Polyester is a synthetic material made from polyethylene terephthalate (PET), which is synthesised from fossil raw materials. Many clothing manufacturers are using polyester in their clothing, which, from an environmental perspective, creates a non-sustainable cycle. However, manufacturing can be made more sustainable by using recycled PET bottles as the raw material for polyester yarn. A clothing company that has taken a stand against materials made from fossil fibres and instead invests in only selling clothes made from sustainable materials is the Swedish children's clothing brand Polarn o. Pyret. Being able to use polyester made from PET bottles is important for Polarn o. Pyret to ensure the use of sustainable fibres in their clothing. In the past, the recycled polyester was used in combination with polyester from virgin fibre, but now the goal is instead to switch completely to the recycled polyester. However, the increased quantity of recycled polyester can involve new risks. The need to map potential contaminants is important because Polarn o. Pyret makes clothes for children, which entails strict requirements on the chemical content of the clothes. The purpose of this work is to get an overview of which contaminants that can accumulate in the polyester fibre and thus pose a risk when using recycled polyester made from PET bottles. The goal is to be able to shed light on these contaminants and write a proposal for a risk assessment guide that can establish a foundation for how Polarn o. Pyret should be able to act when using recycled polyester. The work was carried out through an extensive literature study, where research articles and review articles published on scientific databases were the main source of information. Focus was on the risk of non-intentionally added substances that can be traced from recycled PET bottles. The risk assessment was done in consideration of the regulations that is established within the European Union (EU), using the EU chemicals regulation REACH and the European Chemicals Agency (ECHA) database.  After the mapping of NIAS in r-PET, the literature showed 42 potential contaminants to be present. These substances originated from the degradation of PET or the degradation of additives, and impurities from the recycling process and post-consumption use. Adhesives, labels, and caps are a contributing factor to the formation of NIAS originating from the recycling process. Since PVC was found to be the most common plastic that could contaminate PET via recycling, the additives used in PVC could also migrate to PET and create impurities. The most common phthalate found in this study was DEHP, which was the main plasticiser in PVC.  15 substances of the NIAS found in the literature was CMR substances, which means that they either were, or were suspected to be, carcinogenic, mutagenic and/or toxic to reproduction. Among these were substances such as benzene, antimony, cadmium, lead, acetaldehyde, and formaldehyde. Certain substances found through the literature were classified to be endocrine disruptors. These NIAS were p-nonylphenol, the organophosphite TNPP, the phthalates DEHP, DBP, BBP and, DIBP, nickel and BPA. Some of the NIAS found were under assessment of being classified as persistent, bioaccumulativ and toxic (PBT). The PBT substances found were the organophosphite compound Irgafos 168 and the UV-stabilisers Tinuvin P, UV-234 and UV- 328. The risk assessment showed 20 contaminants that may cause irritation to the skin/eyes and/or throat and 24 contaminants which may be toxic to the aquatic life.  This risk assessment showed that the recycling process of PET bottles is not completely safe, because potential contaminants could be transferred into the polyester yarn, and then carried over into children's garment and pose health risks to children. / Polyester är ett syntetiskt material tillverkat av polyetentereftalat (PET), som är syntetiserat från fossila råvaror. Många klädtillverkare använder polyester i sina kläder vilket ur ett miljöperspektiv skapar ett ohållbart kretslopp. Tillverkningen kan dock göras mer hållbar genom att använda återvunna PET-flaskor som råvara för polyestergarn. Ett klädföretag som tagit ställning mot material tillverkade av fossila fibrer och i stället satsar på att endast sälja kläder av hållbara material är det svenska barnklädesmärket Polarn o. Pyret. Att kunna använda polyester tillverkad av PET-flaskor är viktigt för att Polarn o. Pyret ska kunna säkerställa användningen av hållbara fibrer i sina kläder. Tidigare användes den återvunna polyestern i kombination med polyester från jungfruliga råvaror, men nu är målet i stället att helt gå över till den återvunna polyestern. Den