Rheology of Selected Persian Honeys

2010 ◽  
Vol 6 (3) ◽  
Author(s):  
Hamid Tavakolipour ◽  
Ahmad Kalbasi Ashtari
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Water Content ◽  
Exponential Model ◽  
Temperature Data ◽  
Arrhenius Model ◽  
Better Than ◽  
Glass Viscosity ◽  
Newtonian Behavior

The rheological properties of two types of Persian honeys (Thyme and Shahjahan) were studied over temperature and water content of 10-30°C and 16.8-17.2%, respectively. At these conditions, they exhibited a Newtonian behavior for shear rate in range of 0-100 and apparent viscosity in range of 6.7 and 150 Pa.s. The activation energy, glass transition temperature and glass viscosity of Thyme and Shahjahan honeys were (104.5 and 109.7 kJ/mol), (225.6 and 228.2K), and (1.68 x 1011 and 1.48 x 1011 Pa.s), respectively. The Williams-Landel-Ferry (WLF) and Arrhenius Models used to check the dependency of viscosity and temperature data. The results showed that Thyme and Shahjahan honeys were fitted with WLF much better than Arrhenius model. However, the viscosity and water content data did not match with exponential model of Zaitoun, and the viscosity decreased with water content due to its plasticizing effect.

Recycling of Waste PET into Useful Alkyd Resin Synthesis by Microwave Irradiation and Applied in Textile Printing

2014 ◽  
Vol 18 (1) ◽  
pp. 80-88 ◽  
Author(s):  
K. Haggag ◽  
N.S. Elshemy ◽  
W. Niazy
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Microwave Irradiation ◽  
Oil Content ◽  
Acid Value ◽  
Fastness Properties ◽  
Alkyd Resins ◽  
Textile Printing ◽  
Modified Binder ◽  
Better Than

Modified alkyd resins with different amounts of vegetable oil contents (sunflower oil) and different catalysts are synthesized with the incorporation of post-consumer polyethylene terephthalate (PET) as a partial substitute for phthalic anhydride. It is found that the properties of the products obtained are directly related to the oil content. The polymerization reactions are followed by the acid value. The modified binder contains 50% oil and 10% PET in the presence of LiOH as the catalyst by using microwave irradiation. The AV value is attained in a short amount of time; it is found that the glass Transition Temperature (Tg) of the modified binder is -1.7 °C. The stiffness and roughness of the printed fabrics by using the modified binder are better than those of the commercial binder for both cotton and cotton/polyester fabrics. Moreover, it is clear that the overall fastness properties of the fabrics printed by using the modified binder in the formulation of printing pastes are higher or comparable to those that use commercial binders.

A Copolymerization Modified Acrylate Resin and its Polyhedral Oligomeric Silsesquioxane Composites

2014 ◽  
Vol 887-888 ◽  
pp. 97-100
Author(s):  
Xiao Lan Hu ◽  
Xi Lan ◽  
Teng Fei Lu ◽  
Hong Shan Yang ◽  
Ying Lai Yang
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Polyhedral Oligomeric Silsesquioxane ◽  
Glass Transition Temperatures ◽  
Acrylate Copolymer ◽  
Amino Resin ◽  
Acrylate Resin ◽  
Oligomeric Silsesquioxane ◽  
Physical Blending ◽  
Better Than

An acrylate resin copolymerized with epoxy and amino resin was prepared in this paper, and its polyhedral oligomeric silsesquioxane (POSS) modified nanocomposites were fabricated via physical blending. Results showed that glass transition temperature of the acrylate copolymer was about 7.9 oC via DSC. Dispersion of nanocomposites with aminopropyllsobutyl POSS is better than those with Octalsobutyl POSS. Moreover, glass transition temperatures of the nanocomposites with POSS are close to the acrylate copolymer matrix.

Study on the Crystallization Activation Energy of Poly (L-lactic acid) Nucleated with P-tert-butylcalix[8]arene

2018 ◽  
Vol 26 (2) ◽  
pp. 169-175
Author(s):  
Yaoqi Shi ◽  
Liang Wen ◽  
Zhong Xin
Keyword(s):  
Activation Energy ◽  
Lactic Acid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Crystallization Temperature ◽  
Nucleating Agent ◽  
Crystallization Activation Energy ◽  
Temperature Range ◽  
Chain Mobility

The crystallization activation energy (Δ E) of a polymer comprises the nucleation activation energy Δ F and the transport activation energy Δ E*. In this paper, the Δ E of poly (L-lactic acid) (PLLA) nucleated with nucleating agent p- tert-butylcalix[8]arene (tBC8) was calculated. The results showed that the Δ E of nucleated PLLA was 165.97 kJ/mol, which is higher than that of pure PLLA. The reason why Δ E of PLLA increased when incorporating nucleating agent was studied. The increment of glass transition temperature ( Tg) for nucleated PLLA revealed that the polymer chain mobility was restricted by tBC8, which was considered as the reason for the increase of Δ E*. Further, polyethylene glycol (PEG) was added to improve the chain mobility, thus eliminated the variation of the transport activation energy Δ E* caused by tBC8. Then the effect of the increment of crystallization temperature range on the increase of Δ F was also taken into consideration. It was concluded that both decreasing the mobility of chain segments and increasing the crystallization temperature range caused an increase of Δ E for PLLA/tBC8.

scholarly journals The Glass Transition Temperature and Temperature Dependence of Activation Energy of Viscous Flow of Ovalbumin

