Measurement of Stress-Optical Coefficients of COC’s with Different Composition

2006 ◽  
Vol 326-328 ◽  
pp. 183-186 ◽  
Author(s):  
Jong Sun Kim ◽  
Kyung Hwan Yoon ◽  
Julia A. Kornfield
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Extreme Values ◽  
Frequency Region ◽  
Master Curves ◽  
Type Device ◽  
The Difference ◽  
Optical And Mechanical Properties ◽  
Cyclic Olefin Copolymers

Rheo-optical and mechanical properties of Cyclic Olefin Copolymers(COC’s) with different composition have been investigated across the glass transition temperature. Accurate measurement of stress or strain-optical coefficients and elastic modulus data across the glass transition are essential for predicting optical anisotropy in many optical products like pickup lenses and waveguides in LCD backlight unit since the material of these products have both flow and thermal history from the melt to glass. To obtain stress-optic behavior in the wide frequency region including rubbery, glassy and glass transition regime, extensional bar-type device was used. A shear-sandwich tool was used in the melt region. Master curves for modulus, stress-optical and strain-optical coefficients have been obtained in wide frequency region. The stress-optical coefficients of COC’s with mol fraction of norbornene, 60 ~ 70%, showed almost constant between -8 and -9 Br at glassy region and between +920 and +1,160 Br in the melt region. Even though the glass transition temperature showed the difference of 35, the stress-optical coefficients of COC’s with different composition showed almost same extreme values

Strength of Sulfur-Linked Elastomers

1996 ◽  
Vol 69 (4) ◽  
pp. 577-590 ◽  
Author(s):  
H. Chun ◽  
A. N. Gent
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Crack Propagation ◽  
Test Temperature ◽  
Effective Rate ◽  
Master Curves ◽  
Universal Form ◽  
Wlf Equation ◽  
Test Conditions

Abstract Fracture energies have been determined for tearing through a sheet of a polysulfide elastomer, and for peeling apart two sheets bonded together with sulfur interlinks. Measurements were made over wide ranges of rate of crack propagation and test temperature. By shifting curves at various temperatures along the rate axis, using shift factors aT calculated from the “universal” form of the WLF equation, master curves were obtained for tear and peel energy vs. rate of tear or peel at the glass transition temperature Tg about −55°C. These master curves of strength vs. effective rate of crack propagation at Tg were closely similar to those obtained previously for several hydrocarbon elastomers: BR, SBR and EPR; interlinked with C-C bonds. Thus, under comparable test conditions the strength of the present polysulfide elastomer with sulfur crosslinks is similar to that for hydrocarbon elastomers with C-C crosslinks. The question then arises: Why are sulfur-vulcanized elastomers stronger in common experience than peroxide-cured ones? Possible reasons are discussed.

Thermal Properties of PVP Cryoprotectants With Nanoparticles

2011 ◽  
Vol 2 (2) ◽  
Author(s):  
Baotong Hao ◽  
Baolin Liu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Aqueous Solutions ◽  
Specific Heat ◽  
Warming Rate ◽  
The Difference ◽  
Transfer Properties

Vitrification is an effective way for the cryopreservation of cells and tissues. The critical cooling rates for vitrification solution are relatively high. It is reported that nanoparticles can improve the heat transfer properties of solutions. To increase the heat transfer coefficient of aqueous cryoprotectant solutions, Hydroxyapatite (HA) nanoparticles were added into Polyvinylpyrrolidone (PVP) solutions (50%, 55%, and 60%, w/w). The glass-transition temperature, devitrification temperature, and specific heat of PVP aqueous solutions with/without HA nanoparticles (0.1%, 0.5%, and 1%, w/w) were measured by a differential scanning calorimeter at a cooling rate of 20°C/min and a warming rate of 10°C/min. The change in density of the above solutions with temperature was determined by using a straw that can reveal the volume change of solutions. The thermal conductivity was calculated based on the experimental data. A device that can be used to measure the thermal conductivity of vitrification solutions with/without nanoparticles was developed in this study. The results showed that the glass-transition temperature, devitrification temperature, and specific heat of PVP aqueous solutions with HA nanoparticles are larger than those without HA nanoparticles. The thermal conductivity of solutions with HA nanoparticles is larger than those without HA nanoparticles at a specific temperature. The lower the temperature, the smaller the difference in thermal conductivity between the solutions with and without HA nanoparticles. The calculated thermal conductivity meets the measured data well.

