scholarly journals Effect of Foaming Temperature on Microstructure, Mechanical Properties and Flame Spread Rate in PET–PEN Copolymer

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 957
Author(s):  
Byung Kyu Park ◽  
Charn-Jung Kim ◽  
Byeong Jun Lee
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Functional Materials ◽  
Spreading Rate ◽  
Indentation Hardness ◽  
Polyethylene Naphthalate ◽  
Flame Spreading ◽  
Sem Image ◽  
Thermal Expansion Coefficients ◽  
Foaming Temperature

Polymer foams are expanding their applications into functional materials. Partial foam structure has been fabricated in polyethylene terephthalate–polyethylene naphthalate (PET–PEN) copolymer by solid state foaming. Through SEM image analyses, a potential to fabricate gradient foam structures with micropores and unfoamed skin layers has been identified. The post-foaming temperature Tf tune the pore size distribution. Radial distribution of micromechanical properties, indentation hardness and elastic modulus were measured for the partial foam and their values were around 0.12 GPa and 2.0 GPa, respectively, for the outer foamed region. Foaming temperature affects the glass transition temperature Tg, the coefficient of thermal expansion and the flame spreading rate. For the range of Tf ≤ 60°C, thermal expansion coefficients for T > Tg are about 0.5 m/m°C (steep expansion group, SEG). When Tf is above 80 °C, they are around 0.02 m/m°C (mild expansion group, MEG). The burning rate of SEG is 2.8 times higher than that of MEG.

Bilayer graded Al/B4C/rice husk ash composite: Wettability behavior, thermo-mechanical, and electrical properties

2018 ◽  
Vol 52 (27) ◽  
pp. 3745-3758 ◽  
Author(s):  
Amin Bahrami ◽  
Niloofar Soltani ◽  
Martin I Pech-Canul ◽  
Shaghayegh Soltani ◽  
Luis A González ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Thermal Expansion ◽  
Aluminum Alloys ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Material Selection ◽  
Coefficient Of Thermal Expansion ◽  
Thermal Expansion Coefficients ◽  
One Step ◽  
The Difference

In this study, wettability behavior of B4C substrate as well as B4C/crystalline rice husk ash and B4C/amorphous rice husk ash substrates with two aluminum alloys were studied. The electrical resistivity, thermal expansion coefficients, and thermal diffusivity of bilayer Al/B4C/rice husk ash composite fabricated by one-step pressureless infiltration were measured and the obtained data were systemically analyzed using the Taguchi method and analysis of variance. Boron carbide substrates after addition of amorphous or crystalline rice husk ash display good wettability with molten aluminum alloys. The results show that, electrical resistivity of Al/B4C/rice husk ash composites is mainly influenced by initial preform porosity, while the coefficient of thermal expansion of composites is determined by the chemical composition of infiltrated alloys. The measured values for coefficient of thermal expansion (10.5 × 10−6/℃) and electrical resistivity (0.60 × 10−5 Ω.m) of Al/B4C/rice husk ash composites, fabricated according to analysis of variance's optimal conditions are in good agreement with those of the projected values (11.02 × 10−6/℃ and 0.65 × 10−5 Ω.m, respectively). The difference between the corresponding values obtained from verification tests and projected values, for electrical resistivity and coefficient of thermal expansion are less than 5%. Finally, as a material selection approach, the strengths and weaknesses of the composites have been graphed in the form of radar diagrams.

scholarly journals Determination of the coefficient of expansion of a carbon tube and its assembly for thermal compensation of metrological structures

2019 ◽  
Author(s):  
Salma EL ASMAI ◽  
François HENNEBELLE ◽  
Thierry COOREVITS ◽  
Jean-François FONTAINE
Keyword(s):  
Thermal Expansion ◽  
Composite Materials ◽  
Production Efficiency ◽  
Coefficient Of Thermal Expansion ◽  
Thermal Expansion Coefficients ◽  
Carbon Tube ◽  
Interesting Approach ◽  
Measurement Uncertainties ◽  
3D Metrology

