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Solubility Parameters (solubility + parameter)
Selected AbstractsValidation of a modified Flory-Huggins concept for description of hydrophobic organic compound sorption on dissolved humic substancesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2002Anett Georgi Abstract Sorption coefficients(KDOC) on dissolved organic matter (DOM) have been determined by means of solid-phase microextraction (SPME) for hydrophobic organic compounds (HOCs) of various classes, for example, polycyclic aromatic hydrocarbons (PAHs), noncondensed arenes, and alkanes. Relating the KDOC values obtained to the octanol-water partition coefficients of the solutes results in class-specific correlations. Obviously, PAHs have a higher affinity to DOM than other HOCs with equal KOW values. The different KDOC to KOW correlations can be combined into one general formula based on a modified Flory-Huggins concept. It permits the calculation of sorption coefficients from the solubility parameters (,) and KOW values of the solutes and the solubility parameter of the sorbent. The latter value, which is specific to the DOM under consideration, can be determined from a single measured sorption coefficient. By applying the proposed Flory-Huggins concept, which is based on the presumption of nonspecific interactions between HOCs and DOM, the different affinities of PAHs, noncondensed arenes, and alkanes to DOM can be accurately predicted. [source] Use of Hoy's solubility parameters to predict water sorption/solubility of experimental primers and adhesivesEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2007Yoshihiro Nishitani Self-etching primers and adhesives contain very hydrophilic acidic monomers that result in high water sorption/solubilities of their polymers. However, the chemical composition of these products varies widely. The purpose of this work was to vary the chemical composition of experimental self-etching primers and adhesives to determine if the water sorption/solubility of the polymers were affected in a predictable manner. The Hoy's solubility parameters of these mixtures were calculated to permit ranking of the degree of hydrophilicity of the polymers. Water sorption/solubility was measured according to ISO 4049. The results showed highly significant (R2 = 0.86, P < 0.001) correlations between water sorption and Hoy's solubility parameter for polar forces (,p) of the polymers. Similar correlations were obtained between polymer solubility and ,p. When these results were compared with previously published results obtained with more hydrophobic resins, excellent correlations were obtained, indicating that Hoy's ,p values may be used to predict the water sorption behavior of methylmethacrylate polymers. [source] Degradation of repaired denture base materials in simulated oral fluidJOURNAL OF ORAL REHABILITATION, Issue 3 2000C.-T. Lin This in vitro study evaluates the degradation of repaired denture bases upon immersion in a simulated oral fluid. Denture base materials (Luciton 199®), after being repaired by Repair Material® and Triad®, using three different joint surface designs (butt, round and 45 ° bevel), were immersed onto 99·5 vol.% ethanol/water solution (with similar solubility parameter) for various amounts of time (0,72 h). The flexural loads of the six combination of groups were measured by the three-point bending tests using a universal testing machine. Acoustic emission (AE) during sample fracturing were processed using the MISTRA 2001 system. The fracture pattern and surface details of the interface were examined with a scanning electronic microscope (SEM). Data were analysed using three-way anova and Tukey LSD tests. SEM micrographs of the fracture interface were used to differentiate the fracture mode. The flexural loads (2·72±0·51 Kgf) of the round joint specimens were significantly higher (P<0·05) than those (butt: 1·66±0·38 Kgf, 45 ° bevel: 1·93±0·41 Kgf) of the other two designs. This corresponds to the microscopic examination in which more cohesive failure mode was found for the round joint group after storage. The flexural loads (2·54±0·39 Kgf) of the specimens repaired with Triad® were significantly higher (P<0·05) than those (1·59±0·40 Kgf) of specimens repaired with Repair Material®. Significant progressive reduction of the flexural load and/or AE signals of the specimens was noted in proportion to the length of time of the immersion in the simulated oral fluid. Mechanical strength of a denture base repaired with a round joint design and light-cured material is significantly higher after immersion in simulated oral fluid. [source] Rapid throughput screening of apparent KSP values for weakly basic drugs using 96-well formatJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2008Jeremy Guo Abstract A rapid-throughput screening assay was developed to estimate the salt solubility parameter, KSP, with a minimal quantity of drug. This assay allows for early evaluation of salt limited solubility with a large number of counter-ions and