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The paper industry utilizes fillers either to reduce the cost or to provide desired functional or end-use properties of paper products. However, there are disadvantages associated with higher filler loadings beyond a certain level, which reduces paper strength. The present study focused on improving the physical property of filled papers. Three methods of structuring fillers were designed; precipitation with starch, complexation with starch and fatty acid, and regeneration with cellulose. Because cellulose and starch have hydroxyl groups on the chemical structure, the hydrogen bonding between fillers and wood fibers is assumed to be occurred by structuring fillers. For starch application, we used two different approaches; salt precipitation and fatty acid complexation. The cooked starch can be precipitated by certain salt solutions such as (NH4)2SO4. Also, the cooked starch can be complexed with fatty acid to produce an insoluble crystalline structure. When starch composites with clay made by both methods were put into the furnish as fillers, dramatic strength improvement was achieved such as 100-200% gains in tensile strength. This is due to the strong bonding between clay fillers and wood fibers, which is determined by Z-directional tensile strength. One of advantages is that using the starch-fatty acid complex has an inherent water repellent property, sizing effect. For cellulose as a bonding material, N-methylmorpholine-N-oxide was used as a solvent to dissolve the cellulose. The advantage of using this method is that we can use the low grade cellulose. The physical properties of the cellulose coated clay handsheets were significantly improved, but optical properties such as brightness and opacity were inferior to the hadnsheets filled with starch-clay composites due to relatively large particle size. In order to model the strength improvement by the composite filler, BDT theory, which is a modified Pages Equation, was used. After calculating the factors such as surface area and specific bond strength, the model matched well with the experimental results. Using this model, the tensile strength improvement could be predicted in terms of the change of bond strength and composite size.

Cement penetrability is a key factor in multifilament cement composites. However, the modes of action and the concepts vary because of brittle and ductile fibers. In the case of brittle fibers such as glass, high penetrability of cement products in between the bundle filaments can lead to brittle composite behavior, and therefore addition in ductility is required. In order to have efficient bundle action and high bonding, fillers can be introduced in between the glass filaments, keeping the telescopic mode of failure but at the same time improving the bond and stress transfer within the filaments of the bundle, even at late ages, resulting in a ductile and high strength composite. On the other hand, ductile fibers such as polypropylene (PP), which also developing low bonding with the cement matrix, result in ductile cement composite but with relatively low strength. Therefore, in this case good penetrability of the cement in between the filaments of the bundle is essential in order to maximize the reinforcing efficiency of the bundle by improving bond. The penetrability of the matrix into a fabric structure and especially in between the bundle filaments made up the fabric is a result of fiber- matrix compatibility, which depends on: level of opening and spaces between the filaments, bundle surface properties including wetting and chemical affinity to the cement matrix, matrix viscosity, processing of the composite, and the nature of the fabric junctions and the resulting tightening effects of the bundle, i.e., influenced by the fabric structure itself.

This doctoral thesis is focused on composites based on polypropylene and wood flour. Firstly, the experimental work deals with preparation of composites based on wood flour with various concentrations and isotactic polypropylene with various melt flow indexes. In terms of this study, one polypropylene, which can have also practical use, was chosen. Further, this polypropylene is investigated with various types and concentrations of wood flour. Also, the attention is devoted to the modification of polypropylene by a specific β-nucleating agent. The differences are compared and described between the composites with neat and nucleated polypropylene. Further, the work is focused on solvent extraction of wood flour. The effect of extraction and solvent of wood flour is also examined in composites with neat and nucleated polypropylene. On prepared composites, the rheological, structural and thermal properties are studied. These properties differ depending on specific type of wood flour, its concentration and specific type of polypropylene.

