scholarly journals Influence of accompanying substances of hemp fibres on their electric resistance

2006 ◽  
Vol 60 (1-2) ◽  
pp. 33-38 ◽  
Author(s):  
Biljana Pejic ◽  
Koviljka Asanovic ◽  
Mirjana Kostic ◽  
Petar Skundric ◽  
Tatjana Mihajlidi
Keyword(s):  
Chemical Composition ◽  
Breaking Strength ◽  
Antimicrobial Effect ◽  
Natural Fibre ◽  
Electric Resistance ◽  
Cellulose Fibres ◽  
Natural Cellulose ◽  
Hemp Fibres ◽  
Modification Treatment

Hemp fibres belong to the group of natural, cellulose bast fibres. These fibres have exceptional properties such as: antimicrobial effect, absence of allergy effect, extraordinary sorption properties, good electro-physical properties (small static electricity in regard to other cellulose fibres) as well as high values of breaking strength (the natural fibre with the highest strength). However, hemp fibres have some defects: heterogeneous chemical composition, large quantity of accompanying substances (lignin pectins, waxes) and unsatisfactory fineness and eveness. It is possible to a great extent to eliminate or reduce, the defects of hemp fibres by of appropriate modification treatments. In order to determine the appropriate modification treatment of hemp fibres, the dependences between the chemical composition, fineness and electric resistance of hemp fibres were presented in this paper. In the experimental part of the paper, by the application of a procedure for the determination of the chemical composition, the accompanying supstances of hemp fibres were gradually removed. After each phase some fibrous substrates were separated. After that the fineness and electric resistance were determined. This experiment was conducted in order to define the influence of each component of hemp fibres on the fineness and electric resistance. In this paper, hemp fibres were modified by an aqueous solution of sodium hydroxide, under different conditions of modification. The influence of modification conditions on the fineness and electric resistance were studied.

scholarly journals Extraction and characterization of natural fibres form Elettaria Cardamomum

2021 ◽  
Vol 69 (2) ◽  
pp. 30-33
Author(s):  
Murugesan Sumithra ◽  
Gayathri Murugan
Keyword(s):  
Chemical Composition ◽  
Good Alternative ◽  
Single Fibre ◽  
Natural Fibres ◽  
Fibre Strength ◽  
Cellulose Fibres ◽  
Elettaria Cardamomum ◽  
Natural Cellulose ◽  
Alternative Sources

Natural fibres are one of the good alternative sources for replacing synthetic fibres and reinforcing polymer matrices because of their eco-friendly nature. The present study was undertaken to investigate the fibres extract from Elettaria Cardamomum plant. The extracted Elettaria Cardamomum fibre was treated with NaOH for softening. Natural cellulose fibres extracted from Elettaria Cardamomum stems (ECS) have been characterized for their chemical composition and physical properties.The chemical composition of Elettaria Cardamomumstems (ECS) fi bres is, cellulose 60.44%, lignin 25.25%, wax 0.53%, ash 5.45%. Regarding physical properties of the fibres, single fibre strength was evaluated and the result was compared with cotton fibre and linen fibre.

COMPOSICIÓN QUÍMICA Y ACTIVIDAD ANTIMICROBIANA DE EXTRACTOS DE MACROALGA Gracilaria vermiculophylla SOBRE Vibrio parahaemolyticus/ CHEMICAL COMPOSITION AND ANTIMICROBIAL ACTIVITY OF DIFFERENT EXTRACTS FROM THE MACROALGAE Gracilaria vermiculophylla AGAINST

Biotecnia ◽  
1969 ◽  
Vol 18 (2) ◽  
pp. 27-31
Author(s):  
Pablo Sergio Osuna Amarillas ◽  
Anselmo Miranda Baeza ◽  
Martha Elisa Rivas Vega ◽  
Edgard Esquer Miranda ◽  
Daniel García Bedoya ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Chemical Composition ◽  
Vibrio Parahaemolyticus ◽  
Pathogenic Bacteria ◽  
Antimicrobial Effect ◽  
Marine Macroalgae ◽  
Diffusion Method ◽  
Gracilaria Vermiculophylla ◽  
Agar Diffusion Method