biologically promising drug leads. Drugs dissolved (typically 10 mM) in DMSO are robotically distributed to a 96-well plate. DMSO is evaporated, and drugs are equilibrated with various acids at different concentrations (typically <1 M) to yield final total drug concentrations around 2.5 mM. The plate is checked for precipitation. Filtrates from only those precipitated wells were subjected to rapid gradient HPLC analysis. An iterative procedure is employed to calculate all species concentrations based on mass and charge balance equations. The apparent KSP values assuming 1:1 stoichiometry are determined from counter-ion and ionized drug activities. A correlation coefficient >0.975 for eight drugs totaling 16 salts is reported. Intra-day and inter-day reproducibility was <10%. Conventional apparent KSP measurements were translated to 96-well format for increased throughput and minimal drug consumption (typically 10 mg) to evaluate at least eight different counter-ions. Although the current protocol estimates KSP from 10,3 to 10,7 M, the dynamic range of the assay could be expanded by adjusting drug and counter-ion concentrations. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:2079,2090, 2008 [source] Cagelike polymer microspheres with hollow core/porous shell structuresJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2007Xiaodong He Abstract Submicron-scaled cagelike polymer microspheres with hollow core/porous shell were synthesized by self-assembling of sulfonated polystyrene (PS) latex particles at monomer droplets interface. The swelling of the PS latex particles by the oil phase provided a driving force to develop the hollow core. The latex particles also served as porogen that would disengage automatically during polymerization. Influential factors that control the morphology of the microspheres, including the reserving time of emulsions, polymerization rate, and the Hildebrand solubility parameter and polarity of the oil phase, were studied. A variety of monomers were polymerized into microspheres with hollow core/porous shell structure and microspheres with different diameters and pore sizes were obtained. The polymer microspheres were characterized by scanning electron microscopy, transmission electron microscopy, optical microscopy, and Fourier transform infrared spectroscopy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 933,941, 2007 [source] Polymer Chain Collapse in Supercritical Fluids.MACROMOLECULAR SYMPOSIA, Issue 1 2009Abstract The phase behavior of a polymer in a supercritical solvent at the LCST equilibrium limits is described in this work, in the proximity of , point, proposing the use of a conformational parameter, ,. The results obtained by molecular simulation in an NVT ensemble have been correlated by extensive, varied experimental information. The relationship between polymer/solvent solubility parameters has shown that the behavior of these systems is a function of the energetic structure-interaction relationship between the polymer chain and the solvent. , results in a generalized parameter indicative of the phase stability of the solution. At greater magnitudes, the solution becomes unstable, requiring elevated pressure to stabilize. However, stable solutions are found at lower pressures when , approaches 1. The experimental evidence, together with the determination of the solubility parameter with the Sanchez-Lacombe equation (also obtained from the literature) strengthens this observation. The analysis of the polar contribution on the Hansen Parameter (HSP) enables their effect to be studied in systems where high polar interactions between the polymer and solvent (as in the case of biopolymers) are expected. [source] Bulk High-Impact Polystyrene Process, 1MACROMOLECULAR THEORY AND SIMULATIONS, Issue 7 2007Partitions of tert -Butyl Peroctoate, Styrene in Blends Containing Polystyrene, a Rubber Abstract In relation to the bulk high-impact polystyrene process, this work investigates the partition between phases of styrene and an initiator: tert- butyl peroctoate. A Flory-Huggins model was applied for predicting the phase separation point and the partitions of styrene and tert- butyl peroctoate. For blends of styrene, polystyrene, and a styrene-butadiene diblock copolymer, the model provides reasonable predictions of a ternary equilibrium diagram. For blends of styrene, polystyrene, polybutadiene, and tert- butyl peroctoate, the partition of tert- butyl peroctoate was measured at 25,°C. At emulated conversions of 13% or lower, equilibrium was reached after 1 h of mixing time. For the higher molar masses and conversion of 16%, equilibrium was not reached after 24 h of mixing time. To fit the equilibrium measurements, the solubility parameter of tert- butyl peroctoate was adjusted. [source] Kinetic Analysis and Optimization for the Catalytic Esterification Step of PPT PolymerizationMACROMOLECULAR THEORY AND SIMULATIONS, Issue 1 2005Saptarshi Majumdar Abstract Summary: A well-validated kinetic scheme has been studied for PPT, poly(propylene