scholarly journals Aqueous polyvinyl alcohol solution foaming at different molecular masses

2021 ◽  
Vol 16 (4) ◽  
pp. 337-344
Author(s):  
A. A. Akimova ◽  
V. A. Lomovskoy ◽  
I. D. Simonov-Emel’yanov
Keyword(s):  
Molecular Weight ◽  
Polyvinyl Alcohol ◽  
Solution Structure ◽  
Water Solution ◽  
Solution Temperature ◽  
Process Conditions ◽  
Molecular Weights ◽  
Foaming Process ◽  
Pva Solutions ◽  
Main Component

Objectives. Investigation of aqueous polyvinyl alcohol (PVA) foaming process and the influence of its water solution structure, when possessed of different molecular weights and concentrations, on foaming multiplicity.Methods. Solution foaming analysis was performed on the data of dynamic light scattering obtained on the Zetasizer Nano particle analyzer.Results. In this work, the foaming ability and foaming multiplicity of aqueous PVA solutions (as a main component for obtaining special-purpose foams) have been studied. It is shown that PVA solutions in water are colloidal dispersed systems consisting of different-sized associates (from 4.8 to 68.1 nm), depending on the molecular weight of PVA. Dependencies of aqueous PVA solution foaming multiplicities on the concentration, molecular weight, and solution temperature were given. Optimal values of concentration and molecular PVA weight, as well as optimal foaming process conditions from aqueous PVA solutions, were established.Conclusions. Increasing PVA concentrations in aqueous solutions cause foaming multiplicity to decrease for all molecular weights by 1.5 times, and increasing molecular weight increases foaming multiplicity by 2 times. The foaming ratio of aqueous PVA solutions with different concentrations and molecular weights (depending on a solution temperature characterized by a maximum of 30 °C) is associated with decreased viscosity and surface tension.

Influence of Multiwall Carbon Nanotube on Polyethersulfone/ Polyvinyl Alcohol Blend Membranes

2014 ◽  
Vol 67 (2) ◽  
Author(s):  
Nur Farahah Mohd Khairuddin ◽  
Ani Idris ◽  
Iqbal Ahmed ◽  
Noordin Mohd Yusof
Keyword(s):  
Molecular Weight ◽  
Contact Angle ◽  
Carbon Nanotube ◽  
Polyvinyl Alcohol ◽  
Water Flux ◽  
Multiwall Carbon Nanotube ◽  
Flux Rate ◽  
Molecular Weights ◽  
Blend Membranes ◽  
Multiwall Carbon

This paper investigates the influence of multiwall carbon nanotube (MWCNT) on the morphology and properties of polyethersulfone (PES) and polyvinyl alcohol (PVA) blend membranes. Several membranes were prepared by blending 0.5 wt% MWCNT , 18%wt PES and 1.5wt% PVA of various molecular weights (60, 145 and 200 kDa) in  dimethyl acetate (DMAC) solvent. The membranes were then evaluated in terms of its morphology, contact angle, water flux rate and porosity. The results revealed that MWCNT nanoparticles have decreased the contact angle and increased the flux rate of PES/PVA blend membranes. The presence of MWCNT in the PES/PVA membranes have promoted the formation of fingerlike pores in the membranes structure and thus increased the porosity of the membranes. Besides that, the use of higher molecular weight PVA helped to reduce the contact angle of the membranes reflecting to their hydrophilic nature. However, the use of lower molecular weight PVA was found to enhance the increased of flux rate and porosity of the membrane.

Vaginal Absorption of Polyvinyl Alcohol in Fischer 344 Rats

1990 ◽  
Vol 9 (2) ◽  
pp. 71-77 ◽  
Author(s):  
J.M. Sanders ◽  
H.B. Matthews
Keyword(s):  
Molecular Weight ◽  
Polyvinyl Alcohol ◽  
Low Molecular Weight ◽  
Fischer 344 Rats ◽  
Gi Tract ◽  
Molecular Weights ◽  
Fischer 344 ◽  
Human Dose ◽  
Wide Range ◽  
Intravaginal Administration

