THERMAL STUDIES ON ASBESTOS: II. EFFECT OF HEAT ON THE BREAKING STRENGTH OF ASBESTOS TAPE AND GLASS FIBRE TAPE

1941 ◽  
Vol 19b (2) ◽  
pp. 56-60
Author(s):  
D. Wolochow
Keyword(s):  
Glass Fibre ◽  
Breaking Strength ◽  
Thermal Studies ◽  
Chrysotile Asbestos ◽  
Rapid Loss ◽  
Prolonged Heating ◽  
Adsorbed Moisture

The first result of heating pure chrysotile asbestos tape, crocidolite (blue) asbestos tape, and glass fibre tape to drive off the adsorbed moisture is an increase in breaking strength.Pure chrysotile tape does not lose strength till a temperature of 370 °C. is exceeded. Prolonged heating at 430 °C. causes a loss in strength of about 20%, at 480 °C. of about 40%. Heating at 540 °C. causes a rapid loss in strength.Crocidolite asbestos tape loses strength more rapidly than chrysotile asbestos tape.Glass fibre tape, though initially stronger than chrysotile tape, is considerably less resistant to heat, beginning to lose strength rapidly at about 250 °C., whereas chrysotile asbestos tape does not suffer any appreciable decrease in strength till a temperature of 400 °C. is exceeded.

THERMAL STUDIES ON ASBESTOS: I. EFFECT OF TEMPERATURE AND TIME OF HEATING ON LOSS IN WEIGHT AND RESORPTION OF MOISTURE

1941 ◽  
Vol 19b (2) ◽  
pp. 49-55
Author(s):  
D. Wolochow ◽  
W. Harold White
Keyword(s):  
Rapid Method ◽  
Thermal Studies ◽  
Effect Of Temperature ◽  
Chrysotile Asbestos ◽  
Prolonged Heating ◽  
Temperature Range ◽  
Free Moisture

Heating a chrysotile asbestos mill fibre has shown that in the approximate temperature range of 500 to 700 °C. the loss in weight depends on both the time and temperature. At other temperatures the loss is practically independent of the time.Prolonged heating at about 490 °C. expelled about 25%, and at 510 °C. about 50%, of the combined water. Complete dehydration occurred on prolonged heating at about 580 °C., but only above 700 °C. was the loss in weight rapid.On the basis of the data obtained on the resorption of moisture it is suggested that heating for half an hour at 215 °C. would be a more accurate and rapid method for determining free moisture than that commonly employed.

Properties of Hard Rubber. XI. Experiments on Aging

1944 ◽  
Vol 17 (4) ◽  
pp. 913-922 ◽  
Author(s):  
H. F. Church ◽  
H. A. Daynes
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Short Distance ◽  
Prolonged Exposure ◽  
Breaking Strength ◽  
The Other ◽  
Rapid Loss ◽  
Test Pieces ◽  
Plastic Yield ◽  
The Impact

Abstract Tests have been carried out to find how the mechanical properties of hard rubber change with age. On prolonged exposure of the whole specimen to air at 70° C, the impact strength of notched and unnotched test-pieces may fall by 50 per cent or more. On the other hand, the plastic yield temperature increases appreciably with 200 days' exposure. The conditions affecting the improvement in such an important property are worthy of further serious study. When certain faces of the specimen are protected from the air, the rapid loss of impact strength does not take place, and cross-breaking strength may remain unimpaired for as long as 200 days. The deterioration on aging appears to be confined within a very short distance of the surface, the bulk of the material retaining its full strength for very long periods. The retention of strength when certain faces are protected may have an important bearing on questions of design. Examination of old samples of hard rubber shows that the mechanical properties remain good under ordinary conditions of storage for periods of 20–30 years, but that weakness may be caused at surfaces which are severely exposed to sunlight.

scholarly journals FTIR and Thermal Studies on Nylon-66 and 30% Glass Fibre Reinforced Nylon-66

2009 ◽  
Vol 6 (1) ◽  
pp. 23-33 ◽  
Author(s):  
Julie Charles ◽  
G. R. Ramkumaar ◽  
S. Azhagiri ◽  
S. Gunasekaran
Keyword(s):  
Activation Energy ◽  
Glass Fibre ◽  
Thermal Studies ◽  
Polymeric Materials ◽  
Thermally Stable ◽  
Melting Behaviour ◽  
Thermal Transitions ◽  
Nylon 66 ◽  
Degradation Temperature ◽  
Glass Fibre Reinforced