La búsqueda de compuestos naturales como una alternativa ante el uso de antibióticos sintéticos ha tomado mucha importancia. Se ha demostrado que las macroalgas marinas contienen compuestos capaces de inhibir el crecimiento bacteriano, incluyendo bacterias patógenas para el humano. El objetivo del presente trabajo fue determinar el efecto de dos extractos (acetona y metanol) de la macroalga Gracilaria vermiculophylla sobre el crecimiento de la bacteria Vibrio parahaemolyticus. La determinación del efecto antimicrobiano de los extractos crudos se llevó a cabo utilizando el método de difusión en disco; para lo cual se utilizaron 10, 30 y 50 μL de los extractos en los sensidiscos. Se determinó que el volumen de 50 μL, con ambos extractos presentó los halos de inhibición más altos (3.24 mm para el extracto en metanol y 3.17 mm para el extracto en acetona). ABSTRACT The search for natural compounds as an alternative to the use of synthetic antibiotics has become increasingly important. It has been shown that the marine macroalgae contain compounds capable of inhibiting bacterial growth, including pathogenic bacteria for humans. The aim of this study was to determine the effect of two extracts (acetone and methanol) of macroalgae Gracilaria vermiculophylla on the growth of Vibrio parahaemolyticus. Determination of antimicrobial effect of the crude extracts was performed using the agar diffusion method; for which 10, 30 and 50 μL of the extracts were loaded on sterile antibiotic discs. It was determined that the 50 μL with both extracts showed higher inhibiting zone diameter (3.24 mm for the extract in methanol and 3.17 mm for the extract in acetone).

Preparation of graft copolymers by the reaction of polymeric acyl chlorides with monohydroxy-terminated polymers: An introductory study

1988 ◽  
Vol 53 (8) ◽  
pp. 1735-1744 ◽  
Author(s):  
Jitka Horská ◽  
Jaroslav Stejskal ◽  
Pavel Kratochvíl ◽  
Aubrey D. Jenkins ◽  
Eugenia Tsartolia ◽  
...  
Keyword(s):  
Light Scattering ◽  
Chemical Composition ◽  
Statistical Model ◽  
Graft Copolymers ◽  
Coupling Reaction ◽  
Molecular Characteristics ◽  
Gel Formation ◽  
Acyl Chlorides ◽  
Molecular Weights

An attempt was made to prepare well-defined graft copolymers by the coupling reaction between acyl chloride groups located along the backbone chain and monohydroxy-terminated grafts prepared separately. The molecular weights and the parameters of heterogeneity in chemical composition of the products were determined by light scattering and osmometry. The determination of molecular characteristics revealed that the degree of grafting was low. The results therefore could not be confronted with a statistical model at this stage. The problems encountered in the synthesis, e.g., gel formation, and the data relating to the soluble products are discussed.

Mechanical Behaviour of CoCrMo Alloy with Si Content

2015 ◽  
Vol 754-755 ◽  
pp. 1017-1022 ◽  
Author(s):  
Petrică Vizureanu ◽  
Mirabela Georgiana Minciună ◽  
Dragoş Cristian Achiţei ◽  
Andrei Victor Sandu ◽  
Kamarudin Hussin
Keyword(s):  
Tensile Strength ◽  
Chemical Composition ◽  
Testing Machine ◽  
Base Material ◽  
Optical Emission ◽  
Experimental Tests ◽  
Optical Emission Spectrometry ◽  
Emission Spectrometry ◽  
Standard Samples

.The paper present aspects about the obtaining of non-precious dental alloys (type CoCrMo and CoCrMoSi7), the determination of chemical composition by optical emission spectrometry and the experimental tests for determining the tensile strength, made on standard plate samples. The base material used in experiments was a commercial alloy, from CoCrMo system, which belongs to the class of dental non-precious alloys, intended to medical applications. The obtaining of studied alloy was made on arc re-melting installation, under vacuum, type MRF ABJ 900. The process followed to realize a rapid melting, with a maximum admissible current intensity. The samples for tests were obtained by casting in an electric arc furnace, under vacuum, in optimal conditions for melting and solidification and processing by electro-erosion, to eliminate all the disturbing factors which come by processing conditions for the samples. The determination of chemical composition for cobalt based alloys, by optical emission spectrometry, was made on SpectromaxX equipment with spark. The electrical discharge is made with the elimination of an energy quantity, fact which determine plasma forming and light issue. Tensile tests for standard samples, made from cobalt based alloy, was made on Instron 3382 testing machine, and assisted by computer. The obtained results are: elongation, elasticity modulus, tensile strength and offer complete information about the analyzed mechanical properties. For the certitude of obtained experimental results, the tests were made on samples with specific dimensions according ISO 6892-1:2009(E) standard, both for the tensile strength, and also machine operation.

Determination of Relationship between Chemical Composition of Electrolyte and Surface Sample Quality

2015 ◽  
Vol 669 ◽  
pp. 150-157
Author(s):  
Peter Michal ◽  
Alena Vagaská ◽  
Miroslav Gombár
Keyword(s):  
Sodium Chloride ◽  
Chemical Composition ◽  
Oxalic Acid ◽  
Boric Acid ◽  
Oxide Layer ◽  
Surface Finish ◽  
Chemical Factors ◽  
Substrate Sample

Paper tracks experimentally confirmed relationship between chemical composition of electrolyte and resulting surface finish quality of created oxide layer during the process of anodic oxidation of aluminium. Examined chemical factors were: concentrations of sulphuric acid, oxalic acid, boric acid and sodium chloride. Aggressive effects of electrolyte were chosen as indicator of resulting layer quality – presence and extent of etching of used substrate sample.

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