Polyvinyl alcohol (PVA) is a polymer with a wide range of molecular weights and uses. Recently, low molecular weight formulations of PVA have been used as components of contraceptive products designed for intravaginal administration in human females. Previous studies in animals have determined that little or no absorption of PVA occurs from the gastrointestinal (GI) tract. However, there is some concern that PVA of lower molecular weights might be absorbed across membranes of the reproductive tract. Consequently, this work has investigated the absorption of low molecular weight PVA across biological membranes of the reproductive and GI tracts of Fischer 344 rats. Oral administration of ten consecutive daily doses of 14C PVA resulted in little apparent absorption of the dose from the GI tract. In contrast, intravaginal administration of 14C PVA resulted in increasing concentrations of PVA-derived radioactivity in major tissues following one, three or ten daily doses of the estimated human dose of 3 mg/kg. PVA-derived radioactivity was concentrated mainly in the liver, reaching a peak greater than 1750 ng equivalents/g tissue 24 hours following ten daily doses. Over 300 ng equivalents/g tissue were still present in the liver 30 days following the last dose.

scholarly journals Preparation and Characterization of Chitosan/Polyvinyl Alcohol Blends-A Rheological Study

2010 ◽  
Vol 7 (s1) ◽  
pp. S349-S357 ◽  
Author(s):  
Esam A. El-Hefian ◽  
Mohamed Mahmoud Nasef ◽  
Abdul Hamid Yahaya
Keyword(s):  
Polyvinyl Alcohol ◽  
Arrhenius Equation ◽  
Storage Period ◽  
Mixed Effect ◽  
Pva Solutions ◽  
Main Component ◽  
Storage Times ◽  
Viscosity Changes ◽  
Newtonian Behavior

Blends of chitosan (CS) and polyvinyl alcohol (PVA) of different proportions (considering chitosan as the main component) were prepared. The rheological properties of the obtained blend solutions such as the shearing viscosity and the shear stress were investigated as a function of shear rate under various temperatures, shearing times and solution storage times using a digital viscometer. The CS/PVA solutions showed a Newtonian behavior at temperatures in the range of 40-55 °C regardless of the blend composition. This was accompanied by a general decrease in the viscosity with increasing PVA content in the blend. The heat-dependant viscosity changes of the blend solutions were found to follow Arrhenius equation. The shearing time was found to have no significant effect on the shearing viscosity of all blended solutions. However, the variation of solution storage period was found to have a mixed effect when time was extended to 3 weeks.

Effect of Molecular Weight on Morphological Structure of Electrospun PVA Nanofibre

2015 ◽  
Vol 1134 ◽  
pp. 203-208
Author(s):  
Nur Athirah Abdullah@Shukry ◽  
Khairunnadim Ahmad Sekak ◽  
Mohd Rozi Ahmad
Keyword(s):  
Molecular Weight ◽  
Polyvinyl Alcohol ◽  
Feed Rate ◽  
Fibre Diameter ◽  
Morphological Structure ◽  
Electrospinning Process ◽  
Molecular Weights ◽  
Microscopy Technique ◽  
Average Fibre Diameter ◽  
Average Fibre

This work focuses on the preparation of electrospun Polyvinyl Alcohol (PVA) nanofibres of three different molecular weights. The electrospinning process parameters were varied in terms of the voltage and feed rate. Scanning Electron Microscopy technique was used to characterize the morphological structure of the electrospun PVA nanofibre. The results show that the average fibre diameter increased as the molecular weight of the polymer increased. The formation of beads occurs from the lowest molecular weight sample of 89K However, long, continuous and beaded-free fibres were obtained from the 125K and 205K polymer weight PVA. The results also suggest that higher spinning voltage and feed rate produce larger fibre diameter, respectively.Keywords : Polyvinyl Alcohol, nanofibres, molecular weight, electrospinningCorresponding Author:Khairunnadim Ahmad Sekak, Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), Shah Alam, 40450 Selangor Darul Ehsan.Email: [email protected]

scholarly journals Physicochemical Properties of Solutions of Polyvinyl Alcohol (PVA) of Different Molecular Weights

2021 ◽  
Vol 6 (2) ◽  
pp. 242-248
Author(s):  
V. V. Chekanova ◽  
◽  
Yu. S. Pakhomova ◽  
A. M. Kompaniets ◽  
V. A. Kireev ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Surface Tension ◽  
Physicochemical Properties ◽  
Dynamic Viscosity ◽  
Critical Concentration ◽  
Micelle Formation ◽  
Molecular Weights ◽  
Melting Temperatures ◽  
Molecular Masses ◽  
Pva Solutions