Thermal Properties of PVP Cryoprotectants With Nanoparticles

2009 ◽  
Author(s):  
Baotong Hao ◽  
Baolin Liu ◽  
Senjie Rong ◽  
Yan Zhou ◽  
Zhixin Gao
Keyword(s):  
Thermal Conductivity ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Aqueous Solutions ◽  
Specific Heat ◽  
Warming Rate ◽  
Specific Temperature ◽  
The Difference ◽  
The Heat Transfer Coefficient

Vitrification is an effective way for the cryopreservation of cells and tissues. The critical cooling rates for vitrification solution are relatively high. It is reported that nanoparticles can improve the heat tranfer properties of solutions. To increase the heat transfer coefficient of aqueous cryoprotectant solutions, HA nanoparticles were added into PVP solutions (50%, 55%, 60%, w/w). The glass transition temperature, devitrification temperature and specific heat of PVP aqueous solutions with/without HA nanoparticles (0.1%, 0.5% and 1%, w/w) were measured by differential scanning calorimeter (DSC) at the cooling rate of 20°C/min and warming rate of 10°C/min. The change of density of above solutions with temperature was determined by using a straw that can reveal the volume change of solutions. The thermal conductivity was calculated based on the experimental data. A device that can be used to measure the thermal conductivity of vitrification solutions with/without nanoparticles was developed in this study. The results showed that the glass transition temperature, devitrification temperature and specific heat of PVP aqueous solutions with HA nanoparticles are larger than that without HA nanoparticles. The thermal conductivity of solutions with HA nanoparticles is larger than that without HA nanoparticles at a specific temperature. The lower the temperature, the smaller the difference of thermal conductivity between solutions with and without HA nanoparticles. The calculated thermal conductivity meets the measured data well.

scholarly journals The viscoelasticity and deformation mechanism of Taxodium hybrid ‘Zhongshanshan’ wood by dynamic mechanical analysis

BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 6933-6942
Author(s):  
Yuehua Zhu ◽  
Yaoli Zhang ◽  
Biao Pan
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Moisture Content ◽  
Storage Modulus ◽  
Loss Modulus ◽  
Structural Deformation ◽  
Hydrothermal Processing ◽  
Average Loss ◽  
The Difference

The viscoelasticity of Taxodium hybrid ‘Zhongshanshan’ wood, while undergoing hydrothermal processing, was investigated via dynamic thermomechanical analysis. The results showed that the elastic deformation and viscous deformation of the Taxodium hybrid ‘Zhongshanshan’ heartwood were greater than the sapwood. The heartwood average storage modulus and average loss modulus were greater than the sapwood. The difference between the heartwood and sapwood had little effect on the average glass transition temperature of their hemicellulose, which was approximately 74 °C. The radial average storage modulus was greater than the tangential, and the difference between the average loss modulus in the radial and tangential directions was negligible. The average glass transition temperature in the radial direction was slightly lower than the tangential direction. As the moisture content increased, the average storage modulus and its average hemicellulose glass transition temperature decreased. The average glass transition temperature tended to be lower as the moisture content increased. This study revealed the structural deformation and molecular movement of Taxodium hybrid ‘Zhongshanshan’ wood, while undergoing hydrothermal processing; this has important theoretical value for understanding its characteristics as well as its rational and efficient usage.

Chemical structure and physical properties of cyclic olefin copolymers (IUPAC Technical Report)

2005 ◽  
Vol 77 (5) ◽  
pp. 801-814 ◽  
Author(s):  
Ju Young Shin ◽  
Ji Yong Park ◽  
Chenyang Liu ◽  
Jiasong He ◽  
Sung Chul Kim
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Chemical Structure ◽  
Moisture Absorption ◽  
High Surface ◽  
Polymeric Materials ◽  
Surface Characteristics ◽  
Cyclic Olefin ◽  
Cyclic Olefin Copolymers

