The Role of Intermolecular Forces in the Mechanism of High Elastic Deformation. III. Effect of Swelling on the Mechanical Properties of Vulcanized Rubber

1951 ◽  
Vol 24 (2) ◽  
pp. 344-353
Author(s):  
B. A. Dogadkin ◽  
V. Gul
Keyword(s):  
Elastic Deformation ◽  
Relative Elongation ◽  
Intermolecular Forces ◽  
Deformation Curves ◽  
Vulcanized Rubber ◽  
Maximum Value ◽  
Maximum Time ◽  
Gaseous Media ◽  
Mechanical Investigation

Abstract 1. The construction of an apparatus (elastometer) for the mechanical investigation of high elastic substances is described. This apparatus makes it possible to draw deformation curves and curves of the relaxation of stress atconstant temperature and in different gaseous media, and also to investigate the life at multiple deformations. The sensitivity of the apparatus is: ΔP=0.01 g., Δl=0.01 cm. 2. The molecular weight of the segments of the chains between the bonds of the spatial network of the vulcanizate, calculated by means of Flory's equation, increases with swelling, and approaches a certain maximum value. This is evidence of the rupture of the local intermolecular bonds on swelling. 3. The maximum time of relaxation, calculated according to the equation of Dogadkin, Bartenev, and Reznikovskil, as a consequence of swelling, generally does not change uniformly; it decreases with swelling of natural rubbers in benzene and chloroform in the initial stages, then increases, and finally decreases again in the last stages of swelling. 4. An increase of temperature displaces the minimum times of relaxation to lower degrees of swelling. 5. The increase of the maximum time of relaxation as a result of swelling causes a decrease of the life of the vulcanizate; a decrease of this factor is accompanied, at least within certain limits, by an increase of life. 6. Swelling causes a decrease of tensile strength and of the relative elongation of vulcanizates. 7. The changes recorded above in the equilibrium and kinetic characteristics of high elastic deformation are explained by the presence in the vulcanizate of different intermolecular bonds.

The Role of Intermolecular Forces in the Mechanism of High-Elastic Deformation. I. The Molecular Mechanism and an Equation for the Kinetics of High Elastic Deformation

1951 ◽  
Vol 24 (2) ◽  
pp. 336-343
Author(s):  
B. A. Dogadkin ◽  
G. M. Bartenev ◽  
M. M. Reznikovskii˘
Keyword(s):  
Molecular Structure ◽  
Molecular Mechanism ◽  
Elastic Deformation ◽  
Approximate Equation ◽  
Intermolecular Forces ◽  
Joint Application ◽  
Balanced Configurations ◽  
Kinetics Of ◽  
Constant Deformation

Abstract 1. The molecular mechanism of the relaxation of deformation of high-elastic polymers has been studied. 2. It is shown that the slow relaxation, which is typical of high-elastic polymers, may be best explained as a restoration process, which either partial or complete (depending on the degree of development of side chains in the molecular structure formed by the main valence chains) of the balanced configurations of the molecular chains. 3. It is shown that the rate of the relaxation process in this case is determined by the molecular activity of the particular polymer. 4. An approximate equation for the kinetics of high-elastic deformation which expresses qualitatively the mechanical properties of high-elastic polymers is proposed. 5. Hypotheses concerning the relation between the time of relaxation and the unbalanced stress are advanced. Equation (2) is derived as characteristic of this relation. 6. It is shown that the joint application of Equations (1) and (2) makes it possible to describe qualitatively the relaxation of stress at constant deformation.