The physicochemical properties (surface tension, dynamic viscosity, crystallization and melting temperatures) of polyvinyl alcohol solutions of molecular weight 9, 31 and 72 kDa have been studied. The surface tension and the critical concentration of micelle formation were determined by the method of stalogometry, and the dynamic viscosity was determined using an Oswald viscometer. The crystallization and melting temperatures were determined in a cooled modified chamber of the UOP-6 software freezer at a rate of 2°C/min. Cryomicroscopic studies were carried out on a polarizing microscope "MIN-8". The surface tension reflects the interaction of PVA solutions with the lipid layer of biomembranes and indicates the hydrophobic properties of substances. The viscosity of PVA solutions characterizes their interaction with water molecules and reflects hydrophilic interactions. The purpose of the study is to determine the physicochemical properties of PVS that characterize the hydrophilic-hydrophobic interactions in the studied solutions and the micelle formation of PVА solutions of different molecular weights. Materials and methods. Studies of the dynamic viscosity and density of 0.1%-1% PVA solutions of molecular weight 9, 31 kDa showed that these parameters increase with increasing PVA concentration, which leads to increased hydrophilicity of the solutions. Results and discussion. It was shown that the surface tension of PVA solutions decreases with increasing concentration, which leads to a decrease in the hydrophobic properties of the polymer. It was found that in 0.5% PVА solutions of molecular weight 9 and 31 kDa the crystallization and melting temperatures decrease from -5 to -6°C. At these temperatures, crystallization and melting of the solutions begin. Conclusion. The study of micelle formation in PVА solutions of different molecular masses was carried out, surface tension isotherms were constructed, and the break point on the isotherm corresponding to the CCM was determined. The values of the critical concentration of micelle formation of PVА of molecular masses 9, 31, 72 kDa were determined. Hydrophobic links of PVА of molecular masses 9 and 31 kDa form hydrophobic cavities in the micelle structure, which can reduce recrystallization activity

LONG CARBON CHAIN CARBOHYDRATE POLYMERS: 1,3-(BIS-5-ALDOXYLOSYLIDENE-1)-ACETONE AND ITS POLYMER WITH 1,3-DICARBETHOXYACETONE

1966 ◽  
Vol 44 (15) ◽  
pp. 1841-1845
Author(s):  
Philippos E. Papadakis ◽  
S. M. Philip
Keyword(s):  
Molecular Weight ◽  
Carbon Chain ◽  
Molecular Weights ◽  
Carbohydrate Polymers ◽  
Main Component ◽  
Continuous Chain

1,3-Dicarbethoxy-1,3-(bis-(4′,5′-O-isopropylidene-D-xylofuranosylidene))-acetone was hydrolyzed and decarboxylated to produce 1,3-(bis-D-xylofuranosylidene-5)-acetone (III) and 1,3-(bis-5-aldoxylosylidene-1)-acetone (IV). Compound IV reacted with 1,3-dicarbethoxyacetone in 75% methanol, with piperidine as catalyst, to give polymers V and VI and some intermediates. The main component of polymer V had a molecular weight between 2 000 and 4 000, and there were six to seven components with molecular weights of less than 2 000. Because the molecular weight of the repeating unit is approximately 500, a polymer with a molecular weight of 2 500 would have 80 carbons in a continuous chain, and one with a molecular weight of 3 500 would have 112 carbons. The work presented in this article may open broad areas of further research.

Investigation by HPLC of the Catabolism of Recombinant Tissue Plasminogen Activator in the Rat

1988 ◽  
Vol 60 (01) ◽  
pp. 107-112 ◽  
Author(s):  
Roy Harris ◽  
Louis Garcia Frade ◽  
Lesley J Creighton ◽  
Paul S Gascoine ◽  
Maher M Alexandroni ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Half Life ◽  
Recombinant Tissue Plasminogen Activator ◽  
Rat Plasma ◽  
High Molecular Weight Complex ◽  
Molecular Weights ◽  
Major Activity ◽  
Tissue Plasminogen

SummaryThe catabolism of recombinant tissue plasminogen activator (rt-PA) was investigated after injection of radiolabelled material into rats. Both Iodogen and Chloramine T iodination procedures yielded similar biological activity loss in the resultant labelled rt-PA and had half lives in the rat circulation of 1 and 3 min respectively. Complex formation of rt-PA was investigated by HPLC gel exclusion (TSK G3000 SW) fractionation of rat plasma samples taken 1-2 min after 125I-rt-PA injection. A series of radiolabelled complexes of varying molecular weights were found. However, 60% of the counts were associated with a single large molecular weight complex (350–500 kDa) which was undetectable by immunologically based assays (ELISA and BIA) and showed only low activity with a functional promoter-type t-PA assay. Two major activity peaks in the HPLC fractions were associated with Tree t-PA and a complex having a molecular weight of ̴ 180 kDa. HPLC fractionation to produce these three peaks at various timed intervals after injection of 125I-rt-PA showed each to have a similar initial rate half life in the rat circulation of 4-5 min. The function of these complexes as yet is unclear but since a high proportion of rt-PA is associated with a high molecular weight complex with a short half life in the rat, we suggest that the formation of this complex may be a mechanism by which t-PA activity is initially regulated and finally cleared from the rat circulation.

