Water Sorption (water + sorption)

Distribution by Scientific Domains


Selected Abstracts


Water Sorption and Crispness of Fat-Free Apple Chips

JOURNAL OF FOOD SCIENCE, Issue 1 2002
D. Konopacka
ABSTRACT: Equilibration of fat-free apple chips to predetermined moisture level was achieved by keeping samples over saturated salt solutions. The sorption isotherm obtained indicated absence of a monolayer and was typical for type III according to the Brunauer classification. At water activity below 0.12 apple chips demonstrated excellent crispness and were highly acceptable as a snack food item. They were extremely hygroscopic and lost crispness easily. The critical water activity was found to be ac= 0.18 which corresponds to a water content of 3.5 g H2O/100 g solids. These values were much lower than those found for other crispy snack foods. [source]


Effect of disinfection by microwave irradiation on the strength of intact and relined denture bases and the water sorption and solubility of denture base and reline materials

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008
Rosangela Seiko Se
Abstract This study evaluated the influence of microwave disinfection on the strength of intact and relined denture bases. Water sorption and solubility were also evaluated. A heat-polymerized acrylic resin (Lucitone 550) was used to construct 4-mm-thick (n = 40) and 2-mm-thick (n = 160) denture bases. Denture bases (2-mm) were relined with an autopolymerizing resin (Tokuso Rebase Fast, Ufi Gel Hard, Kooliner, or New Truliner). Specimens were divided into four groups (n = 10): without treatment, one or seven cycles of microwave disinfection (650 W for 6 min), and water storage at 37C for 7 days. Specimens were vertically loaded (5 mm/min) until failure. Disc-shaped specimens (50 mm 0.5 mm) were fabricated (n = 10) to evaluate water sorption and solubility. Data on maximum fracture load (N), deflection at fracture (mm), fracture energy (N mm), water sorption (%), and solubility (%) were analyzed by two-way analysis of variance and Student,Newman,Keuls tests (, = 0.05). One cycle of microwave disinfection decreased the deflection at fracture and fracture energy of Tokuso Rebase Fast and New Truliner specimens. The strength of denture bases microwaved daily for 7 days was similar to the strength of those immersed in water for 7 days. Microwave disinfection increased the water sorption of all materials and affected the solubility of the reline materials. 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]


Water sorption, glass transition, and protein-stabilizing behavior of an amorphous sucrose matrix combined with various materials

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 11 2010
Koreyoshi Imamura
Abstract The effects of various additives on the physical properties of an amorphous sugar matrix were compared. Amorphous, sugar,additive mixtures were prepared by freeze-drying and then rehumidified at given RHs. Sucrose and eighteen types of substances were used as the sugar and the additive, respectively, and water sorption, glass-to-rubber transition, and protein stabilization during freeze-drying for the various sucrose,additive mixtures were examined. The additives were categorized into two groups according to their effects on Tg and water sorption. Presence of polysaccharides, cyclodextrins, and polymers (large-sized additives) resulted in a decrease in equilibrium water content from the ideal value calculated from individual water contents for sucrose and additive, and in contrast, low MW substances containing ionizable groups (small-ionized additives) resulted in an increase. The increase in Tg by the addition of large-sized additives was significant at the additive contents >50,wt.% whereas the Tg was markedly increased in the lower additive content by the addition of small-ionized additives. The addition of small-ionized additives enhanced the decrease in Tg with increasing water content. The protein stabilizing effect was decreased with increasing additive content in the cases of the both groups of the additives. 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:4669,4677, 2010 [source]


Water sorption induced transformations in crystalline solid surfaces: characterization by atomic force microscopy

