Plasticizing of isotactic polypropylene upon addition of hydrocarbon oils

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Koh-hei Nitta ◽  
Hidetaka Ando ◽  
Takuo Asami

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.

Author(s):  
Baotong Hao ◽  
Baolin Liu

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.


2011 ◽  
Vol 31 (4) ◽  
Author(s):  
Yi-Nan Zhang ◽  
Shu-Ling Zhang ◽  
Yan-Hua Yang ◽  
Hong-Yi Qin ◽  
Dong Jiang

Abstract A series of random polysulfone/polyethersulfone (PSF/PES) copolymers were synthesized by the polycondensation of 4,4′-isopropylidenediphenol, 4,4′-dihydroxyldiphenylsulfone, and 4,4′-dichlorodiphenylsulfone in the presence of potassium carbonate. The resulting copolymers displayed similar solubility with PSF and PES. The glass transition temperature and the 5% weight loss temperature of these copolymers varied in the range of 199°C–299°C and 467°C–498°C, respectively, which showed excellent thermal stability. Moreover, the elongation at break of these copolymers was much higher than that of PES, whereas the tensile strength was a little lower.


Author(s):  
Baotong Hao ◽  
Baolin Liu ◽  
Senjie Rong ◽  
Yan Zhou ◽  
Zhixin Gao

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.


2006 ◽  
Vol 326-328 ◽  
pp. 183-186 ◽  
Author(s):  
Jong Sun Kim ◽  
Kyung Hwan Yoon ◽  
Julia A. Kornfield

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


BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 6933-6942
Author(s):  
Yuehua Zhu ◽  
Yaoli Zhang ◽  
Biao Pan

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.


2012 ◽  
Vol 26 (19) ◽  
pp. 1250100 ◽  
Author(s):  
YOU-YUAN WANG ◽  
TAO YANG ◽  
RUI-JIN LIAO

The glass transition temperature (Tg) in the amorphous region of an insulation paper is one of the most important characteristics for thermal stability. Molecular dynamic simulations have been performed on three micro-structural models, namely, amorphous pure cellulose, amorphous cellulose with water and amorphous cellulose with oil, to study the microscopic mechanism of the glass transition process for oil-immersed transformer insulation paper. Using the method of specific volume versus temperature curve, the Tg of amorphous pure cellulose, cellulose with water, and cellulose with oil was determined as 448, 418 and 440 K, respectively. The current study may provide some information for thermal aging. The simulation results show that during the glass transition process, both the chain motion and mechanical properties of cellulose changes significantly. Relative to the oil molecules, water molecules immersed in the amorphous region of insulation paper can disrupt hydrogen bonds between cellulose chains. This phenomenon results in a significant reduction in the glass transition temperature and affects the thermal stability of the insulation paper.


Micromachines ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 54
Author(s):  
Hidetaka Ueno ◽  
Kiichi Sato ◽  
Kou Yamada ◽  
Takaaki Suzuki

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.


Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1153 ◽  
Author(s):  
Osamu Urakawa ◽  
Ayaka Yasue

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.


Sign in / Sign up

Export Citation Format

Share Document