The effect of pH, temperature, and ionic strength on the molecular conformation of five industrial polyacrylamide-based flocculants was investigated by determining intrinsic viscosities on dilute flocculant solutions. The Fedors equation was found to be most suitable for all flocculants for determining the intrinsic viscosity. The results indicated that the flocculants are fully extended in distilled water at natural pH and at 25°C as evidenced by the high intrinsic viscosities. The data pointed to the strong dependence of the intrinsic viscosity on the presence of salts as a result of the shielding of negatively charged carboxylate groups by the counterions. At a constant ionic strength of 0.01M NaCl, the flocculants assumed a coiled conformation, and further coiling was observed in the presence of small quantities of calcium chloride. CaC1₂ (0.001 mo1/L) There was a decrease in intrinsic viscosities at high pH (~8.5 and 10.5) that was merely attributed to an increase in ionic strength with the increase in concentration of Na⁺ at high pH. Intrinsic viscosity measurements at higher temperatures (35°C and 50°C) showed a small effect of temperature on the conformation of the flocculants. Higher temperature, however, seemed to accelerate the aging of the flocculant solutions. The degrees of anionicity of the flocculants were found to be in the range 1.5% to 50%, as determined through chemical analysis. It was established that determination of total organic carbon content and sodium assays is an accurate way of obtaining the degrees of anionicity of industrial flocculants. The solution stability of the flocculants in distilled water and in 0.01M NaCl was investigated over a period of three days. The reduced viscosities of the anionic flocculant in distilled water steadily decreased. The decrease was more dramatic at high temperature (50°C) than at room temperature, but no viscosity loss was observed in the presence of NaCl. The viscosity of the nonionic flocculant was stable in both distilled water and NaCl. The viscosity loss with time in the case of the anionic flocculant can be correlated with the hydrolysis of the weakly acidic carboxylate (C00⁻) groups to release OH⁻ ions and simultaneous association into uncharged carboxylic (C00H) groups that promote coiling of polyacrylamide. This effect is therefore very similar to the earlier-mentioned effect of sodium chloride.

The effect of pH, temperature, and ionic strength on the molecular conformation of five industrial polyacrylamide-based flocculants was investigated by determining intrinsic viscosities on dilute flocculant solutions. The Fedors equation was found to be most suitable for all flocculants for determining the intrinsic viscosity. The results indicated that the flocculants are fully extended in distilled water at natural pH and at 25°C as evidenced by the high intrinsic viscosities. The data pointed to the strong dependence of the intrinsic viscosity on the presence of salts as a result of the shielding of negatively charged carboxylate groups by the counterions. At a constant ionic strength of 0.01M NaCl, the flocculants assumed a coiled conformation, and further coiling was observed in the presence of small quantities of calcium chloride. CaC1₂ (0.001 mo1/L) There was a decrease in intrinsic viscosities at high pH (~8.5 and 10.5) that was merely attributed to an increase in ionic strength with the increase in concentration of Na⁺ at high pH. Intrinsic viscosity measurements at higher temperatures (35°C and 50°C) showed a small effect of temperature on the conformation of the flocculants. Higher temperature, however, seemed to accelerate the aging of the flocculant solutions. The degrees of anionicity of the flocculants were found to be in the range 1.5% to 50%, as determined through chemical analysis. It was established that determination of total organic carbon content and sodium assays is an accurate way of obtaining the degrees of anionicity of industrial flocculants. The solution stability of the flocculants in distilled water and in 0.01M NaCl was investigated over a period of three days. The reduced viscosities of the anionic flocculant in distilled water steadily decreased. The decrease was more dramatic at high temperature (50°C) than at room temperature, but no viscosity loss was observed in the presence of NaCl. The viscosity of the nonionic flocculant was stable in both distilled water and NaCl. The viscosity loss with time in the case of the anionic flocculant can be correlated with the hydrolysis of the weakly acidic carboxylate (C00⁻) groups to release OH⁻ ions and simultaneous association into uncharged carboxylic (C00H) groups that promote coiling of polyacrylamide. This effect is therefore very similar to the earlier-mentioned effect of sodium chloride.

