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.

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.

Acetylene chemisorption at palladium: Effect of temperature and structure of the surface

1984 ◽  
Vol 49 (6) ◽  
pp. 1448-1458
Author(s):  
Josef Kopešťanský
Keyword(s):  
Work Function ◽  
Atomic Hydrogen ◽  
Effect Of Temperature ◽  
Thermally Stable ◽  
Template Effect ◽  
Temperature Range ◽  
Adsorbed Layers ◽  
Different Types ◽  
Adsorption Complexes ◽  
Low Coverage

The effect of temperature and structure of the palladium surfaces on acetylene chemisorption was studied along with the interaction of the adsorbed layers with molecular and atomic hydrogen. The work function changes were measured and combined with the volumetric measurements and analysis of the products. At temperature below 100 °C, acetylene is adsorbed almost without dissociation and forms at least two different types of thermally stable adsorption complexes. Acetylene adsorbed at 200 °C is partly decomposed, especially in the low coverage region. Besides the above mentioned effects, the template effect of adsorbed acetylene was studied in the temperature range from -80° to 25 °C. It has been shown that this effect is a typical phenomenon of the palladium-acetylene system which is not due to surface impurities.

Investigating the Effect of Thermoelectric Processing on Ionic Aggregation in Thermoplastic Ionomers

2017 ◽  
Author(s):  
Prasant Vijayaraghavan ◽  
Vishnu-Baba Sundaresan
Keyword(s):  
Mechanical Properties ◽  
Electrostatic Field ◽  
Thermal Studies ◽  
Effect Of Temperature ◽  
Self Healing ◽  
Polymer Backbone ◽  
Ionic Dissociation ◽  
Dissociation Temperature ◽  
Aggregate Morphology ◽  
Poly Ethylene

Ionomers are a class of polymers which contain a small fraction of charged groups in the polymer backbone. These ionic groups aggregate (termed ionic aggregates) to form temporary cross-links that break apart over the ionic dissociation temperature and re-aggregate on cooling, influencing the mechanical properties of these polymers. In addition to enhanced mechanical properties, some ionomers also exhibit self-healing behavior. The self-healing behavior is a consequence of weakly bonded ionic aggregates breaking apart and re-aggregating after puncture or a ballistic impact. The structure and properties of ionomers have been studied over the last several decades; however, there is a lack of understanding of the influence of an electrostatic field on ionic aggregate morphology. Characterizing the effect of temperature and electric field on the formation and structure of these ionic aggregates will lead to preparation of ionomers with enhanced structural properties. This work focuses on Surlyn 8940 which a poly-ethylene methacryclic acid co-polymer in which a fraction of the carboxylic acid is terminated by sodium. In this work, Surlyn is thermoelectrically processed over its ionic dissociation temperature in the presence of a strong electrostatic field. Thermal studies are performed on the ionomer to study the effect of the thermoelectric processing. It is shown that the application of a thermoelectric field leads to increase in the ionic aggregate order in these materials and reduction in crystal size distribution. Thermal Analysis is performed using a Differential Scanning Calorimeter and the resulting thermogram analysis shows that thermoelectric processing increases the peak temperature and onset temperature of melting by 4 C and 20 C respectively. The peak width at half maximum of the melting endotherm is reduced by 10 C due to thermoelectric processing. This serves as a measure of the increased crystallinity. A parametric study on the effect of field duration and field strength is also performed.

THE EFFECT OF TEMPERATURE ON THE RATE AND VARIATION OF OPERCULAR MOVEMENT IN FUNDULUS DIAPHANUS DIAPHANUS

1947 ◽  
Vol 25d (2) ◽  
pp. 91-95
Author(s):  
Benjamin N. Kropp
Keyword(s):  
Constant Temperature ◽  
Beat Frequency ◽  
Nervous Activity ◽  
Respiratory Movement ◽  
Effect Of Temperature ◽  
Temperature Range ◽  
Sources Of Variation ◽  
Fundulus Diaphanus

The rates of opercular beat of 16 specimens of Fundulus diaphanus diaphanus were recorded over a temperature range from 4.3° to 17.5 °C. in order to determine how this respiratory movement varied with temperature and some of the sources of variation in rate. While the rate of beat varies directly as the temperature, over a period of several hours at any constant temperature continuous recordings of the rate show recurring cycles of rise and fall in beat frequency that are chiefly responsible for the scatter of the observations. Both the duration of a cycle and the limits of rise and fall for each cycle are definitely set by the temperature. The possible dependence of these phenomena upon central nervous activity is discussed.

