scholarly journals EFFECTS OF THE ADDITION OF THE THIRD COMPONENTS ON ACTIVATION ENERGY FOR FLOW AND APPARENT VISCOSITY OF CONCENTRATED CELLULOSE ACETATE SOLUTION

1966 ◽  
Vol 22 (7) ◽  
pp. 320-325
Author(s):  
Shuichi Uchiyama
Keyword(s):  
Activation Energy ◽  
Cellulose Acetate ◽  
Apparent Viscosity ◽  
Acetate Solution ◽  
The Third

Rheological Study on of PBT with High Melt Flow Index

2012 ◽  
Vol 487 ◽  
pp. 644-648
Author(s):  
Yuan Liu ◽  
Lin Wang ◽  
Qing Yan Xu ◽  
Pei Jie Lin ◽  
Zhi Hong Guo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Shear Rate ◽  
Apparent Viscosity ◽  
Melt Flow Index ◽  
Flow Index ◽  
Melt Flow ◽  
Flow Activation Energy ◽  
Nonwoven Fabrics ◽  
Flow Activation ◽  
High Flexibility

Melt-blown generated PBT nonwoven fabrics usually have small fibril diameter, high flexibility, well heat and oil resistance. Therefore, they would have promising application such as vehicle filtering media. The rheological behavior of PBT with High Melt Flow Index for Melt-blown is investigated in this paper. It is a direction of the technology design and fabrication parameters .The relation of apparent viscosity and shear rate is analyzed, as well as flow activation energy and Non-Newtonian indexes. The results suggest that PBT with High Melt Flow Index is Non-Newtonian fluid. Apparent viscosity and flow activation energy show gradually decrease with increasing shear rate, exhibiting typical shear-thinning behavior.

scholarly journals THE LOCATION OF THE XANTHATE GROUPS IN PARTLY SUBSTITUTED CELLULOSE XANTHATES

1957 ◽  
Vol 35 (12) ◽  
pp. 1522-1533 ◽  
Author(s):  
E. P. Swan ◽  
C. B. Purves
Keyword(s):  
Cellulose Acetate ◽  
Chlorine Dioxide ◽  
Methyl Esters ◽  
Lead Tetraacetate ◽  
Degree Of Substitution ◽  
Hydroxyl Groups ◽  
Primary Position ◽  
Standard Methods ◽  
The Third ◽  
Almost All

Cellulose sodium xanthates of degree of substitution (D.S.) 0.4 to 0.66 were methylated to xanthate S-methyl esters which were then acetylated completely, the final xanthate D.S. remaining close to the original value. Dexanthation with aqueous chlorine dioxide near pH 4.5 and −5° removed almost all of the S-methyl xanthate groups, but the loss of a few acetyl groups from, and the retention of 1 to 2% of sulphur in, the resulting cellulose acetate could not be avoided. The original xanthate groups were presumably represented in this acetate as unsubstituted hydroxyl groups, and these were located by standard methods involving tosylation–iodination, tritylation, and oxidations with lead tetraacetate. Xanthate groups appeared to occupy the third and sixth, but not the second, position in the cellulose, and 53 to 61% of the substituent was in the sixth or primary position; one sample of viscose was "ripened" before the cellulose sodium xanthate was isolated, and the value was 81%. The results were of a preliminary nature, because severe technical difficulties reduced their reliability.

Simply Electrospun Gelatin/Cellulose Acetate Nanofibers and their Physico-Chemical Characteristics

2016 ◽  
Vol 880 ◽  
pp. 95-98 ◽  
Author(s):  
Fuji Hernawati Kusumah ◽  
Ida Sriyanti ◽  
Dhewa Edikresnha ◽  
Muhammad Miftahul Munir ◽  
Khairurrijal
Keyword(s):  
Cellulose Acetate ◽  
Structural Changes ◽  
Drug Carrier ◽  
Precursor Solution ◽  
Average Diameter ◽  
Acetate Solution ◽  
Mass Reduction ◽  
Sem Images ◽  
Physico Chemical ◽  
Electrospun Gelatin

Gelatin in fibers form can be used for tissue engineering, wound dressing, or drug carrier. However, it is easily damaged if exposed to water. Thus, it was blended with cellulose acetate. Acetic acid was used as a solvent because it is less toxic. The mass ratios of gelatin to cellulose acetate of 10:0, 8:2, and 6:4 were as precursor solutions. Simple electrospinning was employed to produce gelatin/cellulose acetate fibers. From SEM images, it was shown that the average diameters of gelatin/cellulose acetate fibers from the precursor solutions of 10:0, 8:2, and 6:4 were 534, 649, and 765 nm, respectively. The addition of cellulose acetate increased the viscosity of gelatin/cellulose acetate solution. Moreover, gelatin mass reduction caused a decrease in conductivity of gelatin/cellulose acetate solution. Therefore, increasing in the viscosity or reducing in the conductivity of the precursor solution increased the average diameter of the gelatin/cellulose acetate fibers. The analysis of FTIR spectra showed that the structural changes of gelatin and cellulose acetate occurred after being transformed into gelatin/cellulose acetate nanofibers.

