scholarly journals Effects of SiO2 Filler in the Shell and Wood Fiber in the Core on the Thermal Expansion of Core–Shell Wood/Polyethylene Composites

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2570
Author(s):  
Lichao Sun ◽  
Haiyang Zhou ◽  
Guanggong Zong ◽  
Rongxian Ou ◽  
Qi Fan ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Wood Fiber ◽  
Core Layer ◽  
Element Analysis ◽  
Linear Coefficient ◽  
Anisotropic Thermal Expansion ◽  
The Core ◽  
Expansion Behavior ◽  
Polyethylene Composites

The influence of nano-silica (nSiO2) and micro-silica (mSiO2) in the shell and wood fiber filler in the core on the thermal expansion behavior of co-extruded wood/polyethylene composites (Co-WPCs) was investigated to optimize the thermal expansion resistance. The cut Co-WPCs samples showed anisotropic thermal expansion, and the thermal expansion strain and linear coefficient of thermal expansion (LCTE) decreased by filling the shell layer with rigid silica, especially nSiO2. Finite element analysis indicated that the polymer-filled shell was mainly responsible for the thermal expansion. The entire Co-WPCs samples exhibited a lower thermal expansion strain than the cut Co-WPCs samples due to protection by the shell. Increasing the wood fiber content in the core significantly decreased the thermal expansion strain and LCTE of the Co-WPCs. The Co-WPCs whose core layer was filled with 70% wood fiber exhibited the greatest anisotropic thermal expansion.

Role of Out-of-Plane Coefficient of Thermal Expansion in Electronic Packaging Modeling

1999 ◽  
Vol 122 (2) ◽  
pp. 121-127 ◽  
Author(s):  
Manjula N. Variyam ◽  
Weidong Xie ◽  
Suresh K. Sitaraman
Keyword(s):  
Thermal Expansion ◽  
Electronic Packaging ◽  
Thermal Loading ◽  
Coefficient Of Thermal Expansion ◽  
Plane Deformation ◽  
Three Dimensional ◽  
Dissimilar Materials ◽  
3D Models ◽  
Material Behavior ◽  
Element Analysis

Components in electronic packaging structures are of different dimensions and are made of dissimilar materials that typically have time, temperature, and direction-dependent thermo-mechanical properties. Due to the complexity in geometry, material behavior, and thermal loading patterns, finite-element analysis (FEA) is often used to study the thermo-mechanical behavior of electronic packaging structures. For computational reasons, researchers often use two-dimensional (2D) models instead of three-dimensional (3D) models. Although 2D models are computationally efficient, they could provide misleading results, particularly under thermal loading. The focus of this paper is to compare the results from various 2D, 3D, and generalized plane-deformation strip models and recommend a suitable modeling procedure. Particular emphasis is placed to understand how the third-direction coefficient of thermal expansion (CTE) influences the warpage and the stress results predicted by 2D models under thermal loading. It is seen that the generalized plane-deformation strip models are the best compromise between the 2D and 3D models. Suitable analytical formulations have also been developed to corroborate the findings from the study. [S1043-7398(00)01402-X]

Hygrothermal Behavior of Advanced Polymers Above Water Boiling Temperatures

2014 ◽  
Vol 136 (1) ◽  
Author(s):  
Changsoo Jang ◽  
Bongtae Han
Keyword(s):  
Thermal Expansion ◽  
Moisture Content ◽  
Coefficient Of Thermal Expansion ◽  
Measurement Data ◽  
Hybrid Procedure ◽  
Boiling Temperature ◽  
Hygrothermal Behavior ◽  
Expansion Behavior ◽  
Wide Range ◽  
Moisture Conditions

Hygroscopic and thermal expansion behavior of advanced polymers is investigated when subjected to combined high temperature and moisture conditions. An enhanced experimental–numerical hybrid procedure is proposed to overcome the limitations of the existing methods when used at temperatures above the water boiling temperature. The proposed procedure is implemented to measure the hygrothermal strains of three epoxy molding compounds and a no-filler underfill over a wide range of temperatures including temperatures beyond the water boiling temperature. The effects of moisture content on the glass transition temperature (Tg) and coefficient of thermal expansion (CTE) are evaluated from the measurement data. A formulation to predict the Tg change as a function of moisture content is also presented.

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