The Equation of State and the Temperature, Pressure, and Shear Dependence of Viscosity for a Highly Viscous Reference Liquid, Dipentaerythritol Hexaisononanoate

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Scott Bair ◽  
Tsuyoshi Yamaguchi
Keyword(s):  
Molecular Weight ◽  
Shear Stress ◽  
Equation Of State ◽  
High Molecular Weight ◽  
Free Volume ◽  
Newtonian Limit ◽  
Scaling Models ◽  
The Difference ◽  
Better Than ◽  
Low Shear

Measurements are reported for dipentaerythritol hexaisononanoate (DiPEiC9) of pressure–volume–temperature (pVT) response to pressures to 400 MPa and temperatures to 100 °C, and of viscosity at pressures to 700 MPa and temperatures to 90 °C and shear stress to 18 MPa. These data complement the low-shear viscosities published by Harris to pressures to 200 MPa and the compressions by Fandiño et al. to 70 MPa. The improved Yasutomi correlation reproduces all viscosity measurements with accuracy better than the Doolittle free volume and the Bair and Casalini thermodynamic scaling models which require an equation of state (EoS). The interaction parameter for thermodynamic scaling, γ = 3.6, is less than that reported by Harris (γ = 4.2) and the difference is primarily in the choice of EoS. The shear stress at the Newtonian limit, about 6 MPa, is exceptionally large given the high molecular weight of DiPEiC9. The large Newtonian limit is also seen in the oscillatory shear response.

scholarly journals Alkylation of Aromatic Compounds with Pentabromobenzyl Bromide and Tetrabromoxylene Dibromide as a New Route to High Molecular Weight Brominated Flame Retardants

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 352
Author(s):  
Mark Gelmont ◽  
Michael Yuzefovitch ◽  
David Yoffe ◽  
Eyal Eden ◽  
Sergei Levchik
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Flame Retardants ◽  
Brominated Flame Retardants ◽  
High Thermal Stability ◽  
Aromatic Molecules ◽  
Sustainable Products ◽  
Aromatic Polymers ◽  
International Human ◽  
Better Than

In the view of many national and international human health and environmental regulations, polymeric flame retardants are sustainable products. In this work, a series of high molecular weight and polymeric brominated flame retardants are synthesized by the alkylation of aromatic molecules or the alkylation of aromatic polymers with pentabromobenzyl bromide (PBBB) or tetrabromoxylylene dibromide (TBXDB). The flame retardants prepared via the alkylation of toluene or diphenylethane with PBBB were found to be not truly polymeric but had high Mw > 1400. However, the alkylation of the same aromatic molecules by a mixture of PBBB and TBXDP resulted in polymeric flame retardants with Mw > 130,000. Two other polymeric flame retardants were prepared by the alkylation of aromatic polymers (polyphenylene ether or polystyrene) with PBBB. It was found that the new flame retardants had a high bromine content of more than 68%. They showed high thermal stability with the onset of thermal decomposition above 360 °C and a maximum rate of weight loss at about 375–410 °C. The newly synthesized flame retardants were tested in different thermoplastics. Flame retardant efficiency and physical properties were comparable or better than the reference commercial flame retardants.

scholarly journals Development of the drilling mud composition for directional wellbore drilling considering rheological parameters of the fluid

2020 ◽  
Vol 244 ◽  
pp. 454-461
Author(s):  
Nadezhda Ulyasheva ◽  
Ekaterina Leusheva ◽  
Ramil Galishin
Keyword(s):  
Molecular Weight ◽  
Shear Stress ◽  
High Molecular Weight ◽  
Oil Field ◽  
Rheological Parameters ◽  
Dynamic Shear ◽  
Drilling Mud ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Drilling Muds

Article presents investigations on the development of a drilling mud composition for directional wells in an oil field located in the Republic of Tatarstan (Russia). Various rheological models of fluid flow and their applicability for drilling muds are analyzed. Laboratory experiments to measure the main rheological parameters of a solution, such as plastic viscosity, dynamic shear stress, as well as indicators of non-linearity and consistency are presented. On the basis of laboratory investigations, it was concluded that high molecular weight polymer reagents (for example, xanthan gum) can give tangible pseudoplastic properties to the washing fluid, and their combination with a linear high molecular weight polymer (for example, polyacrylamide) reduces the value of dynamic shear stress. Thus, when selecting polymer reagents for treating drilling muds at directional drilling, it is necessary to take into account their structure, molecular weight and properties. Combination of different types of reagents in the composition of the drilling mud can lead to a synergistic effect and increase the efficiency of the drilling process as a whole.