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 9 2010
Dabing Chen
Abstract The effect of water sorption on the mobility of molecules on the surface of a crystalline anhydrous solid was investigated to understand the mechanism of its transformation to the corresponding hydrate. Theophylline was chosen as the model compound. The transition water activity for anhydrate to hydrate transformation, RHT, and the deliquescence RH, RH0, was determined to be 62% and 99%, respectively (25C). Atomic force microscopy (AFM) was used to study the surface changes of theophylline above and below the transition water activity. Contact-mode AFM showed that the jump-to-contact distance increased appreciably above RHT, suggesting formation of solution on the surface. At RHT,<,RH,<,RH0, using dynamic (AC/"tapping" mode) AFM, the movements of surface steps were visualized. These results from AFM indicated that, below RH0, the formation of a thin solution film significantly increased surface mobility. Furthermore, when the anhydrate crystal surface was seeded with the hydrate, the propagation of a new hydrate phase was observed by polarized light microscopy. In conclusion, atomic force microscopy provided direct evidence that the phase transformation of anhydrous theophylline to theophylline monohydrate in the solid-state is mediated by a surface solution as a result of water adsorption. 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:4032,4041, 2010 [source]


Photopolymerization and Characteristics of Polyurethane/Organoclay Nanocomposites

MACROMOLECULAR REACTION ENGINEERING, Issue 3 2007
Hailin Tan
Abstract Different polymerizable ammonium surfactants were successfully synthesized via Michael-addition and quaternarization reactions. Organoclays containing reactive methacrylate groups were prepared by the cationic exchange process. Intercalated nanocomposites were produced by UV initiated polymerization with 5 wt.-% organophilic clay loading. DMTA tests and tensile analysis implied that a long chain polymerizable modifier could crosslink with the polymer matrix, and mechanical and tensile properties were enhanced dramatically about 80%. Water sorption was not elevated, which was determined by the polymer itself and the hydrophobicity of the modifier, although the water permeation was improved. [source]


Water sorption into poly[(2-hydroxyethyl methacrylate)- co -(1-vinyl-2-pyrrolidone)]at 310 K

POLYMER INTERNATIONAL, Issue 11 2003
Mark Malak
Abstract Poly(2-hydroxyethyl methacrylate) and copolymers of 2-hydroxyethyl methacrylate (HEMA) and 1-vinyl-2-pyrrolidone (VP) in the form of cylindrical samples (,8 mm 20 mm) have been prepared and the sorption of water into these cylinders has been studied by the mass-uptake methods and by magnetic-resonance imaging. The equilibrium water contents for the cylinders were found to vary systematically with the copolymer composition. Diffusion of water into the cylinders was found to follow Fickian behaviour for cylinders with high HEMA contents, with the diffusion coefficients obtained from mass-uptake studies dependent on the copolymer composition, varying from 1.7 10,11 m2 s,1 for poly(HEMA) to 2.0 10,11 m2 s,1 for poly(HEMA- co -VP) with a composition of 1:1. However, NMR-imaging studies showed that, while the profiles of the water diffusion fronts for cylinders with high HEMA contents were Fickian, that for the 1:1 copolymer was not and indicated that the mechanism was Case III. The polymers which were rich in VP were characterized by a water-sorption process which follows Case-III behaviour. Copyright 2003 Society of Chemical Industry [source]


Sorption kinetics of ethanol/water solution by dimethacrylate-based dental resins and resin composites