Composite materials are increasingly used in 3D metrology devices. Their use is justified by their interesting mechanical properties including their low density and good rigidity but especially their low coefficient of thermal expansion. In fact, in order to improve production efficiency, companies nowadays integrate more and more control equipment directly in situ. These are then subject to thermal variations. The use of composite materials is an interesting approach. However, in some cases, the lack of knowledge of their coefficient of thermal expansion and their behavior might increase measurement uncertainties. The objective is to study the thermal behavior of a carbon tube alone and the same tube with aluminium fixing elements at its extremities, in order to determine the coefficients of expansion of the carbon alone and to quantify the influence of the fixation with aluminium elements. This experiment makes it possible to directly compensate the dimensional variations of the metrological structure depending on the temperature variations and thus to limit measurement uncertainties. The thermal expansion coefficients of the carbon tube and its assembly are determined by measuring relative variations in height with a ZERODUR® reference bar. The whole is positioned in a climatic chamber. *

Microstructural Evaluation and Quantitative Analysis in the Unleaded Solder Joint

1999 ◽  
Vol 5 (S2) ◽  
pp. 602-603
Author(s):  
J.G. Duh ◽  
Y.G. Lee ◽  
F.B. Wu
Keyword(s):  
Thermal Expansion ◽  
Solder Joint ◽  
Solder Joints ◽  
Environmental Concern ◽  
Coefficient Of Thermal Expansion ◽  
Practical Importance ◽  
Thermal Expansion Coefficients ◽  
Free Solder ◽  
Joint Quality ◽  
Microelectronic Package

Solder joints provide mechanical and electronic connections between solders and components for various levels in microelectronic package. However, due to different thermal expansion coefficients and elastic modulus of the associated materials, solder joints are susceptible to fatigue degration, microcracks and fracture. The solder joint reliability is, therefore, critical in the evalution of the joint quality. Recently, the employment of lead-free solder is attractive due to the environmental concern of the Pb-containing solder. Hence, the investigation on the unleaded solder joint is of practical importance in the field of microelectronic package.Intermetallic compounds (IMC), which form and grow between solders and metallizations, are considered to be a source of mechanical weakness for its brittleness and different coefficient of thermal expansion from the metallization or the solder.

scholarly journals Thermal and Mechanical Characterization of Copolymer Structure with Gradient Foam Using Additive Manufacturing and CO2 Foaming

2019 ◽  
Author(s):  
Byung Kyu Park ◽  
Charn-Jung Kim ◽  
Dong Eui Kwon ◽  
Youn-Woo Lee
Keyword(s):  
Mechanical Strength ◽  
Thermal Insulation ◽  
Thermo Gravimetric Analysis ◽  
Measurement Data ◽  
Functional Materials ◽  
Functionally Graded ◽  
Gravimetric Analysis ◽  
Polyethylene Naphthalate ◽  
Data Set ◽  
Foaming Temperature

Synthetic polymer-based gradient foams have considered as promising category of functionally graded materials with unique properties. In this study, the carbon dioxide (CO2) foaming technology has used for PET-PEN (Polyethylene Terephthalate - Polyethylene Naphthalate) copolymer towards porous functional materials with thermal insulation with reasonable mechanical strength. Through scanning electron microscope based morphological characterization, a potential to fabricate gradient foam structures with micro-pores has identified. It has shown that variation of post-foaming temperature can tune the pore size distribution although the very high post-foaming temperature tends to cause structural instability. Thermal measurement data set the limits of operation, confirmed by simultaneous differential scanning calorimeter and thermo-gravimetric analysis. Mechanical stress and thermal conductivity also has measured to find rationale of thermal insulation with reasonable mechanical strength and to elucidate the actual 3D grid foam of copolymer.

scholarly journals Structure and Thermal Expansion of Cu−90 vol. % Graphite Composites

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7089
Author(s):  
Andrej Opálek ◽  
Štefan Emmer ◽  
Roman Čička ◽  
Naďa Beronská ◽  
Peter Oslanec ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Volume Fraction ◽  
Coefficient Of Thermal Expansion ◽  
Pure Copper ◽  
Hot Isostatic Pressing ◽  
Functional Materials ◽  
Electrical Equipment ◽  
Internal Stresses ◽  
Schapery Model ◽  
Graphite Composites