ökade mängden återvunnen polyester kan dock medföra nya risker. Behovet av att kartlägga potentiella föroreningar är också viktigt eftersom Polarn o. Pyrets gör kläder för barn, vilket medför hårda krav på klädernas kemikalieinnehåll. Syftet med detta arbete var att få en överblick över vilka kemikalier som kan ansamlas i polyesterfibern och därmed utgöra en risk vid användning av återvunnen polyester tillverkad av PET-flaskor. Målet var att identifiera dessa föroreningar och inkludera dessa ämnen i ett förslag till en riskbedömningsguide. Denna riskbedömningsguide skulle därmed kunna utgöra ett stöd för Polarn o. Pyret vid hantering av återvunnen polyester. Arbetet har utförts genom en omfattande litteraturstudie, där forskningsartiklar och översiktsartiklar publicerade på vetenskapliga databaser var den huvudsakliga informationskällan. Fokus låg på risken för oavsiktligt tillsatta ämnen som kan spåras från återvunna PET-flaskor. Riskbedömningen har gjorts med hänsyn till de regelverk som är etablerade inom Europeiska unionen (EU), med hjälp av EU:s kemikalieförordning REACH och europeiska kemikaliemyndighetens (ECHA) databas.  Efter kartläggningen av oavsiktligt tillsatta ämnen i återvunnen PET visade litteraturen att det fanns 42 potentiella kontaminanter. Dessa ämnen härrörde från nedbrytningen av PET eller nedbrytningen av tillsatser, samt från föroreningar kopplade till återvinningsprocessen. Lim, etiketter och korkar var en bidragande faktor till bildandet av de oavsiktligt tillsatta ämnen som härrörde från återvinningsprocessen. Eftersom PVC visade sig vara den vanligaste plasten som kunde kontaminera PET via återvinningen, kunde tillsatserna som används i PVC också migrera till PET och skapa föroreningar. Den vanligaste ftalaten som förekom i återvunnen PET i denna studie var DEHP, vilken är den huvudsakliga mjukgöraren i PVC.  15 oavsiktligt tillsatta ämnen konstaterades vara CMR-ämnen, vilket betyder att de var, eller misstänktes vara, cancerframkallande, mutagena och/eller reproduktionstoxiska. Bland dessa fanns ämnen som bensen, antimon, kadmium, bly, acetaldehyd och formaldehyd. Vissa ämnen som påträffades genom litteraturstudien klassificerades som hormonstörande. Dessa var p- nonylfenol, organofosfiten TNPP, ftalaterna DEHP, DBP, BBP och DIBP, nickel och BPA. En del av de ämnen som kartlades under riskbedömningen klassificerades som persistenta, bioackumulerande och toxiska (PBT). Bland dessa förekom organofosfitföreningen Irgafos 168 (Tris(2,4-ditert-butylfenyl)fosfit) och UV-stabilisatorerna Tinuvin P, UV-234 och UV-328. Riskbedömningen visade på 20 kontaminanter som kan orsaka irritation på hud/ögon och/eller svalg och 24 föroreningar som kan vara giftiga för vattenlivet.  Denna riskbedömning visade att återvinningsprocessen av PET-flaskor inte är helt säkert, eftersom potentiella kontaminanter kan inkluderas i polyestergarnet och därigenom skapa faror för barnen vid användningen av kläder tillverkade från återvunnen polyester.

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Yes / Healthcare applications are known to have a considerable environmental impact and the use of bio-based polymers has emerged as a powerful approach to reduce the carbon footprint in the sector. This research aims to explore the suitability of using a new sustainable polyester blend (Floreon™) as a scaffold directed to aid in musculoskeletal applications. Musculoskeletal problems arise from a wide range of diseases and injuries related to bones and joints. Specifically, bone injuries may result from trauma, cancer, or long-term infections and they are currently considered a major global problem in both developed and developing countries. In this work we have manufactured a series of 3D-printed constructs from a novel biopolymer blend using fused deposition modelling (FDM), and we have modified these materials using a bioceramic (wollastonite, 15% w/w). We have evaluated their performance in vitro using human dermal fibroblasts and rat mesenchymal stromal cells. The new sustainable blend is biocompatible, showing no differences in cell metabolic activity when compared to PLA controls for periods 1-18 days. FloreonTM blend has proven to be a promising material to be used in bone tissue regeneration as it shows an impact strength in the same range of that shown by native bone (just under 10 kJ/m2) and supports an improvement in osteogenic activity when modified with wollastonite. / We would like to acknowledge the Medical Research Council in the UK (MRC) for funding this research throughout a MRC Proximity to Discovery award (P2D) with grant number MC_PC_16084. We would also like to acknowledge CONACYT for funding DH RamosRodriguez’s work.