terephthalate) polymerization process in batch and semi-batch mode with tetrabutoxytitanium (TBOT), a proven catalyst. Optimization study and analysis for PPT are rare, as the industrial relevance of PPT just became vibrant due to the commercial availability of one of its monomers in industrial scale in the recent past. Correctness of the analysis is checked by a new approach and parameters for the model are estimated from available experimental data. Solubility of terephthalic acid (TPA) is less in reaction medium and this effect is also considered along with the reaction scheme. Several simulations have been performed to see various process dynamics and this ultimately helps in formulating optimization problems. Using recently developed and well tested real-coded non-dominated sorting genetic algorithm-II, a state-of-the art evolutionary optimization algorithm, a couple of three objective optimization problems have been solved and corresponding Pareto sets are presented. Results show remarkably promising aspects of productivity enhancement with an improvement in product quality. Sensitivity analysis for relatively uncertain solubility parameter is also performed to estimate its effect over the proposed optimal solutions. Multiobjective Pareto front for 3 objectives: degree of polymerization, time and (bTPA,+,bPG). [source] Evaluation of model compounds,polypropylene film interactions by Fourier transformed infrared spectroscopy (FTIR) methodPACKAGING TECHNOLOGY AND SCIENCE, Issue 3 2008Laurent Safa Abstract The interactions of methyl esters, methyl ketones and aldehyde compounds with polypropylene (PP) film were investigated. PP film, placed on a glass vial, was immersed in aqueous solution containing a model flavour compound. After a determined time at 45°C, the PP film was analysed by Fourier transform infrared spectroscopy (FTIR), allowing us to follow the speed of sorption and to quantify its relative rate. ,,For PP films, we observed that the sorption strongly depended on the structure of sorbed molecules. For each functional group of flavour compounds, the sorption increased as the carbon chain number increased. A linear chain of 12,14 carbons favours the sorption more than a linear chain of eight carbons. ,,Concerning functions, the rate of sorption usually decreases from esters to ketones and to aldehydes. ,,High sorption was observed for flavour compounds with a low difference of solubility parameter (SP) value between the film and flavour [(,polymer , ,flavour)2 value]. Furthermore, by using the proposed thermodynamic affinity concept, represented as the contribution of three interactive molecular forces [dispersion (dd), polar (dp) and hydrogen bonding (dh)] between two SP values of film and flavour, packaging materials with high flavour preservation against sorption can be designed. ,,We have a good correlation between the kinetic sorption by FTIR and the SP concept. Copyright © 2007 John Wiley & Sons, Ltd. [source] Structure-property relationship in polyurethane elastomers containing starch as a crosslinkerPOLYMER ENGINEERING & SCIENCE, Issue 5 2000Sonal Desai Polyurethane elastomers were synthesized using polypropylene glycol (PPG 2000) as the polyol and starch as the multifunctional crosslinker in varying concentrations. Thermal and mechanical properties were measured by DSC, DMA and tensile tests. The morphology was examined by SEM. The swelling behavior of the polyurethanes in various solvents was investigated and the solubility parameter was determined. All these properties were compared with those of polyurethanes containing 1,1,1 -trimethylol propane (TMP) as the crosslinker. Starch-based polyurethanes exhibited better mechanical properties. The effect of varying the starch:TMP ratio on the mechanical strength was also studied. With increasing starch content, the tensile strength and elongation increased. The starch-based PUs exhibited two glass transitions, whereas TMP-based PUs exhibited one Tg. No significant difference in the Tgs of the two PUs was observed. The activation energy of St-PU calculated from DMA was 69 kcal/mol. Soil degradation tests indicated greater biodegradability in polyurethanes containing starch than in those containing TMP. [source] Effect of sulfonic group on solubility parameters and solubility behavior of poly(2,6-dimethyl-1,4-phenylene oxide)POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 1 2007Chunli Gong Abstract An investigation on the effect of sulfonic group on solubility parameters and solubility behavior of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) is presented. Sulfonated PPO (SPPO) was prepared using chlorosulfonic acid as a sulfonating agent. The structure of SPPO was confirmed by FT-IR, and the ion exchange capacity (IEC) of SPPO was accurately determined by conductometric titration and 1H-NMR. The three-dimensional solubility parameters of SPPO defined by Hansen were estimated by group contribution, and this approach was used to obtain the three coordinates of a solubility parameter in terms of: a dispersion part ,d, a polar