The main objective of this study was to produce flame retardant polyamide-6 (PA-6) and polypropylene (PP) composites and fibers containing boron compounds. The synergistic effect on flame retardancy of boron compounds (boron silicon containing oligomer (BSi), zinc borate (ZnB), boron phosphate (BPO4), metal oxide doped BPO4 and lanthanum borate (LaB)) with conventional flame retardants were investigated. The synergistic effect of nano-clay with commercial flame retardants was also investigated in order to reduce the total amount of flame retardant that is essential for fiber applications. The UL-94, limiting oxygen index (LOI), differential scanning calorimeter (DSC), thermal gravimetric analysis (TGA), fourrier transform infrared spectroscopy (FTIR) and cone calorimeter tests were conducted on composite materials in order to investigate the effect of synergy agents on the flame retardant and thermal properties of conventional flame retardant containing PA-6 and PP composites. According to the results from composite materials, boron compounds and clay showed synergistic effect with phosphorus based commercial flame retardants by acting generally with a condensed phase mechanism by increasing the char formation and/or by increasing the barrier effect of the final char residue. Inspired from the previous studies, firstly, only nano-sized BPO4 containing flame retardant fibers were produced and characterized. In the view of the results obtained from the composite trials, the boron compounds and organo clay were used with phosphorus based flame retardants to produce flame retardant fibers. The characterization of fiber samples were made with mechanical testing, melt flow index measurements (MFI), TGA, DSC, SEM and Micro Combustion Calorimeter (MCC) tests. According to the results from fiber samples, the inclusion of BPO4 reduced the peak heat release rate of the pure PA-6 and PP fiber. The reduction for PA-6 is higher than the PP fiber due to char forming character of PA-6. The usage of boron compounds and clay with phosphorus based flame retardants caused further reduction of peak heat release rate (PHRR) and total heat release values and increased the char formation. The amount of reduction of PHRR and total heat release (THR) is not so much due to the thermally thin character of fiber samples of nearly 40 microns. It is evident that a fabric made with these fibers will show better flame retardant behavior than single fiber tests due to its thick character with respect to the fiber samples.

<p>The extraction and quantitative analysis of low molar mass compounds in polymers is an analytical challenge. It is also important from a practical point of view because the low molar mass compounds in time will migrate from the polymers into the surrounding environment. It is especially important to gain knowledge about the migrating compounds in applications such as medical implants, packaging materials and car interiors. The main aim of this thesis was to develop headspace solid phase microextraction (HS-SPME) methods to meet this challenge. In addition, the work aimed to show the applicability of the methods developed in quality control of polymers, degradation studies and assessment of polymer durability. </p><p>Factors influencing the extraction of low molar mass compounds from polyamide 6.6 were studied. Particular attention was paid to the matrix effects and to the establishment of headspace equilibrium of 2-cyclopentyl-cyclopentanone in solid polyamide. Hydrogen bonding and adsorption of analyte to the polar matrix was observed and found to cause exceedingly slow establishment of equilibrium. The adsorption could be eliminated by the addition of water, which replaced 2-cyclopentyl-cyclopentanone at the adsorption sites of the polyamide and made it possible to measure the 2-cyclopentyl-cyclopentanone content in polyamide 6.6 using multiple headspace solid-phase microextraction (MHS-SPME). </p><p>A correlation between the emitted amount of 2-cyclopentyl-cyclopentanone and the amount 2-cyclopentyl-cyclopentanone in the material was found. The correlation was valid also under non-equilibrium conditions, which allows rapid assessment of the 2-cyclopentyl-cyclopentanone content in polyamide 6.6 using headspace sampling. </p><p>20 different low molar mass compounds were identified in virgin and recycled polyamide 6.6. The compounds could be classified into four groups: cyclic imides, pyridines, chain fragments and cyclopentanones. The structures of the degradation products imply that the thermo-oxidative degradation starts at the N-vicinal methyl group. Larger amounts of degradation products at lower degree of degradation were formed in recycled than in virgin polyamide 6.6. Thus, processing increases the susceptibility of polyamide 6.6 to thermal oxidation. The total amount of cyclopentanones was reduced upon processing and oxidation. Cyclopentanones are thus not thermo-oxidation products of polyamide 6.6. N-pentyl-succinimide showed the most significant increase due to oxidation and processing. The formation of N-pentyl-succinimide was in correlation with the simultaneous changes in tensile strength. The largest increase in N-pentyl-succinimide coincided with the largest drop in tensile strength.</p>

