scholarly journals A quick and accurate method to determine the Poisson's ratio and the coefficient of thermal expansion of PDMS

Soft Matter ◽  
2019 ◽  
Vol 15 (4) ◽  
pp. 779-784 ◽  
Author(s):  
Angelina Müller ◽  
Matthias C. Wapler ◽  
Ulrike Wallrabe
Keyword(s):  
Thermal Expansion ◽  
Poisson’S Ratio ◽  
Coefficient Of Thermal Expansion ◽  
Accurate Method ◽  
Poisson's Ratio

We developed a new and accurate method to determine the Poisson's ratio of PDMS, using thermal expansion and a profilometer.

Bi-Material Re-Entrant Triangle Structures Incorporating Tailorable Thermal Expansion and Tunable Poisson’s Ratio

2019 ◽  
Author(s):  
He Xiaobing ◽  
Xie Yan ◽  
Yu Jingjun
Keyword(s):  
Thermal Expansion ◽  
Poisson’S Ratio ◽  
Coefficient Of Thermal Expansion ◽  
Coupling Effect ◽  
Poisson's Ratio ◽  
Planar Lattice ◽  
Triangle Lattice ◽  
Lattice Material ◽  
The Relationship ◽  
Initial Concept

Abstract Based on the bi-material triangle lattice material, a new cellular structure: bi-material re-entrant triangle (BRT) is devised to incorporate tailorable coefficient of thermal expansion (CTE) and tunable Poisson’s ratio (PR) properties by replacing the straight base of a triangle with two hypotenuse members. An equation to systematically build the relationship among the external force, the temperature increment and the deformation for the planar lattice material with bounded joints is derived and then embedded into a theoretical model for devised BRT structure. Using master stiffness equation, effective PR, effective Young’s modulus as well as effective CTE are computed. In order to guide designers to construct an initial concept quickly, the design domain for coupling negative CTE and negative PR properties is proposed. Nine available paired characteristics for coupling effect are extracted and demonstrated with ABAQUS simulation.

Determination of Poisson's Ratio of Thin low-k Films using Bidirectional Thermal Expansion Measurement

2006 ◽  
Vol 914 ◽  
Author(s):  
Jiping Ye ◽  
Satoshi Shimizu ◽  
Shigeo Sato ◽  
Nobuo Kojima ◽  
Junnji Noro
Keyword(s):  
Thermal Expansion ◽  
Temperature Gradient ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Silicon Oxide ◽  
Young's Modulus ◽  
Polymer Materials ◽  
Poisson's Ratio ◽  
Thermal Expansion Measurement ◽  
Low K

AbstractA recently developed bidirectional thermal expansion measurement (BTEM) method was applied to different types of low-k films to substantiate the reliability of the Poisson's ratio found with this technique and thereby to corroborate its practical utility. In this work, the Poisson's ratio was determined by obtaining the temperature gradient of the biaxial thermal stress from substrate curvature measurements, the temperature gradient of the whole thermal expansion strain along the film thickness from x-ray reflectivity (XRR) measurements, and reduced modulus of the film from nanoindentation measurements. For silicon oxide-based SiOC film having a thickness of 382.5 nm, the Poisson's ratio, Young's modulus and thermal extension coefficient (TEC) were determined to be Vf = 0.26, αf =21 ppm/K and Ef =9,7 GPa. These data are close to the levels of metals and polymers rather than the levels of fused silicon oxide, which is characterized by Vf = 0.17 and Er = 69.6 GPa. The alkyl component in the silicon oxide-based framework is thought to act as an agent in reducing the modulus and elevating the Poisson's ratio in SiOC low-k materials. In the case of an organic polymer SiLK film with a thickness of 501.5 nm, the Poisson's ratio, Young's modulus and TEC were determined to be Vf = 0.39, αf =74 ppm/K and Er =3.1 GPa, which are in the typical range of V= 0.34~0.47 with E =1.0~10 GPa for polymer materials. From the viewpoint of the relationship between the Poisson's ratio and Young's modulus as classified by different material types, the Poisson's ratios found for the silicon oxide-based SiOC and organic SiLK films are reasonable values, thereby confirming that BTEM is a reliable and effective method for evaluating the Poisson's ratio of thin films.

Unusual anisotropic thermal expansion in multilayer SnSe leads to positive-to-negative crossover of Poisson's ratio

2020 ◽  
Vol 116 (8) ◽  
pp. 083101
Author(s):  
Rui-Zi Zhang ◽  
Jian Liu ◽  
Yu-Yang Zhang ◽  
Shixuan Du ◽  
Sokrates T. Pantelides
Keyword(s):  
Thermal Expansion ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Anisotropic Thermal Expansion
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