Change in Degree of Polymerization of Wood Pulp with Cellulase Hydrolysis

1969 ◽  
Vol 39 (5) ◽  
pp. 422-427 ◽  
Author(s):  
Yoshitaka Ogiwara ◽  
Kenichiro Arai
Keyword(s):  
Sodium Hydroxide ◽  
Zinc Chloride ◽  
Water Retention ◽  
Cellulose Fiber ◽  
Amorphous Region ◽  
Degree Of Polymerization ◽  
Crystalline Region ◽  
A Value ◽  
Sulfite Pulp ◽  
Cellulase Hydrolysis

A study was made of the changes in degree of polymerization (DP), water retention value (WRV), and yield when high α-sulfite pulp (α-SP) is beaten or swollen with zinc chloride or sodium hydroxide and treated with cellulase. For a sample swollen with sodium hydroxide, the decrease in DP is large, and the DP decreases easily to a value which corresponds approximately to the level of DP in acid hydrolysis. On the other hand, a sample treated with zinc chloride solution shows a small decrease, while a beaten sample indicates an intermediate DP value. It is assumed from these results that sodium hydroxide swells the amorphous region of the fiber greatly but has little effect on the crystalline region, whereas zinc chloride swells the crystalline region but its swelling effect on the amorphous region is not very great. Cellulase can be utilized for analyzing the structure of cellulose fiber.

Effect of various pulp properties on the solubility of cellulose in sodium hydroxide solutions

Holzforschung ◽  
2012 ◽  
Vol 66 (5) ◽  
pp. 601-606 ◽  
Author(s):  
Martin Kihlman ◽  
Fredrik Aldaeus ◽  
Fadia Chedid ◽  
Ulf Germgård
Keyword(s):  
Sodium Hydroxide ◽  
Water Retention ◽  
Degree Of Polymerization ◽  
Pulp Fibers ◽  
Cellulose Chain ◽  
Dissolving Pulps ◽  
Pulp Properties ◽  
Fiber Dimensions ◽  
Standard Paper ◽  
Solvent Systems

Abstract The dissolution of pulps with varying characteristic properties, for example cellulose chain length or content of hemicellulose, has been investigated in two alkaline solvent systems [sodium hydroxide (NaOH)/urea/thiourea (8:8:6.5 by wt.) and NaOH/zince oxide (ZnO) (9:0.5 by wt.)]. One standard paper pulp, two dissolving pulps and three pretreated pulps were selected for this study. The dissolution parameters in focus were the fiber dimensions, average degree of polymerization (DP), polydispersity, water retention value and content of hemicelluloses. The solubility was not influenced by the fiber dimensions. The only significant properties, according to variable importance plot, were DP and composition of the hemicelluloses. It was also established that mass transfer effects during the dissolution stage plays an important role in the dissolution of cellulose derived from pulp fibers.

Optimization of the process variables for treating cellulose fiber with NaOH/urea aqueous solution for improved water retention value and paper strength

2019 ◽  
Vol 34 (4) ◽  
pp. 475-484
Author(s):  
Yingju Miao ◽  
Chunzuo Yan ◽  
Yingchun Miao ◽  
Qingming Jia ◽  
Yonghao Ni ◽  
...  
Keyword(s):  
Sodium Hydroxide ◽  
Water Retention ◽  
Cellulose Fiber ◽  
Post Treatment ◽  
Urea Concentration ◽  
Paper Strength ◽  
Sodium Hydroxide Concentration ◽  
Treatment Conditions ◽  
Swelling Capacity ◽  
Pretreatment Time

Abstract Cellulose fibers swell significantly in NaOH/urea solutions, and swelling increases with a decrease in temperature and an addition of urea. The combined effects of the factors of a pretreatment procedure (sodium hydroxide concentration, urea concentration, temperature, and time) and post-treatment conditions (medium, stirring speed, and time) of preparing fibers on the properties of pulp and the resulting paper sheets were investigated and optimized using single factor experiments. The optimum sodium hydroxide concentration (1 %), urea concentration (8 %), precooling temperature 0 °C, pretreatment time (12 h), post-treatment medium (7 % {({\mathrm{NH}_{4}})_{2}}{\mathrm{SO}_{4}}), post-treatment stirring speed (1500 rpm), and time (30 min) were obtained. Under the optimal conditions, the water retention values and tear, tensile, and burst indexes increased about 54 %, 277 %, 394 %, and 98 %, respectively. This work demonstrates that this technical route can effectively improve fiber swelling capacity and paper strength.