Syfte – Syftet med examensarbetet är att minimera eller helt eliminera den utböjning som uppstår i Husqvarnas trimmer 536 LiR från handtag ner till motor och trimmerhuvud då en 5 kilos vikt hängs i handtaget. Metod – En konceptstudie har utförts på Husqvarnas trimmer 536 LiR för att undersöka och utvärdera hur problemet med trimmern ser ut i dagsläget och därifrån ta fram olika koncept för att minimera utböjningen. Arbetet har följt en Stage-Gate produktutvecklingsprocess med sju steg från att skriva kravspecifikation till att ta fram och testa prototyper. Koncept genererades med metoderna brainstorming och Reverse Engineering och sållades sedan med Pughs beslutsmatris. Finita elementmetoden användes för att utvärdera produkten och för att analysera vissa koncept. Avancerade prototyper skapades med selektiv lasersintring medan enklare modeller togs fram för hand. Prototyperna testades och jämfördes mot originalprodukten. Resultat – I detta arbete presenteras fem olika förslag för att minska utböjningen i trimmern; en förstyvning av plastkåporna på originalprodukten, tre tillbehör att fästa på den befintliga trimmern och ett förslag på materialbyte. Alla förslag gav positiva resultat med minskad utböjning, men Tillbehör 3 var det som visade sig minimera utböjningen mest och det enda som klarade av att möta syftet. Dock gav detta tillbehör för stort viktpåslag. Förstyvningen och materialbytet gav också bra resultat gällande utböjningen och ökade inte vikten för mycket. Implikationer – Om de förslag som presenteras här skulle implementeras och tas i produktion skulle det innebära vissa tillfälliga konsekvenser vid produktion av trimmern. Verktygen för plastdetaljerna skulle behöva ändras för förstyvningen och kanske också för materialbytet, medan det för de två första tillbehören skulle behöva tillverkas helt nya verktyg för formsprutning. För att implementera Tillbehör 3 skulle nya beräkningar behövas eftersom trimmerns egenfrekvens ändras. Det skulle dock vara billigare att tillverka detta tillbehör än de första två eftersom detta inte behöver formsprutas. Begränsningar – Flertalet av prototyperna framtagna i detta projekt är tillverkade med selektiv lasersintring och inte med formsprutning, som är tillverkningsmetoden för de nuvarande plastkåporna. Detta innebär att hållfasthetsegenskaperna inte är desamma som de skulle bli vid verklig produktion. Dessutom är materialen som används glasfiberfyllda, vilket innebär att hållfastheten kommer att påverkas ytterligare beroende på tillverkningsmetod. Glasfibrernas positioner och riktningar blir olika vid olika processer vilket ger upphov till olika egenskaper. / Purpose – The purpose of this thesis is to minimize or completely eliminate the flexure in Husqvarna’s brush cutter 536 LiR from the handle down to the engine and the blade when a weight of 5 kilogrammes is hanged from the handle. Method – A concept study has been made on Husqvarna’s brush cutter 536 LiR to examine and evaluate what the problem with the model is and from that to develop different concepts to minimize the flexure. The work has followed a Stage-Gate product development process with seven steps from defining the specification of requirements to developing and testing prototypes. Ideas of concepts were generated using the methods brainstorming and Reverse Engineering and were later sifted using Pugh’s matrix. Finite Element Analysis was used to evaluate the product and to analyse certain concepts. Advanced prototypes were created using selective laser-sintering whilst simpler models were created by hand. The prototypes were tested and compared to the original product. Findings – This project presents five different suggestions on how to minimize the flexure in the brush cutter; one stiffer version of the original plastic casings, three accessories to attach to the original product and a proposal for a change of material. All these suggestions gave positive results with a lesser flexure, but the third accessory, Tillbehör 3, was the one that showed the smallest flexure and the only one able to fulfil the purpose of the study. The weight of the accessory was, however, too big. The stiffer version of the original casings and the change of material also showed good results regarding flexure and did not increase the weight too much. Implications – If any of the proposals of this project were to be implemented in production, it would cause certain temporary consequences for the production of the brush cutter. The tools for the plastic components of the current brush cutter would need some changing in order to manufacture the stiffer version of the mouldings or to produce the different material, whilst for the first two accessories completely new tools for injection moulding would have to be developed. To implement the third accessory, new calculations would be needed since the eigenfrequency of the brush cutter would be changed. It would, however, be cheaper to produce this accessory compared to the first two, since the third one does not need to be manufactured using injection moulding. Limitations – Most of the prototypes in this work is manufactured using selective laser sintering and not injection moulding, which is the manufacturing method of the current plastic casings. This means that the properties of the materials will be different than they would be if they were manufactured for production. Furthermore the materials used in the casings of the brush cutter are filled to certain degree with glass fibres, meaning that the material properties will be even more different depending on manufacturing method. The position and direction of the glass fibres will be different depending on which process is used, giving different mechanical properties.