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2007
Irini D. Sideridou
Abstract In the present investigation the sorption,desorption kinetics of 75 vol % ethanol/water solution by dimethacrylate-based dental resins and resin composites was studied in detail. The resins examined were made by light-curing of bisphenol A glycol dimethacrylate (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), bisphenol A ethoxylated dimethacrylate (Bis-EMA), and mixtures of these monomers. The resin composites were prepared from two commercial light-cured restorative materials (Z100 MP and Filtek Z250), the resin matrix of which is based on copolymers of the above-mentioned monomers. Ethanol/water sorption/desorption was examined in both equilibrium and dynamic conditions in two adjacent sorption,desorption cycles. For all the materials studied, it was found that the amount of ethanol/water sorbed or desorbed was always larger than the corresponding one reported in literature in case of water immersion. It was also observed that the chemical structure of the monomers used for the preparation of the resins directly affects the amount of solvent sorbed or desorbed, as well as sorption kinetics, while desorption rate was nearly unaffected. In the case of composites studied, it seems that the sorption/desorption process is not influenced much by the presence of filler. Furthermore, diffusion coefficients calculated for the resins were larger than those of the composites and were always higher during desorption than during sorption. Finally, an interesting finding concerning the rate of ethanol/water sorption was that all resins and composites followed Fickian diffusion kinetics during almost the whole sorption curve; however, during desorption the experimental data were overestimated by the theoretical model. Instead, it was found that a dual diffusion,relaxation model was able to accurately predict experimental data during the whole desorption curve. Kinetic relaxation parameters, together with diffusion coefficients, are reported for all resins and composites. 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source]


Use of Hoy's solubility parameters to predict water sorption/solubility of experimental primers and adhesives

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2007
Yoshihiro 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]


Physicochemical evaluation of silica-glass fiber reinforced polymers for prosthodontic applications

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2005
Gke Meri
This investigation was designed to formulate silica-glass fiber reinforced polymeric materials. Fused silica-glass fibers were chosen for the study. They were heat-treated at various temperatures (500C, 800C and 1100C), silanized, sized and incorporated in two modified resin mixtures (A and B). The flexural properties in dry and wet conditions were tested and statistically analyzed, and the content of residual methyl methacrylate (MMA) monomer, dimensional changes with temperature, water sorption and solubility were determined. Woven fibers [36.9% (wt/wt)], heat-treated at 500C, gave the highest strength values for the polymeric composites (an ultimate transverse strength of 200 Mpa and a flexural modulus of 10 GPa) compared with the fibers heat-treated at other temperatures. There was no statistically significant difference in the measured flexural properties between resins A and B regarding fiber treatment and water storage time. These fiber composites had a small quantity of residual MMA content [0.37 0.007% (wt/wt)] and very low water solubility, indicating good biocompatibility. It was suggested that silica-glass fibers could be used for reinforcement as a result of their anticipated good qualities in aqueous environments, such as the oral environment. [source]


Novel Brush Polymers with Phosphorylcholine Bristle Ends: Synthesis, Structure, Properties, and Biocompatibility

ADVANCED FUNCTIONAL MATERIALS, Issue 10 2009
Gahee Kim
Abstract New brush polymers with various numbers of bristle ends incorporating phosphorylcholine (PC) moieties are synthesized. The polymers are thermally stable up to 175,C and form good-quality films with conventional spin-, roll-, and dip-coating, and subsequent drying processes. Interestingly, all these brush polymers, as a PC-containing polymer, demonstrate a stable molecular multi-bilayer structure in thin films that arise due to the efficient self-assembly of the bristles for temperatures <55,C and PC-rich surfaces, and therefore successfully mimic natural cell-membrane surfaces. These brush-polymer films exhibit excellent water wettability and water sorption whilst retaining the remarkable molecular multi-bilayer structure, and thus have hydrophilic surfaces. These novel multi-bilayer structured films repel fibrinogen molecules and platelets from their surfaces but also have bactericidal effects on bacteria. Moreover, the brush-polymer films are found to provide comfortable surface environments for the successful anchoring and growth of HEp-2 cells, and to exhibit excellent biocompatibility in mice. These newly developed brush polymers are suitable for use in biomedical applications including medical devices and biosensors that require biocompatibility and the reduced possibility of post-operative infection. [source]


Effect of disinfection by microwave irradiation on the strength of intact and relined denture bases and the water sorption and solubility of denture base and reline materials