Investigation on the Rheological Behavior of PA1010/POE/OMMT Nanocomposites

2012 ◽  
Vol 482-484 ◽  
pp. 2582-2586
Author(s):  
Yan Fei Zhang ◽  
Ying Chun Li ◽  
Guo Sheng Hu
Keyword(s):  
Activation Energy ◽  
Rheological Behavior ◽  
Apparent Viscosity ◽  
Experimental Results ◽  
Shearing Stress ◽  
Pseudoplastic Fluid ◽  
High Shearing

The rheological behavior of PA1010/POE/OMMT nanocomposites was studied by using XLY-Ⅱ rheometer. The curves of lgτω～lgγ’ω, lgηa～lgγ’ω, lgηa～1/T were obtained. The experimental results showed that PA1010/POE/OMMT nanocomposites were pseudoplastic fluid. The apparent viscosity of the blends reduced with the increase of the shearing stress．Compared with PA1010/POE blends, the addition of OMMT increased the apparent viscosity. The viscous activation energy of PA1010/POE/OMMT blends declined as the increase of shearing stress, which indicated that the PA1010/POE/OMMT blends could be processed over a wide temperature at a high shearing stress.

Effect of glycerol concentration and temperature on the rheological properties of cassava starch solutions

2013 ◽  
Vol 33 (2) ◽  
pp. 141-148 ◽  
Author(s):  
Germán Ayala Valencia ◽  
Ana Cecilia Agudelo Henao ◽  
Rubén Antonio Vargas Zapata
Keyword(s):  
Activation Energy ◽  
Rheological Properties ◽  
Apparent Viscosity ◽  
Weight Ratio ◽  
Exponential Model ◽  
Cassava Starch ◽  
Flow Index ◽  
Glycerol Concentration ◽  
Glycerol Content ◽  
All Solutions

Abstract Glycerol/starch (G/S) solutions were prepared at different concentrations, with a weight ratio of G/S=0.0, 0.1, 0.2, 0.3, 0.4 and 0.5, and rheological properties were analyzed at 30, 40, 50, 60 and 70°C. Power law dependency of the apparent viscosity as a function of the shear rate is the most appropriate model for describing the rheological behavior of cassava starch solutions as a function of glycerol concentrations. All solutions showed a pseudoplastic behavior; the flow index (n) did not show significant changes as a function of temperature and glycerol concentration. However, the apparent viscosity (μa) and the consistency coefficient (K) did show strong variations with temperature and glycerol content. The temperature variation of both μa and K were better fitted to an exponential model type exp(Ea /RT), logμa(K) vs. 1000/T. The activation energy of the K data for the solution without glycerol (G/S=0.0) was 13.64 KJ/mol, and it decreased with increasing the content of glycerol in the solutions, becoming 6.14 KJ/mol for G/S=0.5. On the contrary, the activation energy for the μa data increased when increasing the glycerol concentration. The effect of glycerol concentration was also modeled using polynomial and exponential fittings.

scholarly journals Comparison of Rosin and Propolis Antimicrobials in Cellulose Acetate Fibers Against Staphylococcus aureus

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3756-3773
Keyword(s):  
Staphylococcus Aureus ◽  
Cellulose Acetate ◽  
Dermal Fibroblast ◽  
Quantitative Difference ◽  
Antibacterial Properties ◽  
Acetate Solution ◽  
Solvent Type ◽  
Colony Forming Units ◽  
High Concentrations ◽  
The Fourier Transform

The quantitative difference in the antibacterial response was measured for pine rosin and propolis against Staphylococcus aureus ATCC 12598. The activity was studied for fibrous networks that form entirely bio-based cellulose-acetate (CA) materials. The analysis considers the effects of bacterial input, additive dosage, solvent type, variation in preparation, as well as the effect of storage time. Based on the results, the electrospun network structure is dependent on the solvent and the concentration of rosin and propolis. Both rosin and propolis improved the cellulose acetate solution processability, yet they formed beads at high concentrations. Rosin and propolis created strong antibacterial properties when these material systems were immersed in the liquid for 24 h at room temperature. The response remained visible for a minimum of two months. The electrospun networks of water and DMAc solvent systems with 1 to 5 wt% rosin content were clearly more efficient (i.e., decrease of 4 to 6 logs in colony forming units per mL) than the propolis networks, even after two months. This efficiency is likely due to the high content of abietic acids present in the rosin, which is based on the Fourier transform infrared spectra. The results of the additional analysis and cell cultivation with dermal fibroblast cells indicated an impairing effect on skin tissue by the rosin at a 1 wt% concentration compared to the pure CA fibers.

scholarly journals Filtration Performance of Ultrathin Electrospun Cellulose Acetate Filters Doped with TiO2 and Activated Charcoal

