The Thermal Shrinkage of an Oriented Polyester Yarn as a Function of Time, Temperature, and Stress

1969 ◽  
Vol 39 (8) ◽  
pp. 742-748 ◽  
Author(s):  
Arthur Ribnick
Keyword(s):  
Activation Energy ◽  
Displacement Transducer ◽  
Semicrystalline Polymers ◽  
Thermal Shrinkage ◽  
Stress Dependence ◽  
Kcal Mole ◽  
Polyester Yarn ◽  
Proposed Model ◽  
Linear Variable Displacement Transducer ◽  
Variable Displacement

Measurements have been made with a linear variable-displacement transducer of the thermal shrinkage of an oriented polyester yarn in dry nitrogen as a function of time, temperature, and stress. The shrinkage of this material has been found to be nonlinear with respect to these three variables. A modified form of the Tobolsky and Eyring creep-rate equation has been found to describe the temperature and stress dependence. The activation energy for the process has been estimated to be 55.6 kcal/mole and the displacement volume to be 810 Å3. Interpretation of these experimental results appears to support a recently proposed model that thermal shrinkage of oriented semicrystalline polymers is a reflection of a structural transformation between extended-chain and folded-chain crystallites.

Thermal Shrinkage of Oriented Nylon 66 Yarns as a Function of Time, Temperature, and Stress

1969 ◽  
Vol 39 (5) ◽  
pp. 428-434 ◽  
Author(s):  
Arthur Ribnick
Keyword(s):  
Activation Energy ◽  
Hydrogen Bonds ◽  
Displacement Transducer ◽  
Thermal Shrinkage ◽  
Nonlinear Functions ◽  
Nylon 66 ◽  
Linear Variable Displacement Transducer ◽  
Variable Displacement

A method employing a linear variable displacement transducer has been adapted to measure the thermal shrinkage of oriented yarns of nylon 66. The thermal shrinkage of this material has been found to be viscoelastic in that nonlinear functions of time, temperature, and stress are required to describe the shrinkage. The activation energy has been estimated to be 40 kcal per mole, which is partly explainable by a dissociation of the hydrogen bonds in the amide groups.

scholarly journals Structural and physical evaluation of a reinforced beam using strain gauges

2022 ◽  
Vol 2153 (1) ◽  
pp. 012003
Author(s):  
N Afanador-Garcia ◽  
G Guerrero-Gomez ◽  
R Gallardo-Amaya
Keyword(s):  
Concrete Beam ◽  
Maximum Load ◽  
Reinforced Concrete Beam ◽  
Displacement Transducer ◽  
Bending Test ◽  
Strain Gauges ◽  
Physical Behavior ◽  
Linear Variable Displacement Transducer ◽  
Strength Tests ◽  
Variable Displacement

Abstract In this research project,the deformations in the longitudinal and transverse reinforcing steel of a reinforced concrete beam with 2ϕ½” were estimated.Additionally,the displacements in thecenter of thespanweremeasuredtogether with theloads, which generatedthecrackingof the beam of dimensions180 mm×240 mm×3100 mm.Displacement were performed using a linear variable displacement transducer, and strain gauges were used to measure deformations. Finally, the applied load’s measurements were obtained with a load cell Pinzuar/Model-100/20T equipment.The physical-mechanical properties of the concreteused were determined through compressive strength tests at 28 days and modulus of elasticity.For this purpose, a load-bearing frame was used to support the beam at three points for load application.The data was collected directly on the Quantum/X2 equipment and analyzed with the help of the Catman/AP software.The maximum deformations found in the bending test at three point since there inforced concrete beam we are not greater than 8483µm/mm,presenting a failure in the center of the beam due to the creep of the tensile steel for a maximum load of 3115 Kg.Finally,the physical behavior of there inforced concrete beam with applying aload allows evaluating and optimizing this kind of systems.

scholarly journals Analisis lendutan balok beton secara eksperimental dan perhitungan metode elemen hingga (MEH) dengan aplikasi SNI 2847 : 2013

2018 ◽  
Vol 12 (3) ◽  
pp. 127-134
Author(s):  
Tri Handayani ◽  
Yudi Irawadi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Displacement Transducer ◽  
Linear Variable Displacement Transducer ◽  
Variable Displacement ◽  
Element Method

Pada makalah ini disajikan analisis lendutan balok beton dari sebuah gedung. Analisa dilakukan menggunakan software berbasis finite element method (FEM) dan eksperimental dengan tujuan untuk mengetahui pengaruh jenis tumpuan dan tipe penampang balok terhadap lendutan.Dalam analisis menggunakan software FEM dilakukan perhitungan lendutan menggunakan persamaan lendutan balok pada dua tumpuan dengan asumsi sebagai penampang balok biasa dan penampang balok T. Selain itu, juga diperhitungkan kondisi tumpuan yaitu sebagai tumpuan sederhana dan tumpuan jepit-jepit. Dalam evaluasi secara eksperimental dilakukan uji beban terhadap balok beton yang bersangkutan sesuai SNI 2847 2013. Sebagai beban uji adalah air dan sebagai pengukur lendutan adalah linear variable displacement transducer (LVDT). Perhitungan lendutan di tengah bentang dengan software berbasis FEM dengan asumsi balok T dan tumpuan jepit-jepit menghasilkan lendutan untuk balok C 1-2 sebesar 1,652 mm dan untuk balok 2 A-B sebesar 1,987 mm. Lendutan netto di tengah bentang hasil uji beban untuk balok C 1-2 adalah sebesar 1,263 mm dan untuk balok 2 A-B adalah sebesar 1,625 mm. Dengan demikian pada eksperimen ini dapat disimpulkan bahwa lendutan balok beton hasil evaluasi menggunakan software FEM melalui perhitungan dengan asumsi penampang balok T dengan kondisi tumpuan jepit-jepit adalah yang paling mendekati lendutan hasil evaluasi secara eksperimental melalui uji beban