Comparative Study on Structural Performance of Several New Regenerated Cellulose Fibers

2012 ◽  
Vol 573-574 ◽  
pp. 174-180
Author(s):  
Rong Zhou ◽  
Chun Guang Li ◽  
Ming Xia Yang
Keyword(s):  
Cellulose Fiber ◽  
Degree Of Polymerization ◽  
Structural Performance ◽  
Regenerated Cellulose ◽  
Pulp Fiber ◽  
Bast Fiber ◽  
Bamboo Pulp ◽  
Lyocell Fiber ◽  
Regenerated Cellulose Fiber ◽  
Sectional Shape

Regenerated cellulose fiber is the most widely-used and most variety of cellulose fiber. Five categories and ten kinds of fibers such as lyocell fiber, viscose fiber, modal fiber, bamboo pulp fiber, and sheng-bast fiber were chosen as the research object. The sectional shape, crystallinity and degree of polymerization of fibers were tested and analysis, to explore the nature of the reasons for the formation of fiber performance difference, and to verify through experiments.

Diffusivity of solvents in semi-crystalline polyethylene using the Vrentas-Duda free-volume theory

2018 ◽  
Vol 38 (10) ◽  
pp. 925-931 ◽  
Author(s):  
Derek R. Sturm ◽  
Kevin J. Caputo ◽  
Siyang Liu ◽  
Ronald P. Danner
Keyword(s):  
Free Volume ◽  
Weight Fraction ◽  
Amorphous Region ◽  
Model Parameters ◽  
Crystalline Region ◽  
Free Volume Theory ◽  
Melt Temperature ◽  
Tortuosity Factor ◽  
Crystalline Polyethylene

Abstract Diffusion of penetrants in polyethylene below the melt temperature is heavily dependent on the crystallinity of the polyethylene, the temperature of the experiment, and the concentration of solvent in the polymer. As the crystallinity of the polyethylene increases, there is an increase in the path that the solvent must travel as the solvent cannot penetrate the tightly packed chains in the crystalline domain. This effect is typically accounted for by a tortuosity factor. In this work, a simple and effective characterization of the tortuosity factor based simply on the crystal weight fraction has been developed. Data have been collected for six polyethylenes having densities ranging from 0.912 to 0.961 g/cm3 and for three solvents – isopentane, cyclohexane, and 1-hexene. Diffusivity predictions have been obtained using the free-volume theory of Vrentas and Duda in conjunction with the new tortuosity factor. The polyethylenes had crystallinities varying from 40% to 82% effecting an approximately 60% change in the diffusivity. The decrease resulting from ignoring the crystallinity altogether was in some cases essentially a factor of 5. The error in the predicted diffusivities over all the systems was 25%. For cyclohexane, it is shown that the same model parameters characterize data below the melt temperature (in the semi-crystalline region) as well as above the melt temperature (in the amorphous region).