Buildings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 557
Author(s):  
Roberta Orlando ◽  
Yilun Gao ◽  
Peter Fojan ◽  
Jinhan Mo ◽  
Alireza Afshari
Keyword(s):  
Pressure Drop ◽  
Cellulose Acetate ◽  
Removal Efficiency ◽  
Activated Charcoal ◽  
Charged Particles ◽  
Particle Sizes ◽  
Acetate Solution ◽  
Electrospun Fibre ◽  
Filtration Performance ◽  
Composite Filter

Air filters are crucial components of a building ventilation system that contribute to improving indoor air quality, but they are typically associated with relatively high pressure drops. The purpose of the study is to evaluate the effect of additives on ultrathin electrospun filters, the pressure drop, and the particle removal efficiency of uniformly charged particles. The fibres were electrospun under optimised conditions that resulted in a fast-fabricating process due to the properties of the cellulose acetate solution. Different ultrathin electrospun fibre filters based on cellulose acetate (CA) were fabricated: a pure CA electrospun fibre filter, two filters based on CA fibres separately doped with activated charcoal (AC) and titanium dioxide (TiO2), respectively, and a composite filter where the two additives, AC and TiO2, were embedded between two CA fibres layers. The ultrathin filters exhibited a low pressure drop of between 63.0 and 63.8 Pa at a face velocity of 0.8 m s−1. The filtration performance of uniformly charged particles showed a removal efficiency above 70% for particle sizes between 0.3 and 0.5 μm for all filters, rising above 90% for larger particles between 1 and 10 μm, which translates to the average sizes of pollens and other allergenic contaminant particles. Due to the positive impact on the fibre morphology caused by the additives, the composite filter showed the highest filtration performance among the produced filters, reaching 82.3% removal efficiency towards smaller particles and a removal of up to 100% for particle sizes between 5 and 10 μm. Furthermore, cellulose acetate itself is not a source of microparticles and is fully biodegradable compared to other polymers commonly used for filters. These ultrathin electrospun filters are expected to be practical in applications for better building environments.

Chemometrics and Thermal Analytical Investigation of Ancient Human Bones Through the Estimation of Activation Energy Values of Main Degradation Processes

2020 ◽  
Vol 16 (5) ◽  
pp. 580-592
Author(s):  
Alessandra Biancolillo ◽  
Mauro Tomassetti ◽  
Remo Bucci ◽  
Federico Marini ◽  
Luigi Campanella
Keyword(s):  
Activation Energy ◽  
Principal Component ◽  
Human Remains ◽  
Analytical Investigation ◽  
Pca Analysis ◽  
Third Order ◽  
Funeral Ritual ◽  
The Third ◽  
Degradation Processes ◽  
Human Bones

Background: The investigation of human bones unearthed from necropolises is a useful tool to enhance our knowledge about ancient cultures. In the present study, the possibility of using the activation energy (EA) values of thermogravimetric degradation processes coupled with exploratory analysis methods in order to investigate human remains, has been tested. Methods: Several human bones from four distinct necropolises have been analyzed by thermogravimetry and then thirteen different approaches have been used to estimate their activation energy of the degradation processes of carbonate and collagen. The entire set of data has been analyzed by Principal Component Analysis (PCA) in order to draw some preliminary considerations over the remains. Results: PCA analysis highlighted the possibility of recognizing grouping tendencies related to the funeral ritual bodies underwent and/or their age. Additionally, in the second part of the work, where the focus is on the activation energies of collagen and carbonates degradation processes estimated by the method which was considered the most reliable (i.e., the Arrhenius formula with the third order decay), some tentative considerations about a trend in cremation temperatures are drawn. Conclusion: The estimation of values from thermogravimetric signals combined with chemometrics is a useful tool for the investigation of bone samples, which allow obtaining additional info about trends and/or grouping tendencies in complex systems as human remains.

The Thermal Decomposition of Silver(I) Oxide

1960 ◽  
Vol 13 (4) ◽  
pp. 431 ◽  
Author(s):  
JA Allen
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Lattice Parameter ◽  
Activation Energies ◽  
Metallic Silver ◽  
Cent Oxygen ◽  
Total Oxygen ◽  
The Third ◽  
Limiting Value ◽  
Silver Atoms

The thermal decomposition of precipitated silver(I) oxide in a vacuum has been studied over the range 100-350 �C. Three regions are identified : in the fist, 100-200 �C, the activation energy is 30 kcal, 5 per cent. of the total oxygen is evolved, and the lattice parameter increases to a limiting value ; in the second, 200-300 �C, the activation energy is 50 kcal, and a further 1-2 per cent. oxygen is evolved; in the third, above 300 �C, metallic silver crystallizes, the oxide lattice contracts to a constant value, and the activation energy becomes 36 kcal. The activation energies in the three regions are interpreted as being associated, respectively, with (i) the diffusion of silver into the oxide lattice, (ii) the formation of aggregates of silver " atoms " not conforming to the normal silver lattice in an oxide lattice saturated with silver, and (iii) the reaction at the interface between metallic silver and the oxide.

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