Vulcanization of Elastomers. 23. The Chemical Kinetics of Vulcanization Reactions and The Physical Properties of The Vulcanizates. I

1960 ◽  
Vol 33 (2) ◽  
pp. 335-341
Author(s):  
Walter Scheele ◽  
Karl-Heinz Hillmer
Keyword(s):  
Activation Energy ◽  
Physical Properties ◽  
Chemical Kinetics ◽  
Kcal Mole ◽  
First Order ◽  
Equilibrium Swelling ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization ◽  
Limiting Value ◽  
Good Agreement

Abstract As a complement to earlier investigations, and in order to examine more closely the connection between the chemical kinetics and the changes with vulcanization time of the physical properties in the case of vulcanization reactions, we used thiuram vulcanizations as an example, and concerned ourselves with the dependence of stress values (moduli) at different degrees of elongation and different vulcanization temperatures. We found: 1. Stress values attain a limiting value, dependent on the degree of elongation, but independent of the vulcanization temperature at constant elongation. 2. The rise in stress values with the vulcanization time is characterized by an initial delay, which, however, is practically nonexistent at higher temperatures. 3. The kinetics of the increase in stress values with vulcanization time are both qualitatively and quantitatively in accord with the dependence of the reciprocal equilibrium swelling on the vulcanization time; both processes, after a retardation, go according to the first order law and at the same rate. 4. From the temperature dependence of the rate constants of reciprocal equilibrium swelling, as well as of the increase in stress, an activation energy of 22 kcal/mole can be calculated, in good agreement with the activation energy of dithiocarbamate formation in thiuram vulcanizations.

The slow oxidation of methane

1956 ◽  
Vol 235 (1201) ◽  
pp. 158-173 ◽  
Keyword(s):  
Activation Energy ◽  
Hydrogen Peroxide ◽  
Induction Period ◽  
Hydrofluoric Acid ◽  
Pressure Rise ◽  
Pressure Change ◽  
Kcal Mole ◽  
Gaseous Products ◽  
Oxidation Of Methane ◽  
Reproducible Manner

Mixtures of methane and oxygen behave in a reproducible manner at temperatures of 440 to 520°C and initial pressures of 100 to 350 mm when reacting in Pyrex vessels freshly cleaned with hydrofluoric acid. The apparent order of the reaction ranged from 2∙3 to 2∙6 and the overall activation energy from 29 to 41 kcal/mole. Analyses of the products formed have been made, together with measurements of pressure change. Formaldehyde is formed from the commencement of the reaction including the induction period, but its concentra­tion reaches a maximum near the stage where the pressure rise is a maximum, and then falls off. Hydrogen peroxide is also formed, less rapidly in the earliest stage, but its rate of formation overtakes that of formaldehyde and it reaches an even higher concentration. No other peroxides were detected, nor was methanol found. Hydrogen was present in the gaseous products. These observations are not in full accord with some of the conclusions derived from earlier investigations.

POLYMÉRISATION PAR LES RAYONS-X DU CHLORURE DE VINYLE À L'ÉTAT DE VAPEUR

1963 ◽  
Vol 41 (6) ◽  
pp. 1578-1587 ◽  
Author(s):  
Jan A. Herman ◽  
Pierre M. Hupin
Keyword(s):  
Activation Energy ◽  
Gas Phase ◽  
Average Molecular Weight ◽  
Negative Temperature ◽  
Solid Polymer ◽  
X Rays ◽  
Kcal Mole ◽  
Rate Of Polymerization ◽  
G Value ◽  
Termination Process

The polymerization of vinyl chloride in the gas phase by X rays gives a solid polymer of 1140 average molecular weight. The G value of monomer disappearance varies from 100 to 400 and depends on pressure and temperature. From the measure of the rate of polymerization it was possible to deduce the activation energy of the chain propagation steps: 2.5 kcal/mole, and that of the hindered termination process: 7.4 kcal/mole. The negative temperature co-efficient of the polymerization is explained by the importance of this hindered termination process.

THE REACTION OF METHYL RADICALS WITH FORMALDEHYDE

1959 ◽  
Vol 37 (9) ◽  
pp. 1462-1468 ◽  
Author(s):  
A. R. Blake ◽  
K. O. Kutschke
Keyword(s):  
Activation Energy ◽  
Kinetic Analysis ◽  
Addition Reactions ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
A Value ◽  
Abstraction Reaction ◽  
Butyl Peroxide

The pyrolysis of di-t-butyl peroxide has been reinvestigated and used as a source of methyl radicals to study the abstraction reaction between methyl radicals and formaldehyde. At low [HCHO]/[peroxide] ratios the system was simple enough for kinetic analysis, and a value of 6.6 kcal/mole was obtained for the activation energy. At higher [HCHO]/[peroxide] ratios the system became very complicated, possibly due to the increased importance of addition reactions.

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