part ,p and a hydrogen bonding part ,h. The theoretical predications of solubility behavior were characterized using "soluble sphere" in three-dimensional space. The estimated results were in accordance with the solubility experiments in different solvents. Copyright © 2006 John Wiley & Sons, Ltd. [source] Surfactant Effects on Morphology and Switching of Holographic PDLCs Based on Polyurethane Acrylates,CHEMPHYSCHEM, Issue 1 2007Ju Yeon Woo Abstract Effects of octanoic acid (OA) on the morphology, diffraction efficiency, and electro-optic properties of the transmission mode of holographic polymer,dispersed liquid crystals (HPDLC) are studied. Droplet size decreases with increasing OA content (0,9,%), and this leads to a monotonic increase in off-state diffraction with increasing OA content. However, on-state diffraction decreases with increasing applied voltage and shows a minimum at 6,% OA, for which minimum switching voltage (5 V,,m,1) and maximum contrast ratio (10) are obtained. Rise time and decay time decrease with increasing OA content. Interposition of OA between polymer and LC droplet is theoretically predicted by the spreading coefficient (,>0) calculated on the basis of the solubility parameter, while the coalescence behavior of droplets is described by a dimensionless group () called coalescence number. [source] Validation of a modified Flory-Huggins concept for description of hydrophobic organic compound sorption on dissolved humic substancesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2002Anett Georgi Abstract Sorption coefficients(KDOC) on dissolved organic matter (DOM) have been determined by means of solid-phase microextraction (SPME) for hydrophobic organic compounds (HOCs) of various classes, for example, polycyclic aromatic hydrocarbons (PAHs), noncondensed arenes, and alkanes. Relating the KDOC values obtained to the octanol-water partition coefficients of the solutes results in class-specific correlations. Obviously, PAHs have a higher affinity to DOM than other HOCs with equal KOW values. The different KDOC to KOW correlations can be combined into one general formula based on a modified Flory-Huggins concept. It permits the calculation of sorption coefficients from the solubility parameters (,) and KOW values of the solutes and the solubility parameter of the sorbent. The latter value, which is specific to the DOM under consideration, can be determined from a single measured sorption coefficient. By applying the proposed Flory-Huggins concept, which is based on the presumption of nonspecific interactions between HOCs and DOM, the different affinities of PAHs, noncondensed arenes, and alkanes to DOM can be accurately predicted. [source] Use of Hoy's solubility parameters to predict water sorption/solubility of experimental primers and adhesivesEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2007Yoshihiro Nishitani Self-etching primers and adhesives contain very hydrophilic acidic monomers that result in high water sorption/solubilities of their polymers. However, the chemical composition of these products varies widely. The purpose of this work was to vary the chemical composition of experimental self-etching primers and adhesives to determine if the water sorption/solubility of the polymers were affected in a predictable manner. The Hoy's solubility parameters of these mixtures were calculated to permit ranking of the degree of hydrophilicity of the polymers. Water sorption/solubility was measured according to ISO 4049. The results showed highly significant (R2 = 0.86, P < 0.001) correlations between water sorption and Hoy's solubility parameter for polar forces (,p) of the polymers. Similar correlations were obtained between polymer solubility and ,p. When these results were compared with previously published results obtained with more hydrophobic resins, excellent correlations were obtained, indicating that Hoy's ,p values may be used to predict the water sorption behavior of methylmethacrylate polymers. [source] New sets of solubility parameters of linear and crosslinked aromatic polyamidesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Stefano Fiori Abstract As generally accepted, also in the case of polyamides linear and crosslinked polymeric materials are believed to be characterized by the same solution properties and, consequently, by the same solubility parameters. However, despite their great practical importance, a thorough study aimed to determine the best solvent media able to dissolve linear aromatic polyamides has not been performed yet or, at least, has not been published. In this study, we report on our study on the solubility parameters of linear and crosslinked aromatic polyamides. We demonstrate that the assumption of considering these two classes as having the same solubility properties can lead to dramatically erroneous results. Two new different sets for linear and crosslinked aromatic polyamides are proposed. Namely, linear poly(p -phenylene terephthalamide) is characterized by ,p, ,d, and ,H equal to 8.6, 18.4, and 11.3, respectively; by contrast, the corresponding values of the crosslinked aromatic polyamides taken into consideration are: 11.5, 16.8, and 10.2. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Compatibility studies with blends based on poly(n -butyl methacrylate) and polyacrylonitrileJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Zhaogang Ge Abstract In this study, poly(n -butyl methacrylate) (PBMA) was prepared by a suspension polymerization process, and blending with polyacrylonitrile (PAN) in N,N -dimethyl acetamide to prepare PAN/PBMA blends in various proportions. Hansen's three dimensional solubility parameters of PAN and PBMA were calculated approximately through the contributions of the structural groups. The compatibility in these blend systems was studied with theoretical calculations as well as experimental measurements. Viscometric methods, Fourier transform infrared spectroscopy, dynamic mechanical analysis, scanning electron microscopy, and thermogravimetric analysis were used for this investigation. All the results showed that a partial compatibility existed in PAN/PBMA blend system, which may be due to the intermolecular interactions between the two polymers. And, the adsorption experiment results showed that the addition of PBMA contributed to the enhancing adsorptive properties of blend fibers, which lays the foundation for further studying PAN/PBMA blend fibers with adsorptive function. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Synthesis, characterization, and acoustic properties of new soluble polyurethanes based on 2,2,-[1,4-phenylenebis(nitrilomethylylidene)diphenol and 2,2,-[4,4,-methylene-di-2-methylphenylene-1,1,-bis(nitrilomethylylidene)]diphenol,JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007A. V. Raghu Abstract Eight novel polyurethanes based on 2,2,-[1,4-phenylenebis(nitrilomethylylidene)]diphenol and 2,2,-[4,4,-methylene-di-2-methylphenylene-1,1,-bis(nitrilomethylylidene)]diphenol acting as hard segments with two aromatic and two aliphatic diisocyanates (4,4,-diphenylmethane diisocyanate, toluene 2,4-diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate) were prepared and characterized with Fourier transform infrared, UV spectrophotometry, fluorescence spectroscopy, 1H-NMR and 13C-NMR spectroscopy, thermogravimetric analysis, and differential thermal analysis. All the polyurethanes contained domains of semicrystalline and amorphous structures, as indicated by X-ray diffraction. The acoustic properties and solubility parameters were calculated with the group contribution method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Hildebrand and Hansen solubility parameters from Molecular Dynamics with applications to electronic nose polymer sensorsJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 15 2004M. Belmares Abstract We introduce the Cohesive Energy Density (CED) method, a multiple sampling Molecular Dynamics computer simulation procedure that may offer higher consistency in the estimation of Hildebrand and Hansen solubility parameters. The use of a multiple sampling technique, combined with a simple but consistent molecular force field and quantum mechanically determined atomic charges, allows for the precise determination of solubility parameters in a systematic way (, = 0.4 hildebrands). The CED method yields first-principles Hildebrand parameter predictions in good agreement with experiment [root-mean-square (rms) = 1.1 hildebrands]. We apply the CED method to model the Caltech electronic nose, an array of 20 polymer sensors. Sensors are built with conducting leads connected through thin-film polymers loaded with carbon black. Odorant detection relies on a change in electric resistivity of the polymer film as function of the amount of swelling caused by the odorant compound. The amount of swelling depends upon the chemical composition of the polymer and the odorant molecule. The pattern is unique, and unambiguously identifies the compound. Experimentally determined changes in relative resistivity of seven polymer sensors upon exposure to 24 solvent vapors were modeled with the CED estimated Hansen solubility components. Predictions of polymer sensor responses result in Pearson R2 coefficients between 0.82 and 0.99. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1814,1826, 2004 [source] Modeling the solid,liquid equilibrium in pharmaceutical-solvent mixtures: Systems with complex hydrogen bonding behaviorAICHE JOURNAL, Issue 3 2009Ioannis Tsivintzelis Abstract A methodology is suggested for modeling the phase equilibria of complex chemical mixtures with an equation of state (EoS) for the case where only limited experimental data exist. The complex hydrogen bonding behavior is explicitly accounted for and the corresponding parameters are adopted from simpler molecules of similar chemical structure and/or are fitted to Hansen's partial solubility parameters. The methodology is applied to modeling the solubility of three pharmaceuticals, namely acetanilide, phenacetin, and paracetamol, using the nonrandom hydrogen bonding (NRHB) EoS. In all cases, accurate correlations were obtained. The prediction ability of the approach was evaluated against predictions from the COSMO-RS model. A thorough discussion is made for the appropriate modeling of solid solubility considering the effect of the difference of the heat capacities of the solute in liquid and solid state, ,Cp = Cpl , Cps, in the determination of solid chemical potential and, also, of the polymorphism of drugs. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Immiscible Poly(L -lactide)/Poly(, -caprolactone) Blends: Influence of the Addition of a Poly(L -lactide)-Poly(oxyethylene) Block Copolymer on Thermal Behavior and MorphologyMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 7 2004Giovanni Maglio Abstract Summary: A binary blend of poly (L -lactide) (PLLA) and poly(, -caprolactone) (PCL) of composition 70:30 by weight was prepared using a twin screw miniextruder and investigated by differential scanning calorimetry (DSC), optical microscopy and scanning electron microscopy (SEM). Ternary 70:30:2 blends were also obtained by adding either a diblock copolymer of PLLA and poly(oxyethylene) (PEO) or a triblock PLLA-PCL-PLLA copolymer as a third component. Optical microscopy revealed that the domain size of dispersed PCL domains is reduced by one order of magnitude in the presence of both copolymers. SEM confirmed the strong reduction in particle size upon the addition of the copolymers, with an indication of an enhanced emulsifying effect in the case of the PLLA-PEO copolymer. These results are analyzed on the basis of solubility parameters of the blend components. Optical micrograph of M3EG2 blend melt quenched at 125,°C. [source] Polymer Chain Collapse in Supercritical Fluids.MACROMOLECULAR SYMPOSIA, Issue 1 2009Abstract The phase behavior of a polymer in a supercritical solvent at the LCST equilibrium limits is described in this work, in the proximity of , point, proposing the use of a conformational parameter, ,. The results obtained by molecular simulation in an NVT ensemble have been correlated by extensive, varied experimental information. The relationship between polymer/solvent solubility parameters has shown that the behavior of these systems is a function of the energetic structure-interaction relationship between the polymer chain and the solvent. , results in a generalized parameter indicative of the phase stability of the solution. At greater magnitudes, the solution becomes unstable, requiring elevated pressure to stabilize. However, stable solutions are found at lower pressures when , approaches 1. The experimental evidence, together with the determination of the solubility parameter with the Sanchez-Lacombe equation (also obtained from the literature) strengthens this observation. The analysis of the polar contribution on the Hansen Parameter (HSP) enables their effect to be studied in systems where high polar interactions between the polymer and solvent (as in the case of biopolymers) are expected. [source] Solubility properties of human tooth mineral and pathogenesis of dental cariesORAL DISEASES, Issue 5 2004T Aoba Dental research over the last century has advanced our understanding of the etiology and pathogenesis of caries lesions. Increasing knowledge of the dynamic demineralization/remineralization processes has led to the current consensus that bacteria-mediated tooth destruction can be arrested or even to some degree reversed by adopting fluoride and other preventive measures without using restorative materials. Our experimental approach provided new insight into the stoichiometries and solubility properties of human enamel and dentin mineral. The determination of the solubility product constant on the basis of the stoichiometric model (Ca)5·x(Mg)q(Na)u(HPO4)v(CO3)w(PO4)3·y(OH,F)1·z, verifies the difference in their solubility properties, supporting the phase transformation between tooth mineral and calcium phosphates in a wide range of fluid compositions as found in the oral environment. Further refinement of the stoichiometry and solubility parameters is essential to assess quantitatively the driving force for de- and remineralization of enamel and dentin in the oral fluid environment. Prediction of the effects of a combination of inhibitors and accelerator(s) on remineralization kinetics is also required. In order to develop devices efficient for optimizing remineralization in the lesion body, it is a critical question how, and to what extent, fluoride can compensate for the activity of any inhibitors in the mineralizing media. [source] Interactions between aroma compounds and latex films: partition coefficients and influence on latex film formationPACKAGING TECHNOLOGY AND SCIENCE, Issue 2 2006A. Nestorson Abstract The potential of various latex grades to take up, retain and release different types of aroma compound has been explored. The latex grades used included two styrene,acrylate latices and two styrene,butadiene latices, of which one contained talc. The aroma compounds used were ethyl butyrate, 1-hexanol, heptanal, 