The effect of pH, temperature, and ionic strength on the molecular conformation of five industrial polyacrylamide-based flocculants was investigated by determining intrinsic viscosities on dilute flocculant solutions. The Fedors equation was found to be most suitable for all flocculants for determining the intrinsic viscosity. The results indicated that the flocculants are fully extended in distilled water at natural pH and at 25°C as evidenced by the high intrinsic viscosities. The data pointed to the strong dependence of the intrinsic viscosity on the presence of salts as a result of the shielding of negatively charged carboxylate groups by the counterions. At a constant ionic strength of 0.01M NaCl, the flocculants assumed a coiled conformation, and further coiling was observed in the presence of small quantities of calcium chloride. CaC1₂ (0.001 mo1/L) There was a decrease in intrinsic viscosities at high pH (~8.5 and 10.5) that was merely attributed to an increase in ionic strength with the increase in concentration of Na⁺ at high pH. Intrinsic viscosity measurements at higher temperatures (35°C and 50°C) showed a small effect of temperature on the conformation of the flocculants. Higher temperature, however, seemed to accelerate the aging of the flocculant solutions. The degrees of anionicity of the flocculants were found to be in the range 1.5% to 50%, as determined through chemical analysis. It was established that determination of total organic carbon content and sodium assays is an accurate way of obtaining the degrees of anionicity of industrial flocculants. The solution stability of the flocculants in distilled water and in 0.01M NaCl was investigated over a period of three days. The reduced viscosities of the anionic flocculant in distilled water steadily decreased. The decrease was more dramatic at high temperature (50°C) than at room temperature, but no viscosity loss was observed in the presence of NaCl. The viscosity of the nonionic flocculant was stable in both distilled water and NaCl. The viscosity loss with time in the case of the anionic flocculant can be correlated with the hydrolysis of the weakly acidic carboxylate (C00⁻) groups to release OH⁻ ions and simultaneous association into uncharged carboxylic (C00H) groups that promote coiling of polyacrylamide. This effect is therefore very similar to the earlier-mentioned effect of sodium chloride. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate

A study of the effect of shear rate on the inherent and intrinsic viscosities of polystyrene fractions, in dilute solution was carried out. Inherent viscosities were determined for five fractions (of molecular weights ranging from 2.9 x 10 to 4.8 x 106); in three solvents (Benzene, Toluene and Methyl Ethyl Ketone); at five temperatures (from 15°C to 85°C); and shear rates ranging from 1.0 x 103 to 2.8 x 104 sec.-1. Inherent viscosities thus determined were extrapolated to zero rate of shear and the extrapolated values plotted against concentration to determine intrinsic viscosities at zero rate of shear, [N] D=0 The inherent viscosity decreased with increasing shear rate. The slope of the curve of inherent viscosity vs shear rate was found to increase (ie become more negative) with increasing concentration, temperature and molecular weight and to be less in a poor solvent than in a good solvent. At very high molecular weights the value of inherent viscosity was found to decrease non-linearly with shear rate. The intrinsic viscosity was found to decrease with increasing shear rate. The slope of the [N] vs D curve was found to increase with increasing molecular weight and decreasing temperature; the slopes were smaller the poorer the solvent. For the three lower fractions the intrinsic viscosity was found to decrease with increasing temperature, very slightly in Methyl Ethyl Ketone and appreciably in Benzene and Toluene, the relative being greater at higher molecular weights. With the two highest fractions this trend was reversed. The slope of the [N] D=0 vs T curve becoming less negative (and actually positive for Benzene end Toluene). The [N] vs T curves ( [N] at free fall) for the three lower fractions were parallel to those at zero rate of shears but of lower intrinsic viscosity values. With the two highest fractions, the slope of the [N] vs T curve became less negative but not to as great a degree as was found with [N] D=0 vs curves. Intrinsic viscosities obtained at zero rate of shear were applied to the Flory-Fox theory. Calculated intrinsic viscosities for polystyrene fractions in Benzene and Toluene were found to agree to within+-4% of the experimental results. For Methyl Ethyl Ketone a wide variation in values was obtained. / Thesis / Master of Science (MS)

