Effects of electronic and recoil processes in polymers during ion implantation

1994 ◽  
Vol 9 (4) ◽  
pp. 1043-1050 ◽  
Author(s):  
E. H. Lee ◽  
G. R. Rao ◽  
M. B. Lewis ◽  
L. K. Mansur
Keyword(s):  
Energy Transfer ◽  
Ion Implantation ◽  
Cross Sections ◽  
Linear Energy Transfer ◽  
Chemical Properties ◽  
Polymeric Materials ◽  
Track Length ◽  
Property Changes ◽  
Physical And Chemical ◽  
Ion Species

It has been shown that ion implantation produces remarkable improvements in surface-sensitive mechanical properties, as well as other physical and chemical properties in polymers. To understand mechanisms underlying such property changes, various polymeric materials were subjected to bombardment by energetic ions in the range of 200 keV to 2 MeV. The magnitude of property changes is strongly dependent upon ion species, energy, and dose. Analysis indicated that hardness and electrical conductivity increased by employing ion species with larger electronic cross sections and with increasing ion energy and dose. The results showed that electronic stopping or linear energy transfer (LET, energy deposited per unit track length per ion) for ionization was the most important factor for the enhancement of hardness, while nuclear stopping or linear energy transfer for displacement generally appeared to reduce hardness.

scholarly journals The Impact of an Inert Gas Atmosphere on the Kinetics of Changes in the Physical and Chemical Properties of Carrot Lyophilisate

2019 ◽  
Vol 16 (1-2) ◽  
Author(s):  
D. Nowak
Keyword(s):  
Cross Sections ◽  
Storage Time ◽  
Chemical Properties ◽  
Sorption Properties ◽  
Carotenoid Content ◽  
Freeze Dried ◽  
Gas Atmosphere ◽  
Colour Parameters ◽  
Physical And Chemical ◽  
The Impact

AbstractThe purpose of this study was to analyse the impact of blanching, the atmosphere of nitrogen and storage time on carotenoids content, colour and sorption properties of freeze-dried carrot. The material was stored for up to 16 weeks, in the dark, at room temperature. The colour was measured on the surface and in cross sections. As the storage time increased, there was a continual decrease in the carotenoids content in the carrot packed in atmospheric air. In the carrots packed in the atmosphere of nitrogen, no changes in carotenoid content were observed. The colour parameters correlated with the changes in the carotenoids content. The colour parameters changed on the surface and in cross sections in the same manner. During storage, a significant decrease in sorption properties of freeze-dried carrots was noted after 2 weeks of storage.

scholarly journals The Bilateral Structure of Wool Cortex and Its Relation to Crimp

1955 ◽  
Vol 8 (2) ◽  
pp. 288 ◽  
Author(s):  
RDB Fraser ◽  
GE Rogers
Keyword(s):  
Cross Sections ◽  
Chemical Properties ◽  
Sulphur Content ◽  
Wool Fibre ◽  
Physical And Chemical Properties ◽  
Cortical Cells ◽  
Basic Dyes ◽  
The Difference ◽  
Physical And Chemical ◽  
And Chemical Properties

Xew evidence of the nature of the bilateral cortex in crimped wool is presented and discussed in relation to the physical and chemical properties of the wool fibre. The origin of the asymmetry in the cortex was studied by cutting cross sections of sheep skin and swelling plucked wool roots. It is shown that the bilateral structure is present before the cortex is keratinized and does not originate from an asymmetrical keratinization as has been suggested. Coarse wools, in which crimp is much less, are shown to possess a radial asymmetry in which the peripheral cortical cells are less accessible to basic dyes and have a higher sulphur content than the central cells. This is related to the difference between the curved follicles from which fine fibres are produced and the straighter follicles producing coarse fibres.

scholarly journals Distribution of fire extinguishing powder fractions in simulated non-stationary gas stream

2020 ◽  
Vol 28 (6) ◽  
pp. 80-88
Author(s):  
A. S. Polyakov ◽  
D. F. Kozhevin ◽  
A. S. Konstantinova
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Fractional Composition ◽  
Chemical Properties ◽  
Fire Extinguisher ◽  
Fire Extinguishing ◽  
Powder Samples ◽  
Powder Particles ◽  
Physical And Chemical ◽  
Flow Cross

