Thermal Expansion and Viscoelasticity of Rubber in Relation to Crosslinking and Molecular Packing

1966 ◽  
Vol 39 (2) ◽  
pp. 408-417
Author(s):  
P. Mason
Keyword(s):  
Thermal Expansion ◽  
Free Volume ◽  
Specific Volume ◽  
Crosslink Density ◽  
Qualitative Change ◽  
Linear Increase ◽  
Thermal Expansion Coefficients ◽  
Expansion Behavior ◽  
Expansion Coefficients ◽  
Packing Effects

Abstract Effects of crosslinking on specific volume, thermal expansion coefficient, glass transition temperature (Tg) and viscoelasticity of rubber have been studied. Materials were prepared by heating purified natural rubber with varying amounts of cumyl peroxide. This procedure formed networks by intermolecular carbon-to-carbon bonding, and an approximately sixty-fold range of crosslink density was obtained. Crosslink density could be estimated with reasonable confidence up to about 1020/g. At this level the effects observed were, approximately, a one per cent decrease in specific volume; 23 per cent and 6 per cent decreases in the thermal expansion coefficients respectively below and above Tg; 5° C increase in Tg; and a displacement of the viscoelastic response by +5° C. These changes are accounted for in terms of the reduction in free volume consequent on crosslinking. There was also a qualitative change in behavior, the thermal expansion and viscoelastic transitional regions widening as crosslinking increased. The thermal expansion behavior is explained in terms of a linear increase in the variance of monomeric free volume with crosslinking up to 1020/g. At higher densities crosslinks are so close that their packing effects interact and the nature of the phenomenon changes.

Structure and Thermal Expansion Behavior of Dy2-xGdxMo4O15 Solid Solution

2008 ◽  
Vol 368-372 ◽  
pp. 1665-1667
Author(s):  
M.M. Wu ◽  
X.L. Xiao ◽  
Y.Z. Cheng ◽  
J. Peng ◽  
D.F. Chen ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Thermal Expansion ◽  
Monoclinic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Behavior ◽  
Expansion Coefficients ◽  
Cell Volumes

A new series of solid solutions Dy2-xGdxMo4O15 (x = 0.0-0.9) were prepared. These compounds all crystallize in monoclinic structure with space group P21/c. The lattice parameters a, b, c and unit cell volumes V increase almost linearly with increasing gadolinium content. The intrinsic thermal expansion coefficients of Dy2-xGdxMo4O15 (x = 0.0 and 0.25) were obtained in the temperature range of 25 to 500°C with high-temperature X-ray diffraction. The correlation between thermal expansion and crystal structure was discussed.

scholarly journals Thermal Expansion of a Multiphase Intermetallic Ti-Al-Nb-Mo Alloy Studied by High-Energy X-ray Diffraction

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 727
Author(s):  
Peter Staron ◽  
Andreas Stark ◽  
Norbert Schell ◽  
Petra Spoerk-Erdely ◽  
Helmut Clemens
Keyword(s):  
Thermal Expansion ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Behavior ◽  
Different Temperatures ◽  
Service Conditions ◽  
Expansion Coefficients ◽  
Alloy Properties

Intermetallic γ-TiAl-based alloys are lightweight materials for high-temperature applications, e.g., in the aerospace and automotive industries. They can replace much heavier Ni-based alloys at operating temperatures up to 750 °C. Advanced variants of this alloy class enable processing routes that include hot forming. These alloys consist of three relevant crystallographic phases (γ-TiAl, α2-Ti3Al, βo-TiAl) that transform into each other at different temperatures. For thermo-mechanical treatments as well as for adjusting alloy properties required under service conditions, the knowledge of the thermal expansion behavior of these phases is important. Therefore, thermal expansion coefficients were determined for the relevant phases in a Ti-Al-Nb-Mo alloy for temperatures up to 1100 °C using high-energy X-ray diffraction.

