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Cloud Point (cloud + point)

Distribution by Scientific Domains
Polymers and Materials Science81%

Terms modified by Cloud Point

  • cloud point temperature
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    Selected Abstracts

    Cold flow properties of fuel mixtures containing biodiesel derived from animal fatty waste

    EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 9 2006
    Kiril Kazancev
    Abstract The aims of the present study were to evaluate the cold temperature behavior of methyl esters of vegetable and animal origin and of their mixtures with fossil diesel fuel, as well as to investigate the effectiveness of different depressants. Various blends of rapeseed oil methyl esters, linseed oil methyl esters, pork lard methyl esters and fossil diesel fuel were prepared, and both cloud point and cold filter plugging point (CFPP) were analyzed. It was found that mixtures with CFPP values of ,5,°C and lower may contain up to 25% of pork lard methyl esters; whereas the ratio of summer fossil diesel fuel and rapeseed oil methyl esters may vary over a wide range, i.e. such mixtures can be used in a diesel engine in the summer. In the transitory periods it is possible to use up to 20% animal and vegetable ester blends (3,:,7) with winter fossil diesel, whereas only up to 5% of esters can be added to the fuel used in winter. In order to improve the cold properties of rapeseed oil, pork lard and linseed oil methyl ester mixtures, various additives were tested. Depressant Viscoplex 10,35 with an optimal dose of 5000,mg/kg was found to be the most effective. [source]

    Properties of High-Oleic Palm Oils Derived by Fractional Crystallization

    JOURNAL OF FOOD SCIENCE, Issue 3 2008
    M.R. Ramli
    ABSTRACT:, High-oleic palm oil (HOPO) with an oleic acid content of 59.0% and an iodine value (IV) of 78.2 was crystallized in a 200-kg De Smet crystallizer with a predetermined cooling program and appropriate agitation. The slurry was then fractionated by means of dry fractionation at 4, 8, 10, 12, and 15 °C. The oil and the fractionated products were subjected to physical and chemical analyses, including fatty acid composition, triacylglycerol and diacylglycerol composition, solid fat content, cloud point, slip melting point, and cold stability test. Fractionation at 15 °C resulted in the highest olein yield but with minimal oleic acid content. Due to the enhanced unsaturation of the oil, fractionation at relatively lower crystallization temperature showed a considerable effect on fatty acid composition as well as triacylglycerol and diacylglycerol composition of liquid fractions compared to higher crystallization temperature. The olein and stearin fractionated at 4 °C had the best cold stability at 0 °C and sharper melting profile, respectively. [source]

    Multistimuli responsive micelles based on well-defined amphiphilic comb poly(ether amine) (acPEA)

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2010
    Chunfeng Di
    Abstract A series of well-defined amphiphilic comb poly (ether amine)s (acPEAs) were successfully synthesized through nucleophilic addition/ring-opening reaction of commercial available poly(propylene glycol) (PPO) diglycidyl ether and Jeffamine L100, followed by esterification of hydroxyl groups in backbone by alkyl carboxylic acid with different chain length. acPEAs are comprised of hydrophilic short PEO chains and hydrophobic alkyl chains as comb chains, which are grafted on PPO backbone alternately to form well-defined structure. With the very low critical micelle concentration (CMC) of around 3.0 × 10,3 g/L, the obtained acPEAs can self-assemble into stable nanomicelles, whose aggregation is responsive to temperature, pH, and ionic strength with tunable cloud point (CP). The CP of acPEAs' aqueous solution increases with the decrease of the length of graft alkyl chains, the decrease of pH value, and the decrease of ionic strength. A transition behavior in the responsive aggregation of micelles formed by acPEA8 and acPEA10 in aqueous solution, especially at low pH value (<7.0), was observed, which was also revealed by DLS results. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3468,3475, 2010 [source]

    Rheological Investigation of Shear Induced-Mixing and Shear Induced-Demixing for Polystyrene/Poly(vinyl methyl ether) Blend

    MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 9 2004
    Samy A. Madbouly
    Abstract Full Paper: The phase behavior of polystyrene (PS) and poly(vinyl methyl ether) (PVME) blend has been investigated rheologically as a function of temperature, composition and oscillating shear rate as well as different heating rates. An LCST (lower critical solution temperature)-type phase diagram was detected rheologically from the sudden changes in the slopes of the dynamic temperature ramps of G, at given heating and shear rate values. The rheological cloud points were dependent on the heating rate, , and oscillating shear rate, . The cloud points shifted a few degrees to higher temperatures with increasing and reached an equilibrium value (heating rate independent) at ,°C/min. The phase diagrams of the blends detected at ,=,0.1 and 1 rad/s were located in lower temperature ranges than the quiescent phase diagram, i.e., oscillating shear rate induced-demixing at these two values for the shear rate. On the other hand, at ,=,10 rad/s, the phase diagram shifted to higher temperatures, higher than the corresponding values found under quiescent conditions, i.e., shear induced-mixing took place. Based on these two observations, shear induced-demixing and shear induced-mixing can be detected rheologically within a single composition at low and high shear rate values, respectively, and this is in good agreement with the previous investigation using simple shear flow techniques. In addition, the William, Landel and Ferry (WLF)-superposition principle was found to be applicable only in the single-phase regime; however, the principle broke-down at a temperature higher than or equal to the cloud point. Furthermore, different spinodal phase diagrams were estimated at different oscillating shear rates based on the theoretical approach of Ajji and Choplin. Spinodal phase diagrams at different oscillating shear rates. [source]

    In situ monitoring of reaction-induced phase separation with modulated temperature DSC

    MACROMOLECULAR SYMPOSIA, Issue 1 2003
    Steven Swier
    Abstract A linearly polymerizing and network forming epoxy-amine system, DGEBA-aniline and DGEBA-MDA, respectively, will be modified with 20 wt% and 50 wt% of a high- Tg thermoplastic poly(ether sulphone) (Tg=223°C), respectively, both showing LCST-type demixing behavior. Reaction-induced phase separation (RIPS) in these modified systems is studied using Modulated Temperature DSC (MTDSC) as an in situ tool. Phase separation in the linear system can be probed by vitrification of the PES-rich phase, occurring at a higher conversion than the actual cloud point from light scattering measurements. The negative slope of the cloud point curve in a temperature-conversion-transformation diagram unambiguously shows the LCST-type demixing behavior of this system, while the relation between the composition/glass transition of the PES-rich phase and the cure temperature is responsible for the positive slope of its vitrification line. Phase separation in the network forming system appears as reactivity increases at the cloud point due to the concentration of reactive groups. Different mixture compositions alter the ratio between the rate of phase separation and the rate of reaction, greatly affecting the morphology. Information about this in situ developed structure can be obtained from the heat capacity evolutions in non-isothermal post-cures. [source]

    Ternary miscibility in blends of three polymers with balanced binary interactions

    POLYMER ENGINEERING & SCIENCE, Issue 3 2003
    E. M. Woo
    This study demonstrates and discusses ternary miscibility in a three-polymer blend system based on balanced binary interactions. A truly miscible ternary blend comprising poly(,-caprolactone) (PCL), poly(benzyl methacrylate) (PBzMA), and poly(vinyl methyl ether) (PVME), was discovered and reported. Miscibility with phase homogeneity (excluding the PCL crystalline domain) in a wide composition range has been demonstrated using criteria of thermal transition behavior, cloud point, and microscopy characterization. At ambient temperature, the three-polymer ternary system is completely miscible within the entire composition range (i.e., no immiscibility loop). However, at slightly elevated temperatures above the ambient. phase separation readily occurred in this originally miscible ternary blend. A quite low "lower critical solution temperature" (LCST) near 75°C was found for the ternary blend, which is much lower than any of those for the binary pairs. Balanced interactions with no offsetting ,, among the three binary pairs were a key factor leading to a ternary miscible system. [source]

    Polymerization of methyl methacrylate in the presence of a nonpolar hydrocarbon solvent.