The Role of Saline Aerosols in the Prevention and Therapy of Cardio-respiratory and Osteo-muscular Afflictions

2018 ◽  
Vol 69 (10) ◽  
pp. 2826-2832
Author(s):  
Ioan Gabriel Sandu ◽  
Viorica Vasilache ◽  
Andrei Victor Sandu ◽  
Marin Chirazi ◽  
Cezar Honceriu ◽  
...  
Keyword(s):  
Athletic Performance ◽  
Gaseous Medium ◽  
Human Subjects ◽  
Active Surface ◽  
Positive Influence ◽  
Climatic Parameters ◽  
Gaussian Distributions ◽  
Gaseous Media ◽  
Source Number

The saline aerosols generated in gaseous media, as nanodispersions, behave, with respect to the concentration levels and the lifespan, as trimodal distributions (the three domains with Gaussian distributions: fine or Aitken under 50 �m, medium between 50 and 500 mm and, respectively, coarse or large between 500 and 1000 mm). The generation in latent state is dependent on the active surface of the source (number of generator centres, the size and position of the fluorescences, the porosity, size and shape of the source, etc.), the climatic parameters, but also on a series of other characteristics of the gaseous medium. Our team has demonstrated experimentally that saline aerosols, NaCl type, besides the ability to prevent and treat broncho-respiratory and cardiac conditions, through coassistance of saline aerosols of other cations than sodium, and of the iodine anion, have for certain levels of concentrations propitious effects over the immune, bone and muscular systems. Similarly proved has been the positive influence on the development of children, as well the determinant role in increasing athletic performance and of other human subjects performing intense activities.

scholarly journals Influence of the Electrolyte Salt Concentration on DNA Detection with Graphene Transistors

Biosensors ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 24
Author(s):  
Agnes Purwidyantri ◽  
Telma Domingues ◽  
Jérôme Borme ◽  
Joana Rafaela Guerreiro ◽  
Andrey Ipatov ◽  
...  
Keyword(s):  
Phosphate Buffer ◽  
Species Interactions ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Limit Of Detection ◽  
Debye Length ◽  
Intermolecular Forces ◽  
Single Layer Graphene ◽  
Dna Adsorption

Liquid-gated Graphene Field-Effect Transistors (GFET) are ultrasensitive bio-detection platforms carrying out the graphene’s exceptional intrinsic functionalities. Buffer and dilution factor are prevalent strategies towards the optimum performance of the GFETs. However, beyond the Debye length (λD), the role of the graphene-electrolytes’ ionic species interactions on the DNA behavior at the nanoscale interface is complicated. We studied the characteristics of the GFETs under different ionic strength, pH, and electrolyte type, e.g., phosphate buffer (PB), and phosphate buffer saline (PBS), in an automatic portable built-in system. The electrostatic gating and charge transfer phenomena were inferred from the field-effect measurements of the Dirac point position in single-layer graphene (SLG) transistors transfer curves. Results denote that λD is not the main factor governing the effective nanoscale screening environment. We observed that the longer λD was not the determining characteristic for sensitivity increment and limit of detection (LoD) as demonstrated by different types and ionic strengths of measuring buffers. In the DNA hybridization study, our findings show the role of the additional salts present in PBS, as compared to PB, in increasing graphene electron mobility, electrostatic shielding, intermolecular forces and DNA adsorption kinetics leading to an improved sensitivity.

Role of Intermolecular Forces in Defining Material Properties of Protein Nanofibrils

Science ◽  
2007 ◽  
Vol 318 (5858) ◽  
pp. 1900-1903 ◽  
Author(s):  
T. P. Knowles ◽  
A. W. Fitzpatrick ◽  
S. Meehan ◽  
H. R. Mott ◽  
M. Vendruscolo ◽  
...  
Keyword(s):  
Material Properties ◽  
Intermolecular Forces

Workload Thresholds for Human Performance Models

2017 ◽  
Vol 61 (1) ◽  
pp. 781-785
Author(s):  
Dick Steinberg ◽  
Dan Donohoo ◽  
Laura Strater ◽  
Alice Diggs
Keyword(s):  
Human Performance ◽  
Food Service ◽  
Design Decisions ◽  
Service Workers ◽  
Loss Of Life ◽  
Maximum Time ◽  
Operator Tasks ◽  
Food Service Workers ◽  
The Times