Yes / Size Exclusion Chromatography is traditionally carried out in either aqueous or non-polar solvents. A system to present molar mass distributions of polymers using methanol as a mobile phase is presented. This is shown to be a suitable system for determining the molar mass distributions poly(N-isopropylacrylamide)s (PNIPAM); a polymer class that is often difficult to analyze by size exclusion chromatography. DOSY NMR was used to provide intrinsic viscosity data that was used in conjunction with a viscometric detector to provide absolute calibration. Then the utility of the system was shown by providing the absolute molar mass distributions of dispersed highly branched PNIPAM with biologically functional end groups. / Wellcome Trust

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / In this work six galactomannans (Adenanthera pavonina, Caesalpinia pulcherrima, Delonix regia, Dimorphera mollis, Prosopis glandulosa, Schizolobium parahyba) and three xyloglucans (Hymenaea courbaril, Mucuna sloanei e Tamarindus indica) were isolated from seed endosperm and cotyledon, respectively, by aqueous extraction followed by precipitation with ethanol. Yield of extraction, monosaccharide ratio, macromolecular parameters as well as molar mass distribution were determined and compared to guar gum (Cyamopsis tetragonoloba), LBG (Ceratonia siliqua) and xanthan (Xanthomonas campestris). Extraction yield in relation to seed mass ranged from 7.0 to 40.63%, with xyloglucan yields higher than the galactomannans ones. Schizolobium parahyba and Caesalpinia pulcherrima galactomannans presented the lowest protein content of 0.05% e 0.08%, respectively. The Mw values ranged from 0.09 â 3.37 x107 g mol-1 Flow curves of hemicelluloses solutions at 1% (w:v) were measured by varying the shear rate from 0.1 to 100 s-1. The resulting data were fit to the Power law e Herschel-Bulkley models. All the hemicelluloses presented shear-thinning behavior. Galactomannan and xyloglucans with different monosaccharide ratio showed similar consistency index; it may be influenced of the galactose distribution pattern on the chains and the interactions among the polysaccharides molecules. Rheological properties were compared and the results suggest new hemicelluloses sources which offer more profound applications in areas such as materials science, medicine e biology. / As hemiceluloses sÃo polissacarÃdeos presentes na parede celular de vegetais, onde funcionam como polissacarÃdeos de reserva e possuem uma cadeia principal composta por ligaÃÃes β-(1→4) em configuraÃÃo equatorial. Neste trabalho, hemiceluloses de sementes foram avaliadas quanto as suas propriedades reolÃgicas. Como resultado, galactomananas endospÃrmicas de Adenanthera pavonina, Caesalpinia pulcherrima, Delonix regia, Dimorphera mollis, Prosopis glandulosa e Schizolobium parahyba e xiloglucanas cotiledonÃrias de Hymenaea courbaril, Mucuna sloanei e Tamarindus indica foram isoladas por extraÃÃo aquosa, seguida por precipitaÃÃo em etanol. O rendimento das extraÃÃes, razÃo monossacarÃdica, parÃmetros macromoleculares, assim como distribuiÃÃo de massa molar foram determinados e comparados Ãs jà comercializadas goma guar (Cyamopsis tetragonoloba), LBG (Ceratonia siliqua) e goma xantana (Xanthomonas campestris). O rendimento das extraÃÃes em relaÃÃo à massa das sementes mostrou um intervalo de 7,0 a 40,63%, com os maiores valores para as xiloglucanas. Galactomananas de Schizolobium parahyba e Caesalpinia pulcherrima apresentaram os menores percentuais de proteÃnas, 0,05% e 0,08%, respectivamente. Valores de Mw variaram dentro de um intervalo entre 0,09 â 3,37 x107 g mol-1. Curvas de fluxo das soluÃÃes de hemiceluloses a 1% (m:v) foram obtidas pela variaÃÃo da taxa de cisalhamento entre 0,1 a 100 s-1. Os dados obtidos foram analisados pelos modelos de Lei das PotÃncias e Hershel-Bulkley demonstrando carÃter pseudoplÃstico para todas as hemiceluloses estudadas nessa concentraÃÃo. Galactomananas e xiloglucanas com diferentes razÃes monossacarÃdicas apresentaram Ãndice de consistÃncia similar, provavelmente influenciado pelo padrÃo de distribuiÃÃo de galactose nas cadeias e as interaÃÃes entre as molÃculas desses polissacarÃdeos. As propriedades reolÃgicas foram comparadas e os resultados sugerem novas fontes de hemiceluloses que permitem mais aplicaÃÃes em Ãreas como ciÃncia dos materiais, medicina e biologia.