2016 ◽  
Vol 39 (1) ◽  
pp. 13-25
Author(s):  
Karol Monkos
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscous Flow ◽  
Solvent Interactions ◽  
Model Free ◽  
Free Volume Model ◽  
Wide Range ◽  
Different Temperatures

Abstract The paper presents the results of viscosity determinations on aqueous solutions of ovalbumin at a wide range of concentrations and at temperatures ranging from 5°C to 55°C. On the basis of these measurements and three models of viscosity for glass-forming liquids: Avramov’s model, free-volume model and power-law model, the activation energy of viscous flow for solutions and ovalbumin molecules, at different temperatures, was calculated. The obtained results show that activation energy monotonically decreases with increasing temperature both for solutions and ovalbumin molecules. The influence of the energy of translational heat motion, protein-protein and protein-solvent interactions, flexibility and hydrodynamic radius of ovalbumin on the rate of decrease in activation energy with temperature has been discussed. One of the parameters in the Avramov’s equation is the glass transition temperature Tg. It turns out that the Tg of ovalbumin solutions increases with increasing concentration. To obtain the glass transition temperature of the dry ovalbumin, a modified Gordon-Taylor equation is used. Thus determined the glass transition temperature for dry ovalbumin is equal to (231.8 ± 6.1) K.

The Influence of Gamma Radiation on the Glass Transition of Hydroxyapatite/Poly L-Lactide Composite

2007 ◽  
Vol 555 ◽  
pp. 497-502
Author(s):  
Dejan Miličević ◽  
S. Trifunović ◽  
N. Ignjatović ◽  
E. Suljovrujić
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Structural Relaxation ◽  
Absorbed Dose ◽  
Gel Permeation Chromatography ◽  
Chain Scission ◽  
Scanning Calorimetry ◽  
Dsc Measurements

Hydroxyapatite/poly L-lactide (HAp/PLLA) is a composite biomaterial which has been widely utilized for substitution and reparation of the hard bone tissue. It is well known that gamma irradiation has been successfully employed in the modification/sterilization of such porous composites and that it has advantages over other procedures. In this study, differential scanning calorimetry (DSC) measurements were made to investigate the influence of the radiation on glass transition behavior and structural relaxation, as well as to estimate the activation energy for this process. The apparent activation energy ΔH* for structural relaxation in the glass transition region was determined on the basis of the heating rate dependence of the glass transition temperature Tg. Furthermore, the results were correlated with those obtained by gel permeation chromatography (GPC). Our findings support the fact that the radiation-induced chain scission in the PLLA phase is the main reason for the decrease of the glass transition temperature and/or activation energy with the absorbed dose.

On the Possibility to Observe a Compensation Effect around the Glass Transition Temperature

2006 ◽  
Vol 514-516 ◽  
pp. 1462-1466
Author(s):  
Rodica M. Neagu ◽  
José N. Marat-Mendes ◽  
Eugen R. Neagu
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Compensation Effect ◽  
Depolarization Current ◽  
Exponential Factor ◽  
Relaxation Parameters ◽  
Maximum Current ◽  
Thermally Stimulated Depolarization

Compensation has been reported for the relaxation parameters: the activation energy W and the pre-exponential factor τ0, determined from the Thermal Sampling of Thermally Stimulated Depolarization Current technique. Below the glass transition it is assumed that the relaxation time follows an Arrhenius equation. In the vicinity of glass transition temperature an experimental thermogram may be analyzed using the Vogel-Fulcher-Tamman-Hesse (VFTH) or the Williams- Landel -Ferry equation. In this article we use the VFTH relationship to study the compensation effect in the range of glass transition. For an elementary peak obtained by TS there is a relationship between the activation energy W, the temperature of the maximum current Tm, the VFTH temperature, the compensation temperature Tc and the compensation time τ c. We employ this relationship for a basic analysis of the compensation effect in the temperature range around Tg. By numerical simulations, and assuming parameters similar to those measured experimentally, we show that it is possible to observe a compensation point in some well defined conditions

Application of ionic liquid [bmim]PF6 as green plasticizer for poly(L-lactide)

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Puyu Zhang ◽  
Lichao Peng ◽  
Wenbin Li
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Ionic Liquid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Poly Ethylene Glycol ◽  
Scanning Calorimetry ◽  
Poly Ethylene ◽  
Thermal Stability Of ◽  
Better Than

AbstractIonic liquid [bmim]PF6 (1-butyl-3-methylimidazolium hexafluoro phosphate) was synthesized and characterized. It was used as the plasticizer for poly(L-lactide) (PLLA). The glass transition temperature (Tg) and the thermal stability of the plasticized PLLA samples were measured by thermogravimetry (TG) and differential scanning calorimetry (DSC). Compared with poly(ethylene glycol) having Mw of 300 g/mol (PEG300), TG results showed that the thermal stability of PLLA plasticized with ionic liquid was better than that of PLLA plasticized with PEG300. The Tg of plasticized PLLA decrease with increasing the content of ionic liquid [bmim]PF6 from 2 wt.% to 10 wt.%. The Tg of PLLA can be reduced to 40°C when the content of ionic liquid [bmim]PF6 was 10 wt.%. The materials of PLLA with plasticizer were also investigated using polarizing microscope (POM), the results of which indicate that the movements of PLLA chains were improved when ionic liquid plasticizer was used.

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