Viscosity estimation of triacylglycerols and of some vegetable oils, based on their triacylglycerol composition

The experimentally determined kinematic viscosities of simple triacylglycerols [trilaurin, trimyristin (MMM), tripalmitin (PPP), tristearin (SSS), triolein (OOO), and trilinolein (LiLiLi) were correlated to a modified Andrade-type equation. The constants for the modified equation were derived for each simple triacylglycerol. The method was also used to estimate the viscosity of mixed triacylglycerols [1,2-dimyristoyl-3-palmitoyl (MMP), 1,2-dioleoyl-3-palmitoyl (OOP), 1,2-dimyristoyl-3-oleoyl (MMO), and 1,2-dipalmitoyl-3-oleoyl (PPO)], binary triacylglycerol mixtures (PPO/OOP, PPP/SSS, and OOO/SSS of different portions), and three types of vegetable oils [refined, bleached, and deodorized palm oil; cocoa butter; and canola oil] by applying modified Kay’s rule utilizing the simple triacylglycerol constants derived earlier. In all cases, the estimated values for liquid viscosity were compared with experimental values determined in this work and with previous work from the literature. When applied to vegetable oils, the method requires knowledge of their triacylglycerol composition. Despite its simplicity, the method gives a reasonable estimate. The method may be used to predict the viscosity of different blends of vegetable oils, and the accuracy is expected to increase when more experimental data on simple triacylglycerols become available.     

The Effect of Spray-Freeze Drying of Montmorillonite on the Morphology,Dispersion, and Crystallization in Polypropylene Nanocomposites

The spray-freeze drying (SFD) technique was applied to sonicated aqueous suspensions of spray-dried montmorillonite clay (MMT) to produce highly porous agglomerates (SFD-MMT). Both MMT (used as a reference) and SFD-MMT were subsequently incorporated in polypropylene (PP) via melt compounding to produce 2 wt % nanocomposites with and without maleic anhydride grafted polypropylene (PP-g-MA). Polypropylene nanocomposites containing SFD-MMT exhibited thinner silicate flake layers compared to large agglomerates in PP/MMT nanocomposites. SFD-MMT particles became even more finer in the presence of PP-g-MA (i.e., in PP/PP-g-MA /SFD-MMT) where it hindered PP crystallization instead of serving as nucleation sites for the PP crystallization during rapid cooling. SFD-MMT improved the thermal stability of PP/PP-g-MA by 30°C compared to only 5–8°C for MMT/nanocomposites. MMT acts as a heterogeneous nucleating agent in the nucleation-controlled PP nanocomposites, but the hindrance effect was observed for the PP/PP-g-MA with SFD-MMT. PP/PP-g-MA/SFD-MMT exhibited twice the edge surface energy as compared to PP/PP-g-MA/MMT. The incorporation of both types of MMT raised the tensile moduli of PP and PP/PP-g-MA, with no improvement in their tensile strength and a decrease in the elongation at break. The PP/PP-g-MA/SFD-MMT showed brittle failure. POLYM. ENG. SCI., 60:168–179, 2020. © 2019 Society of Plastics Engineers     

Electrical,mechanical, and thermal properties of exfoliated graphite/phenolic resin composite bipolar plate for polymer electrolyte membrane fuel cell

Exfoliated graphite (EG) was synthesized from natural flake graphite by acid treatment followed by microwave irradiation. A maximum expanded volume of 560 mL/g was achieved for this exfoliation of graphite. EG/phenolic resin composite bipolar plates for polymer electrolyte membrane fuel cell were fabricated with a high loading of EG by compression molding. The composites possess low density, high electrical conductivity, high thermal stability, and high compressive strength. The composite bipolar plates were also characterized by X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, and so on. The composite prepared with 50 wt% of EG has shown the desired properties for bipolar plate as per the US Department of Energy (DOE‐2015) targets. As a result, the EG–resin composites can be used as bipolar plates for polymer electrolyte membrane fuel cell applications. POLYM. ENG. SCI., 55:917–923, 2015. © 2014 Society of Plastics Engineers     

Effect of N‐isopropyl‐N′‐phenyl‐p‐phenylenediamine antioxidant on the adhesion properties of (zinc oxide)‐filled (epoxidized natural rubber 25)‐based pressure‐sensitive adhesives