Permeability Enhancing and Chemotactic Activities of Lower Molecular Weight Degradation Products of Human Fibrinogen

1981 ◽  
Vol 45 (01) ◽  
pp. 090-094 ◽  
Author(s):  
Katsuo Sueishi ◽  
Shigeru Nanno ◽  
Kenzo Tanaka
Keyword(s):  
Molecular Weight ◽  
Degradation Products ◽  
Electron Microscopic Observation ◽  
Chemotactic Activity ◽  
Lower Molecular Weight ◽  
Electron Microscopic ◽  
Human Fibrinogen ◽  
Rabbit Skin ◽  
Molecular Weights ◽  
Active Fragments

SummaryFibrinogen degradation products were investigated for leukocyte chemotactic activity and for enhancement of vascular permeability. Both activities increased progressively with plasmin digestion of fibrinogen. Active fragments were partially purified from 24 hr-plasmin digests. Molecular weights of the permeability increasing and chemotactic activity fractions were 25,000-15,000 and 25,000 respectively. Both fractions had much higher activities than the fragment X, Y, D or E. Electron microscopic observation of the small blood vessels in rabbit skin correlated increased permeability with the formation of characteristic gaps between adjoining endothelial cells and their contraction.These findings suggest that lower molecular weight degradation products of fibrinogen may be influential in contributing to granulocytic infiltration and enhanced permeability in lesions characterized by deposits of fibrin and/or fibrinogen.

Toxicity of Heparinoids, with Special Reference to the Precipitation of Fibrinogen

1964 ◽  
Vol 12 (01) ◽  
pp. 232-261 ◽  
Author(s):  
S Sasaki ◽  
T Takemoto ◽  
S Oka
Keyword(s):  
Molecular Weight ◽  
Dextran Sulfate ◽  
Anticoagulant Activity ◽  
Molecular Structures ◽  
Severe Reaction ◽  
Clinical Use ◽  
Molecular Weights ◽  
Close Relationship

SummaryTo demonstrate whether the intravascular precipitation of fibrinogen is responsible for the toxicity of heparinoid, the relation between the toxicity of heparinoid in vivo and the precipitation of fibrinogen in vitro was investigated, using dextran sulfate of various molecular weights and various heparinoids.1. There are close relationships between the molecular weight of dextran sulfate, its toxicity, and the quantity of fibrinogen precipitated.2. The close relationship between the toxicity and the precipitation of fibrinogen found for dextran sulfate holds good for other heparinoids regardless of their molecular structures.3. Histological findings suggest strongly that the pathological changes produced with dextran sulfate are caused primarily by the intravascular precipitates with occlusion of the capillaries.From these facts, it is concluded that the precipitates of fibrinogen with heparinoid may be the cause or at least the major cause of the toxicity of heparinoid.4. The most suitable molecular weight of dextran sulfate for clinical use was found to be 5,300 ~ 6,700, from the maximum value of the product (LD50 · Anticoagulant activity). This product (LD50 · Anticoagulant activity) can be employed generally to assess the comparative merits of various heparinoids.5. Clinical use of the dextran sulfate prepared on this basis gave satisfactory results. No severe reaction was observed. However, two delayed reactions, alopecia and thrombocytopenia, were observed. These two reactions seem to come from the cause other than intravascular precipitation.

Molecular Weights of Factor VIII (AHF) and Factor IX (PTC) by Electron Irradiation

1962 ◽  
Vol 08 (02) ◽  
pp. 270-275 ◽  
Author(s):  
David L Aronson ◽  
John W Preiss ◽  
Michael W Mosesson
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
Electron Irradiation ◽  
Factor Ix ◽  
Molecular Weights

SummaryThe molecular weights of AHF (factor VIII) and of PTC (factor IX) have been estimated by their sensitivity to inactivation by 7 kilovolt electrons. The molecular weight of AHF was found to be 180 000 by this method and that of PTC was found to be 110 000.

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