Investigation of Hygroscopic Swelling of Polymers in Freezing Temperature

2007 ◽  
Author(s):  
Seungbae Park ◽  
Haojun Zhang
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Room Temperature ◽  
Correlation Method ◽  
Freezing Temperature ◽  
Image Correlation ◽  
Temperature Dependent ◽  
Hygroscopic Swelling ◽  
Most Significant Change

It is well known that coefficients of thermal expansion and hygroscopic swelling vary with temperature. The most significant change takes place at the glass transition temperature of a polymer. The phenomenon of temperature-dependent CHS has been studied by several authors [1, 2] in polymers and polymer-based composites mainly at room temperature and above. However, effect of freezing temperature on hygroscopic swelling of polymers has not been demonstrated. In this study, the behavior of CHS at and below freezing temperature is investigated. Reported results are obtained using a new CHS measurement technique, the digital image correlation method.

The Effect of Thermal History on Porcelain Expansion Behavior

1989 ◽  
Vol 68 (9) ◽  
pp. 1313-1315 ◽  
Author(s):  
C.W. Fairhurst ◽  
D.T. Hashinger ◽  
S.W. Twiggs
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Heating Rate ◽  
Room Temperature ◽  
Heating Rates ◽  
Thermal Expansion Data ◽  
Temperature Range ◽  
Expansion Behavior

Porcelain-fused-to-metal restorations are fired several hundred degrees above the glass-transition temperature and cooled rapidly through the glass-transition temperature range. Thermal expansion data from room temperature to above the glass-transition temperature range are important for the thermal expansion of the porcelain to be matched to the alloy. The effect of heating rate during measurement of thermal expansion was determined for NBS SRM 710 glass and four commercial opaque and body porcelain products. Thermal expansion data were obtained at heating rates of from 3 to 30°C/min after the porcelain was cooled at the same rate. By use of the Moynihan equation (where Tg systematically increases in temperature with an increase in cooling/heating rate), the glass-transition temperatures (Tg) derived from these data were shown to be related to the heating rate.

Proposal for a material with negative thermal expansion

2016 ◽  
Vol 30 (32) ◽  
pp. 1650238
Author(s):  
Mikrajuddin Abdullah
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Metal Organic Framework ◽  
Negative Thermal Expansion ◽  
Lennard Jones ◽  
Model Predictions ◽  
Metal Organic ◽  
Organic Framework

I propose a model of a material that exhibits negative thermal expansion (NTE) properties and criteria for the occurrence of linear and volumetric NTE. I derived the criteria for an arbitrary force between rigid units in the material. These criteria are also discussed specifically for the Lennard–Jones (6–12) potential and in more detail for metal–organic framework (MOF) materials comprising rigid units connected by organic linkers. Qualitatively, the model predictions can explain some observed results. Surprisingly, the model can produce equations for the transition temperature from NTE to positive thermal expansion (PTE), [Formula: see text] K, which is exactly the same as the temperature at which the glass transition begins to occur in most polymers, i.e., [Formula: see text] K.

scholarly journals Core/Clad Phosphate Glass Fibres Containing Iron and/or Titanium

2015 ◽  
Vol 1 (1) ◽  
Author(s):  
Ifty Ahmed ◽  
S. S. Shaharuddin ◽  
N. Sharmin ◽  
D. Furniss ◽  
C. Rudd
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Tensile Modulus ◽  
Average Diameter ◽  
Phosphate Glasses ◽  
Dissolution Medium ◽  
The Core ◽  
Controllable Degradation