Morphological, structural and physicochemical properties of rice starch nanoparticles prepared via ultra-high pressure homogenization

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Chengyi Sun ◽  
Yuqing Hu ◽  
Xietian Yu ◽  
Zhijie Zhu ◽  
Shuai Hao ◽  
...  
Keyword(s):  
High Pressure ◽  
Physicochemical Properties ◽  
Particle Diameter ◽  
Amorphous Region ◽  
Rice Starch ◽  
Crystalline Region ◽  
High Pressure Homogenization ◽  
Relative Crystallinity ◽  
Ultra High Pressure ◽  
Starch Nanoparticles

Abstract Native rice starches were treated with five periods of ultra-high pressure homogenization (UHPH) under each of 60, 80, 100, 120, 140 and 160 MPa, respectively. The morphological, structural and physicochemical properties of starches treated with UHPH were examined. The mean particle diameter of starch nanoparticles ranged between 154.20 and 260.40 nm. SEM revealed that the granular amorphous region of starch granules was damaged under pressures between 60 and 80 MPa, and the crystalline region was further destroyed under pressures as high as 100–160 MPa. DSC demonstrated that the gelatinization temperatures and enthalpies of nanoparticles reduced. The relative crystallinity reduced from 22.90 to 13.61% as the pressure increased. FTIR showed that the absorbance ratio at 1047/1022 cm−1 decreased, and increased at 1022/995 cm−1. RVA results indicated that the viscosity of starch samples increased between 60 and 120 MPa, and the reverse effect was observed under 140 and 160 MPa.

Study on effect of supercritical CO2 on structural ordering and charge transporting property in thiophene-based block copolymer

2022 ◽  
Author(s):  
Satomi Hosokawa ◽  
Eri Tomita ◽  
Shinji Kanehashi ◽  
Kenji Ogino
Keyword(s):  
Supercritical Co2 ◽  
Hole Mobility ◽  
Amorphous Region ◽  
Crystalline Region ◽  
Space Charge Limited Current ◽  
Conjugation Length ◽  
Enhanced Mobility ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Effective Conjugation Length

Abstract We reported that supercritical (sc) annealing of poly(3-hexylthiophene) (P3HT), and its block copolymers with poly(ethylene oxide) (PEO) and polystyrene (PSt) brought about improvements in the crystal structure and hole mobility, determined by the space charge limited current (SCLC) measurement. P3HT-b-PEO showed the largest increase in mobility. From XRD profile, it was found that the treatment with scCO2 increased the crystallite size and crystallinity. UV-vis spectra showed that the effective conjugation length in the scCO2 treated films was increased compared to the as-spun, suggesting that CO2 molecules are incorporated into domains of the second block domains and P3HT amorphous region, and assist to alter the characteristics of the crystalline region. Then, it was considered that the change in the crystalline structure and the improvement of P3HT chains packing led to the enhanced mobility. Since PEO is known to have a higher affinity for CO2, the increase of mobility was specifically intensive.

Recycled fiber treated with NaOH/urea aqueous solution: effects on physical properties of paper sheets and on hornification

2018 ◽  
Vol 33 (4) ◽  
pp. 651-660 ◽  
Author(s):  
Yingju Miao ◽  
Yunfei Zhi ◽  
Heng Zhang ◽  
Ying Chen ◽  
Shaoyun Shan ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Physical Properties ◽  
Water Retention ◽  
Crystalline Region ◽  
Cellulose Film ◽  
Reinforced Concrete Structure ◽  
Water Retention Value ◽  
Fiber Network ◽  
Urea Aqueous Solution ◽  
Intramolecular Hydrogen

Abstract Hydrogen bonding among fiber microfibrils is the primary cause of fiber hornification, wherein NaOH/urea aqueous solution precooled to −13 °C can disassemble inter- and intramolecular hydrogen bonds. Whether hornified fibers treated with this process can significantly improve fiber swelling ability and physical properties of the resulting paper sheets remains a problem. In this investigation, the 6th cycle fiber was pretreated with this procedure, and the water retention value of the fiber before and after treatment and the physical properties of the resulting paper sheets were studied. The results indicate that the lignin decline, complete swelling of flat fiber, filling of cellulose film between the interfiber network, and decreasing crystalline region all contribute to the increase in water retention value. The water retention value of repaired fiber is equivalent to that of virgin pulp, and hornification reverses by 89 %. In addition, the cellulose film filling among the fiber network constructs a similar reinforced concrete structure, which causes the tear, burst, and tensile index of the resulting paper sheets to increase by 145 %, 98 %, and 43 %, respectively.