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008
Rosangela Seiko Se
Abstract This study evaluated the influence of microwave disinfection on the strength of intact and relined denture bases. Water sorption and solubility were also evaluated. A heat-polymerized acrylic resin (Lucitone 550) was used to construct 4-mm-thick (n = 40) and 2-mm-thick (n = 160) denture bases. Denture bases (2-mm) were relined with an autopolymerizing resin (Tokuso Rebase Fast, Ufi Gel Hard, Kooliner, or New Truliner). Specimens were divided into four groups (n = 10): without treatment, one or seven cycles of microwave disinfection (650 W for 6 min), and water storage at 37C for 7 days. Specimens were vertically loaded (5 mm/min) until failure. Disc-shaped specimens (50 mm 0.5 mm) were fabricated (n = 10) to evaluate water sorption and solubility. Data on maximum fracture load (N), deflection at fracture (mm), fracture energy (N mm), water sorption (%), and solubility (%) were analyzed by two-way analysis of variance and Student,Newman,Keuls tests (, = 0.05). One cycle of microwave disinfection decreased the deflection at fracture and fracture energy of Tokuso Rebase Fast and New Truliner specimens. The strength of denture bases microwaved daily for 7 days was similar to the strength of those immersed in water for 7 days. Microwave disinfection increased the water sorption of all materials and affected the solubility of the reline materials. 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]


Fiber introduction mass spectrometry: determination of pesticides in herbal infusions using a novel sol,gel PDMS/PVA fiber for solid-phase microextraction

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 6 2007
Rogrio Cesar da Silva
Abstract An application of the direct coupling of solid-phase microextraction (SPME) with mass spectrometry (MS), a technique known as fiber introduction mass spectrometry (FIMS), is described to determine organochlorine (OCP) and organophosphorus (OPP) pesticides in herbal infusions of Passiflora L. A new fiber coated with a composite of poly(dimethylsiloxane) and poly(vinyl alcohol) (PDMS/PVA) was used. Sensitive, selective, simple and simultaneous quantification of several OCP and OPP was achieved by monitoring diagnostic fragment ions of m/z 266 (chlorothalonil), m/z 195 (,-endosulfan), m/z 278 (fenthion), m/z 263 (methyl parathion) and m/z 173 (malathion). Simple headspace SPME extraction (25 min) and fast FIMS detection (less than 40 s) of OCP and OPP from a highly complex herbal matrix provided good linearity with correlation coefficients of 0.991,0.999 for concentrations ranging from 10 to 140 ng ml,1 of each compound. Good accuracy (80 to 110%), precision (0.6,14.9%) and low limits of detection (0.3,3.9 ng ml,1) were also obtained. Even after 400 desorption cycles inside the ionization source of the mass spectrometer, no visible degradation of the novel PDMS/PVA fiber was detected, confirming its suitability for FIMS. Fast (ca 20 s) pesticide desorption occurs for the PDMS/PVA fiber owing to the small thickness of the film and its reduced water sorption. Copyright 2007 John Wiley & Sons, Ltd. [source]


Fracture toughness of modified dental resin systems

JOURNAL OF ORAL REHABILITATION, Issue 8 2003
R. E. Kerby
summary This study compared the relative fracture toughness of a Bis-GMA//TEGDMA (50:50 wt%)-based resin system modified by 5, 10, and 15 wt% of a methacrylate-terminated poly(butadiene-acrylonitrile-acrylic acid) terpolymer toughening agent. After storage in distilled water at 37 2 C for 7 days, plane strain fracture toughness (KIC) was determined on an Instron testing machine at a 05-mm min,1 displacement rate. The glass transition temperature (Tg) in C was determined after 7 days (dry and wet) storage by thermomechanical analysis. The results of this study showed significantly improved fracture toughness and lowered water sorption with the modified resin systems which was indicated by higher wet glass transition temperatures. [source]


Water sorption, glass transition, and protein-stabilizing behavior of an amorphous sucrose matrix combined with various materials