The current reverse osmosis desalination membrane market is dominated by aromatic polyamide thin film composite (TFC) membranes. However, these polyamide membranes suffer from poor resistance to continual exposure to oxidizing agents such as chlorine in desalination applications. To overcome these problems, we have synthesized and characterized a new generation of materials, disulfonated poly(arylene ether sulfone) (BPS) random copolymer, for desalination membranes. A key technical feature of these new materials is their high tolerance to chlorine in feed water and their excellent reproducibility in synthesis. In this study, water and sodium chloride solubility, diffusivity and permeability in BPS copolymers were measured for both acid and salt form samples at sulfonation levels from 20 to 40 mol percent. The hydrophilicity of these materials, based on water uptake, increased significantly as sulfonation level increased. The water and salt diffusivity and permeability were correlated with water uptake, consistent with expectations from free volume theory. In addition, a tradeoff was observed between water/salt solubility, diffusivity, and permeability selectivity and water solubility, diffusivity and permeability, respectively. The influence of cation form and degree of sulfonation on free volume, as probed via positron annihilation lifetime spectroscopy (PALS), was determined in BPS random copolymers in both the dry and hydrated states. PALS-based free volume data for hydrated polymers were correlated with water and salt transport properties. The influence of processing history on transport properties of BPS films was also studied. Potassium form BPS films having a 32 mol% sulfonation level were acidified using solid state and solution routes. Additionally, several films were subjected to various thermal treatments in the solid state. The influence of acidification, thermal treatment, and counter-ion form on transport properties was investigated. Finally, the influence of synthesis methods of polyamide TFC membranes from m-phenylenediamine (MPD) and trimesoyl chloride (TMC) via interfacial polymerization on transport properties is reported. Then, a disulfonated diamine monomer (S-BAPS) was used instead of MPD to prepare TFC membranes. The resulting membranes exhibited reduced chlorine tolerance than those prepared from MPD. However, introduction of S-BAPS to the MPD/TMC polymerization system increased the fouling resistance of the resulting polyamide TFC membranes. / text

Polyamide 6 (PA6) was melt-blended with an intumescent flame retardant (FR) and nanoparticles (multi-wall carbon nanotubes [MWNTs] and nanoclays) to produce multi-component FR-PA6 nanocomposites. Thermal, flammability properties, char residue morphology, and mechanical properties of FR-PA6 nanocomposites were characterized. The flame retardant properties were enhanced according to UL 94 and microscale combustion calorimeter (MCC) measurements, whereas the thermal stability was decreased. Mechanical properties of the bulk material, especially elongation at break, were severely reduced, with the exception of tensile modulus which increased significantly. FR-PA6 nanofibers were processed via electrospinning. Electrospinnability, morphology of the nanofibers, combustion, and thermal properties were also analyzed. As for the bulk-form nanocomposite, improved combustion properties of these nanofibers were successfully achieved though thermal stability was compromised. With proper FR additive, the synergism between MWNTs and nanoclays was observed in PA6 resin. / text