Mitochondrial membrane fluorescence and temperature adaptation in Schistocephalus solidus (Cestoda: Pseudophyllidea)

Parasitology ◽  
1985 ◽  
Vol 90 (1) ◽  
pp. 131-135 ◽  
Author(s):  
R. W. Walker ◽  
J. Barrett
Keyword(s):  
Gasterosteus Aculeatus ◽  
Arrhenius Plot ◽  
Gallus Domesticus ◽  
Temperature Adaptation ◽  
Effect Of Temperature ◽  
Acclimation Temperature ◽  
Membrane Composition ◽  
Mitochondrial Membranes ◽  
Temperature Range ◽  
Schistocephalus Solidus

The fluorescent probe 1-anilino-8-naphthalene suiphonic acid (ANS) was used to investigate the effect of temperature on the physical state of the mitochondrial membranes of adult and larval schistocephalus solzdus together with that of their hosts Gasterosteus aculeatus and Gallus domesticus. Arrhenius plots of ANS/membrane fluorescence for S. solidus plerocercoids was linear over the temperature range 15 to 58 °C, while that for the adult was biphasic with a discontinuity at 39·9 °C. This was interpreted as a physical change which occurred in the adult membrane but not in the plerocercoid membrane and pointed to an alteration in membrane composition during infection. Gasierosteus aculeatus showed a linear Arrhenius plot for membrane fluorescence, irrespective of acclimation temperature. Gallus domesticus showed a discontinuity in the Arrhenius plot for membrane fluorescence at 46·9 °C, outside the normal physiological temperature range.

NQR Relaxation Studies on Halogenomethyl Groups in Halogenoacetates

1998 ◽  
Vol 53 (6-7) ◽  
pp. 480-483 ◽  
Author(s):  
Maria Zdanowska-Fnjczek
Keyword(s):  
Room Temperature ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Effect Of Temperature ◽  
Relaxation Theory ◽  
Temperature Range ◽  
Spin Lattice ◽  
Relaxation Studies

Abstract The effect of temperature on the chlorine NQR spin-lattice relaxation times in CsH(ClH2-CCOO)2 , KH(Cl3 CCOO) 2 and N(CH3)4 H(ClF2CCOO)2 has been studied in the temperature range 77 K to room temperature. The results were discussed on the basis of NQR relaxation theory.

scholarly journals Effect of Temperature, Pressure, and Chemical Composition on the Electrical Conductivity of Schist: Implications for Electrical Structures under the Tibetan Plateau

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 961 ◽  
Author(s):  
Wenqing Sun ◽  
Lidong Dai ◽  
Heping Li ◽  
Haiying Hu ◽  
Changcai Liu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
High Pressures ◽  
High Conductivity ◽  
Effect Of Temperature ◽  
The Tibetan Plateau ◽  
Temperature Range ◽  
Electrical Conductivities ◽  
Conductivity Anomalies ◽  
Lower Temperature Range ◽  
Lower Temperature

The experimental study on the electrical conductivities of schists with various contents of alkali ions (CA = K2O + Na2O = 3.94, 5.17, and 5.78 wt.%) were performed at high temperatures (623–1073 K) and high pressures (0.5–2.5 GPa). Experimental results indicated that the conductivities of schist markedly increased with the rise of temperature. Pressure influence on the conductivities of schist was extremely weak at the entire range of experimental temperatures. Alkali ion content has a significant influence on the conductivities of the schist samples in a lower temperature range (623–773 K), and the influence gradually decreases with increasing temperature in a higher temperature range (823–1073 K). In addition, the activation enthalpies for the conductivities of three schist samples were fitted as being 44.16–61.44 kJ/mol. Based on the activation enthalpies and previous studies, impurity alkaline ions (K+ and Na+) were proposed as the charge carriers of schist. Furthermore, electrical conductivities of schist (10−3.5–10−1.5 S/m) were lower than those of high-conductivity layers under the Tibetan Plateau (10−1–100 S/m). It was implied that the presence of schist cannot cause the high-conductivity anomalies in the middle to lower crust beneath the Tibetan Plateau.

