scholarly journals Additives Incorporated in Cellulose Acetate Membranes to Improve Its Performance as a Barrier in Periodontal Treatment

2021 ◽  
Vol 2 ◽  
Author(s):  
Mariana Fornazier ◽  
Patricia Gontijo de Melo ◽  
Daniel Pasquini ◽  
Harumi Otaguro ◽  
Gabriela Ciribelli Santos Pompêu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cellulose Acetate ◽  
Physiological Solution ◽  
Point Of View ◽  
Lignin Concentration ◽  
Physical Chemical ◽  
Long Run ◽  
Cellulose Acetate Membranes ◽  
Sample Weight Loss ◽  
Calcium Glycerophosphate

In this study, we prepared cellulose acetate membranes, by means of casting mold, incorporated with two additives, sodium carboxymethyl lignin and calcium glycerophosphate, in order to improve properties for periodontal applications. The membranes were characterized from the morphological, structural, thermal and mechanical point of view, as well as by physiological pH tests. The results showed that membranes with additives improve the physical-chemical and mechanical properties, especially when the two additives are present in the same membrane, which can be attributed to the important synergy between them. The most significant effects occur in increasing the thickness and decreasing the density, which reflects in the porosity of the membranes, although the added amounts do not exceed 1.4%. A 1% increase in lignin concentration does not change the thickness and density of the membrane, but that amount of lignin plus 0.4% calcium glycerophosphate increases the thickness of the membrane by 42% and decreases the density by about 6%. Although there is a decrease in mechanical properties, as observed in Young's modulus and crystallinity, the significant and intermittent increase in sample weight loss with both additives in physiological solution indicates that, in the long run, it can be used as a degradable barrier.

Kinetics and Optimum Phenomenon of Vulcanization

1947 ◽  
Vol 20 (4) ◽  
pp. 933-937
Author(s):  
B. Dogadkin ◽  
B. Karmin ◽  
I. Golberg
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Point Of View ◽  
Sulfur Monochloride ◽  
Physical Chemical ◽  
Fundamental Process ◽  
Technical Properties ◽  
Kinetics Of ◽  
Homogeneous Reactions

Abstract The fundamental process of vulcanization consists in the combination of rubber with a vulcanizing agent : sulfur, sulfur monochloride, etc. The kinetics of this process may be expressed by monotonous curves. These may be interpreted either as the result of the heterogeneous character of the reaction or as the result of the combination of several homogeneous reactions. At the same time that the rubber combines with the vulcanizing agent, and largely as a consequence of this, a number of its physical-chemical and mechanical properties—solubility, density, tensile strength and other properties—undergo a change. These changes are extremely interesting from the technological point of view. In distinction to the kinetics of the combination of rubber with the vulcanizing agent, the kinetics of these processes can in most cases be represented by curves with a maximum or minimum. Thus, in the vulcanization of crude rubber, the tensile strength and modulus change according to a curve having a maximum; the solubility change follows a curve with a minimum. This character of the change experienced by the principal technical properties of the rubber determines the so-called “vulcanization optimum”. This term refers to that moment in the process of vulcanization when the particular property attains the necessary maximum or minimum, depending on the technical purposes of the vulcanizate.

USE OF STARCH SYRUPS IN THE PRODUCTION OF JELLY

2019 ◽  
pp. 457-462
Author(s):  
Kateryna Iorgachova ◽  
Olga Makarova ◽  
Karyne Avetisian
Keyword(s):  
Mechanical Properties ◽  
Carbohydrate Composition ◽  
Foam Layer ◽  
Quality Indices ◽  
Organoleptic Quality ◽  
Physical Chemical

In the presented work the choice of starch syrup for the jelly products production has been substantiated. It was based on the analysis of the starch syrup carbohydrate profiles and recipes of jelly products. The influence of syrup on the rheological and structural-mechanical properties of jelly and aerated masses for a two-layer jelly has been determined. The expediency of polydextrose usage has been demonstrated. Its adding leads to the regulation of the jelly structure and foam layer for the samples with more than 50% of sugar replaced by starch syrup. Depending on the ratio of carbohydrates in jelly it was determined the amount of polydextrose adding of which provides the required firming and prebiotic properties of finish products. The change of physical-chemical, structural-mechanical, and organoleptic quality indices of two-layer jelly with modified carbohydrate composition has been investigated during storage.

Effect of the structure of cellulose acetate membranes on their permeability, electrical conductivity and rejection

1990 ◽  
Vol 55 (12) ◽  
pp. 2933-2939 ◽  
Author(s):  
Hans-Hartmut Schwarz ◽  
Vlastimil Kůdela ◽  
Klaus Richau
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Cellulose Acetate ◽  
Reverse Osmosis ◽  
Water Flux ◽  
Cellulose Acetate Membrane ◽  
Structure Parameters ◽  
Dc Electrical Conductivity ◽  
Cellulose Acetate Membranes

Ultrafiltration cellulose acetate membrane can be transformed by annealing into reverse osmosis membranes (RO type). Annealing brings about changes in structural properties of the membranes, accompanied by changes in their permeability behaviour and electrical properties. Correlations between structure parameters and electrochemical properties are shown for the temperature range 20-90 °C. Relations have been derived which explain the role played by the dc electrical conductivity in the characterization of rejection ability of the membranes in the reverse osmosis, i.e. rRO = (1 + exp (A-B))-1, where exp A and exp B are statistically significant correlation functions of electrical conductivity and salt permeation, or of electrical conductivity and water flux through the membrane, respectively.

