Preparation and characterization of covalently functionalized graphene using vinyl-terminated benzoxazine monomer and associated nanocomposites with low coefficient of thermal expansion

2012 ◽  
Vol 62 (6) ◽  
pp. 966-973 ◽  
Author(s):  
Kuan-Ku Ho ◽  
Min-Chien Hsiao ◽  
Tsung-Yu Chou ◽  
Chen-Chi M Ma ◽  
Xiao-Feng Xie ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Functionalized Graphene

Transient and Residual Stresses and Displacements in Self-Curing Bone Cement—Part I: Characterization of Relevant Volumetric Behavior of Bone Cement

1982 ◽  
Vol 104 (1) ◽  
pp. 21-27 ◽  
Author(s):  
A. M. Ahmed ◽  
W. Pak ◽  
D. L. Burke ◽  
J. Miller
Keyword(s):  
Thermal Expansion ◽  
Residual Stresses ◽  
Bone Cement ◽  
Coefficient Of Thermal Expansion ◽  
Stress Generation ◽  
Curing Process ◽  
Cooling Phase ◽  
Volumetric Behavior ◽  
Fixation System

In this first part of a two-part report, some aspects of the volumetric behavior of bone cement during its curing process are examined as a prelude to an analysis for the transient and residual stresses and displacements in stem fixation systems. Experiments show that stress generation in the cement is associated with its temperature while curing and that during the cooling phase, the stresses are mainly due to thermal as opposed to bulk shrinkage. The appropriate coefficient of thermal expansion of bone cement has been evaluated from measurements in a simulated fixation system in conjunction with a thermoelastic analysis.

Synthesis of Ca-Al-Si-O Compounds from Local Wastes

2009 ◽  
Vol 620-622 ◽  
pp. 121-124
Author(s):  
U.Sangwanna Sanewirush ◽  
P. Saewong
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Rice Husk Ash ◽  
Coefficient Of Thermal Expansion ◽  
Ternary Diagram ◽  
Alumina Ceramics ◽  
Calcium Aluminosilicate ◽  
Pulp Production ◽  
Aluminum Anodizing

The local wastes, which are sources of SiO2, Al2O3 and CaO, are rice husk ash, waste sediment from aluminum anodizing process and dreg from pulp production, respectively. The wastes are mixed in three different compositions in ranges of 20-50 SiO2, 20-35 CaO and 20-45 Al2O3, wet milled, slip casted and then fired at 1,100 °C. Characterization of the fired bodies reveals the formation of calcium-aluminosilicate compounds: gehlenite and anorthite as major phases, in accordance with the SiO2-CaO-Al2O3 ternary diagram. Their bulk densities and % water absorption lies between 0.95-1.42 g/cm3 and 37.40-67.95%, respectively. While flexural strength and coefficient of thermal expansion are between 4.09-9.56 MPa and 6.14 - 10.1 x 10-6 °C-1, respectively. By simple thermal conductivity comparison, the materials themselves have thermal conductivity comparable to alumina ceramics. These wastes, therefore, may be used as precursors for the production of some insulating refractory members, in place of minerals from natural resources.

scholarly journals A Comparative Study on the Characterization of Nanofibers with Cellulose I, I/II, and II Polymorphs from Wood

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 153 ◽  
Author(s):  
Haiying Wang ◽  
Suiyi Li ◽  
Tiantian Wu ◽  
Xiaoxuan Wang ◽  
Xudong Cheng ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Comparative Study ◽  
Coefficient Of Thermal Expansion ◽  
Cellulose Nanofibers ◽  
High Yield ◽  
Chemical Extraction ◽  
Cellulose Content ◽  
Cellulose I ◽  
Aspect Ratios

Polymorphic changes in cellulose nanofibers (CNFs) are closely related to their properties and applications, and it is of interest to investigate how polymorphic changes influence their properties. A comparative study on the properties of CNFs with cellulose I, I/II, and II polymorphs from wood was conducted herein. CNFs were obtained by chemical extraction combined with a simple and efficient mechanical treatment (one pass through a grinder). This process resulted in a relatively high yield of 80–85% after a simple grinding treatment. The polymorphic changes in the CNFs and the chemical composition, morphology, tensile performances, and thermal properties were systematically characterized and compared. The X-ray diffraction and FTIR analyses verified the existence of three types of purified pulps and CNFs with cellulose I, cellulose I/II, and cellulose II polymorphs (CNF-I, CNF-I/II, CNF-II). Morphological observations presented that these three types of CNFs all exhibited high aspect ratios and entangled structures. Tensile testing showed that the CNF films all exhibited high tensile strengths, and the fracture strains of the CNF-I/II (11.8%) and CNF-II (13.0%) films were noticeably increased compared to those of the CNF-I film (6.0%). If CNF-II is used as reinforcing material, its larger fracture strain can improve the mechanical performance of the CNF composites, such as fracture toughness and impact strength. In addition, CNF-I, CNF-I/II, and CNF-II films showed very low thermal expansion in the range 20–150 °C, with the coefficient of thermal expansion values of 9.4, 17.1, and 17.3 ppm/K, respectively. Thermogravimetric analysis (TGA) revealed that the degradation temperature of CNF-I and CNF-II was greater than that of CNF-I/II, which was likely due to increased α-cellulose content. This comparative study of the characterization of CNF-I, CNF-I/II, and CNF-II provides a theoretical basis for the application of CNFs with different polymorphs and could broaden the applications of CNFs.

