Measurement of the loss tangent of low-density polyethylene with a nanoindentation technique

2000 ◽  
Vol 15 (5) ◽  
pp. 1195-1198 ◽  
Author(s):  
J. L. Loubet ◽  
W. C. Oliver ◽  
B. N. Lucas
Keyword(s):  
Loss Tangent ◽  
Arrhenius Equation ◽  
Viscoelastic Behavior ◽  
Low Density ◽  
Diamond Indenter ◽  
Different Temperatures ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic ◽  
Two Temperatures ◽  
Good Agreement

This paper describes experimental measurements of the linear viscoelastic behavior of the surface of low-density (LD) polyethylene in contact with a pyramidal Berkovich diamond indenter. The experiments were carried out at two different temperatures, 15.9 and 27.2 °C, between frequencies of 0.1 and 800 Hz. Using the shift of the loss tangent between the two temperatures at frequencies lower than 20 Hz and an Arrhenius equation, an activation energy of 105 ± 2 kJ/mol was obtained. This value is in good agreement with the bulk value of the a relaxation of LD polyethylene reported in the literature.

Evolution of Prony Parameters for Underfills Subjected to High Temperature Long Term Aging

2021 ◽  
Author(s):  
Pradeep Lall ◽  
Yunli Zhang ◽  
Haotian Wu ◽  
Jeff Suhling ◽  
Edward Davis
Keyword(s):  
High Temperature ◽  
Power Systems ◽  
Flip Chip ◽  
Loss Modulus ◽  
Viscoelastic Behavior ◽  
Aging Effect ◽  
Ball Grid Arrays ◽  
Different Temperatures ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic

Abstract Advanced drive assist systems and support power systems reside underhood where operating temperatures are much higher than in traditional consumer applications. Temperatures in automotive underhood electronics may range from −40 °C to +150°C for long periods of time during operation. Much of the advanced functionality is enable through the use of advanced architectures including flip-chip ball-grid arrays. Underfills are used to enhance the solder joint reliability between the chip and the substrate. However, there is insufficient information about the viscoelasticity of Underfills stored in sustained high temperature for long period of time. In this paper, two different types of Underfills have been cured and aged under two different temperatures: 100 °C and 150 °C. Multi-frequency scan dynamic mechanical analyzer (DMA) test has been conducted to study the viscoelasticity evolution from pristine, 30 days, 60 days, 90 days and 120 days. The master curve has been obtained and the pony pairs of UFs have been calculated. The linear viscoelastic behavior of two kinds of Underfills as the function of aging time and aging temperature has been investigated. Elastic modulus, loss modulus and glass transition temperature are extracted from the results of dynamic loading tests. The aging effect of linear viscoelasticity has been discussed.

Combined Statistical-Mechanical Characterization of a Next Generation Textured PTFE for Extreme Environments

2018 ◽  
Author(s):  
Sannmit Shinde ◽  
Ali P. Gordon ◽  
Zachary Poust ◽  
Steve Pitolaj ◽  
Jim Drago ◽  
...  
Keyword(s):  
Extreme Environments ◽  
Viscoelastic Behavior ◽  
Ceramic Particle ◽  
Operating Conditions ◽  
Operating Environments ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic ◽  
Statistical Mechanical ◽  
Relaxation Responses

Pressurized vessels that transfer media from one location to another often contain a bolted connection. Gaskets are essential for these systems since they confer high levels of leak mitigation across of range of operating environments (i.e., internal pressure and temperature). The balance of both sealability and compressibility must be displayed in candidate gasket materials to be subjected to aggressive operating conditions. Historically, thin gauge gasket (i.e., 1/16” thick) confer high sealability while thick gaskets offer superior compressibility (i.e., 1/8”). Fabricated with skive cut, ceramic particle-reinforced PTFE, these materials display linear viscoelastic behavior that allow consolidation to occur. For example, GYLON® 3504 is filled with Aluminosilicate Microspheres, GYLON®3510 is filled with barium sulfate, respectively, to efficiently fill crevices along the surfaces of the flange. Novel textured PTFE gasket (3504 EPX and 3510 EPX) have been developed to simultaneously confer sealability and compressibility compared to flat products. A design of experiments (DoE) approach is applied to characterize the factors that influence load relaxation responses of the both candidate textured PTFE (dual-face honeycomb) and existing (flat) gasket styles. Using an instrumented test platform analyzed. A new parameter is presented to quantify gasket efficiency. The collection of efficiency measurement methods and approach to re-torque optimization convey a novel framework that designers can invoke to facilitate improved flange performance.

Linear Viscoelastic Behavior of Symmetric and Asymmetric Star Polymer Solutions

2006 ◽  
Vol 39 (19) ◽  
pp. 6677-6685 ◽  
Author(s):  
Jung Hun Lee ◽  
Justin M. Goldberg ◽  
Lewis J. Fetters ◽  
Lynden A. Archer
Keyword(s):  
Polymer Solutions ◽  
Viscoelastic Behavior ◽  
Star Polymer ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic

Effect of the chemical structure on the linear viscoelastic behavior of acrylic and styrenic polymer blends

2018 ◽  
Vol 67 ◽  
pp. 257-265 ◽  
Author(s):  
Juciklécia S. Reinaldo ◽  
Laurenice Martins Pereira ◽  
Erik dos Santos Silva ◽  
Marcelo M. Ueki ◽  
Edson N. Ito
Keyword(s):  
Polymer Blends ◽  
Chemical Structure ◽  
Viscoelastic Behavior ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic ◽  
Styrenic Polymer
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