There are mainly two manufacturing processes used in the pharmaceutical industry, namely direct compression and granulation of which granulation can be subdivided into wet granulation and dry granulation. Wet granulation is a process still widely used in the pharmaceutical industry and provides better control of drug content uniformity and compactibility at low drug concentrations. Lactose monohydrate and microcrystalline cellulose (MCC) were used as fillers in this study. Both these fillers possess unacceptable powder flow properties and the use of wet granulation may improve this property. One of the advantages of lactose monohydrate over MCC is that it is partially water soluble. A fractional factorial design was used in this study. Twelve tablet formulations were formulated containing different combinations of active ingredients (furosemide or pyridoxine hydrochloride), fillers (lactose monohydrate or MCC) and a binder (Kollidon® VA64) in three different concentrations (0.75, 1.5 or 3.0% w/w). The binder was used to produce granules by means of wet granulation, using ethanol as granulating fluid. The granules were dried in an oven and screened through different sized sieves to produce the final granulated powder formulations ready for tableting. A disintegrant (Ac-di-sol®) and lubricant (magnesium stearate) were incorporated into the granulated powder formulations extra-granular (0.5% w/w) and were kept as a constant in this study throughout all the formulations. A Turbula® mixer was used to mix the granulated powder formulations for a constant 5 minutes. During the first phase of the study, tablets were compressed using 2 compression settings (22 and 24). These compression settings were used to determine what effect different external pressures would have on the different tablet properties. Tablet weight for all the formulations was kept constant at 250 mg, although the volume of the matrix differed for each tablet formulation. The physical properties of the tablets were evaluated with regard to weight variation, mechanical strength (crushing strength and friability) and disintegration. Tablet formulation 12 yielded unsatisfactory tablets, due to poor powder flow into the die. Tablet formulations that contained the highest binder concentration (3.0% w/w) and were compressed at the highest compression setting (24) (formulations 4 and 9), exhibited the highest mechanical strength. The disintegration results revealed that the tablet formulations containing MCC as filler disintegrated faster compared to those containing lactose monohydrate. The increase in binder concentration caused an increase in mechanical strength, possibly decreasing tablet porosity, therefore prolonging disintegration time due to impeded water penetration into the tablet matrix. During the final phase of the study, dissolution studies were conducted on the different tablet formulations in 0.1 M HCl for 120 minutes. In terms of dissolution results, the initial dissolution rate (DRi) and extent of dissolution (AUC) were compared. It was found that the tablet formulations containing pyridoxine hydrochloride as active pharmaceutical ingredient (API) exhibited faster drug dissolution (higher DRi and AUC-values) compared to those tablet formulations containing furosemide. The faster dissolution exhibited by the pyridoxine hydro- chloride containing formulations can possibly be attributed to the fact that pyridoxine hydrochloride is good water soluble whereas furosemide is practically insoluble in water. The effect of the filler depended on the aqueous solubility of the filler and the concentration of the binder (Kollidon VA64) employed. An increase in binder concentration led to a decrease in the initial rate of dissolution as well as the extent of drug dissolution. In the case of the pyridoxine hydrochloride containing formulations, formulation 9 exhibited the slowest DRi and lowest extent of drug dissolution (1.40 ± 0.03 µg.cm-3.min-1 and 2396.52 ± 26.43 µg.cm-3.min respectively). In the case of the furosemide containing formulations, formulation 4 exhibited the slowest DRi and lowest extent of drug dissolution (0.22 ± 0.07 µg.cm-3.min-1 and 1018.62 ± 59.74 µg.cm-3 min respectively). In both cases, the formulations contained Kollidon VA64 in a concentration of 3% w/w and were compressed at compression setting 24. The disintegration process of tablets goes hand in hand with the dissolution process and results have shown that by establishing rapid contact between drug particles and the surrounding medium proves to be a necessity for rapid drug dissolution. Disintegration does not assure drug dissolution, but when prolonged, slower dissolution rates can be obtained, implying a slow rate and low extent of drug dissolution. The disintegrant in this study was incorporated extra-granular ensuring rapid tablet disintegration. However, due to binder concentration of 3% w/w, granule disintegration was probably negatively affected resulting in a lower drug surface area exposed to the surrounding dissolution medium, leading to a slower initial rate and extent of drug dissolution. From the results obtained during this study it was evident that formulation variables such as the type of filler, the concentration of the binder and compression setting employed during tablet manufacturing can have a ronounced effect on the pharmaceutical availability of the active ingredient. However, the extent of the effect was dependent on the aqueous solubility of the active ingredient. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