Introduction. The article presents the regularities of particles distribution of fire extinguishing powder fractions in the cross sections of the simulated unregulated non-stationary gas stream. The distance from the fire extinguisher cut which the stream is most stable in terms of the content of fire extinguishing powder particles is determined. There are works in which the physical and chemical properties of fire-extinguishing powders are considered, the movement of powder particles in the stream is modeled, the influence of the fractional composition of the powder on its fire-extinguishing capacity is determined. At the same time distribution of powder fractions during its movement in gas-powder stream is not considered. The purpose of the present work is to find ways to improve the efficiency of powder extinguishers by controlling the distribution of powder fractions in a non-stationary gas stream.Materials and methods. Experimental study installation consists of coordinate table oriented perpendicular to gas-powder stream direction. The table is equipped with collectors that allow to collect powder samples at control points of flow cross-section. Food sodium chloride (further — salt) was used in the experiment. Its characteristics correspond to GOST R 53280.4–2009 and allow to apply it as a model. The coordinate table was installed sequentially at a distance of 500, 750, 1000 and 1250 mm from the fire extinguisher cut. Next, a shot of salt with a known fractional composition was supplied with a fire extinguisher model to a coordinate table and the retained powder samples were taken. The mass and fractional composition of the samples collected by each collector were then determined. Stability of the particle distribution in the gas stream by statistical analysis (by Fischer’s criterion) was measured for their content.Conclusions. Regularities of different fire extinguishing powder fractions distribution in cross section of non-regulated non-stationary gas stream are established and analytically described. These regularities can be used in finding ways to regulate fire extinguishing powder fractions during fire extinguishing. The most representative and stable in accuracy (correctness and precision) results of powder fractions content in the section of non-stationary gas stream at a distance of 1000 mm from the fire extinguisher cut. This should be taken into account in further research.

scholarly journals Influence of NaCl on the polymerization of vinyl monomers by the suspension process

2019 ◽  
pp. 19-23
Author(s):  
Erika Montero ◽  
David Contreras-López ◽  
Rosalba Fuentes ◽  
María Del Rosario Galindo
Keyword(s):  
Batch Reactor ◽  
Research Work ◽  
Chemical Properties ◽  
Polymeric Materials ◽  
Operating Conditions ◽  
Suspension Process ◽  
Different Types ◽  
Physical And Chemical ◽  
And Chemical Properties

The production of artificial polymers is, today, one of themost important activities of the chemical industry, polymersare widely used in everyday life, as, there are different types of polymers, they can be used for different uses. These polymeric materials have unique mechanical, physical and chemical properties, which most other materials do not possess, not to mention that its cost is lower than the other materials. The present research work focuses on the determination of optimal operating conditions for the polymerization of styrene and methyl methacrylate in a Batch reactor, as well as the influence of inorganic salt in this case NaCl in the performance of reaction and in the size of the material polymer, through the process of suspension using a synthetic route of polymerization by radical free conventional (FRP), where viscometry to the polymeric material testing was performed for this way characterize it, and to determine factors of interest such as the molecular weight, etc.

scholarly journals Novelty Designed Hybrid Organic-Inorganic Nanocomposites from Functional Palm Oil

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Suryani Suryani
Keyword(s):  
Thermal Stability ◽  
Palm Oil ◽  
Chemical Properties ◽  
Polymeric Materials ◽  
Clay Nanocomposites ◽  
X Ray Diffraction ◽  
Domain Structures ◽  
Wide Range ◽  
Inorganic Nanocomposites ◽  
Physical And Chemical