scholarly journals The Influence of Low Shear Microbore Extrusion on the Properties of High Molecular Weight Poly(l-Lactic Acid) for Medical Tubing Applications

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 710 ◽  
Author(s):  
Dillon ◽  
Doran ◽  
Fuenmayor ◽  
Healy ◽  
Gately ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Lactic Acid ◽  
High Molecular Weight ◽  
Biodegradable Polymers ◽  
Degradation Mechanism ◽  
Fold Increase ◽  
Morphological Properties ◽  
Shear Rates ◽  
Low Shear

Biodegradable polymers play a crucial role in the medical device field, with a broad range of applications such as suturing, drug delivery, tissue engineering, scaffolding, orthopaedics, and fixation devices. Poly-l-lactic acid (PLLA) is one of the most commonly used and investigated biodegradable polymers. The objective of this study was to determine the influence low shear microbore extrusion exerts on the properties of high molecular weight PLLA for medical tubing applications. Results showed that even at low shear rates there was a considerable reduction in molecular weight (Mn = 7–18%) during processing, with a further loss (Mn 11%) associated with resin drying. An increase in melt residence time from ~4 mins to ~6 mins, translated into a 12% greater reduction in molecular weight. The degradation mechanism was determined to be thermal and resulted in a ~22-fold increase in residual monomer. The differences in molecular weight between both batches had no effect on the materials thermal or morphological properties. However, it did affect its mechanical properties, with a significant impact on tensile strength and modulus. Interestingly there was no effect on the elongational proprieties of the tubing. There was also an observed temperature-dependence of mechanical properties below the glass transition temperature.

Studies on the Free-Volume Change in Annealed Ultra-High Molecular Weight Polyethylene by the Positron Annihilation Technique

1995 ◽  
Vol 147 (2) ◽  
pp. 447-452 ◽  
Author(s):  
Shiyu Shen ◽  
Jihong Lou ◽  
Jixin Cheng ◽  
Kunlun Hong ◽  
Qingren Zhu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Positron Annihilation ◽  
High Molecular Weight ◽  
Free Volume ◽  
Volume Change ◽  
Ultra High Molecular Weight

Positron Lifetime Studies of Irradiated Ultra-High Molecular Weight Polyethylene and Composites Made of Martian Regolith

2014 ◽  
Vol 783-786 ◽  
pp. 1585-1590 ◽  
Author(s):  
Naidu V. Seetala ◽  
Naeem Tull-Walker ◽  
Abhijit Baburaj ◽  
Jian Ren Zhou ◽  
Richard Wilkins ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Positron Annihilation ◽  
High Molecular Weight ◽  
Free Volume ◽  
Irradiation Dose ◽  
Positron Lifetime ◽  
Positron Source ◽  
Vacancy Defects ◽  
Martian Regolith ◽  
Ultra High Molecular Weight

Positron Annihilation Lifetime Spectroscopy (PALS) is used to study the nanoporosity and fractional free volume in Ultra High Molecular Weight Polyethylene (UHMWPE) and composites with the addition of Martian Regolith (UHMWPE-MR) as-made and irradiated with56Fe heavy ions at an energy of 600 MeV/u to three different doses (10, 32, 64 Gy). The positron lifetime spectra were obtained using22Na positron source and the spectra were analyzed to two lifetime components using POSFIT program. First short lifetime component around 0.28 ns is related to positron annihilation in material including vacancy defects and the second long lived component around 1.7 ns is due to Positronium formation in free volume pores. UHMWPE-MR composites were shown to be less porous with much lower nanopores concentration compared to the UHMWPE polymer. The average size of the nanopores is around 0.5 nm (obtained from a simple model). Larger variations in positron lifetime parameters are observed with increasing irradiation dose for UHMWPE polymer compared to UHMWPE+MR composites. The 3-point bend test results also showed larger variations with increasing irradiation dose for the UHMWPE polymer. The variations in PALS parameters may indicate an increasing competition between two processes at higher irradiation doses: 1) vacancy defects aggregation and 2) escape of vacancy defects as the local temperature increases at higher doses resulting in increased vacancy defects mobility. Present results clearly indicate a qualitative inverse relationship between nanoscale porosity measured by positron life time and mechanical properties of UHMWPE and its composite with MR.

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