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PLA nanofibers were successively produced by thermo-responsive transformation of PLA particles in water. The morphological structure of the nanofibers could be optimized by the heat treatment as well as the incorporation of GO to the fiber surface. PLA/GO fiber demonstrated a more stable morphology and GO provided good compatibility between PLA and starch. Both PLA and PLA/GO fibers incorporated in starch films resulted in increased thermal stability and mechanical properties. However, the most favorable properties were assigned starch films containing high concentration of PLA/GO fibers. These films with completely green components could possibly be utilized in biodegradable packaging applications.

Solvent-free extrusion emulsification (SFEE) is a novel emulsification technology that operates without solvent to produce sub-micron sized particles (100–200 nm) using a twin-screw extruder (TSE) with high viscosity polymers (up to 600 Pa.s has been tested to date) and only water as the liquid medium. Surfactants have always been known to play a key role in the success of the SFEE process, however very little work has been done to investigate the mechanisms by which they operate, along with isolating the region of the process to which they play the most vital role. The first part of this thesis focused on an investigation into how different surface-active properties impacted the mechanism of SFEE. Three ionic (SDBS, Unicid 350, Calfax DB-45) and three non-ionic surfactants (Igepal CO-890, Brij 58, Synperonic F-108), each with differing surface-active properties were tested in solvent emulsification (SE) prior to their evaluation in SFEE. Synperonic F-108 was the only surfactant found unsuccessful in the SE process, and was therefore disregarded prior to SFEE testing. Of the three ionic surfactants, SDBS and Calfax were the only ones found to successfully create a stable emulsion in SFEE; the latter species doing so with 50% reduced molar loading. Igepal and Brij were found to produce very low amounts of emulsified material (5-25% of the total solids mass), requiring molar loadings that greatly exceed those of SDBS and Calfax to do so. Particles generated by both SE and SFEE were tested at extreme operating conditions to compare their relative stabilities, and were found to experience similar stability behaviours. This result reinforces previous findings that the dispersion stage controls the SFEE technique. The second part of this thesis continued the investigation on the use of non-ionics in SFEE, with a focus on the impact of their molecular structure on the overall process. Non-ionic surfactants with varying hydrophilic end group chain lengths were tested in SFEE, and it was determined that the optimal hydrophilic chain length was between 10–12 ethoxy units, where shorter chains resulted in coarse particle generation. The structure of the hydrophobic end group was tested as well, and through experimentation it was determined that a branched end group structure was slightly more beneficial than a linear end group to emulsion stabilization. As seen in the first part of this thesis, none of the new selection of non-ionic surfactants were capable of inducing sufficient phase inversion to result in a high percentage of emulsion leaving the extruder. The most promising ionic surfactant, Calfax DB-45, was combined with various promising non-ionic surfactants to create binary surfactant mixtures, and were tested in SFEE. Initial results yielded the most promising blend as Calfax/Igepal CA-630. After manipulation of both molar ratio and total surfactant loading, it was determined that a minimum Calfax loading of 0.06 mmol/g resin was required in the blend to achieve a stable 100 – 200 nm emulsion in both SE and SFEE processes, regardless of non-ionic concentration. The benefits of adding a non-ionic surfactant in the blend were seen with the substantial reduction of Calfax entrapped in the final latex particles, apparent by the distinct decrease in overall particle charge. A mini-study examining the impacts of increasing the viscosity of the water phase by hydrocolloid addition for the dilution stage has shown that positive changes to emulsion properties can be seen by this approach, but further experimentation is required before concrete conclusions can be made. / Thesis / Master of Applied Science (MASc) / The creation of nanoparticles has been a growing area of research in recent years, with numerous different means of generation being developed. Extruders have seldom been used for the generation of nanoparticles due to issues related to controlling generated particle characteristics. Previous work has shown that twin-screw extruders are capable of generating 100–200 nm particles, but the process has shown minimal robustness to variations in operating conditions. The aim of this study has been to continue the work of nanoparticle generation within a twin-screw extruder, with a specific focus on the impacts that special soap-like particles (surfactants) have on the process. Surfactants are special particles consisting of both a hydrophilic (“water-loving”) and hydrophobic (“water-hating”) end group that allows multiple substances to combine on a chemical level. Variations in the molecular structure and electronic charge of these surfactants, along with blends of different types of surfactants have been tested to gain a better understanding of their role in the process, and hopefully increase the overall robustness of the process. Overall, it was determined that surfactants with a negative charge were more successful in creating polyester latex particles than ones with a neutral molecular structure. The blending of a charged and neutral surfactant has been shown in this study to not only be successful in generating particles of desired size, but have also shown the ability to reduce the overall charge of the final latex particles.