The present study deals with the characterization of the polymeric materialsviz.,nylon-66 and 30% glass fibre reinforced nylon-66 (GF Nylon-66) by employing FTIR and thermal measurements. The complete vibrational band assignment made available for nylon-66 and GF nylon-66 using FTIR spectra confirm their chemical structure. FTIR spectroscopy provides detailed information on polymer structure through the characteristic vibrational energies of the various groups present in the molecule. The thermal behavior of nylon-66 and GF nylon-66 essential for proper processing and fabrication was studied from TGA and DTA thermograms. The thermal stability of the polymers was studied from TGA and the activation energy for the degradation of the polymeric materials was calculated using Murray-White plot and Coats-Redfern plot. The polymer with high activation energy is more thermally stable. GF nylon-66 is found to be more thermally stable than nylon-66. The major thermal transitions such as crystalline melting temperature (Tm) and degradation temperature (Td) of the polymers were detected from DTA curves. The melting behaviour of the polymer depends upon the specimen history and in particular upon the temperature of crystallization. The melting behaviour also depends upon the rate at which the specimen is heated. The various factors such as molar mass and degree of chain branching govern the value of Tmin different polymers.

THERMAL STUDIES ON ASBESTOS: III. EFFECT OF HEAT ON THE BREAKING STRENGTH OF ASBESTOS CLOTH CONTAINING COTTON

1941 ◽  
Vol 19b (3) ◽  
pp. 65-67
Author(s):  
D. Wolochow
Keyword(s):  
Breaking Strength ◽  
Thermal Studies

Commercial, Underwriters', and A grades of asbestos cloth begin to lose strength as soon as heat is applied. On heating for five minutes at 300 °C. these three grades of asbestos cloth lose approximately 60, 35, and 25% of their original (conditioned) breaking strength, respectively. Charts are given showing the effect of heating, at temperatures up to 600 °C., for periods up to one hour.

Studies on the Degradation of Human Fibrinogen by Plasmin and Trypsin

1966 ◽  
Vol 16 (03/04) ◽  
pp. 526-540 ◽  
Author(s):  
E. A Beck ◽  
D. P Jackson
Keyword(s):  
Physicochemical Properties ◽  
Electrophoretic Mobility ◽  
Rapid Loss ◽  
Clotting System ◽  
Human Fibrinogen ◽  
Peptide Bonds ◽  
Physico Chemical ◽  
Starch Gel ◽  
Ph Stat ◽  
Rapid Appearance

SummaryThe effects of trypsin and plasmin on the functional and physicochemical properties of purified human fibrinogen were observed at various stages of proteolysis. Concentrations of plasmin and trypsin that produced fibrinogenolysis at comparable rates as measured in a pH stat produced, at similar rates, loss of precipitability of fibrinogen by heat and ammonium sulphate and alterations in electrophoretic mobility on starch gel. Trypsin produced a more rapid loss of clottability of fibrinogen and a more rapid appearance of inhibitors of the thrombin-fibrinogen clotting system than did plasmin. Consistent differences were noted between the effects of trypsin and plasmin on the immunoelectrophoretic properties of fibrinogen during the early stages of proteolysis.These results are consistent with the hypothesis that trypsin initially reacts with the same peptide bonds of fibrinogen that are split by thrombin, but these same bonds do not appear to be split initially by plasmin. Measurement of the various functional and physico-chemical changes produced by the action of trypsin and plasmin on fibrinogen can be used to recognize various stages of proteolysis.

Heparin, Protamine and Polybrene

1965 ◽  
Vol 13 (02) ◽  
pp. 550-560 ◽  
Author(s):  
Anthony Britten
Keyword(s):  
Factor Viii ◽  
Incubation Mixture ◽  
Factor V ◽  
Factor Viii Activity ◽  
Rapid Loss

SummaryThe effects of incubating heparin, protamine or Polybrene with plasma were studied. All three drugs cause rapid loss of factor V from decalcified plasma, while Polybrene also accelerates the loss of factor VIII activity. These changes are related to temperature, the period of incubation and the dose of the drug used, and can be partially prevented by inclusion of neutralizing doses of the appropriate antagonist in the incubation mixture.The implications of these findings are discussed.

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