Mechanical Method of Determination of the Vitrification Temperature of Rubberlike Polymers

1956 ◽  
Vol 29 (4) ◽  
pp. 1174-1180
Author(s):  
A. I. Marei
Keyword(s):  
Temperature Region ◽  
Constant Stress ◽  
Mechanical Method ◽  
Vitrification Temperature ◽  
Method Of Determination ◽  
Compression Deformation

Abstract 1. A mechanical method has been developed for the determination of the vitrification temperature of rubberlike polymers, based on measurement of the compression deformation of polymer samples in the vitrification temperature region under a constant stress. 2. An apparatus for the determination of the vitrification temperature of polymers by the mechanical method is described. 3. The vitrification temperatures of a series of polymers have been determined. The agreement of results of the determination of the vitrification temperature of the polymers by mechanical and by other methods is shown.

The Determination of the Optimum Vulcanization by Means of the Residual Elongation

1935 ◽  
Vol 8 (4) ◽  
pp. 548-553 ◽  
Author(s):  
A. Kusov
Keyword(s):  
Bending Strength ◽  
Mechanical Tests ◽  
Mechanical Method ◽  
Chemical Examination ◽  
Method Of Determination ◽  
Physico Chemical ◽  
Special Cases ◽  
Actual Service ◽  
The Many

Abstract As is well known, various methods have been proposed for determining the optimum vulcanization of rubber. These methods depend either upon physico-chemical examination or upon mechanical tests. In routine control the mechanical method of determination is used for the most part, because it requires but little time, and in addition this method has the advantage of showing directly by mechanical tests whether the vulcanizate being tested passes the requirements or not. The results obtained by this method frequently do not agree with those obtained by other methods. Of the many common methods of testing, determinations of the tensile strength and of the ultimate and residual elongation are the methods most frequently used. These three properties are measured simultaneously by one determination with the apparatus in most widespread use, i. e., the Schopper and the Scott machines. In special cases the resistance to abrasion, bending strength, hardness, and other properties are determined in addition. Considerably less often the hysteresis and Young's modulus of elasticity are determined. All these determinations are of significance in only a limited way, for the conditions under which the tests are carried out in the laboratory are not comparable to the actual service of the products. For basic reasons, this fundamental shortcoming cannot be avoided in the laboratory, though a few of the measurements do approach the true properties found in service. Of course, the results obtained in the laboratory are greatly influenced and made less reliable by other secondary factors, among which are the phenomenon of aging under natural conditions, prolonged stressing, etc.

Development of a method for multielemental determination in water by EDXRF with radioisotopic source of 238Pu.

2019 ◽  
Vol 7 (2A) ◽  
Author(s):  
Camilo Fuentes Serrano ◽  
Juan Reinaldo Estevez Alvares ◽  
Alfredo Montero Alvarez ◽  
Ivan Pupo Gonzales ◽  
Zahily Herrero Fernandez ◽  
...  
Keyword(s):  
Thin Layer ◽  
Expanded Uncertainty ◽  
Considerable Decrease ◽  
X Ray ◽  
Precipitation Efficiency ◽  
Method Of Determination ◽  
Sensitivity Curves ◽  
Order Of Magnitude ◽  
Metrological Parameters

A method for determination of Cr, Fe, Co, Ni, Cu, Zn, Hg and Pb in waters by Energy Dispersive X Ray Fluorescence (EDXRF) was implemented, using a radioisotopic source of 238Pu. For previous concentration was employed a procedure including a coprecipitation step with ammonium pyrrolidinedithiocarbamate (APDC) as quelant agent, the separation of the phases by filtration, the measurement of filter by EDXRF and quantification by a thin layer absolute method. Sensitivity curves for K and L lines were obtained respectively. The sensitivity for most elements was greater by an order of magnitude in the case of measurement with a source of 238Pu instead of 109Cd, which means a considerable decrease in measurement times. The influence of the concentration in the precipitation efficiency was evaluated for each element. In all cases the recoveries are close to 100%, for this reason it can be affirmed that the method of determination of the studied elements is quantitative. Metrological parameters of the method such as trueness, precision, detection limit and uncertainty were calculated. A procedure to calculate the uncertainty of the method was elaborated; the most significant source of uncertainty for the thin layer EDXRF method is associated with the determination of instrumental sensitivities. The error associated with the determination, expressed as expanded uncertainty (in %), varied from 15.4% for low element concentrations (2.5-5 μg/L) to 5.4% for the higher concentration range (20-25 μg/L).

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