scholarly journals Recuperative Amino Acids Separation through Cellulose Derivative Membranes with Microporous Polypropylene Fiber Matrix

Membranes ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 429
Author(s):  
Aurelia Cristina Nechifor ◽  
Andreia Pîrțac ◽  
Paul Constantin Albu ◽  
Alexandra Raluca Grosu ◽  
Florina Dumitru ◽  
...  
Keyword(s):  
Amino Acids ◽  
Cellulose Acetate ◽  
Polypropylene Fiber ◽  
Point Of View ◽  
Hydroxyethyl Cellulose ◽  
Separation Performance ◽  
Thermal Gravimetric Analyzer ◽  
Microfiltration Membranes ◽  
Ft Ir ◽  
Structural Point

The separation, concentration and transport of the amino acids through membranes have been continuously developed due to the multitude of interest amino acids of interest and the sources from which they must be recovered. At the same time, the types of membranes used in the sepa-ration of the amino acids are the most diverse: liquids, ion exchangers, inorganic, polymeric or composites. This paper addresses the recuperative separation of three amino acids (alanine, phe-nylalanine, and methionine) using membranes from cellulosic derivatives in polypropylene ma-trix. The microfiltration membranes (polypropylene hollow fibers) were impregnated with solu-tions of some cellulosic derivatives: cellulose acetate, 2-hydroxyethyl-cellulose, methyl 2-hydroxyethyl-celluloseand sodium carboxymethyl-cellulose. The obtained membranes were characterized in terms of the separation performance of the amino acids considered (retention, flux, and selectivity) and from a morphological and structural point of view: scanning electron microscopy (SEM), high resolution SEM (HR-SEM), Fourier transform infrared spectroscopy (FT-IR), energy dispersive spectroscopy (EDS) and thermal gravimetric analyzer (TGA). The re-sults obtained show that phenylalanine has the highest fluxes through all four types of mem-branes, followed by methionine and alanine. Of the four kinds of membrane, the most suitable for recuperative separation of the considered amino acids are those based on cellulose acetate and methyl 2-hydroxyethyl-cellulose.

Transport properties of Toray's asymmetric cellulose acetate membranes

Desalination ◽  
1985 ◽  
Vol 56 ◽  
pp. 251-260 ◽  
Author(s):  
M. Kurihara ◽  
W. Pusch ◽  
T. Tanaka
Keyword(s):  
Transport Properties ◽  
Cellulose Acetate ◽  
Cellulose Acetate Membranes

Quantitative alkaline phosphatase isoenzyme determination by electrophoresis on cellulose acetate membranes.

1977 ◽  
Vol 23 (1) ◽  
pp. 28-34 ◽  
Author(s):  
W H Siede ◽  
U B Seiffert
Keyword(s):  
Alkaline Phosphatase ◽  
Cellulose Acetate ◽  
Clinical Laboratory ◽  
Kinetic Assay ◽  
Specific Staining ◽  
Cellulose Acetate Membranes ◽  
Alkaline Phosphatase Isoenzymes ◽  
Elution Method ◽  
Routine Clinical Laboratory ◽  
Alkaline Phosphatase Isoenzyme

Abstract We present a new method for quantitative determination of alkaline phosphatase isoenzymes. This method consists of electrophoretic separation on cellulose acetate membranes, special fixation technique to avoid elution and diffusion of enzyme protein during incubation, specific staining, and quantitative evaluation by densitometric measurement. We highly recommend the precedure for routine clinical laboratory use. In all normal individuals we observe two isoenzymes of hepatic origin and one isoenzyme each of osseous, intestinal, and biliary origin. Quantitative normal values are presented. Precision of the method is calculated, the CV being less than 10%. The exactness of densitometric quantification is proved by comparison with kinetic assay of alkaline phosphatase isoenzymes by use of an elution method. Clinical implications of alkaline phosphatase isoenzymograms are reported and discussed in detail.

Rheology of hydrocarbon gels

1950 ◽  
Vol 200 (1061) ◽  
pp. 183-188 ◽  
Keyword(s):  
Mechanical Properties ◽  
Experimental Measurement ◽  
Theoretical Basis ◽  
Continuous Media ◽  
Point Of View ◽  
Coarse Grained ◽  
Testing Instrument ◽  
Fine Grained ◽  
Mineral Oils ◽  
Space And Time

Hydrocarbon gels contain a number of materials, such as rubber, greases, saponified mineral oils, etc., of great interest for various engineering purposes. Specific requirements in mechanical properties have been met by producing gels in appropriately chosen patterns of constituent components of visible, colloidal, molecular and atomic sizes, ranging from coarse-grained aggregates, represented by sponges, foams, emulsions, etc.; to fine-grained and apparently homogeneous ones, represented by optically clear compounds. The engineer who has to deal with the whole range of such materials will adopt a macroscopic point of view, based on an apparent continuity of all the material structures and of the distributions in space and time of the displacements and forces occurring under mechanical actions. It has been possible to determine these distributions in the framework of a comprehensive scheme in which the fundamental principles of the mechanics of continuous media provide the theoretical basis, and a testing instrument of new design, termed Rheogoniometer, the means of experimental measurement (Weissenberg 1931, 1934, 1946, 1947, 1948).

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