Characterization of Epoxy-Functionalized Silsesquioxanes as Potential Underfill Encapsulants

1998 ◽  
Vol 519 ◽  
Author(s):  
E. K. Lin ◽  
C. R. Snyder ◽  
F. I. Mopsik ◽  
W. E. Wallace ◽  
W. L. Wu ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Flip Chip ◽  
Coefficient Of Thermal Expansion ◽  
Silica Particles ◽  
Critical Parameters ◽  
Organic Hybrid ◽  
Solder Bumps ◽  
The Difference ◽  
Electronics Packages

AbstractIn electronics packaging, underfill encapsulants are needed to improve package reliability in flip-chip devices. The underfill generally consists of an epoxy resin highly filled with silica particles and is designed to reduce the stress arising from the difference in the thermal expansion between the solder bumps and the substrate. Currently, concerns about the flow of the silica particles and surface phenomena are arising as electronics packages reduce in size. Newly developed epoxy-functionalized octameric silsesquioxanes provide an intriguing alternative to current formulations. These single-phase inorganic/organic hybrid materials may have properties similar to filled materials without the complications from the rheology of filled materials. The physical properties of the functionalized silsesquioxanes are measured with respect to the critical parameters for underfill materials. Measurements of properties such as the coefficient of thermal expansion and density are performed to evaluate the suitability of these materials as potential underfill encapsulants.

Processing, Microstructure, and Thermal Expansion Measurements for High Temperature Ru-Al-Cr B2 Alloys

2008 ◽  
Vol 1128 ◽  
Author(s):  
Yutaka Hashimoto ◽  
Norihiko L. Okamoto ◽  
Manuel Acosta ◽  
David R Johnson ◽  
Haruyuki Inui
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Room Temperature ◽  
Coefficient Of Thermal Expansion ◽  
Directionally Solidified ◽  
Average Value ◽  
Heat Treated ◽  
Structural Applications ◽  
Cr System

AbstractThe B2 intermetallic compound RuAl has a melting temperature above 2000 °C and is a candidate for high temperature structural applications. A large extension of the B2 phase field is found in the Ru-Al-Cr system as was documented by the characterization of arc-melted and heat treated alloys. Two compositions consisting of Ru-35Al-19Cr and Ru-20Al-38Cr (at. %) were directionally solidified in an optical floating zone furnace. Depending upon the processing conditions, single phase, polycrystalline, B2 microstructures could be produced. The coefficient of thermal expansion (CTE) was measured from room temperature to 1250 °C for the Ru-20Al-38Cr alloy, and an average value of 11×10-6 K-1 was found. Additionally, the thermal conductivity was measured as 27 W/mK at room temperature for the Ru-20Al-38Cr B2 alloy and as 89 W/mK for binary RuAl.

Direct CTE Measurement Technique for the MEMS Materials

2006 ◽  
Vol 326-328 ◽  
pp. 199-202 ◽  
Author(s):  
Chung Seog Oh ◽  
Sung Hoon Choa ◽  
Chang Seung Lee ◽  
Hak Joo Lee
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Test System ◽  
Test Method ◽  
Linear Coefficient ◽  
Aln Film ◽  
Certified Value ◽  
Plane Displacement

The accurate characterization of linear coefficient of thermal expansion (CTE) of thin films is vital for predicting the thermal stress, which often results in warpage and failure of a MEMS structure. In this paper, special emphasis is placed on the development of novel test method to extend an ISDG (Interferometric Strain/Displacement Gage) technique to the direct and accurate CTE measurement of MEMS materials, AlN and Au. The freestanding AlN and Au films are 1 μm thick and 5 mm wide. Strain is directly measured by a brand-new digital type ISDG with two Cr lines deposited on the specimen while heating a specimen in a furnace. The whole test system is verified first by measuring the CTE for the NIST’s SRM (Standard Reference Material) 736 (Cu) block. The measured CTE is 17.3 με/oC up to 167 oC, which agrees well with the NIST’s certified value. The CTE of Au is 25.4 ± 1.15 με/oC and that of AlN film is 3.77 ± 0.12 με/oC. The in-plane displacement resolution is about 5 nm at the best circumstances.

Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

1991 ◽  
Vol 49 ◽  
pp. 962-963
Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Glass Matrix ◽  
Nickel Sulfide ◽  
Plate Glass ◽  
Thermal Expansion Mismatch ◽  
Volume Increase ◽  
Β Phase ◽  
Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

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