Specific Volume and Ultrasonic Velocity Studies of the Liquid Crystal N-(p-n-hexyloxybenzylidene)-p-n-butylaniline (Hx BBA)

1983 ◽  
Vol 38 (7) ◽  
pp. 762-764 ◽  
Author(s):  
L. V. Choudary ◽  
J. V. Rao ◽  
P. N. Murty ◽  
C. R. K. Murty
Keyword(s):  
Thermal Expansion ◽  
Liquid Crystal ◽  
Ultrasonic Velocity ◽  
Specific Volume ◽  
Velocity Variation ◽  
Velocity Measurements ◽  
First Order ◽  
Smectic A ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

Abstract Specific volume and ultrasonic velocity measurements have been carried out on the liquid crystal N-(p-n-hexyloxybenzylidene)-p-n-butylaniline in the isotropic, nematic, smectic A, smectic B and smectic G phases. The variation of the specific volume with temperature shows that the corresponding transitions are of first order. Thermal expansion coefficients have been calculated for all the mesophases. The ultrasonic velocity variation with temperature confirms the transitions.

Thermal Expansion of Anti-Perovskite Mn3Zn1-xSnxN Compounds

2012 ◽  
Vol 512-515 ◽  
pp. 890-893 ◽  
Author(s):  
Xue Hua Yan ◽  
Jia Qi Liu ◽  
Zhu Yuan Hua ◽  
Bing Yun Li ◽  
Xiao Nong Cheng
Keyword(s):  
Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Cubic Crystal ◽  
Thermal Expansion Behavior ◽  
Sn Doping ◽  
Thermal Expansion Coefficients ◽  
Expansion Behavior ◽  
Expansion Curve ◽  
Wide Perspective ◽  
Expansion Coefficients

The anti-perovskite structured Mn3XN(X=Cu,Al,Ag,Zn,Ga,Sn,In) have wide perspective and practicability with unique advantages compared with other materials as a new negative thermal expansion (NTE) material. Because of its simple preparation and unique properties of NTE, this kind of compounds aroused scientists’ attention. The metallic nitrides Mn3Zn1-xSnxN (x=0.1, 0.2, 0.3, 0.4, 0.5) were prepared by solid-state sintering. The anti-perovskite compound Mn3Zn1-xSnxN has a cubic crystal structure with space group Pm3m. It shows that Zn element is partial replaced by Sn element. The Sn doping in Mn3Zn1-xSnxN compound can cause the thermal expansion behavior of the compound to change between positive and negative by analyzing the curve of thermal expansivity with the temperature. Mn3Zn0.7Sn0.3N shows a very strong NTE. Its negative thermal expansion coefficients were -4.39×10-4/K from 345.4 °C to 476.2 °C. In addition, the variation of the thermal expansion curve for Mn3Zn0.8Sn0.2N is almost negligible with the increasing of temperature to 600 °C, exhibiting nearly zero thermal expansion behavior. Therefore, the thermal expansion of Mn3Zn1-xSnxN could be tuned via different contents of Sn in Mn3ZnN.

Thermal Expansion Behavior of ZnSe and ZnS0.03Se0.97 Epilayers on GaAs at Temperatures in the Range, 25°C - 250°C

1994 ◽  
Vol 340 ◽  
Author(s):  
J. R. Kim ◽  
R. M. Park ◽  
K. S. Jones
Keyword(s):  
Thermal Expansion ◽  
Room Temperature ◽  
Lattice Mismatch ◽  
X Ray Diffraction ◽  
Thermal Expansion Behavior ◽  
Lattice Constants ◽  
Thermal Expansion Coefficients ◽  
Expansion Behavior ◽  
Expansion Coefficients ◽  
Lattice Matched

ABSTRACTThe thermal expansion behavior of ZnSe and ZnS0.03Se0.97 epilayers grown on GaAs has been investigated using high resolution X-ray diffraction at temperatures between room temperature and the growth temperature. The lattice parameters perpendicular and parallel to the surface were measured with the Bond's method. The lattice mismatch for a partially relaxed ZnSe layer was Δa(⊥)/a =2300 ppm and Δa(‖)/a = 2600 ppm at room temperature(R.T.) and Δa (⊥)/a =3600 ppm and Δa(‖)/a =2400 ppm at 250°C. For ZnS0.03Se0.97 which is almost lattice matched at R.T. to GaAs, Δa(⊥)/a =200 ppm, Δa(⊥)/a =20ppmatR.T. and Δa(⊥)/a =1400ppm, Δa(⊥)/a =50ppm at 250°C. The relaxed lattice constants were evaluated and the thermal expansion coefficients of relaxed ZnSe layers were found to vary from 7.8*10−6/°C at room temperature to 12.2*10−6/°C at 250°C and for ZnS0.03Se0.97 layers the variation was from 7.5*10−6/°C at R.T. to 11.7*10−6/°C at 250°C.