PET har under lång tid använts för flasktillverkning eftersom den är lätt, har goda barriäregenskaper och kan enkelt bearbetas industriellt. På senare tid har miljömedvetenheten ökat i samhället och därmed efterfrågan på återvunnet material, däribland PET-flaskor. Redan idag tillverkas flaskor med helt återvunnen PET.  Återvunnen PET har dock kvalitetsproblem. Därför uppstår frågan hur materialegenskaperna hos 100% återvunna PET-flaskor påverkas av upprepade återvinningscykler.  I den här rapporten undersöks hur den kemiska strukturen och egenskaperna förändras hos materialen allt eftersom fler återvinningscykler genomförs. Tre olika återvunna PET-material används för att ge ett bredare undersökningsunderlag och dessa tre material jämförs sedan sinsemellan samt med jungfrulig PET (icke-återvunnen PET) som referens.  Egenskaperna analyseras med DSC för att ge information om termiska egenskaper, ATR-FTIR utförs för att detektera nedbrytning och förändring i den kemiska strukturen, dragprovning görs för att se hur återvinningen påverkar de mekaniska egenskaperna hos materialen och slutligen analyseras även den inneboende viskositeten hos de återvunna materialen.  Examensarbetet visar på en markant minskning av inneboende viskositet med antalet återvinningscykler. Dessutom kan viss nedbrytning hos den kemiska strukturen ses via ATR-FTIR fastän inte så tydligt. Även en tendens till minskad kristallinitet med återvinning kan ses med DSC. En minskning i kristallinitet möjliggör produktion av mer transparenta flaskor, vilket ofta är eftertraktat. Emellertid får materialet försämrade barriäregenskaper. Dock krävs mer forskning för att kunna dra några slutsatser gällande materialegenskaper i industriell skala. / PET has been used in bottle production for a long time since it is lightweight, easily processable and has good barrier properties. In recent years, the awareness of environmental issues has increased and thereby the demand for recycled materials, including PET bottles. Already today PET bottles with 100% recycled PET are produced. However, recycled PET bottles have quality problems. Thereby, the question arises how the material properties of 100% recycled PET bottles are affected when subjected to multiple recycling loops.  In this report the changes in chemical structure and material properties of the materials are investigated as more recycling loops are performed. Three different recycled PET materials are used to give a broader base of information. These materials are compared to each other and to virgin PET (not recycled PET) as a reference.  The materials are analysed with DSC to give information about the thermal properties, ATR-FTIR to detect changes in the chemical structure, tensile testing to see how the recycling affects the mechanical properties of the material and finally the intrinsic viscosity is analysed for the recycled materials.  In this master thesis a clear decrease in intrinsic viscosity with increasing number of recycling loops can be observed. In addition, some degradation of the chemical structure can be seen through ATR-FTIR, although not very clearly. Also, a decrease in crystallinity with the number of recycling loops can be seen from DSC. A decrease in crystallinity enables production of more transparent bottles, which is often desired, although the material will have reduced barrier properties. However, more research is required to draw any conclusions regarding the material properties on an industrial scale.