There are mainly two manufacturing processes used in the pharmaceutical industry, namely direct compression and granulation of which granulation can be subdivided into wet granulation and dry granulation. Wet granulation is a process still widely used in the pharmaceutical industry and provides better control of drug content uniformity and compactibility at low drug concentrations. Lactose monohydrate and microcrystalline cellulose (MCC) were used as fillers in this study. Both these fillers possess unacceptable powder flow properties and the use of wet granulation may improve this property. One of the advantages of lactose monohydrate over MCC is that it is partially water soluble. A fractional factorial design was used in this study. Twelve tablet formulations were formulated containing different combinations of active ingredients (furosemide or pyridoxine hydrochloride), fillers (lactose monohydrate or MCC) and a binder (Kollidon® VA64) in three different concentrations (0.75, 1.5 or 3.0% w/w). The binder was used to produce granules by means of wet granulation, using ethanol as granulating fluid. The granules were dried in an oven and screened through different sized sieves to produce the final granulated powder formulations ready for tableting. A disintegrant (Ac-di-sol®) and lubricant (magnesium stearate) were incorporated into the granulated powder formulations extra-granular (0.5% w/w) and were kept as a constant in this study throughout all the formulations. A Turbula® mixer was used to mix the granulated powder formulations for a constant 5 minutes. During the first phase of the study, tablets were compressed using 2 compression settings (22 and 24). These compression settings were used to determine what effect different external pressures would have on the different tablet properties. Tablet weight for all the formulations was kept constant at 250 mg, although the volume of the matrix differed for each tablet formulation. The physical properties of the tablets were evaluated with regard to weight variation, mechanical strength (crushing strength and friability) and disintegration. Tablet formulation 12 yielded unsatisfactory tablets, due to poor powder flow into the die. Tablet formulations that contained the highest binder concentration (3.0% w/w) and were compressed at the highest compression setting (24) (formulations 4 and 9), exhibited the highest mechanical strength. The disintegration results revealed that the tablet formulations containing MCC as filler disintegrated faster compared to those containing lactose monohydrate. The increase in binder concentration caused an increase in mechanical strength, possibly decreasing tablet porosity, therefore prolonging disintegration time due to impeded water penetration into the tablet matrix. During the final phase of the study, dissolution studies were conducted on the different tablet formulations in 0.1 M HCl for 120 minutes. In terms of dissolution results, the initial dissolution rate (DRi) and extent of dissolution (AUC) were compared. It was found that the tablet formulations containing pyridoxine hydrochloride as active pharmaceutical ingredient (API) exhibited faster drug dissolution (higher DRi and AUC-values) compared to those tablet formulations containing furosemide. The faster dissolution exhibited by the pyridoxine hydro- chloride containing formulations can possibly be attributed to the fact that pyridoxine hydrochloride is good water soluble whereas furosemide is practically insoluble in water. The effect of the filler depended on the aqueous solubility of the filler and the concentration of the binder (Kollidon VA64) employed. An increase in binder concentration led to a decrease in the initial rate of dissolution as well as the extent of drug dissolution. In the case of the pyridoxine hydrochloride containing formulations, formulation 9 exhibited the slowest DRi and lowest extent of drug dissolution (1.40 ± 0.03 µg.cm-3.min-1 and 2396.52 ± 26.43 µg.cm-3.min respectively). In the case of the furosemide containing formulations, formulation 4 exhibited the slowest DRi and lowest extent of drug dissolution (0.22 ± 0.07 µg.cm-3.min-1 and 1018.62 ± 59.74 µg.cm-3 min respectively). In both cases, the formulations contained Kollidon VA64 in a concentration of 3% w/w and were compressed at compression setting 24. The disintegration process of tablets goes hand in hand with the dissolution process and results have shown that by establishing rapid contact between drug particles and the surrounding medium proves to be a necessity for rapid drug dissolution. Disintegration does not assure drug dissolution, but when prolonged, slower dissolution rates can be obtained, implying a slow rate and low extent of drug dissolution. The disintegrant in this study was incorporated extra-granular ensuring rapid tablet disintegration. However, due to binder concentration of 3% w/w, granule disintegration was probably negatively affected resulting in a lower drug surface area exposed to the surrounding dissolution medium, leading to a slower initial rate and extent of drug dissolution. From the results obtained during this study it was evident that formulation variables such as the type of filler, the concentration of the binder and compression setting employed during tablet manufacturing can have a ronounced effect on the pharmaceutical availability of the active ingredient. However, the extent of the effect was dependent on the aqueous solubility of the active ingredient. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