Cyclic olefin copolymers comprise a new class of polymeric materials showing properties of high glass-transition temperature, optical clarity, low shrinkage, low moisture absorption, and low birefringence. There are several types of cyclic olefin copolymers based on different types of cyclic monomers and polymerization methods. In this work, we have analyzed the chemical structure of the currently commercialized cyclic olefin copolymers by 13C NMR, and investigated their glass-transition temperatures and surface characteristics. It was observed that the glass-transition temperature, Tg, of cyclic olefin copolymers depended on the bulkiness of the main chain, and the number of rings had an important role in increasing the bulkiness of cyclic olefin copolymers. Cyclic olefin copolymers with polar substituents such as ester or ether groups showed high surface energy per area and peel strength.

scholarly journals Micropatterning Method for Porous Materials Using the Difference of the Glass Transition Temperature between Exposed and Unexposed Areas of a Thick-Photoresist

Micromachines ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 54
Author(s):  
Hidetaka Ueno ◽  
Kiichi Sato ◽  
Kou Yamada ◽  
Takaaki Suzuki
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Porous Material ◽  
3D Structure ◽  
Porous Membrane ◽  
Cellular Tissue ◽  
A Cell ◽  
Thick Photoresist ◽  
The Difference

A cell culture on a scaffold has the advantages of functionality and easy handling, because the geometry of the cellular tissue is controlled by designing the scaffold. To create complex cellular tissue, scaffolds should be complex two-dimensional (2D) and three-dimensional (3D) structures. However, it is difficult to fabricate a scaffold with a 2D and 3D structure because the shape, size, and fabrication processes of a 2D structure in creating a cell layer, and a 3D structure containing cells, are different. In this research, we propose a micropatterning method for porous materials using the difference of the glass transition temperature between exposed and unexposed areas of a thick-photoresist. Since the proposed method does not require a vacuum, high temperature, or high voltage, it can be used for fabricating various structures with a wide range of scales, regardless of the materials used. Additionally, the patterning area can be fabricated accurately by photolithography. To evaluate the proposed method, a membrane integrated scaffold (MIS) with a 2D porous membrane and 3D porous material was fabricated. The MIS had a porous membrane with a pore size of 4 μm or less, which was impermeable to cells, and a porous material which was capable of containing cells. By seeding HUVECs and HeLa cells on each side of the MIS, the cellular tissue was formed with the designed geometry.

scholarly journals Glass Transition Behaviors of Poly (Vinyl Pyridine)/Poly (Vinyl Phenol) Revisited

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1153 ◽  
Author(s):  
Osamu Urakawa ◽  
Ayaka Yasue
Keyword(s):  
Molecular Weight ◽  
Hydrogen Bonding ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Polymer Chain ◽  
Molecular Weight Dependence ◽  
Vinyl Pyridine ◽  
The Difference ◽  
Vinyl Phenol

We examined the composition and molecular weight dependence of the glass transition temperature in detail for two types of hydrogen bonding miscible blends: poly (2-vinyl pyridine)/poly (vinyl phenol) (2VPy/VPh) and poly (4-vinyl pyridine)/poly (vinyl phenol) (4VPy/VPh). Regarding the functional form of the glass transition temperature, Tg, as a function of the weight fraction, we found a weak deviation from the Kwei equation for 2VPy/VPh blends. In contrast, such a deviation was not observed for the 4VPy/VPh blend. By relating the difference in the functional forms of Tg between the two blend systems to the difference in hydrogen bonding ability, we proposed a modified version of the Kwei equation. As for the interaction parameter, q in the Kwei equation, clear molecular weight dependence was observed for 2VPy/VPh blends: the lower the VPh molecular weight in the oligomer level, the higher the q values, suggesting the higher hydrogen bonding formability near the polymer chain ends than the middle part of a polymer chain.