AbstractPhosphate glasses are novel amorphous biomaterials due to their fully resorbable characteristics, with controllable degradation profiles. In this study, phosphate glasses containing titanium and/or iron were identified to exhibit sufficiently matched thermal properties (glass transition temperature, thermal expansion coefficient and viscosity) which enabled successful co-extrusion of glass billets to form a core/clad preform. The cladding composition for the core/clad preforms were also reversed. Fe clad and Ti clad fibres were successfully drawn with an average diameter of between 30~50 μm. The average cladding annular thickness was estimated to be less than 2 μm. Annealed core/clad fibres were degraded in PBS for a period of 27 days. The strength of the Fe clad fibres appeared to increase from 303 ± 73 MPa to 386 ± 45 MPa after nearly 2 weeks in the dissolution medium (phosphate buffered solution) before decreasing by day 27. The strength of the Ti clad fibres revealed an increase from 236 ± 53 MPa to 295 ± 61 MPa when compared at week 3. The tensile modulus measured for both core/clad fibres ranged between 51 GPa to 60 GPa. During the dissolution study, Fe clad fibres showed a peeling mechanism compared to the Ti clad fibres.

Silk Polymer Coating with Low Dielectric Constant and High Thermal Stability for Ulsi Interlayer Dielectric

1997 ◽  
Vol 476 ◽  
Author(s):  
P. H. Townsend ◽  
S. J. Martin ◽  
J. Godschalx ◽  
D. R. Romer ◽  
D. W. Smith ◽  
...  
Keyword(s):  
Thin Film ◽  
Dielectric Constant ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Integrated Circuits ◽  
Room Temperature ◽  
Polymer Network ◽  
Flow Characteristics ◽  
Interlayer Dielectric

AbstractA novel polymer has been developed for use as a thin film dielectric in the interconnect structure of high density integrated circuits. The coating is applied to the substrate as an oligomeric solution, SiLK*, using conventional spin coating equipment and produces highly uniform films after curing at 400 °C to 450 °C. The oligomeric solution, with a viscosity of ca. 30 cPs, is readily handled on standard thin film coating equipment. Polymerization does not require a catalyst. There is no water evolved during the polymerization. The resulting polymer network is an aromatic hydrocarbon with an isotropie structure and contains no fluorine.The properties of the cured films are designed to permit integration with current ILD processes. In particular, the rate of weight-loss during isothermal exposures at 450 °C is ca. 0.7 wt.%/hour. The dielectric constant of cured SiLK has been measured at 2.65. The refractive index in both the in-plane and out-of-plane directions is 1.63. The flow characteristics of SiLK lead to broad topographic planarization and permit the filling of gaps at least as narrow as 0.1 μm. The glass transition temperature for the fully cured film is greater than 490 °C. The coefficient of thermal expansivity is 66 ppm/°C below the glass transition temperature. The stress in fully cured films on Si wafers is ca. 60 MPa at room temperature. The fracture toughness measured on thin films is 0.62 MPa m ½. Thin coatings absorb less than 0.25 wt.% water when exposed to 80% relative humidity at room temperature.

Highly transparent polyhydroxyimide/TiO2 and ZrO2 hybrid films with high glass transition temperature (Tg) and low coefficient of thermal expansion (CTE) for optoelectronic application

2017 ◽  
Vol 5 (33) ◽  
pp. 8444-8453 ◽  
Author(s):  
Shun-Wen Cheng ◽  
Tzu-Tien Huang ◽  
Chia-Liang Tsai ◽  
Guey-Sheng Liou
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermal Expansion Coefficient ◽  
Coefficient Of Thermal Expansion ◽  
High Glass Transition Temperature ◽  
Hybrid Films ◽  
Optoelectronic Application ◽  
Low Thermal Expansion

Highly transparent polyhydroxyimide/TiO2 and ZrO2 hybrids films with high glass transition temperature and low thermal expansion coefficient for optoelectronic application.

scholarly journals Determination of glass transition temperature using temperature dependent signal from a cryogenic photopyroelectric instrument

2019 ◽  
Vol 676 ◽  
pp. 7-12 ◽  
Author(s):  
Allen Mathew ◽  
Fabrice Goutier ◽  
Benoit Escorne ◽  
Abdelaziz Elass ◽  
Gérard Louis ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Temperature Dependent ◽  
Dependent Signal
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