Human performance modeling (HPM) can be an effective tool to use for determining crew designs. Crew design includes determining the number of operators needed, the role of automation, and member task responsibilities required to operate a system. Without effective measures of performance and thresholds for assessing success, design decisions from HPM will be erroneous. Operator tasks can be assigned and allocated to crew members in a simulation to estimate the workload for each operator during a period of performance. The methods for determining when an operator exceeds workload thresholds create challenges for those using HPM for crew design. Some types of analysis have more clearly defined thresholds. For example, if a military operator has too many tasks to complete to effectively initiate countermeasures between the times they receive a warning until the time the threat arrives, they are overloaded and cannot complete their mission. However, many missions do not have such a severe penalty for not completing the tasks within a given time. For example, pharmacists, satellite managers, traffic managers, food service workers do not have such stringent task timing completion thresholds. For example, the penalty for a food service provider to be overloaded is typically extended wait times rather than risk of a loss of life. For these types of operational situations, determining overload is much more challenging. This paper describes a new workload thresholds for operator workflow models. It incorporates the vigilance effort, the maximum time a crew member will be fully loaded, and determining the maximum time worked without a break.

The Enhanced Pyrocatalysis of the Pyroelectric BiFeO3/g-C3N4 Heterostructure for Dye Decomposition Driven by Cold-hot Temperature Alternation

2020 ◽  
Author(s):  
Mingzi Chen ◽  
Yanmin Jia ◽  
Huamei Li ◽  
Zheng Wu
Keyword(s):  
Rhodamine B ◽  
Potential Application ◽  
Temperature Fluctuation ◽  
Dye Wastewater ◽  
Pyroelectric Effect ◽  
Intermediate Products ◽  
Hot Temperature ◽  
Dye Decomposition ◽  
Maximum Value

Abstract The BiFeO3/g-C3N4 heterostructure, which is fabricated via a simple mixing-calcining method, benefits the significant enhancement of the pyrocatalytic performance. With the growth of the g-C3N4 content in the heterostructure pyrocatalysts from 0 to 25 %, the decomposition ratio of Rhodamine B (RhB) dye after 18 cold-hot temperature fluctuation (25 oC - 65 oC) cycles increases at first and then decreases, reaching a maximum value of ~ 94.2 % at 10% while that of the pure BiFeO 3 is ~ 67.7 %. The enhanced dye decomposition may be due to the fabrication of the heterostructure which strengthens the separation of the positive and negative carriers and further accelerates their migration. The intermediate products in the pyrocatalytic reaction also have been detected and confirmed, which proves the key role of the pyroelectric effect in realizing the dye decomposition using BiFeO3/g-C3N4 heterostructure catalyst. The pyroelectric BiFeO3/g-C3N4 heterostructure shows the potential application in pyrocatalytically degrading dye wastewater.

Role of Long-Range Intermolecular Forces in the Formation of Inorganic Nanoparticle Clusters

2011 ◽  
Vol 115 (45) ◽  
pp. 12933-12940 ◽  
Author(s):  
G. V. Gibbs ◽  
T. D. Crawford ◽  
A. F. Wallace ◽  
D. F. Cox ◽  
R. M. Parrish ◽  
...  
Keyword(s):  
Long Range ◽  
Intermolecular Forces ◽  
Inorganic Nanoparticle ◽  
Nanoparticle Clusters

Intermolecular forces between low generation PAMAM dendrimer condensed DNA helices: role of cation architecture

Soft Matter ◽  
2014 ◽  
Vol 10 (4) ◽  
pp. 590-599 ◽  
Author(s):  
Min An ◽  
Sean R. Parkin ◽  
Jason E. DeRouchey
Keyword(s):  
Intermolecular Forces ◽  
Pamam Dendrimer ◽  
Condensed Dna
Sign in / Sign up

Export Citation Format

Share Document