Membrane biofouling is a common occurrence in water treatment plants that utilize reverse osmosis (RO). As bacteria and biofilm material build up on the membrane surface, it becomes more difficult for clean water to permeate through the membrane, and more pressure is required to produce the same amount of water. When pressures become critically high, membranes must be cleaned. This process is expensive in terms of chemical cost, labor, and downtime. Even after membranes have been cleaned, they can re-foul quickly if the cleaning did not effectively remove the biofilm. The water treatment plant in Dunedin, FL, which uses RO for treating groundwater, has experienced membrane biofouling since it began operation in 1992. Without the means to systematically evaluate a multitude of cleaning strategies on the bench scale, cleaning optimization must be conducted on the production skid level, which restricts the evaluation of alternative protocols. This problem is typical for many RO plants. The objectives of this project are: (1) using a multi-level and systematic approach, develop cleaning strategies for biofouled membranes that will lead to improved cleaning and decreased operational costs; (2) develop other cleaning strategies that will add to the scientific knowledge base; (3) quantify the effects of improved protocols; and (4) determine the policy implications of developed protocols in terms of cost suitability to Dunedin and elsewhere in Florida. This project consists of three phases, with phases progressively more similar to the water production environment. In the first phase, a series of bench tests were performed in the laboratory. Fouled membrane swatches were soaked and agitated in different cleaning solutions for different lengths of time, at different temperatures and pH. Protein and carbohydrate assays were then performed on both the cleaning solution and the membrane swatch to determine which conditions yield most complete removal of protein and carbohydrate from the membrane surface. Results indicate that carbohydrate removal does not appear to depend strongly on pH or temperature. Protein removal increases with increasing pH and is slightly greater at higher temperatures. The second phase of testing employed a 4"x6" stainless steel flat-sheet module in which cleanings were performed under different conditions to document corresponding changes in water flux and salt rejection. Operational parameters were based on pertinent literature and optimization results from Phase 1. Results indicate that water flux increases in response to cleaning at increasing pHs and increasing temperatures with best performances occuring after 30 minutes of cleaning. Salt rejection appears to decrease with pH. The most effective cleaning protocols, determined through trials in Phases 1 and 2, were put to the test again in Phase 3 where cleanings were performed on a specially constructed single-element cleaning system (for 8.5" x 40" elements), designed to clean a membrane element in isolation. This phase also served as final verification of new cleaning protocols before implementation on the production scale. Results from this phase were inconclusive due to mechanical problems. A multi-level, systematic cleaning evaluation leads to better understanding of the dependence of biofilm material removal and membrane performance on critical factors such as temperature, pH, time of cleaning, and chemical dose, which results in improved cleaning protocols and ultimately cost savings to RO water utilities such as Dunedin.

En raison de leur Tf très élevée, les polyamides ne sont pas exploités comme revêtements poudre UV. Dans ce travail, de nouveaux revêtements poudre UV, à base de copolyamides de type AA,BB/ AB, de faible masse molaire et porteurs de groupements réactifs sous UV, ont été élaborés en vue d'une application sur supports sensibles aux hautes températures. En variant la composition relative en co-monomères dérivés d'acides gras(synthétisé ou commerciaux) et la teneur en ramifications et doubles liaisons carbone-carbone,des copolyamides renfermant de 63 à 100% de carbone biosourcé, présentant des Tg de -31 à 3°C et des Tf de 60 à 143°C, ont été développés. L'irradiation sous UV d'un copolyamide linéaire (Tf = 114°C) et de son analogue ramifié (Tf = 96°C), en présence de benzophénone et à T≥Tf, a permis de trouver un bon compromis entre la perte de cristallinité et la réticulation. En effet, les revêtements obtenus ont montré des propriétés très intéressantes pour l'application visée.