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 11 2010
Koreyoshi Imamura
Abstract The effects of various additives on the physical properties of an amorphous sugar matrix were compared. Amorphous, sugar,additive mixtures were prepared by freeze-drying and then rehumidified at given RHs. Sucrose and eighteen types of substances were used as the sugar and the additive, respectively, and water sorption, glass-to-rubber transition, and protein stabilization during freeze-drying for the various sucrose,additive mixtures were examined. The additives were categorized into two groups according to their effects on Tg and water sorption. Presence of polysaccharides, cyclodextrins, and polymers (large-sized additives) resulted in a decrease in equilibrium water content from the ideal value calculated from individual water contents for sucrose and additive, and in contrast, low MW substances containing ionizable groups (small-ionized additives) resulted in an increase. The increase in Tg by the addition of large-sized additives was significant at the additive contents >50,wt.% whereas the Tg was markedly increased in the lower additive content by the addition of small-ionized additives. The addition of small-ionized additives enhanced the decrease in Tg with increasing water content. The protein stabilizing effect was decreased with increasing additive content in the cases of the both groups of the additives. 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:4669,4677, 2010 [source]


Water sorption induced transformations in crystalline solid surfaces: characterization by atomic force microscopy

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 9 2010
Dabing Chen
Abstract The effect of water sorption on the mobility of molecules on the surface of a crystalline anhydrous solid was investigated to understand the mechanism of its transformation to the corresponding hydrate. Theophylline was chosen as the model compound. The transition water activity for anhydrate to hydrate transformation, RHT, and the deliquescence RH, RH0, was determined to be 62% and 99%, respectively (25C). Atomic force microscopy (AFM) was used to study the surface changes of theophylline above and below the transition water activity. Contact-mode AFM showed that the jump-to-contact distance increased appreciably above RHT, suggesting formation of solution on the surface. At RHT,<,RH,<,RH0, using dynamic (AC/"tapping" mode) AFM, the movements of surface steps were visualized. These results from AFM indicated that, below RH0, the formation of a thin solution film significantly increased surface mobility. Furthermore, when the anhydrate crystal surface was seeded with the hydrate, the propagation of a new hydrate phase was observed by polarized light microscopy. In conclusion, atomic force microscopy provided direct evidence that the phase transformation of anhydrous theophylline to theophylline monohydrate in the solid-state is mediated by a surface solution as a result of water adsorption. 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:4032,4041, 2010 [source]


Effect of moisture and pressure on tablet compaction studied with FTIR spectroscopic imaging

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2007
Noha Elkhider
Abstract FTIR spectroscopic imaging using a diamond ATR accessory has been applied to examine the influence of moisture and compression pressure on the density and components distribution of compacted pharmaceutical tablets. The model drug and excipient used within this study are ibuprofen and hydroxypropylmethylcellulose (HPMC). Chemical images of these compacted tablets were captured in situ without removing the tablet between measurements. A powder mixture of both, drug and excipient, prior to compaction, were subjected to a controlled environment, using a controlled humidity cell. Histograms were plotted to assess the density distribution quantitatively. This FTIR spectroscopic imaging approach enabled both measurement of water sorption and enhanced visualization of the density distribution of the compacted tablets. 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96:351,360, 2007 [source]


Changes in Diapered and Nondiapered Infant Skin Over the First Month of Life

PEDIATRIC DERMATOLOGY, Issue 1 2000
Marty O. Visscher Ph.D.
Diapered and nondiapered skin sites were contrasted to the volar forearm of adults (mothers). Thirty-one term infants were evaluated in the hospital on postnatal day 1 and at home on days 4, 7, 14, 21, and 28 for a total of six visits. Measurements included baseline skin hydration, continuous capacitive reactance, peak water sorption, rate of water desorption, skin pH, skin temperature, and environmental conditions. Changes in epidermal barrier properties over the first 4 weeks of life included an increase in surface hydration, a decrease in transepidermal water movement under occlusion, a decrease in surface water desorption rate, and a decrease in surface pH. Diapered and nondiapered regions were indistinguishable at birth but exhibited differential behavior over the first 14 days, with the diapered region showing a higher pH and increased hydration. Maternal measurements remained constant throughout the period. We conclude that healthy newborn skin undergoes progressive changes in epidermal barrier properties over the first 28 days. Adult skin testing does not replicate newborn skin during the first month of life. [source]


