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.

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.

Thermal properties enhancement of poly(lactic acid) by corn cob cellulose nanocrystals

2019 ◽  
Vol 10 (4) ◽  
pp. 63-76
Author(s):  
Wei Keat Ng ◽  
Wen Shyang Chow ◽  
Hanafi Ismail
Keyword(s):  
Thermal Stability ◽  
Lactic Acid ◽  
Thermal Properties ◽  
Zeta Potential ◽  
Acid Hydrolysis ◽  
Cellulose Nanocrystals ◽  
Agricultural Waste ◽  
Poly Lactic Acid ◽  
Corn Cob ◽  
Thermal Stability Of

Cellulose nanocrystals were extracted from agricultural waste corn cob using acid hydrolysis followed by freeze drying. Poly(lactic acid)/corn cob cellulose nanocrystals (PLA/CCNC) composites were prepared using solvent casting. The properties of CCNC were characterized using transmission electron microscope (TEM), zeta potential analyzer, and thermogravimetric analyzer (TGA). The effects of CCNC on the thermal properties of PLA were examined using differential scanning calorimetry (DSC) and TGA. From the SEM and TEM results, the irregular shaped and micron-sized corn cob powder was transformed to needle-like shaped nanocellulose (aspect ratio approximately 30.80) after the acid hydrolysis process. TGA results show that the thermal stability of CCNC is higher than that of corn cob powder. The zeta potential of CCNC is −24.6 mV, which indicates there is a repulsion force between the individual CCNC and making them disperse uniformly and stable in aqueous media. DSC and TGA results show that the crystallinity and thermal stability of PLA were increased by the incorporation of CCNC. This demonstrates that the CCNC is a potential bio-nanofiller with good thermal stability and nucleating-ability for PLA.

Evaluation of mulberry branch waste as raw material for nanocellulose synthesis: effects of the synthesis method on product properties

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hui Zhao ◽  
Wenjuan Tao ◽  
Haoming Gu ◽  
Lifang Guo ◽  
Mai Han ◽  
...  
Keyword(s):  
Thermal Stability ◽  
High Pressure ◽  
Sulfuric Acid ◽  
Acid Hydrolysis ◽  
Synthesis Method ◽  
Raw Material ◽  
Diffraction Field ◽  
High Pressure Homogenization ◽  
Tempo Oxidation ◽  
Retention System

Abstract The mechanical pulp of mulberry branches was evaluated as a raw material for the production of cellulose II and its subsequent conversion to nanocellulose via high-pressure homogenization, 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidation, and sulfuric acid hydrolysis. The morphology, chemical structure, crystallinity, and thermal stability of the nanocellulose samples prepared by each method were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, atomic force microscopy, and thermogravimetric analysis. The results showed that nanocellulose prepared by high-pressure homogenization exhibited higher aspect ratio (>100), and the weight loss peak in the DTG chart was 361 °C, with the best thermal stability, whereas that prepared by sulfuric acid hydrolysis featured shorter fiber length (96±31 nm) and a higher crystallinity (78.2 %).The TEMPO oxidized nanocellulose (TOCN) had smaller width (5.5±1.6 nm) and high carboxyl content (1.5 mmol/g). In addition, we have further studied the application of TOCN in the wet end of papermaking, replacing the colloidal SiO2 in CPAM/ colloidal SiO2/APAM retention system with the same amount (3600 ppm) of TOCN. The study found that the strength of the paper obtained by adding TOCN instead of the traditional wet end additives is similar, and the water drainage and retention properties of the pulp are improved.

scholarly journals Thermal stability of a nanocrystalline HfNbTiZr multi-principal element alloy processed by high-pressure torsion

2020 ◽  
Vol 168 ◽  
pp. 110550 ◽  
Author(s):  
Pham Tran Hung ◽  
Megumi Kawasaki ◽  
Jae-Kyung Han ◽  
János L. Lábár ◽  
Jenő Gubicza
Keyword(s):  
Thermal Stability ◽  
High Pressure ◽  
High Pressure Torsion ◽  
Principal Element ◽  
Thermal Stability Of

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.

Microstructure, mechanical properties, and thermal stability of γ-Nb5Si3 under high temperature and high pressure

2021 ◽  
Vol 130 (13) ◽  
pp. 135104
Author(s):  
Juwei Wang ◽  
Haihua Chen ◽  
Zhengang Zhang ◽  
Bin Wang ◽  
Hongtao Ma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
High Pressure ◽  
High Temperature ◽  
Thermal Stability Of

Thermal Stability of Ultrafine-Grained Pure Titanium Processed by High-Pressure Torsion

2021 ◽  
Vol 1016 ◽  
pp. 338-344
Author(s):  
Wan Ji Chen ◽  
Jie Xu ◽  
De Tong Liu ◽  
De Bin Shan ◽  
Bin Guo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Grain Size ◽  
High Pressure ◽  
Annealing Temperature ◽  
High Pressure Torsion ◽  
Stored Energy ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
Thermal Stability Of

High-pressure torsion (HPT) was conducted under 6.0 GPa on commercial purity titanium up to 10 turns. An ultrafine-grained (UFG) pure Ti with an average grain size of ~96 nm was obtained. The thermal properties of these samples were studied by using differential scanning calorimeter (DSC) which allowed the quantitative determination of the evolution of stored energy, the recrystallization temperatures, the activation energy involved in the recrystallization of the material and the evolution of the recrystallized fraction with temperature. The results show that the stored energy increases, beyond which the stored energy seems to level off to a saturated value with increase of HPT up to 5 turns. An average activation energy of about 101 kJ/mol for the recrystallization of 5 turns samples was determined. Also, the thermal stability of the grains of the 5 turns samples with subsequent heat treatments were investigated by microstructural analysis and Vickers microhardness measurements. It is shown that the average grain size remains below 246 nm when the annealing temperature is below 500 °C, and the size of the grains increases significantly for samples at the annealing temperature of 600 °C.

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