Polymers play an integral part in the semiconductor electronic industry. Due to the expanding diversity of a polymer s structural design and the resulting properties, different polymers serve as different components in the makeup and fabrication of the electronic package. The limiting factor in computer processing speed shifts from the transistors gate delay to the interconnect delay below a circuit line width of 1.8 μm for interlayer dielectrics. Silicon dioxide has been used as the insulating layer between metal lines for many computer chip generations. Low dielectric constant polymers will need to supplant silicon dioxide as interlayer dielectrics in order to develop reliable circuits for future generations. Along with serving as interlayer dielectrics, low dielectric constant polymers are also incorporated in first and second level electronic packaging. Deposition and patterning of these polymers can be significantly reduced by using photodefinable polymers. Most photodefinable polymers are in a precursor form for exposure and development in order to dissolve in industrial developers. Once developed, the polymer precursors are cured to produce the final polymer structure. This temperature is as high as 350 oC for many polymers. Thermal curing sets limitations on the use of the polymer in the electronics industry because of either the unwanted stress produced or the incompatibility of other electronic components that do not survive the thermal cure. In addition to a low dielectric constant and photodefinability, many other properties are needed for successful implementation. Polymers must be soluble in organic solvents in order to spin coat films. Water absorption increases the dielectric constant of the patterned films and can lead to various adhesion problems and cause delamination of the film. Mismatches between the coefficients of thermal expansion in adjacent layers can produce residual film stresses which leads to warping of the substrate or interfacial delamination. The glass transition temperature must be high because the thermal expansion is greatly increased when the glass transition temperature is exceeded. A high Young s modulus is also required to withstand external forces from thermal, electrical, and packaging stresses. The goal of this research was to develop novel, low dielectric, photodefinable polymers that can be processed at low temperatures. All polymers discussed will contain one of two monomers with hexafluoroalcohol (HFA) functional groups. Fluorine provides many properties that are advantageous for low dielectric applications whereas alcohols absorb water and increase the dielectric constant. Characterization of the polymers show the effect the fluorine has on the alcohol s high water absorption. All polymers will be synthesized by condensation polymerization of a diamine with a dianhydride or diacid chloride. All other polymers will contain a novel HFA diamine. A new thermoplastic polymer structure based on the cyclization of an HFA situated ortho to an amide linkage produces a benzoxazine ring in the polymer backbone. Cyclization to form polybenzoxazines occurs at temperatures considerably lower than that needed to form polyimides. The lowest processing temperatures are achieved with protection of the HFA that can be cleaved with a photoacid generator.

Dans ce travail, nous montrons que les liquides ioniques (ILs) sont des milieux réactionnels efficaces pour des polycondensations difficiles ou impossibles à mener dans les milieux classiques. Des liquides ioniques acides de Brønsted (BAILs) ont été utilisés à la fois comme milieux réactionnels et comme catalyseurs pour la polyestérification de l'acide 12-hydroxy-dodecanoïque (12-HDA), pour celle d'oligoesters préformés à partir de mélanges diol/diacide équimolaires et pour celles de l'acide 2,2- bis(hydroxymethyl)propanoïque. Les polyestérifications dans les BAILs sont beaucoup plus rapides que les polyestérifications traditionnelles en masse. Des polyesters linéaires de Mw environ 40000 g/mol ont été obtenus après seulement 5-30 min de réaction à 110°C au lieu de plusieurs heures à 200 °C en masse. De la même manière, des polyesters hyperramifiés de Mw=10000 g/mol ont été obtenus après 1 h de réaction à 150°C dans les BAILs au lieu de plus de 8 h en masse. Des polyéthers linéaires de diols à longues chaînes aliphatiques, difficiles à synthétiser par les méthodes traditionnelles ont été obtenus très simplement par polyétherification directe dans des BAILs. Nous avons également mené des synthèses de polyamides difficiles ou impossibles à obtenir par polyamidification directe. Nous avons ainsi pu préparer des homopolyamides de la β-alanine, de la Lvaline et de la L-isoleucine et des copolyamides de l'acide 12-amino-dodécanoïque et d'acides α- et β- aminés naturels dans des ILs à anion phosphoré en présence de triphénylphosphite comme agent de condensation.

Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: William J. Koros; Committee Member: Amyn Teja; Committee Member: Carson Meredith; Committee Member: Sankar Nair; Committee Member: Wallace W. Carr.