Copper–graphite composites are promising functional materials exhibiting application potential in electrical equipment and heat exchangers, due to their lower expansion coefficient and high electrical and thermal conductivities. Here, copper–graphite composites with 10–90 vol. % graphite were prepared by hot isostatic pressing, and their microstructure and coefficient of thermal expansion (CTE) were experimentally examined. The CTE decreased with increasing graphite volume fraction, from 17.8 × 10−6 K−1 for HIPed pure copper to 4.9 × 10−6 K−1 for 90 vol. % graphite. In the HIPed pure copper, the presence of cuprous oxide was detected by SEM-EDS. In contrast, Cu–graphite composites contained only a very small amount of oxygen (OHN analysis). There was only one exception, the composite with 90 vol. % graphite contained around 1.8 wt. % water absorbed inside the structure. The internal stresses in the composites were released during the first heating cycle of the CTE measurement. The permanent prolongation and shape of CTE curves were strongly affected by composition. After the release of internal stresses, the CTE curves of composites did not change any further. Finally, the modified Schapery model, including anisotropy and the clustering of graphite, was used to model the dependence of CTE on graphite volume fraction. Modeling suggested that the clustering of graphite via van der Waals bonds (out of hexagonal plane) is the most critical parameter and significantly affects the microstructure and CTE of the Cu–graphite composites when more than 30 vol. % graphite is present.

Thermo-physical properties of nonlinear optical crystal K3B6O10Br

2016 ◽  
Vol 49 (2) ◽  
pp. 539-543 ◽  
Author(s):  
Mingjun Xia ◽  
Bo Xu ◽  
Lijuan Liu ◽  
Xiaoyang Wang ◽  
Rukang Li ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Physical Properties ◽  
Specific Heat ◽  
Nonlinear Optical ◽  
Coefficient Of Thermal Expansion ◽  
Second Harmonic ◽  
Damage Threshold ◽  
Thermal Expansion Coefficients ◽  
Lower Temperature ◽  
Thermo Physical Properties

The thermo-physical properties of the nonlinear optical (NLO) crystal K3B6O10Br (KBB) were experimentally investigated, including specific heat, thermal conductivity, coefficient of thermal expansion and refractive index. The specific heat of KBB is lower than that of LiB3O5 and higher than that of other borate NLO crystals, such as β-BaB2O4, CsLiB6O10 and CsB3O5, and KBB manifests a high damage threshold because of its lower temperature gradient during laser pulse irradiation. The thermal expansion coefficients were obtained as α x = 5.09 × 10−6 K−1 and α z = 2.39 × 10−5 K−1, showing weaker anisotropy than those of commonly used NLO crystals. The temperature-dependent Sellmeier dispersion equations of the refractive indices were also obtained, and the phase-matching angles for second harmonic generation (SHG) at temperatures of 313, 343, 373, 403 and 433 K which were calculated from these equations are in good agreement with the experimental values. All results are indicative of the KBB crystal as a novel promising NLO crystal for high power SHG.

New Ti-Alloy with Negative and Zero Thermal Expansion Coefficients

2011 ◽  
Vol 495 ◽  
pp. 62-66 ◽  
Author(s):  
Mohamed Abdel Hady Gepreel
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Coefficient Of Thermal Expansion ◽  
Cold Deformation ◽  
Negative Thermal Expansion ◽  
Expansion Factor ◽  
Thermal Expansion Coefficients ◽  
Ti Alloys ◽  
History Of

Most materials expand upon heating due to the anharmonicity of the atomic potential energy. This thermal expansion is one of the intrinsic properties of any material which is very difficult to be controlled. Recently, a negative thermal expansion factor was introduced to those Ti-alloys with high elastic softening when cold deformed. This negative thermal expansion factor is changeable in these types of alloys depending on the alloy composition, degree of cold deformation, and thermal history of the alloy. This change gives a lot of room to control the coefficient of thermal expansion (CTE) of those Ti-alloys to turn from positive though zero to negative values and vice versa. In this paper, the appearance of the NTE factor is discussed and the possible methods to control the final thermal expansion coefficient to achieve a zero thermal expansion coefficient are presented. The unique thermal expansion behavior of the alloys will locate them as an excellent candidate in sensing apparatus and other precious equipments.

Thermal expansion and pore pressure generation in oil sands

1986 ◽  
Vol 23 (3) ◽  
pp. 327-333 ◽  
Author(s):  
J. G. Agar ◽  
N. R. Morgenstern ◽  
J. D. Scott
Keyword(s):  
Thermal Expansion ◽  
Pore Pressure ◽  
Oil Sands ◽  
Thermal Stresses ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Oil Sand ◽  
Thermal Expansion Coefficients ◽  
Stress Changes ◽  
Expansion Coefficients

