The Impact Resiliometer

1934 ◽  
Vol 7 (3) ◽  
pp. 591-598 ◽  
Author(s):  
Paul Lüpke
Keyword(s):  
Elastic Properties ◽  
Physical Science ◽  
Sustained Load ◽  
Plastic Properties ◽  
Dual Nature ◽  
Hardness Tester ◽  
Vulcanized Rubber ◽  
Rubber Compounds ◽  
The Impact ◽  
Average User

Abstract Original Purpose The writer's first conception of an instrument for quickly measuring the resilience of rubber samples arose in connection with the basic idea for and development of the present A.S.T.M. hardness tester, in an endeavor to provide a reproducible means of measuring and expressing those properties of rubber compounds superficially apparent to the average user. It seemed that if the resistance to pressure (indenting or flexing) and the pressure, or force, of recovery, of a sample were duplicated, the article produced would “feel” the same as the sample, and under normal conditions of use would act mechanically the same. Nature of Problem This problem of measurement, as is generally known, is complicated by the time-hysteresis characteristic of vulcanized rubber compounds, arising through a dual nature, and causing them to manifest both elastic and plastic properties. Any instrument which applies load momentarily measures the almost purely elastic properties, while one which applies a more or less sustained load measures elastic properties modified by the material's partially plastic nature. These ideas are expressed from commercial and industrial viewpoints without regard to their possible deviations from the strict definitions accepted in physical science.

High Temperature Vulcanization of Elastomers

1979 ◽  
Vol 52 (4) ◽  
pp. 725-734 ◽  
Author(s):  
A. K. Bhowmick ◽  
R. Mukhopadhyay ◽  
S. K. De
Keyword(s):  
Thermal Conductivity ◽  
Plastic Material ◽  
Plastic Properties ◽  
Microwave Curing ◽  
The Past ◽  
Vulcanized Rubber ◽  
Upper Limit ◽  
Rubber Compounds ◽  
Higher Temperature ◽  
Made In

Abstract Vulcanization is a process which decreases the plastic properties of rubber while maintaining or improving the elastic properties. The term vulcanization has been applied in the past mainly to the reaction of rubber with sulfur, but now is generally used for the process which results in changes in properties, by sulfur or some other agent. There are four principal changes brought about by vulcanization: (1) rubber is changed from essentially a plastic to a non-plastic material; (2) rubber is changed from a material soluble in a number of solvents to one which is insoluble; (3) rubber is changed to a material with greatly improved physical properties; (4) these properties of vulcanized rubber are maintained over a much wider range of temperature than those of unvulcanized rubber. What is meant by high vulcanizing temperature? There is no unique answer. About 160°C can be taken conveniently as the lower limit; this temperature has been suggested as the highest suitable for some normally compounded sulfur curing rubbers. The upper limit may be 220°C, above which the polymer may begin to degrade. The range in practice extends up to about 250°C in fluid beds and salt baths. Practical vulcanization processes apply heat to the outside of the article being cured and rely on the conduction of heat to the inside. Since no drastic change can be made in the thermal conductivity of practical rubber compounds by compounding modifications, higher temperature is a common method of achieving faster vulcanization. Higher curing temperatures are used in the newer curing or molding processes such as injection molding, the liquid curing medium (LCM) process, and microwave curing.

The Behavior of Rubber at Low Temperatures

1939 ◽  
Vol 12 (2) ◽  
pp. 344-364 ◽  
Author(s):  
M. Sagajłło ◽  
J. BobiŃska ◽  
H. Saganowski
Keyword(s):  
Elastic Properties ◽  
Low Temperatures ◽  
Small Degree ◽  
Freezing Resistance ◽  
Shock Absorbers ◽  
Vulcanized Rubber ◽  
Rubber Compounds ◽  
The Difference ◽  
Winter Time ◽  
High Degree