Studies of Chemically Modified Cotton

1969 ◽  
Vol 39 (1) ◽  
pp. 15-23 ◽  
Author(s):  
S. N. Pandey ◽  
R. L. N. Iyengar
Keyword(s):  
Sodium Hydroxide ◽  
Potassium Hydroxide ◽  
Marked Effect ◽  
Chemical Reactivity ◽  
Degree Of Polymerization ◽  
Cotton Fibers ◽  
Cellulose Crystallinity ◽  
Moisture Regain ◽  
Chemically Modified ◽  
Degree Of Swelling

High crystallinity of cellulose is the cause of undue stiffness and brittleness as well as low absorptioh and chemical reactivity. With a view to overcome these drawbacks and bring about changes in the elastic and other properties of cotton fibers, two cottons, Gaorani and 170-Co.2, were treated with anhydrous ethylamine, diethylamine, pyridine, and aqueous solutions of sodium hydroxide (30%) and potassium hydroxide (40%) for 15 min to 50 hr. Modified lint samples showed interesting changes in cellulose crystallinity and moisture regain, on treatment with ethylamine, sodium hydroxide, and potassium hydroxide after certain periods. Some of the treatments also showed a marked effect on the degree of polymerization and the tensile, mechanical, swelling, and optical properties of the fiber. Moisture regain and degree of swelling were found to be higher in the case of samples treated with alkali, compared with those treated with amines.

scholarly journals Thermo-Mechanical Behaviour of Human Nasal Cartilage

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 177 ◽  
Author(s):  
Aureliano Fertuzinhos ◽  
Marta A. Teixeira ◽  
Miguel Goncalves Ferreira ◽  
Rui Fernandes ◽  
Rossana Correia ◽  
...  
Keyword(s):  
Mechanical Behaviour ◽  
Subcutaneous Tissue ◽  
Amorphous Region ◽  
Cartilage Matrix ◽  
Water Evaporation ◽  
Glass Transition Point ◽  
Crystalline Region ◽  
Scanning Calorimetry ◽  
Nasal Cartilage ◽  
Human Nose

The aim of this study was to undergo a comprehensive analysis of the thermo-mechanical properties of nasal cartilages for the future design of a composite polymeric material to be used in human nose reconstruction surgery. A thermal and dynamic mechanical analysis (DMA) in tension and compression modes within the ranges 1 to 20 Hz and 30 °C to 250 °C was performed on human nasal cartilage. Differential scanning calorimetry (DSC), as well as characterization of the nasal septum (NS), upper lateral cartilages (ULC), and lower lateral cartilages (LLC) reveals the different nature of the binding water inside the studied specimens. Three peaks at 60–80 °C, 100–130 °C, and 200 °C were attributed to melting of the crystalline region of collagen matrix, water evaporation, and the strongly bound non-interstitial water in the cartilage and composite specimens, respectively. Thermogravimetric analysis (TGA) showed that the degradation of cartilage, composite, and subcutaneous tissue of the NS, ULC, and LLC take place in three thermal events (~37 °C, ~189 °C, and ~290 °C) showing that cartilage releases more water and more rapidly than the subcutaneous tissue. The water content of nasal cartilage was estimated to be 42 wt %. The results of the DMA analyses demonstrated that tensile mode is ruled by flow-independent behaviour produced by the time-dependent deformability of the solid cartilage matrix that is strongly frequency-dependent, showing an unstable crystalline region between 80–180 °C, an amorphous region at around 120 °C, and a clear glass transition point at 200 °C (780 kJ/mol). Instead, the unconfined compressive mode is clearly ruled by a flow-dependent process caused by the frictional force of the interstitial fluid that flows within the cartilage matrix resulting in higher stiffness (from 12 MPa at 1 Hz to 16 MPa at 20 Hz in storage modulus). The outcomes of this study will support the development of an artificial material to mimic the thermo-mechanical behaviour of the natural cartilage of the human nose.

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