Biological degradable polymers on a basis of renewable raw materials, such as polysaccharides, represent promising alternatives to synthetic polymers used as flocculant or stabilizing agents. Polysaccharides derived from potato starch and chitosan have been modified with benzyl- and the first one with additionally cationic hydroxypropyl-trimethylammonium groups of different degrees of substitution (DS). The aim of this work was to characterize the solution properties of these novel amphiphilic polysaccharides concerning the impact of their DS on charge density, particle size, dynamic surface tension and viscosity behaviour. The work is further focused on investigations on flocculation properties of these amphiphilic polyelectrolytes in dispersions of kaolin and silica to identify the interplay between charge density and hydrophobicity. Flocculation efficiency has been evaluated via joint analysis of charge density measurements (using polyelectrolyte titration), turbidity and TOC measurements, as well as dynamic surface tension measurements applying the drop profile analysis. Particle sizes and particle size distributions have been determined by dynamic light scattering and laser diffraction methods. In addition, these amphiphilic starch derivatives have been used to remove substances which impact negatively the paper production process when using recycled paper, so called stickies. Model suspensions have been studied using a multitude of different measurement techniques with the aim to predict a “sticky potential” and to reduce containing dissolved and colloidal substances such as micro stickies. The surface activity and viscometric behaviour have been studied of solely cationic and moderately and highly substituted, amphiphilic polysaccharides in salt-free and 0.05 M NaCl aqueous solution. For the first time dynamic surface tension measurement results have been correlated with particle sizes and apparent charge density. Rheological investigation of large concentration ranges (0.01–20 g/L) was used to discuss Huggins plots and typical polyelectrolyte behaviour for all polysaccharide derivatives could be found. Overlap concentration and, in dilute aqueous solution, intrinsic viscosity could be determined. For polysaccharide solution in dilute regime semi-empirical equations of Rao and Wolf have been applied, making it possible to get insights to polyelectrolyte conformation in dependence on the DS of both substituents. It is shown that for intrinsic viscosity a change of the impact of both substituents takes place when having derivatives with enhanced hydrophobicity. Data evaluation via the ratio of both DS values had been successfully utilized and thus, the applied method has been identified as being a promising tool to compare a multitude of starch derivatives with substituents of different polarity in various degrees of substitution to get tendencies regarding overall hydrophobicity. Moderate hydrophobic substitution was found to lead to a decrease of the efficient flocculant dose and to an increase of the flocculation window width. Amphiphilic starch derivatives with high DS of hydrophobic moieties showing strong hydrophobic association are effective only at significantly higher doses, but in a broader concentration range compared to cationic starch of the same DS. Joint analysis of adsorption isotherms and flocculation test data has revealed, that the surface coverage required to induce phase separation ranges between 10 and 25 % and is minimal for amphiphilic starch derivatives. This gave the evidence of the complex mechanism of flocculation via combination of electrostatic “charge patch” interactions and bridging. Concerning sticky reduction experiments by systematically studying the interactions between the novel amphiphilic starch derivatives and the model suspension it turned out, that dynamic surface tension is a very suitable property to characterize the surface active compounds in the model suspension giving additional information about the sticky potential of waste water, e.g. white water, being a new and sensitive method to describe the parameter “hydrophobicity”. Moderate cationic and hydrophobic starch derivatives have been proved to be the most effective ones for sticky removal.

Made available in DSpace on 2016-03-15T19:36:55Z (GMT). No. of bitstreams: 1 Paula Junqueira de Castro.pdf: 2618815 bytes, checksum: 92b10379ab9b859ea52e163bf40779ee (MD5) Previous issue date: 2015-08-14 / The use of PET in cosmetics packaging is growing and the use of post-consumer recycled material is an alternative with the development of recycling process and also with all the discussions about the increase of environmental impact. The objective of this project is to evaluate the influence of post-consumer recycled PET in the mechanical properties and the aesthetics appearance in cosmetics packaging. The materials used was virgin PET with nominal value of intrinsic viscosity (IV) of 0,80 dL/g and two grades of post-consumer recycled PET with nominal value of IV of 0,68dL/g and 0,80dL/g. The main parameter used in the PET industry is the IV because it is directly related to the molar mass of the polymer and also to the quality of the material. The packages were manufactured by injection stretch blow molding process with different percentages of virgin PET and post-consumer recycled PET. The characterization was realized by visual analysis, spectroscopy to evaluate the variation of color and mechanical tests. The results were satisfactory for the mechanical tests, showing no major differences in results when compared to virgin PET. In aesthetics appearance, the color variation is noticeable, due to the thermal degradation of the material, but less noticeable in the packages with the post-consumer recycled PET with lower IV. / A utilização de embalagens de PET na indústria de cosméticos é ampla e crescente, a incorporação de material reciclado pós-consumo passa a ser uma alternativa com o avanço da tecnologia da reciclagem mecânica do PET e do aumento da discussão de impacto ambiental. O objetivo principal do trabalho é avaliar a influencia na estética e na resistência mecânica do PET reciclado pós-consumo em embalagens de cosméticos com diferentes composições e valores de viscosidade intrínseca (VI). Utilizou-se PET virgem com valor nominal de VI 0,80 dL/g, PET reciclado pós-consumo com valor nominal de VI de 0,68dL/g e 0,80dL/. A VI é a medida mais difundida na indústria do PET, um importante parâmetro de qualidade do material, relacionado diretamente com a massa molar do mesmo. As embalagens foram produzidas através do processo de injeção-sopro com diferentes porcentagens de PET virgem e PET reciclado pós-consumo. A caracterização foi realizada através de analise visual, espectroscopia para avaliação da variação da cor e ensaios mecânicos. Os resultados foram satisfatórios para os ensaios mecânicos, não apresentando diferenças significativas dos resultados quando comparado ao PET virgem. Na questão estética, a variação de cor é bastante perceptível, decorrente da degradação termo-oxidativa do material, porém menos aparente para o PET reciclado pós-consumo com menor valor de VI.