Silicone rubber insulators have been replacing conventional insulators made from toughened glass and porcelain in the power system, due to the non-wetting properties of silicone rubber insulation housing. However, silicone elastomers will eventually wet-out leading to leakage current and dry-band arcing giving rise to erosion of the silicone housing material, and eventually insulation failure. Well-established formulations of insulation housing composites have been developed and validated for erosion performance using the standard inclined plane tracking and erosion test, yet no such formulations have been developed and validated for DC. With the assumption that equivalent performance will be obtained, an adjustment to the creepage distance has been the measure taken in using the AC insulators for DC, without taking into consideration the differing aspects of the DC as compared to the AC dry-band arcing. This practice questions the existing DC insulators as an unknown entity that requires further investigation to ensure the reliability of the power supply. In addition recent demands have been raised to develop housing composites specifically for DC outdoor insulation, particularly with the increased interest in DC. It follows that developing a standard DC inclined plane tracking and erosion test is necessary for the development of more suitable materials for outdoor DC insulation applications. This thesis provides a thorough study of the DC dry-band arcing mechanism as opposed to the well understood mechanism of the AC dry-band arcing and provides a mechanistic understanding to the dry-band arcing leading to erosion as a foundation for the development of a standard DC inclined plane tracking and erosion test. To this end, the influence of inorganic fillers in silicone rubber on resisting erosion due to dry-band arcing is also presented, as an essential step towards obtaining more suitable silicone composite for DC outdoor insulation applications.

The primary prerequisites for powder mixtures/granules intended for tableting is to posses the quality of (i) homogenous composition; (ii) acceptable flowability, (iii) sufficient compressibility; and (iv) anti-adhesiveness. The most important prerequisite for these powder mixture/granulates is undoubtedly the ability to flow, due to its effect on product quality, especially dose and dosage form uniformity. A comprehensive literature study on the flowability of powders revealed that flow is affected by physical properties such as molecular- and interparticle forces, particle size and size distribution, particle shape, particle density, surface structure of the particle, and particle packing geometry. Various flow tests are available to determine powder flow, each measuring a variety of the properties mentioned above, resulting in different flow results and a subsequent variation in the classification of powders. Particle characterization of a wide range of pharmaceutical fillers through SEM and particle size analysis, indicated considerable differences between physical properties of the various fillers, which suggested significant differences in their flow behaviour. Flow tests were conducted determining the critical orifice diameter (COD); percentage compressibility (%C); angle of repose (AoR) and flow rate (FR) of the fillers in the absence and presence of a glidant (0.25% Aerosil® 200). The results confirmed the expected differences in flow obtained from the various tests, with no one of the fillers achieving the same flow behaviour in all the tests. The difference in flow amongst the fillers for a specific test could, to a large extent, been correlated with specific physical properties of the particles within the powder bed. COD results illustrated the influence of particle size and shape and surface structure on the flowability of these materials, with fillers with a smaller average particle size, less spherical shaped particles and uneven / rough surface structures performing poorer than their counterparts. The percentage compressibility (%C) of the materials was affected by the shape and size of the particles and the density of the materials, whilst the packing geometry also affected flow behaviour. Particles with high density and a low internal porosity tended to posses free flowing properties. Powders with a larger difference in the ratio between their respective bulk and tapped densities/volumes presented better flow results. The AoR of the fillers was affected by the cohesiveness and friction between the particles as well as the shape, surface structure and size of the particles. This method was less discriminative in terms of indicating differences in the flow of powders with comparable physical properties. A further drawback of this method was the variation in results between repetitions, which is affected by the way the samples were handled prior to measurement. The flow rate (FR) of the fillers was predominantly affected by the density of the materials and the size, shape, and surface structure of the particles. Powders with a higher density seemed to exhibit a better flow rate, although some of the other factors affected the flow rate more when the densities were very close or identical. The following general rank order for the various fillers (as an average of their performance in all the tests) were established (with no glidant present): Cellactose® 80 > FlowLac® 100 > Prosolv® HD90 * Ludipress® > Emcompress® >Avicel® PH200 > Starlac® » Emcocel® 50M * chitosan » lactose monohydrate. Addition of a glidant failed to change the rank order significantly. During the final stage of the study an attempt was made to modify and/or refine the composite flow index (CFI) proposed by Taylor ef a/. (2000:6) through (i) inclusion of flow rate results in its computation and/or (ii) varying the contribution (percentage) of each test to the CFI (Taylor & co-workers used equal contributions, namely 33 V* %, in their calculation of the CFI). The results indicated that including the results from the flow rate test was not beneficial in terms of providing a more representative CFI (in fact it reduced the accuracy of the index). Next various weight ratios for COD, %C and AoR was used to determine the CFI of each filler, and an optimum ratio was found at 50%:40%:10% (COD:%C:AoR) resulting in the highest CFI for each powder and the widest range for the CFI (largest difference between minimum and maximum values). This ratio was found in the presence and absence of a glidant. At this ratio the CFI discriminated well between the different powders in terms of their flowability. Lastly, the flowability scale for powders as used by the USP (20007:644) for %C and AoR results was adapted and fitted on the CFI results obtained for the various powders. This scale provided an exceptional fit for the powders both in the absence and presence of a glidant) and offered an excellent means for the grouping and classifcation of powders based on their CFI. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2009.