Abstract (1) Raw rubber, smoked sheet as well as crepe, freezes to a high degree at low temperatures. The difference between the freezing at −10° and −60° C. is comparatively small at initial elongations of 300 and 400%. With smaller initial elongations there is a greater difference in degree of freezing at temperatures of − 10° and −60° C. A complete loss of the elastic properties of the rubber takes place at −70° C. (2) Previous heating of raw rubber, even at a temperature of 140° C, has no effect on its freezing-resistance. (3) The susceptibility of rubber to freezing increases with increase of the elongation, this effect being strongly marked above an elongation of 200%. (4) An increase in the vulcanization temperature, and therefore a shortening of the vulcanizing time, has only an insignificant effect on the freezing-resistance of rubber compounds. (5) The freezing effect increases as the temperature is lowered. (6) An entire loss of the elastic properties of vulcanized rubber takes place for the lower initial elongations at a temperature of —70° C; for higher elongations; however, they are still retanied at this temperature in a very small degree. (7) “Pure” rubber compounds have a much greater resistance to freezing than loaded ones. (8) The minimum susceptibility to freezing for loaded compounds is obtained with those that are slightly overvulcanized. At the higher elongations this minimum is distinctly shifted into the region of overvulcanization. (9) Softeners have in general no effect in reducing susceptibility to freezing. (10) The use of phenyl-β-naphthylamine has no effect on the susceptibility to freezing. (11) The aging of rubber, even when producing 40% of loss of tensile product, has no effect in lowering its resistance to freezing either at −10° or −60° C. and at initial elongations of from 100 to 400%. On the other hand, the resistance to freezing of aged samples is less at temperatures of −40° and −50° C. with initial elongations of 100 to 200% ; at an initial elongation of 300% they show almost no change in relation to unaged samples, while at an elongation of 400% they show a distinct increase in resistance to freezing. (12) Airplane and balloon shock-absorbers of “pure” rubber compounds possess, within the limits of their elongation during use, even at a temperature of — 40° C, quite insignificant susceptibility to freezing. An entire loss of their elastic properties occurs at −70° C. (13) Keeping airplanes in improvised sheds in winter time even at −20° C. has practically no effect on the usefulness of rubber shock-absorbers.

scholarly journals Air mediates the impact of a compliant hemisphere on a rigid smooth surface

Soft Matter ◽  
2021 ◽  
Author(s):  
Siqi Zheng ◽  
Sam Dillavou ◽  
John M. Kolinski
Keyword(s):  
Elastic Body ◽  
Elastic Properties ◽  
Impact Velocity ◽  
Solid Surface ◽  
High Speed ◽  
Smooth Surface ◽  
High Speed Imaging ◽  
The Impact ◽  
Rigid Smooth

When a soft elastic body impacts upon a smooth solid surface, the intervening air fails to drain, deforming the impactor. High-speed imaging with the VFT reveal rich dynamics and sensitivity to the impactor's elastic properties and the impact velocity.

scholarly journals The Impact of the Church–State Model for an Effective Guarantee of Religious Freedom: A Study of the Peruvian Experience during the COVID-19 Pandemic

Laws ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 40
Author(s):  
Susana Mosquera
Keyword(s):  
Religious Freedom ◽  
Current Crisis ◽  
Dual Nature ◽  
Legal Model ◽  
The Individual ◽  
The Right ◽  
Institutional Guarantee ◽  
The Impact ◽  
Individual Dimension ◽  
The Church

During the COVID-19 pandemic, many governments established important restrictions on religious freedom. Due to a restrictive interpretation of the right to religious freedom, religion was placed in the category of “non-essential activity” and was, therefore, unprotected. Within this framework, this paper tries to offer a reflection on the relevance of the dual nature of religious freedom as an individual and collective right, since the current crisis has made it clear that the individual dimension of religious freedom is vulnerable when the legal model does not offer an adequate institutional guarantee to the collective dimension of religious freedom.

Effect on Vulcanized Rubber Compounds of Immersion in Boiling Water

1931 ◽  
Vol 4 (3) ◽  
pp. 426-436
Author(s):  
K. J. Soule
Keyword(s):  
Water Absorption ◽  
Room Temperature ◽  
Anomalous Behavior ◽  
Boiling Water ◽  
Vulcanized Rubber ◽  
Rubber Compounds ◽  
Different Temperatures ◽  
Actual Change

Abstract Further work is very desirable on the effect of different accelerators, antioxidants, and fluxes. It is possible that their study will throw more light on the mechanism of the swelling phenomena, and also help to explain the anomalous behavior of some of the fillers tested. It would also seem to be worth while to study the action of a few selected stocks in water, at several temperatures between room temperature and 100° C., to determine if the water absorption and swelling merely increase with rising temperatures, or whether there might be an actual change in behavior at different temperatures.