3-octanone, ,-pinene and limonene dissolved in propylene glycol. It was shown that talc improves both the uptake of aroma compounds in the dispersion phase and the retention during the film formation process. However, the styrene,acrylate latex had a greater ability than the styrene,butadiene latex to hold the aroma compounds once the films were formed. These results have been compared to calculated solubility parameters. The uptake of 1-hexanol and propylene glycol in the latex dispersions were higher than expected from the theoretical calculations, probably because of the amphiphilic nature of these molecules. In addition, the influence of aroma compounds on the film formation was evaluated. Copyright © 2005 John Wiley & Sons, Ltd. [source] Dissolution of waste plastics in biodieselPOLYMER ENGINEERING & SCIENCE, Issue 5 2010Ying Zhang The dissolution behavior of polystyrene (PS) and low-density polyethylene (LDPE) in biodiesel was investigated with an eye towards developing methods to dispose waste plastics by burning them with fuel. To complement and guide the experimental investigations, molecular dynamics simulations were performed to calculate solubility parameters, cohesive energy densities, Flory-Huggins , parameters and phase diagrams of the target systems. Dissolution kinetics of PS and LDPE in methyl esters was monitored by gravimetry, from which parameters such as dissolution rates, activation energies, and scaling indices were estimated. The shear viscosity of the polymer solutions was measured to ascertain their suitability as fuel mixtures. The dissolution of PS in biodiesel appears to be controlled by the diffusion of polymer chains through a boundary layer adjacent to the polymer/solvent interface. Taken together, the experimental and modeling studies provide a predictive toolbox to design biodiesels of different compositions that will dissolve commodity polymers such as PS and LDPE to be used as fuels in engines. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers [source] On the use of pressure-volume-temperature data of polyethylene liquids for the determination of their solubility and interaction parametersPOLYMER ENGINEERING & SCIENCE, Issue 5 2004L. Zhao 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 and isothermal compressibility 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 , and , obtained from the above methods differ significantly, indicating that the S-L equation of state may not be suitable for determining , and , at elevated temperatures. When these two sets of , and , were used to calculate the corresponding solubility parameters and then the Flory-Huggins interaction parameters (,) of the polymers, the results also differ considerably. Nonetheless, , 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. [source] Effect of sulfonic group on solubility parameters and solubility behavior of poly(2,6-dimethyl-1,4-phenylene oxide)POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 1 2007Chunli Gong Abstract An investigation on the effect of sulfonic group on solubility parameters and solubility behavior of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) is presented. Sulfonated PPO (SPPO) was prepared using chlorosulfonic acid as a sulfonating agent. The structure of SPPO was confirmed by FT-IR, and the ion exchange capacity (IEC) of SPPO was accurately determined by conductometric titration and 1H-NMR. The three-dimensional solubility parameters of SPPO defined by Hansen were estimated by group contribution, and this approach was used to obtain the three coordinates of a solubility parameter in terms of: a dispersion part ,d, a polar part ,p and a hydrogen bonding part ,h. The theoretical predications of solubility behavior were characterized using "soluble sphere" in three-dimensional space. The estimated results were in accordance with the solubility experiments in different solvents. Copyright © 2006 John Wiley & Sons, Ltd. [source] Engineering an Anti-Graffiti System: A Study in Industrial Product DesignCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 8 2004A.J. Hutchinson Abstract The objective of this work was to develop products for the anti-graffiti market using a product design framework that takes into account the company core practices and meets customer expectations. Product development comprised several concurrent steps including market research and analysis to determine the market potential using a Quality Functional Deployment tool. From market research it was estimated that anti-graffiti products had significant potential within Australia. A range of technical and quality parameters were tested. The Hildebrand and Hansen solubility parameters, viscosity and diffusivity estimates were mainly used for technical evaluation of products. An iterative process was used throughout in conjunction with parameter restraints to meet environmental sustainability, waste reduction and minimize resource consumption. The result was a cost effective product, tailored to customer expectations. [source] | ||||||||||||||||