The primary prerequisites for powder mixtures/granules intended for tableting is to posses the quality of (i) homogenous composition; (ii) acceptable flowability, (iii) sufficient compressibility; and (iv) anti-adhesiveness. The most important prerequisite for these powder mixture/granulates is undoubtedly the ability to flow, due to its effect on product quality, especially dose and dosage form uniformity. A comprehensive literature study on the flowability of powders revealed that flow is affected by physical properties such as molecular- and interparticle forces, particle size and size distribution, particle shape, particle density, surface structure of the particle, and particle packing geometry. Various flow tests are available to determine powder flow, each measuring a variety of the properties mentioned above, resulting in different flow results and a subsequent variation in the classification of powders. Particle characterization of a wide range of pharmaceutical fillers through SEM and particle size analysis, indicated considerable differences between physical properties of the various fillers, which suggested significant differences in their flow behaviour. Flow tests were conducted determining the critical orifice diameter (COD); percentage compressibility (%C); angle of repose (AoR) and flow rate (FR) of the fillers in the absence and presence of a glidant (0.25% Aerosil® 200). The results confirmed the expected differences in flow obtained from the various tests, with no one of the fillers achieving the same flow behaviour in all the tests. The difference in flow amongst the fillers for a specific test could, to a large extent, been correlated with specific physical properties of the particles within the powder bed. COD results illustrated the influence of particle size and shape and surface structure on the flowability of these materials, with fillers with a smaller average particle size, less spherical shaped particles and uneven / rough surface structures performing poorer than their counterparts. The percentage compressibility (%C) of the materials was affected by the shape and size of the particles and the density of the materials, whilst the packing geometry also affected flow behaviour. Particles with high density and a low internal porosity tended to posses free flowing properties. Powders with a larger difference in the ratio between their respective bulk and tapped densities/volumes presented better flow results. The AoR of the fillers was affected by the cohesiveness and friction between the particles as well as the shape, surface structure and size of the particles. This method was less discriminative in terms of indicating differences in the flow of powders with comparable physical properties. A further drawback of this method was the variation in results between repetitions, which is affected by the way the samples were handled prior to measurement. The flow rate (FR) of the fillers was predominantly affected by the density of the materials and the size, shape, and surface structure of the particles. Powders with a higher density seemed to exhibit a better flow rate, although some of the other factors affected the flow rate more when the densities were very close or identical. The following general rank order for the various fillers (as an average of their performance in all the tests) were established (with no glidant present): Cellactose® 80 > FlowLac® 100 > Prosolv® HD90 * Ludipress® > Emcompress® >Avicel® PH200 > Starlac® » Emcocel® 50M * chitosan » lactose monohydrate. Addition of a glidant failed to change the rank order significantly. During the final stage of the study an attempt was made to modify and/or refine the composite flow index (CFI) proposed by Taylor ef a/. (2000:6) through (i) inclusion of flow rate results in its computation and/or (ii) varying the contribution (percentage) of each test to the CFI (Taylor & co-workers used equal contributions, namely 33 V* %, in their calculation of the CFI). The results indicated that including the results from the flow rate test was not beneficial in terms of providing a more representative CFI (in fact it reduced the accuracy of the index). Next various weight ratios for COD, %C and AoR was used to determine the CFI of each filler, and an optimum ratio was found at 50%:40%:10% (COD:%C:AoR) resulting in the highest CFI for each powder and the widest range for the CFI (largest difference between minimum and maximum values). This ratio was found in the presence and absence of a glidant. At this ratio the CFI discriminated well between the different powders in terms of their flowability. Lastly, the flowability scale for powders as used by the USP (20007:644) for %C and AoR results was adapted and fitted on the CFI results obtained for the various powders. This scale provided an exceptional fit for the powders both in the absence and presence of a glidant) and offered an excellent means for the grouping and classifcation of powders based on their CFI. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2009.