The Oil Resistance of Rubber. I Study of the Swelling of Vulcanized Rubber

1936 ◽  
Vol 9 (1) ◽  
pp. 70-73
Author(s):  
Yoshio Tanaka ◽  
Shû Kambara ◽  
Jirô Noto
Keyword(s):  
Molecular Structure ◽  
Elastic Properties ◽  
Mixed Solvents ◽  
Experimental Results ◽  
Stress Strain ◽  
Oil Resistance ◽  
Effect Of Solvents ◽  
Vulcanized Rubber

Abstract To study the effect of solvents on the elastic properties of vulcanized rubber, the following three points were investigated. 1. The swelling maximum obtained by various mixed solvents. 2. The stress-strain curves of rubber swollen to different degrees. 3. Time-swelling and time-deswelling curves. The spiral theory of molecular structure of rubber proposed by Fikentscher and Mark is utilized to explain the experimental results.

scholarly journals On Selecting Approaches to Analysis of the Residential Property Market

2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Natalya Kovalevskaya ◽  
Vladislav Tyunkov
Keyword(s):  
Real Estate ◽  
Residential Property ◽  
Property Market ◽  
Dual Nature ◽  
Factors Affecting ◽  
Market Participants ◽  
Consumer Interests ◽  
Private Investors ◽  
The Impact ◽  
Private Individual

The article examines the issues of developing the residential property market taking into account the specifics of real estate as an object of the economic analysis. It reveals the terms of implementing economic interest in investing in residential property, identifies the features inherent in the residential property market as investment and commodity markets. It analyses the dual nature of real estate which explains the development of investment and consumer interests of the residential property market participants. The article analyses the interrelation of «saving - investment - consumption» at the level of implementing private (individual) interests of economic subject. It makes a comparison of various investment assets in terms of their attractiveness for private investors, depending on various factors affecting the decision to invest. It analyses the terms that allow to fully disclose the investment or consumer aspects of the residential property market. It considers the impact of the governmental investment policy directed at supporting and promoting development aspects of the residential property market.

scholarly journals The family social status role in formation of competitive orientation and competitiveness of high school students

2019 ◽  
Vol 25 (3) ◽  
pp. 140-155
Author(s):  
L. V. Gulyayeva ◽  
M. Y. Semenov
Keyword(s):  
High School ◽  
High School Students ◽  
Social Status ◽  
Questionnaire Survey ◽  
Family Income ◽  
School Students ◽  
Dual Nature ◽  
The Family ◽  
The Impact

The family is one of the key factors influencing values, attitudes to work, professional self-determination and life plans of high school students. The article is devoted to the consideration of family social status role of modern high school students in formation of their competitive orientation and competitiveness.The article analyzes results of theoretical works of Russian and foreign researchers devoted to the analysis of family social capital influence to the educational strategies of adolescents. The methodological basis of the study was a questionnaire survey of high school students conducted in the cities of Tyumen, Tobolsk, Ishim and rural areas of the Tyumen region. IBM SPSS Statistics 23 was used to analyze the data.Considering family social status as the basis of young people “social start” in adulthood, authors note the dual nature of the role of this characteristic in the process of social adaptation of the younger generation. Based on the analysis of the data of questionnaire survey of high school students, the authors conclude differences of opinion on the importance of competitiveness as a necessary quality of personality.According to the results of the study it is shown that in addition to the level of family income, significant characteristics in their social status that affect the competitive orientation and competitiveness of high school students are also the level of parent’s education and their composition (full or single-parent families). It was confirmed that there is a correlation between the respondents’ assessment of personal competitive potential and the socio-professional status of the family.As possible directions for further research can be considered the study of the impact of the level of regional development on competitiveness formation process of high school students, as well as the role of teachers in this process.

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