Comparison of the roles of two shrinkage-controlled low-profile additives in water aging of polyster resin,glass fiber composites

POLYMER COMPOSITES, Issue 5 2000
G. Camino
A model previously formulated or water sorption in polyester resin-glass fiber composites has been applied to the kinetic analysis of experimental data for two composites containing a hydrolysable (polyvinyl acetate-PVAc) and a non-hydrolyzable (polystyrene-PS) shrinkage-controlling low-profile additive (LPA) respectively. It was found that the equilibrium water uptake in the composites and their unreinforced matrix is not drastically affected by the type of LPA. The kinetics of water sorption in the composites, however, were substantially different. The PVAc composite displayed a two-stage sorption process, the first stage being attributed to diffusion combined with hydrolysis, and the second to matrix swelling and plasticizing. A maximum in the kinetic curve was observed, and was due to changes in water solubility inside the matrix during sorption. In contrast, the PS composite displayed the typical kinetics of materials with slowly increasing hydrophilicity. [source]


Preparation and characterization of tetracycline-loaded interpenetrating polymer networks of carboxymethyl cellulose and poly(acrylic acid): water sorption and drug release study

POLYMER INTERNATIONAL, Issue 10 2005
Anil Kumar Bajpai
Abstract Tetracycline (TC)-loaded ionic interpenetrating polymer networks (IPNs) of carboxymethyl cellulose (CMC) and crosslinked poly(acrylic acid) (PAA) were prepared and characterized by infrared spectral analysis, differential scanning calorimetry and scanning electron microscopy techniques. The prepared IPNs were evaluated for in vitro blood compatibility by clot formation and hemolysis methods and their water imbibitions capacity was determined. Fractional release dynamics of tetracycline was also investigated from loaded IPNs of CMC and PAA. The entrapped drug was examined for antibacterial activity and structural integrity and effects of various parameters such as percentage loading of the drug, chemical composition of the carrier IPN, pH and temperature of the release medium were investigated on the release profiles of TC. The drug was also released in different simulated biological fluids. Copyright 2005 Society of Chemical Industry [source]


Preparation and characterization of biocompatible spongy cryogels of poly(vinyl alcohol),gelatin and study of water sorption behaviour

POLYMER INTERNATIONAL, Issue 9 2005
Dr AK Bajpai
Abstract Porous biocompatible spongy hydrogels of poly(vinyl alcohol) (PVA),gelatin were prepared by the freezing,thawing method and characterized by infrared and differential scanning calorimetry. The prepared so-called ,cryogels' were evaluated for their water-uptake potential and the influence of various factors, such as the chemical architecture of the spongy hydrogels, pH and the temperature of the swelling bath, on the degree of water sorption by the cryogels was investigated. It was found that the water sorption capacity constantly decreased with increasing concentration of PVA while initially an increase and thereafter a decrease in swelling was obtained with increasing amounts of gelatin in the cryogel. The water sorption capacity decreased with an increase in the number of freeze,thaw cycles. The hydrogels were also swollen in salt solutions and various simulated biological fluids and a fall in swelling ratio was noticed. The effect of the drying temperature of the cryogel on its water sorption capacity was also investigated, and a decrease in swelling was obtained with increasing temperature of drying. The biocompatibility of the prepared materials was assessed by in vitro methods of blood-clot formation, platelet adhesion, and per cent haemolysis. It was noticed that with increasing concentration of PVA and gelatin the biocompatibility increased, while a reduced biocompatibility was noted with an increasing number of freeze,thaw cycles. Copyright 2005 Society of Chemical Industry [source]


Use of Hoy's solubility parameters to predict water sorption/solubility of experimental primers and adhesives

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2007
Yoshihiro 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]