Orientador: Silvana Artioli Schellini / Resumo: OBJETIVO: Avaliar a eficiência da injeção de ácido hialurônico (AH) ou de soro fisiológico (SF), aplicados no subcutâneo da pálpebra inferior de portadores de ectrópio cicatricial, visando à correção não cirúrgica do mal posicionamento palpebral. MÉTODOS: este foi um estudo prospectivo, intervencionista, envolvendo 23 pálpebras de 15 portadores de ectrópio cicatricial, divididos aleatoriamente em dois grupos: G1 (13 pálpebras) no qual foram feitas quatro aplicações de 4ml de SF (Cloreto de Sódio 0,9%, Equiplex, Goiás, Brasil), associado a 1ml de cloridrato de lidocaína a 2,0% sem vasoconstritor (Xylestesin®, Cristália, São Paulo, Brasil), em intervalos de uma semana entre as aplicações; e G2 (10 pálpebras) que receberam aplicação de 1 ml de AH (Restylane® Lidocaine, Q med, Uppsala, Suécia) em aplicação única. Foram avaliadas as variáveis demográficas dos participantes, as queixas, o grau do ectrópio, o grau de flacidez palpebral, a localização do ectrópio, além de avaliações quantitativas realizadas utilizando-se a fotodocumentação sistematizada dos olhos dos pacientes, 30 dias após a primeira aplicação no G1 e 7 e 30 dias após as aplicações do G2. As imagens obtidas foram transferidas para um computador e avaliadas utilizando-se o programa Image J, avaliando-se a distância da pálpebra inferior até o reflexo corneano (DMR2), distância limbo-margem (LM), ângulo da comissura interna (AI) e externa (AE), área total (AT), lateral (AL) e medial (AM). As áreas a serem avaliadas for... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: PURPOSE: Evaluate the efficiency of injection of hyaluronic acid (HA) or saline solution (SF) applied to the lower eyelid subcutaneous, aiming at the non-surgical correction of cicatricial ectropion. METHODS: This was a prospective study involving 23 eyelids of 15 patients with cicatricial ectropion, randomly divided into two groups: G1 (13 eyelids) with four applications of 4ml of SF (Sodium Chloride 0.9%, Equiplex, Goiás , Brazil), associated to 1ml of lidocaine hydrochloride 2% without vasoconstrictor (Xylestesin®, Cristália, São Paulo, Brazil), with a one-week interval between applications; and G2 (10 eyelids) which received single application of 1 ml of AH (Restylane® Lidocaine, Q med, Uppsala, Sweden). Demographic variables, complaints, ectropion degree, eyelid flaccidity degree, ectropion location, and quantitative assessments using the systematized photodocumentation of patients eyelids 30 days after the first application in G1 and 7 and 30 days after applications in G2 were studied. The images were transferred to a computer and evaluated using the Image J program and the distance between the lower eyelid margin to corneal reflex (DMR2), limbus margin distance (LM), internal angle (IA) and external angle (EA), total (TA), lateral (LA) and medial areas (MA) were analyzed. The area measurements were delimited by a line between the two commissures and along the lid margin of the lower eyelid. The evaluations were done without traction and with traction downward of the lo... (Complete abstract click electronic access below) / Mestre