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Digitale Medien

Evaluation of free and hydrostatic equibiaxial deformation of poly(ethylene terephthalate) by trirefringence measurement (1987)

Guan, Jia Y. ; Saraf, Ravi F. ; Porter, Roger S.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 33 (1987), S. 1517-1523

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: Understanding the deformation behavior of an amorphous thermoplastic, e.g., poly(ethylene terephthalate) (a-PET) and one of semicrystallinity, viz., i-PP, can be is of both fundamental and practical importance. Much has been done to study the influence of temperature and strain, but not the influence of deformation conditions on the three-dimensional orientation of many thermoplastic. In this study we consider the incremental effect of hydrostatic pressure and process geometry on strain-induced deformation. a-PET has been free drawn (i.e., no hydrostatic pressure) isothermally on a tenter frame device. The hydrostatic, equibiaxial deformation was achieved by a forging process involving squeezing between two circular plates. These two processes have been carried out at a series of deformation rates, with the three-dimensional refractive index measurements having been made on the PET and i-PP films using a modified Abbe refractometer, as per Samuels. The reported trirefringence measurement provides a sensitive scale for the planar deformation.

Zusätzliches Material: 6 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1987.070330508

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Digitale Medien

Planar deformation of amorphous poly(ethylene terephthalate) by stretching and forging (1992)

Guan, Jia Y. ; Wang, Li-Hui ; Porter, Roger S.

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part B: Polymer Physics 30 (1992), S. 687-691

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ISSN: 0887-6266

Schlagwort(e): poly(ethylene terephthalate), amorphous, planar deformation of ; deformation of PET by stretching and forging ; drawing techniques and deformation of PET ; crystallization in drawn PET ; Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: The planar deformation of amorphous poly(ethylene terephthalate) (PET) was performed by stretching and by forging under comparable conditions at a series of constant temperatures, 80, 90, 100, and 110°C. The highest planar draw ratios of 4.5 × 4.5 and 3.5 × 3.5 were obtained by forging and stretching, respectively. Samples were studied before and after deformation by wide angle x-ray scattering (WAXS), differential scanning calorimetry (DSC), density measurements, and elastic recovery at 100°C. A distinct difference in efficiency of draw between these two techniques is found, as judged mainly by the straininduced crystallization. The forging is more effective than stretching in achieving stabilized planar draw under comparable process conditions.

Zusätzliches Material: 5 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/polb.1992.090300705

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Simultaneous Carbonation and Sulfation of CaO in Oxy-Fuel CFB Combustion (2011)

C. Wang; L. Jia; Y. Tan

Wiley-Blackwell

In: Chemical Engineering and Technology

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Publikationsdatum: 2011-09-28

Beschreibung: For anthracites and petroleum cokes, the typical combustion temperature in a circulating fluidized bed (CFB) is 〉 900 °C. At CO 2 concentrations of 80–85 % (typical of oxy-fuel CFBC conditions), limestone still calcines. When the ash which includes unreacted CaO cools to the calcination temperature, carbonation of fly ash deposited on cool surfaces may occur. At the same time, indirect and direct sulfation of limestone also will occur, possibly leading to more deposition. In this study, CaO was carbonated and sulfated simultaneously in a thermogravimetric analyzer (TGA) under conditions expected in an oxy-fuel CFBC. It was found that temperature, and concentrations of CO 2 , SO 2 , and especially H 2 O are important factors in determining the carbonation/sulfation reactions of CaO. An investigation on simultaneous carbonation and sulfation of CaO in oxy-fuel CFB combustion was conducted to understand the mechanisms of fly ash deposition on cooler surfaces in boilers. The role of H 2 O was studied for the first time. Simultaneous carbonation and sulfation showed different characteristics from either carbonation or sulfation alone.

Print ISSN: 0930-7516

Digitale ISSN: 1521-4125

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Publiziert von Wiley-Blackwell

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An analytical solution for rainfall infiltration into an unsaturated infinite slope and its application to slope stability analysis (2012)

Tony L. T. Zhan, G. W. Jia, Y.-M. Chen, D. G. Fredlund, H. Li

Wiley-Blackwell

In: International Journal for Numerical and Analytical Methods in Geomechanics

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Publikationsdatum: 2012-06-14

Beschreibung: SUMMARY Surficial slope failures in residual soils are common in tropical and subtropical regions as a result of rainfall infiltration. This study develops an analytical solution for simulating rainfall infiltration into an infinite unsaturated soil slope. The analytical solution is based on the general partial differential equation for water flow through unsaturated soils. It can accept soil–water characteristic curve and unsaturated permeability function of the exponential form into account. Numerical simulations are conducted to verify the assumptions of the analytical solution and demonstrate that the proposed analytical solution is acceptable for the coarse soils with low air entry values. The pore-water pressure (pwp) distributions obtained from the analytical solution can be incorporated into a limit equilibrium method to do infinite slope stability analysis for a rain-induced shallow slip. The analysis method takes into account the influence of the water content change on unit weight and hence on factor of safety. A series of analytical parametric analyses have been performed using the developed model. The analyses indicate that when the residual soil slope, consisting of a completely decomposed granite layer underlain by a less permeable layer, is subjected to a continuous heavy rainfall, the loss of negative pwp and the reduction in factor of safety were found to be most significant for the shallow soil layer and during the first 12 h. The antecedent and subsequent rainfall intensity, depth of a less permeable layer and slope angle all have a significant influence on the pwp response and hence the slope stability. Copyright © 2012 John Wiley & Sons, Ltd.

Print ISSN: 0363-9061

Digitale ISSN: 1096-9853

Thema: Architektur, Bauingenieurwesen, Vermessung , Geologie und Paläontologie

Publiziert von Wiley-Blackwell

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