Biological degradable polymers on a basis of renewable raw materials, such as polysaccharides, represent promising alternatives to synthetic polymers used as flocculant or stabilizing agents. Polysaccharides derived from potato starch and chitosan have been modified with benzyl- and the first one with additionally cationic hydroxypropyl-trimethylammonium groups of different degrees of substitution (DS). The aim of this work was to characterize the solution properties of these novel amphiphilic polysaccharides concerning the impact of their DS on charge density, particle size, dynamic surface tension and viscosity behaviour. The work is further focused on investigations on flocculation properties of these amphiphilic polyelectrolytes in dispersions of kaolin and silica to identify the interplay between charge density and hydrophobicity. Flocculation efficiency has been evaluated via joint analysis of charge density measurements (using polyelectrolyte titration), turbidity and TOC measurements, as well as dynamic surface tension measurements applying the drop profile analysis. Particle sizes and particle size distributions have been determined by dynamic light scattering and laser diffraction methods. In addition, these amphiphilic starch derivatives have been used to remove substances which impact negatively the paper production process when using recycled paper, so called stickies. Model suspensions have been studied using a multitude of different measurement techniques with the aim to predict a “sticky potential” and to reduce containing dissolved and colloidal substances such as micro stickies. The surface activity and viscometric behaviour have been studied of solely cationic and moderately and highly substituted, amphiphilic polysaccharides in salt-free and 0.05 M NaCl aqueous solution. For the first time dynamic surface tension measurement results have been correlated with particle sizes and apparent charge density. Rheological investigation of large concentration ranges (0.01–20 g/L) was used to discuss Huggins plots and typical polyelectrolyte behaviour for all polysaccharide derivatives could be found. Overlap concentration and, in dilute aqueous solution, intrinsic viscosity could be determined. For polysaccharide solution in dilute regime semi-empirical equations of Rao and Wolf have been applied, making it possible to get insights to polyelectrolyte conformation in dependence on the DS of both substituents. It is shown that for intrinsic viscosity a change of the impact of both substituents takes place when having derivatives with enhanced hydrophobicity. Data evaluation via the ratio of both DS values had been successfully utilized and thus, the applied method has been identified as being a promising tool to compare a multitude of starch derivatives with substituents of different polarity in various degrees of substitution to get tendencies regarding overall hydrophobicity. Moderate hydrophobic substitution was found to lead to a decrease of the efficient flocculant dose and to an increase of the flocculation window width. Amphiphilic starch derivatives with high DS of hydrophobic moieties showing strong hydrophobic association are effective only at significantly higher doses, but in a broader concentration range compared to cationic starch of the same DS. Joint analysis of adsorption isotherms and flocculation test data has revealed, that the surface coverage required to induce phase separation ranges between 10 and 25 % and is minimal for amphiphilic starch derivatives. This gave the evidence of the complex mechanism of flocculation via combination of electrostatic “charge patch” interactions and bridging. Concerning sticky reduction experiments by systematically studying the interactions between the novel amphiphilic starch derivatives and the model suspension it turned out, that dynamic surface tension is a very suitable property to characterize the surface active compounds in the model suspension giving additional information about the sticky potential of waste water, e.g. white water, being a new and sensitive method to describe the parameter “hydrophobicity”. Moderate cationic and hydrophobic starch derivatives have been proved to be the most effective ones for sticky removal.