor pretreatment is an effective method to prepare CNFs. Conclusively, this research provides a basic theory for the preparation of CNFs and allows the improvement of CNF films in the application of thermal stability management and UV resistance fields.

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.

Effect of Acid/Fiber Ratio on Physical Properties of Cellulose Nanofibers Extracted from Cassava Pulp

2017 ◽  
Vol 890 ◽  
pp. 103-107
Author(s):  
Thanh Chi Nguyen ◽  
Ruksakulpiwat Chaiwat ◽  
Yupaporn Ruksakulpiwat
Keyword(s):  
Thermal Stability ◽  
Physical Properties ◽  
Acid Hydrolysis ◽  
Cellulose Nanofibers ◽  
X Ray Diffraction ◽  
Cassava Pulp ◽  
Transmission Electron ◽  
Naoh Solution ◽  
Bleaching Treatment ◽  
Thermal Stability Of

Cellulose nanofibers (CeNF) were extracted successfully from cassava pulp (CP) by submitting to alkali, bleaching and acid hydrolysis treatments. The raw CP was mercerized with NaOH solution and then followed by bleaching treatment using a solution made up of equal parts (v:v) of acetate buffer and aqueous chlorite. In order to obtain cellulose nanofibers, the acid hydrolysis treatment of bleached fibers was performed using a mixture of HCl/H2SO4 (1:2 v/v). In this acid treatment reaction, the effects of acid/fiber ratio (ml/g) on physical properties of obtained cellulose nanofibers were investigated. Nanofibers were morphologically characterized by transmission electron microscopy (TEM) revealing the nanofibers with diameter in the range of 12-24 nm and immeasurable length were obtained. An increase in crystallinity of fibers after treatments was revealed by X-ray diffraction (XRD). Due to the introduction of sulfate groups at the outer surfaces of fibers during the hydrolysis, thermal stability of nanofibers, characterized by thermogravimetric analysis (TGA), was lower than that of raw CP. The acid/fiber ratio of 150ml/2g was found to be a proper ratio for thermal stability of obtained nanofibers. The crystallinity of nanofibers increased with the increase of acid/fiber ratio.

scholarly journals New liquid-free proton conductive nanocomposite based on imidazole-functionalized cellulose nanofibers

Cellulose ◽  
2020 ◽  
Author(s):  
Iga Aleksandra Jankowska ◽  
Katarzyna Pogorzelec-Glaser ◽  
Paweł Ławniczak ◽  
Michał Matczak ◽  
Radosław Pankiewicz
Keyword(s):  
Thermal Stability ◽  
Proton Transport ◽  
Cellulose Nanofibers ◽  
Solid Polymer ◽  
Water Evaporation ◽  
Scanning Calorimetry ◽  
Pure Cellulose ◽  
Maximum Conductivity ◽  
Cellulose Materials ◽  
Thermal Stability Of

AbstractThe first successful attempt to synthesize a new proton conducting polymeric nanocomposite film based on pure cellulose nanofibers (CNF) as a polymer matrix functionalized on their surface with imidazole molecules (Im) as a dopant, was made. The 2CNF-Im nanomaterial contains on average one molecule of imidazole per 2 glucose units from cellulose chains. Water evaporation and thermal stability of 2CNF-Im were studied by thermogravimetric analysis (TGA and DTG) and differential scanning calorimetry (DSC). The temperature dependence of electrical conductivity was studied by the impedance spectroscopy. At 140 °C, the 2CNF-Im nanocomposite has a maximum conductivity of 7.0 × 10−3 S/m, i.e. four orders of magnitude higher than that of non-functionalized CNF matrix. The newly synthesized cellulose nanocomposite exhibits high electrical and thermal stability. In 2CNF-Im, the activation energy of the proton transport process is the lowest compared to the previously synthesized imidazole-functionalized composites based on other pure cellulose materials and equals 0.62 eV. The synthesized nanomaterial is liquid-free solid polymer electrolyte showing proton conductivity above the boiling point of water.

scholarly journals The Effect of Chemical and High-Pressure Homogenization Treatment Conditions on the Morphology of Cellulose Nanoparticles

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Suxia Ren ◽  
Xiuxuan Sun ◽  
Tingzhou Lei ◽  
Qinglin Wu
Keyword(s):  
Thermal Stability ◽  
High Pressure ◽  
Acid Hydrolysis ◽  
Cellulose Nanocrystals ◽  
Cellulose Nanofibers ◽  
High Pressure Homogenization ◽  
Homogenization Treatment ◽  
Cellulose Nanoparticles ◽  
Nanofiber Bundles ◽  
Thermal Stability Of

Cellulose nanoparticles were fabricated from microcrystalline cellulose (MCC) through combined acid hydrolysis with sulfuric and hydrochloric acids and high-pressure homogenization. The effect of acid type, acid-to-MCC ratio, reaction time, and numbers of high-pressure homogenization passes on morphology and thermal stability of the nanoparticles was studied. An aggressive acid hydrolysis was shown to lead to rod-like cellulose nanocrystals with diameter about 10 nm and lengths in the range of 50–200 nm. Increased acid-to-MCC ratio and number of homogenization treatments reduced the dimension of the nanocrystals produced. Weak acid hydrolysis treatment led to a network of cellulose nanofiber bundles having diameters in the range of 20–100 nm and lengths of a few thousands of nanometers. The high-pressure homogenization treatment helped separate the nanofiber bundles. The thermal degradation behaviors characterized by thermogravimetric analysis at nitrogen atmosphere indicated that the degradation of cellulose nanocrystals from sulfuric acid hydrolysis started at a lower temperature and had two remarkable pyrolysis processes. The thermal stability of cellulose nanofibers produced from hydrochloric acid hydrolysis improved significantly.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

Microstructure studies of tungsten silicide schottky contacts on Gaas

1987 ◽  
Vol 45 ◽  
pp. 328-329
Author(s):  
Yih-Cheng Shih ◽  
E. L. Wilkie
Keyword(s):  
Thermal Stability ◽  
Field Effect Transistors ◽  
Schottky Contact ◽  
Schottky Contacts ◽  
Excellent Thermal Stability ◽  
Barrier Heights ◽  
Gaas Substrates ◽  
Film Adhesion ◽  
Threshold Voltages ◽  
Thermal Stability Of

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.

Thermal stability of Al-Cu-Fe icosahedral alloys

1991 ◽  
Vol 1 (12) ◽  
pp. 1823-1836 ◽  
Author(s):  
M. Bessière ◽  
A. Quivy ◽  
S. Lefebvre ◽  
J. Devaud-Rzepski ◽  
Y. Calvayrac
Keyword(s):  
Thermal Stability ◽  
Thermal Stability Of

Practical criteria for the thermal stability of a unidimensional superconductor

1994 ◽  
Vol 4 (4) ◽  
pp. 653-657
Author(s):  
B. Bonzi ◽  
M. El Khomssi ◽  
H. Lanchon-Ducauquis
Keyword(s):  
Thermal Stability ◽  
Thermal Stability Of
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