An extended criterion for estimation of glass-forming ability of metals

2007 ◽  
Vol 22 (5) ◽  
pp. 1378-1383 ◽  
Author(s):  
Dmitri V. Louzguine-Luzgin ◽  
Akihisa Inoue
Keyword(s):  
Thermal Expansion ◽  
Specific Volume ◽  
Intersection Point ◽  
Glass Forming Ability ◽  
Molten Metals ◽  
Metallic Liquid ◽  
Glass Forming ◽  
Thermal Expansion Coefficients ◽  
Pure Metals ◽  
Expansion Coefficients

If a metal contracts upon solidification, the specific volume of a metallic liquid phase must not be smaller than that of the corresponding crystal. As molten metals have higher thermal expansion coefficients compared with those of the corresponding crystals, the intersection point of two specific-volume–temperature plots of the liquid and the corresponding solid crystalline phase by analogy with Kauzmann’s paradox for entropy could be treated as an ideal glass-transition temperature. This paper describes this phenomenon observed for a number of pure metals and gives a semiempirical criterion for the achievement of a good glass-forming ability.

Influence of Cr deficiency on sintering, thermal expansion and electrical properties of La0.75Sr0.25Cr1−xO3−δ as a SOFC interconnect material

2016 ◽  
Vol 30 (11) ◽  
pp. 1650127 ◽  
Author(s):  
Yi Ren ◽  
Wen Ma ◽  
Xiaoying Li ◽  
Jun Wang ◽  
Yu Bai ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Electrical Properties ◽  
Perovskite Phase ◽  
Ignition Process ◽  
Thermal Expansion Coefficients ◽  
Auto Ignition ◽  
Pure Perovskite Phase ◽  
Maximum Conductivity ◽  
Expansion Coefficients ◽  
Interconnect Material

The SOFC interconnect materials La[Formula: see text]Sr[Formula: see text]Cr[Formula: see text]O[Formula: see text] [Formula: see text]–[Formula: see text] were prepared using an auto-ignition process. The influences of Cr deficiency on their sintering, thermal expansion and electrical properties were investigated. All the samples were pure perovskite phase after sintering at 1400[Formula: see text]C for 4 h. The cell volume of La[Formula: see text]Sr[Formula: see text]Cr[Formula: see text]O[Formula: see text] decreased with increasing Cr deficient content. The relative density of the sintered bulk samples increased from 93.2% [Formula: see text] to a maximum value of 94.7% [Formula: see text] and then decreased to 87.7% [Formula: see text]. The thermal expansion coefficients of the sintered bulk samples were in the range of [Formula: see text]–[Formula: see text] (30–1000[Formula: see text]C), which are compatible with that of YSZ. Among the investigated samples, the sample with 0.02 Cr deficiency had a maximum conductivity of 40.4 Scm[Formula: see text] and the lowest Seebeck coefficient of 154.8 [Formula: see text]VK[Formula: see text] at 850[Formula: see text]C in pure He. The experimental results indicate that La[Formula: see text]Sr[Formula: see text]Cr[Formula: see text]O[Formula: see text] has the best properties and is much suitable for SOFC interconnect material application.

Novel Silicon-Elastomers for Advanced Soft Lithography

2006 ◽  
Vol 947 ◽  
Author(s):  
Kyung Choi
Keyword(s):  
Thermal Expansion ◽  
High Resolution ◽  
Soft Lithography ◽  
Materials Properties ◽  
Nano Scale ◽  
Thermal Expansion Coefficients ◽  
High Thermal Expansion ◽  
Expansion Coefficients

ABSTRACTHigh resolution pattern transfers in the nano-scale regime have been considerable challenges in ‘soft lithography’ to achieve nanodevices with enhanced performances. In this technology, the resolution of pattern integrations is significantly rely on the materials' properties of polydimethylsiloxane (PDMS) stamps. Since commercial PDMS stamps have shown limitations in nano-scale resolution soft lithography due to their low physical toughness and high thermal expansion coefficients, we developed stiffer, photocured PDMS silicon elastomers designed, specifically for nano-sized soft lithography and photopatternable nanofabrications.

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