Critical Cooling Rate Vs. Reduced Glass Transition: Scaling Factors and Master Curves

1998 ◽  
Vol 554 ◽  
Author(s):  
N. Clavaguera ◽  
M. T. Clavaguera-Mora
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Cooling Rate ◽  
Glass Formation ◽  
Supercooled Liquid ◽  
High Viscosity ◽  
Master Curves ◽  
Critical Cooling Rate ◽  
Equilibrium Solidification

AbstractThe aim of the present paper is to analyse the glass formation and stability of bulk metallic glasses. Attention is focused to metallic alloys as systems which may develop a large glassforming ability. Glass formation when quenching from the liquid state is discussed in terms of the thermodynamics and kinetics of the stable/metastable competing phases. Thermodynamics is required to relate glass transition temperature, Tg, to the energetics of the supercooled liquid. Kinetic destabilisation of equilibrium solidification and, consequently, glass forming ability are favoured by the high viscosity values achieved under continuous cooling. The relative thermal stability of the supercooled liquid depends on the thermodynamic driving force and interfacial energy between each competing nucleating phase and the molten alloy. It is shown that the quantities representative of the process, once scaled, have a temperature dependence that is mostly fixed by the reduced glass transition temperature, Tgr= Tg/Tm, Tm being the melting temperature. Based on the classical models of nucleation and crystal growth, the reduced critical cooling rate is shown to follow master curves when plotted against Tgr. Experimental trends for specific systems are compared to predicted values from these master curves.

Plasticizing of isotactic polypropylene upon addition of hydrocarbon oils

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Koh-hei Nitta ◽  
Hidetaka Ando ◽  
Takuo Asami
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Oil Content ◽  
Amorphous Region ◽  
Elongation At Break ◽  
Measurement Temperature ◽  
Oil Blends ◽  
The Difference ◽  
Hydrocarbon Oil

Abstract The effect of the addition of hydrocarbon oil on the mechanical behaviour of isotactic polypropylenes (iPPs) was examined. It was found that the oil molecules are completely dissolved in the amorphous region of iPP so that the blending lowers the glass transition temperature, Tg, of iPP. As a result, Young’s modulus of iPP/oil blends is dominated by the difference between the measurement temperature and Tg (ΔTg = T - Tg), independent of the oil content. The elongation at break is proportional to ΔTg, while the strength at break increases linearly with increasing tie-molecule fraction (which increases with decreasing oil content), being independent of ΔTg.

Thermal Behavior of Chalcogenide glasses Te90Se10 and Se90Te10

2015 ◽  
Vol 7 (02) ◽  
pp. 113-118
Author(s):  
Arvind Kumar Verma ◽  
Anchal Srivastava ◽  
R. K Shukla ◽  
K. C Dubey
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Glass Forming Ability ◽  
Scanning Calorimetry ◽  
Glass Forming ◽  
The Difference ◽  
Thermal Stability Of

In the present research work melt quenching method has been adopted to prepare the glassy Te-rich (Te90Se10) and Se-rich (Se90Te10 ) Chalcogenide at a pressure of 10-2 Torr with constant Temperature at 1000°C for 8 hours. Devitrification characteristics of the pure glassy Chalcogenide Te90Se10 and Se90Te90 were investigated by using Differential scanning Calorimetry (DSC) 4000 Perkin Elmer. All the measurements carried out at fixed heating rate 10 0C/min under non-isothermal conditions. The Glass transition temperature (Tg) and other thermal properties were examined by temperature modulated differential scanning Calorimetry at 40 oC to 445 oC. Glass transition temperature (Tg) represents the strength or rigidity of the glass structure. Tg affords valuable information on the thermal stability of the glassy state but Tg alone does not give any information on the glass forming tendency. The difference of the Peak crystallization temperature (Tp) and Glass transition temperature (Tg) is a strong indication of the thermal stability. The higher the value of Tc and Tg the greater is the thermal stability. Glass transition temperature (Tg=2160C) of Tellurium rich (Te90Se10) is more than Glass transition temperature (Tg=730C) of Selenium rich (Se90Te90) due to semi metallic nature of Tellurium. The difference of (Tp-Tg) is a strong indicator of both the thermal stability and Glass forming ability (GFA). Higher the value of (Tp-Tg), higher is the thermal stability and GFA because higher values of this difference indicate more kinetic resistance to the crystallization. Glass forming ability (GFA) and thermal stability of Te90Se10 is greater than Se90Te90. For memory and switching materials, glass thermal stability and GFA parameters are very important. Intensity of Se-rich (Se90Te10) is more than Te-rich (Te90Se10) and both samples are polycrystalline in nature.

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