The prediction of stress changes and deformations arising from ground heating requires the coupled solution of the heat transfer and consolidation equations. Heat consolidation as a class of problems is distinct from other thermally induced consolidation problems involving processes such as frost heave and thaw consolidation in that it involves heating to elevated temperatures well above normal ground temperatures. Two of the important parameters required in analyses of heat consolidation problems are thermal expansion coefficients and a coefficient of thermal pore pressure generation.Relationships describing thermal expansion behaviour and thermal pore pressure generation in oil sands are presented. Both drained and undrained thermal expansion coefficients for Athabasca oil sand were determined by means of heating experiments in the temperature range 20–300 °C. The thermal pore pressure generation coefficient was evaluated in undrained heating experiments under constant total confining stresses and under constant effective confining stresses. The equipment and experimental methods developed during this study are appropriate for determination of thermal expansion and pore pressure generation properties of oil sands and other unconsolidated geologic materials. Key words: thermal expansion, oil sand, tar sand, thermal pore pressure generation, heat consolidation, thermal consolidation, coefficient of thermal expansion, thermal stresses, ground heating, thermally enhanced oil recovery, thermoelasticity, undrained heating.

Preparation of solution-processable colorless polyamide-imides with extremely low thermal expansion coefficients through an in-situ silylation method for potential space optical applications

e-Polymers ◽  
2016 ◽  
Vol 16 (5) ◽  
pp. 395-402 ◽  
Author(s):  
Song Wang ◽  
Guangjie Yang ◽  
Shibin Wu ◽  
Ge Ren ◽  
Wei Yang ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Linear Chain ◽  
Tensile Modulus ◽  
Optical Homogeneity ◽  
One Pot ◽  
System Architectures ◽  
Thermal Expansion Coefficients ◽  
Low Thermal Expansion

AbstractSeveral tough and flexible fluorinated polyamide-imide films were prepared from trimellitic anhydride chloride and 2,2′-bis(trifluoromethyl)benzidine through a facile one-pot in-situ silylation method. By incorporating fluorinated side groups, the solubility of the prepared polyamide-imide was greatly enhanced. Meanwhile, due to their linear chain configuration and the existence of hydrogen bonding, the prepared polyamide-imide films revealed high tensile strength, high tensile modulus, high glass transition temperature (Tg) and most interestingly, very low coefficient of thermal expansion (CTE) of 11 ppm/°C. Copolymerization with pyromellitic dianhydride (PMDA) led to an extremely low CTE of 4 ppm/°C which should be among the lowest values available for soluble polyamide-imides. The optical homogeneity and stress homogeneity of the obtained polyamide-imide films were also tested. After non-contact with substance and thermal treatment at 300°C, they revealed a better optical homogeneity and stress homogeneity than that of the commercially available Kapton polyimide (PI) films, with a PV value of 0.915 λ and RMS value of 0.163 λ. Thus, these colorless and soluble polyamide-imide films simultaneously possessing promising optical imaging performance are good candidates as novel diffractive membrane optical system architectures.

Precise Determination of Thermal Expansion Coefficients Observed in 4H-SiC Single Crystals

2006 ◽  
Vol 527-529 ◽  
pp. 699-702 ◽  
Author(s):  
Masashi Nakabayashi ◽  
Tatsuo Fujimoto ◽  
Masakazu Katsuno ◽  
Noboru Ohtani
Keyword(s):  
Thermal Expansion ◽  
Single Crystals ◽  
Coefficient Of Thermal Expansion ◽  
Laser Interferometry ◽  
Precise Determination ◽  
Stress Distributions ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
Nippon Steel Corporation ◽  
Interferometry Method

The coefficient of thermal expansion (CTE) of SiC single crystals is important, in particular, for both designing device assembly and controlling stress distributions in heteroepitaxial thin film structures grown onto SiC substrates. We have performed very precise measurements of the CTEs for SiC single crystals comprising of single 4H polytype PVT-grown in NIPPON Steel Corporation for a temperature range from 123 K to 473 K using a laser interferometry method. This method allows us to directly measure the temperature dependent variation in thermal expansion of the crystal volume with much higher accuracy, and enables us to straightforwardly obtain practical information of CTE data. Furthermore in order to discuss the CTE behavior for a wider temperature range the CTEs at higher temperatures up to 1573 K have been also measured using dilatometer method. The CTE obtained for a nitrogen-doped 4H-SiC single crystal increases continuously from 0.8 ppm/K to 3.1 ppm/K for temperatures of 273 K and 423 K respectively, and further increases to 5.4 ppm/K at 1273 K. We conclude from our data that the CTE variations are likely to be almost independent of the crystal axis directions of SiC from 123 K up to 1573 K.

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