The effect of antioxidant, namely, N‐isopropyl‐N′‐phenyl‐p‐phenylenediamine (IPPD), on the adhesion properties of epoxidized natural rubber (ENR 25)‐based pressure‐sensitive adhesive was investigated. The concentration of the IPPD was varied from 0 to 5 parts by weight per hundred parts of rubber (phr). Coumarone‐indene resin, zinc oxide, toluene, and polyethylene terephthalate were used as the tackifier, filler, solvent, and substrate, respectively. A Lloyd Adhesion Tester operating at different testing rates (10–60 cm/min) was used to determine the loop tack, peel strength, and shear strength at 60‐µm and 120‐µm coating thicknesses. Results indicate that adhesion properties increase with IPPD up to 2 phr of content, after which it decreases with further addition of the antioxidant. This observation is attributed to the culmination of wettability and compatibility at the optimum IPPD concentration. The 60‐µm coated sample consistently shows higher adhesion strength than that of 120‐µm coated sample. Loop tack and peel strength increase with testing rate up to 30 cm/min. However, shear strength increases with increasing testing rate in the testing rate investigated in this study. J. VINYL ADDIT. TECHNOL., 21:111–115, 2015. © 2014 Society of Plastics Engineers     

On the use of pressure‐volume‐temperature data of polyethylene liquids for the determination of their solubility and interaction parameters

Specific volumes of high‐density and low‐density polyethylene liquids at several elevated temperatures and pressures were measured. The measured specific volumes were then used to estimate the thermal expansion coefficients $\left( {{\rm \alpha = }\frac{{\rm 1}}{v}\left( {\frac{{\partial v}}{{\partial T}}} \right)_P } \right)$ and isothermal compressibility $\left( {{\rm \beta = } - \frac{{\rm 1}}{v}\left( {\frac{{\partial v}}{{\partial P}}} \right)_T } \right)$ of the polymers. Two different approaches were used in which one was simply to fit the raw data by second order polynomials to obtain (?v/?T)_P and (?v/?P)_T, while the other by the Sanchez‐Lacombe (S‐L) equation of state. It was found that the resultant α and β obtained from the above methods differ significantly, indicating that the S‐L equation of state may not be suitable for determining α and β at elevated temperatures. When these two sets of α and β were used to calculate the corresponding solubility parameters and then the Flory‐Huggins interaction parameters (χ) of the polymers, the results also differ considerably. Nonetheless, χ obtained from the first method agrees well with the results obtained from small angle neutron scattering measurements while the S‐L equation of state method does not. The current results suggest that solubility and interaction parameters obtained from pressure‐volume‐temperature experiments depend critically on the manner by which the data analysis is performed. Polym. Eng. Sci. 44:853–860, 2004. © 2004 Society of Plastics Engineers.     

Investigations Towards the Chemoselective Thioacetaliztion of Carbonyl Compounds by Using Ionic Liquid [bmim]Br as a Recyclable Catalytic Medium

The ionic liquid based on the 1‐n‐butyl‐3‐methylimidazolium cation has been prepared and used as an efficient catalytic medum for the chemoselective thioacetalization of carbonyl compounds. Furthermore, recycling and reuse of this ionic liquid medium has been demonstrated. Moreover, the use of this catalytic medium not only avoids the generation of waste but also provides a green process with minimal hazards.     

Effects of Rheological Behavior of Viscoelastic Surfactants on Formation Damage in Carbonate Rocks

Viscoelastic surfactants (VES) are used in various oilfield applications such as matrix stimulation and enhanced oil recovery. The loss of surfactants during the propagation of VES could result in a significant reduction in the permeability of the rock (formation damage). The objective of the current work was to identify the effect of rheological behavior of the VES on the formation damage using core‐flooding experiments, nuclear magnetic resonance (NMR), and scanning electron microscopy (SEM) analysis. A combination of core‐flooding, NMR, and SEM techniques was used to quantify and identify the location of formation damage in carbonate core samples. The viscosity and storage modulus strongly depend on the nature and concentration of salts. The viscosity increased by increasing the salt concentration up to a specific point (15 wt% CaCl₂) and then starts decreasing. The VES formulations that displayed the maximum and minimum viscosities were used to identify the impact of rheological behavior on formation damage. Core‐flooding experiments were performed to assess the formation damage due to high‐viscosity and low‐viscosity VES formulations. The reduction in the permeability of carbonate rocks reaches more than 90% of the initial permeability. It was found that low‐viscosity VES caused more damage compared with high‐viscosity VES when they were used at constant concentrations. NMR and core‐flooding results revealed that the damage took place both in pore body and pore throat. However, most of the surfactant was retained at the pore throat.     

Possible origin of ferromagnetism in antiferromagnetic orthorhombic-YFeO3: A first-principles study

Rare-earth orthoferrites (RFeO₃) are well-known for the antiferromagnetic ground state. However, some of the recent experimental results suggest that the few members of RFeO₃ family possess ferromagnetism. In the present investigation we report the possible origin of ferromagnetism in antiferromagnetic YFeO₃ using density functional theory. For this purpose, we have considered pure as well as self-doping in YFeO₃ i.e. by considering the point defect at Y, Fe and O sites. Our finding suggests that the point defects in YFeO₃ results in the mixed-valence state of Fe, which may result in ferromagnetism through Zener double exchange mechanism.