Effect of temperature on damage mechanisms and mechanical behaviour of an acrylic-thermoplastic-matrix and glass-fibre-reinforced composite

2020 ◽  
Vol 54 (27) ◽  
pp. 4269-4282
Author(s):  
E Boissin ◽  
C Bois ◽  
J-C Wahl ◽  
T Palin-Luc
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Polymer Matrix ◽  
Mechanical Response ◽  
Polymer Matrix Composites ◽  
Effect Of Temperature ◽  
Matrix Composites ◽  
Service Temperature ◽  
Damage Mechanisms ◽  
Temperature Range

The mechanical response of polymer matrix composites exhibits a temperature dependency even if the service temperature range is lower than the glass transition temperature of the polymer matrix. This dependency is mainly due to the temperature effect on the mechanical behaviour of the polymer matrix. However, the micro- and meso-structures driving the composite anisotropy and local stress distribution play an essential role regarding the effect of temperature on damage mechanisms specific to reinforced polymers. There are few data in the literature on the sensitivity to temperature of damage mechanisms and scenarios of polymer matrix composites regardless of loading type. In this paper, after a synthetic literature review of the effect of temperature on polymers and polymer composites, several complementary tests are proposed to analyse the temperature effect on damage mechanisms undergone by laminated composites under in-plane quasi static loadings. These tests are applied to an acrylic-thermoplastic composite reinforced by glass fibres in its service temperature range of –20℃ to 60℃. The results show that the testing temperature has a significant impact on the mechanical response and damage mechanisms of the composite material in the selected temperature range, which is markedly lower than the glass transition temperature (around 100℃). While the temperature rise generates a gradual decrease in matrix stiffness and strength, the increase in matrix ductility associated to the stress heterogeneity in the composite microstructure produces a rise in the transverse cracking threshold and removes this damage mode during quasi-static tensile tests when the temperature shifts from 15℃ to 40℃.

Thermal polymerization of arylacetylenes: spectroscopic and thermal studies

1994 ◽  
Vol 6 (4) ◽  
pp. 347-383 ◽  
Author(s):  
Marie-Florence Grenier-Loustalot
Keyword(s):  
Thermal Properties ◽  
Reaction Mechanisms ◽  
Thermal Studies ◽  
Thermal Polymerization ◽  
Temperature Range ◽  
H Nmr ◽  
Kinetics Of ◽  
Competing Reactions

The reaction mechanisms and kinetics of endcapped ethynyl polyethers were studies in the temperature range 150-220C. The results obtained by '3C and 'H NMR, FrTIR, HPLC and DSC indicate reactivity differences and competing reactions. These materials were cured and their thermal properties evaluated.

Effect of Temperature on Ozone Cracking of Butyl Rubbers

1968 ◽  
Vol 41 (5) ◽  
pp. 1294-1299 ◽  
Author(s):  
A. N. Gent ◽  
H. Hirakawa
Keyword(s):  
Crack Growth ◽  
Ozone Concentration ◽  
Effect Of Temperature ◽  
Segmental Mobility ◽  
Temperature Range ◽  
Styrene Copolymers ◽  
The Difference ◽  
Rates Of Growth ◽  
Rate Controlling Step ◽  
Butadiene Styrene

Abstract Rates of growth of single ozone cracks have been measured for vulcanizates of two butyl rubbers over the temperature range of 20-160° C. Over most of this range the rates are quantitatively related to the segmental mobility of the polymer and depend upon temperature in accord with the appropriate form of the WLF relation. The rates are also proportional to the concentration of ozone. It is therefore concluded that diffusion of ozone into the polymer before reaction is the rate-controlling step. This is contrasted with the behavior of butadiene styrene copolymers, for which rates of crack growth are also quantitatively related to the segmental mobility, but the rates are somewhat larger at equivalent mobilities and the dependence upon ozone concentration is smaller. The difference is attributed to different penetration distances before reaction in polymers containing low and high densities of reactive sites.

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