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010

    Abstract This article presents the ternary phase diagram for methyl methacrylate (MMA), poly(methyl methacrylate) (PMMA), and n -hexane system at 70°C. It was constructed by both theoretical calculations and online laser light scattering (LLS) technique. In situ polymerization of MMA in a nonpolar nonsolvent carried out in a LLS cell provides a new means for the accurate detection of the cloud points of highly viscous polymer mixtures, with polymer weight fractions over 0.6. The ternary phase diagram measured in this study can be used to design the reaction conditions for the precipitation and/or dispersion polymerization in a nonpolar nonsolvent medium where polymerization kinetics as well as polymer particle morphologies are strongly affected by thermodynamic phase separation phenomena. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Acid-labile, thermoresponsive (meth)acrylamide polymers with pendant cyclic acetal moieties

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2008
    Xiao-Nan Huang
    Abstract Acid-labile, thermoresponsive polymers with pendant six-membered cyclic acetal groups were prepared by radical polymerization of two monomers, N -(2,2-dimethyl-1,3-dioxan-5-yl) methacrylamide (NDMM) and N -(2,2-dimethyl-1,3-dioxan-5-yl) acrylamide (NDMA). The aqueous solution properties of the polymers, PNDMM and PNDMA, were studied by turbidimetry, 1H NMR, fluorescence, and DSC measurements. It is found that both polymers show sensitive and reversible phase transitions with distinct lower critical solution temperatures (LCST). Below their LCSTs, there are still some polymer aggregates as evidenced by measurements of pyrene excitation spectra and urea effects on the cloud points (CP) of polymers. The salting effect of six inorganic sodium salts on the phase transition behavior of PNDMM was investigated by turbidimetric approach. The salting-out to salting-in effect is in the order of SO42, > F, > Cl, > Br, > I, > SCN,, following the Hofmeister's series. pH-dependent hydrolysis of PNDMM and PNDMA was studied by turbidimetric and 1H NMR methods. They are both pH-sensitive and their hydrolysis rates significantly increase with decreasing pH value. The CP of PNDMM gradually increases with the acid-triggered hydrolysis of the acetal groups and the hydrolyzed polymer with , 30% hydrolysis degree does not show thermally induced phase transition. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4332,4343, 2008 [source]

    Synthesis of hydrophilic/CO2 -philic poly(ethylene oxide)- b -poly(1,1,2,2-tetrahydroperfluorodecyl acrylate) block copolymers via controlled/living radical polymerizations and their properties in liquid and supercritical CO2

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2004
    Zhi Ma
    Abstract Hydrophilic/CO2 -philic poly(ethylene oxide)- b -poly(1,1,2,2-tetrahydroperfluorodecyl acrylate) block copolymers were synthesized via reversible addition,fragmentation chain transfer (RAFT) polymerization, iodine transfer polymerization (ITP), and atom transfer radical polymerization (ATRP) in the presence of either degenerative transfer agents or a macroinitiator based on poly(ethylene oxide). In this work, both RAFT and ATRP showed higher efficiency than ITP for the preparation of the expected copolymers. More detailed research was carried out on RAFT, and the living character of the polymerization was confirmed by an ultraviolet (UV) analysis of the SC(S)Ph or SC(S)SC12H25 end groups in the polymer chains. The quantitative UV analysis of the copolymers indicated a number-average molecular weight in good agreement with the value determined by 1H NMR analysis. The properties of the macromolecular surfactants were investigated through the determination of the cloud points in neat liquid and supercritical CO2 and through the formation of water-in-CO2 emulsions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2405,2415, 2004 [source]

    Thermal Sensitivity of tert -Butyloxycarbonylmethyl-Modified Polyquats in Condensed Phase and Solubility Properties of Copolymers with N -Isopropylacrylamide

    MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2010
    Nina Gonsior
    Abstract The synthesis of the easily decomposable ionic monomer 2- tert -butoxy- N -[2-(methacryloyl-oxy)ethyl]- N,N -dimethyl-2-oxoethanammonium chloride (3) via thermally induced syn-elimination of a tert -butyl ester group was realized simply by mixing N,N -dimethylaminoethyl methacrylate (1) and tert -butyl chloroacetate (2) at ambient temperature without solvent. The obtained salt was polymerized via free radical polymerization. The decomposition and foaming via iso -butene formation takes place by heating up to about 160,°C. IR, DSC, TGA, and GC/MS measurements were performed to follow this pyrolysis reaction. Furthermore, the copolymerization of 3 with N -isopropylacrylamid (NiPAAm, 5) was carried out with different monomer ratios. Molar mass distributions were measured using an asymmetrical flow field-flow fractionation (aFFFF) system. The obtained copolymers 6,10 exhibit lower critical solution temperature (LCST) behaviour in water with cloud points at different temperatures depending on the monomer ratio. [source]