Polyurethanes (PUs) are very versatile polymeric materials with a wide range of physical and chemical properties. PUs also have desirable properties such as high abrasion resistance, tear strength, shock absorption, flexibility and elasticity. Although they have poor thermal stability that however can be improved by using treated clay. The objective of the present work is to study the thermal stability of polyurethane, polyurethane/montmorillonite (PU CTAB-mont 3% wt) and polyurethane/montmorillonite that contain moca nanocomposites are based on palm oil polyol. The interest of investigating the synthesis of polyurethane/clay nanocomposites based on palm oil polyol is to explore the use of palm oil polyol to replace petrochemical based polyol partially. Polyurethane/clay nanocomposites were prepared by a pre-polymer method and were evaluated by fourier transform infrared spectra (FTIR) to determine micro-domain structures of segmented PU, PU CTAB-mont 3% wt, and PU Moca CTAB-mont 3% wt. The morphology of the nanocomposites were characterized by X-ray diffraction (X-RD) and flame retardant was investigated with thermogravimetric analysis (TGA). The result showed that adding clay and moca demonstrated better thermal stability in comparison with the virgin polyurethane.Keywords : Nanocomposite, polyurethane, synthesis, palm oil polyol

scholarly journals Implementation of a remote laboratory for the identification of polymeric materials by means of physical properties analysis

2021 ◽  
Vol 2102 (1) ◽  
pp. 012008
Author(s):  
C O Vargas-Mantilla ◽  
W Palacios-Alvarado ◽  
B Medina-Delgado
Keyword(s):  
Physical Properties ◽  
Engineering Students ◽  
Chemical Properties ◽  
Polymeric Materials ◽  
Experimental Tests ◽  
Nonparametric Tests ◽  
Point Of View ◽  
Remote Laboratory ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract Due to the strategies implemented to carry out the development of a correct teaching by virtual means, a methodological strategy of experimental tests was developed for the identification of polymeric materials through the identification of physical and chemical properties, with the objective of providing the engineering student a greater approach to the application of the scientific method and the activation of the capacity of reasoning and deductive thinking from the physical and chemical point of view. Therefore, the purpose of this research was to validate this strategy implemented with a group of engineering students, for this purpose, the strategy was implemented, and the results obtained by the students from the development of the experimentation were analyzed, the data were analyzed by means of nonparametric tests, in this case binomial test. Finally, it is concluded that the polymer identification test is feasible to be implemented as a remote laboratory, as a methodical strategy in teaching, since it allows the development of experimentation, in this case, the identification of polymeric materials, which present diverse physical properties.

Glass-Iron-Clay interactions in a radioactive waste geological disposal: a multiscale approach

2013 ◽  
Vol 1518 ◽  
pp. 185-190 ◽  
Author(s):  
Diane Rébiscoul ◽  
Emilien Burger ◽  
Florence Bruguier ◽  
Nicole Godon ◽  
Jean-Louis Chouchan ◽  
...  
Keyword(s):  
Cross Sections ◽  
Metallic Iron ◽  
Driving Forces ◽  
Chemical Properties ◽  
Multiscale Approach ◽  
Spent Fuel ◽  
Iron Source ◽  
Geological Repository ◽  
Physical And Chemical ◽  
The Impact

ABSTRACTIn France, nuclear glass canisters arising from spent fuel reprocessing are expected to be disposed in a deep geological repository using a multi-barrier concept (glass/canister/steel overpack and claystone). In this context, glass - iron or corrosion products interactions were investigated in a clayey environment to better understand the mechanisms and driving forces controlling the glass alteration. Integrated experiments involving glass - metallic iron or magnetite - clay stacks were run at laboratory scale in anoxic conditions for two years. The interfaces were characterized by a multiscale approach using SEM, TEM, EDX and STXM at the SLS Synchrotron. Characterization of glass alteration patterns on cross sections revealed various morphologies or microstructures and an increase of the glass alteration with the proximity between the glass and the source of iron (metallic iron or magnetite) due to the consumption of the silica coming from the glass alteration. In case of magnetite, the silica consumption is mainly driven by a sorption of silica onto the magnetite. For experiments containing metallic iron, the silica consumption seems to be strongly driven by silicates precipitation including Fe and Fe/Mg when the Fe is not enough available. Moreover, in addition to Fe-silicates observed at the surface of the gel layers, iron is incorporated within the gel probably as nanosized precipitates of Fe-silicates which could affect its physical and chemical properties. Those results highlighted the impact of the distance between glass and iron source and the nature of the iron source which drive the process consuming the silica coming from the glass alteration.

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