Research efforts have focused on synthesis of linear, long-chain branched, and novel crosslinked polyesters for applications spanning from pressure sensitive adhesives to biomedical applications. Altering polymer topology and functionality using different synthetic strategies was enabled tailoring the thermomechanical, rheological, and adhesive properties of polyesters. The synthesis and characterization of linear, long-chain branched, and crosslinked networks are described focusing on the structure-property relationships. Aliphatic low-Tg polyesters with linear and long-chain branched topology were synthesized using melt polycondensation for pressure sensitive adhesive applications. Relationships between molecular weight, polymer composition, and adhesive performance were investigated. Melt rheological studies and the characterization of adhesive properties indicated that adhesive performance was enhanced with increasing molecular weight. Moreover, a series of long-chain branched low-Tg polyester were investigated to determine the influence of branching and molecular weight. Tailoring the degree of branching enabled the control of rheological and adhesive properties. Characterization of adhesive properties revealed that long-chain branched polymers displayed an enhanced cohesive strength. In addition, utilization of different comonomer compositions allowed tailoring thermal and adhesive properties of low-Tg polyesters over a wide range. Biodegradable networks were synthesized for the first time using base-catalyzed Michael addition of acetoacetate functionalized polyesters with acrylates. Linear and star-shaped poly(caprolactone) (PCL) oligomers with different molecular weights were functionalized and crosslinked. Thermomechanical properties were evaluated as a function of precursor molecular weight and crosslink density. The glass transition temperature and the extent of crystallinity of the networks were dependent on the molecular weight of the PCL segment. Moreover, dynamic mechanical analysis (DMA) indicated that molecular weight of the oligomeric precursors influenced the plateau modulus of the networks as a result of the differences in crosslink density of the networks. In addition, covalently crosslinked networks were synthesized from Michael addition reaction of acetoacetate-functional oligomeric poly(trimethylene succinate)s and poly(trimethylene adipate)s with neopentylglycol diacrylate. The oligomeric polyesters with telechelic hydroxyl functionality were synthesized from renewable monomers, adipic acid, succinic acid, and 1,3-propanediol using melt polycondensation. The molecular weights of the precursors were varied systematically to probe the influence of molecular weight on thermomechanical properties of the networks. The extent of crystallinity and mechanical properties were dependent on the molecular weight of the oligomeric polyester precursors which also controlled crosslink density. Moreover, Michael addition chemistry was utilized to crosslink low-Tg polyesters to improve cohesive strength for PSA applications. In order to determine the influence of temperature and catalyst levels, crosslinking reactions were monitoring using measurement of loss and storage moduli during the reaction. Networks having different levels of gel fractions were investigated to elucidate the influence of degree of crosslinking on thermomechanical and adhesive properties of low-Tg polyesters. / Ph. D.

Melt polymerization and novel monomers enabled the synthesis of polyesters for electronic and biological applications. Inspiration from nature and a passion for environmental preservation instigated an emphasis on the incorporation of renewable resources into polymeric materials. Critical analysis of current research surrounding bisphenol-A replacements and ioncontaining segmented polyurethanes aided in identifying benchmark polymers, including limitations, challenges, and future needs. Structure-property-morphology relationships were investigated to evaluate the polymers for success in the proposed applications as well as to improve understanding of polyester compositions to further design and develop sophisticated polymers for emerging applications. Aiming to utilize the reported [2 + 2] cycloaddition of the known mesogen 4,4’-dimethyltrans-stilbene dicarboxylate (SDE) to overcome ultraviolet (UV) induced degradation issues in electronic encasings, the synthesis of copolyesters containing SDE ensued. 1,6-Hexanediol (HD) and 1,4-butanediol comonomers in varying weight ratios readily copolymerized with SDE under melt transesterification conditions to afford a systematic series of copolyesters. Differential scanning calorimetry revealed all copolyesters exhibited liquid crystalline transitions and melting temperatures ranged from 196 °C – 317 °C. Additionally, melt rheology displayed shear thinning to facilitate melt processing. Compression molded films exhibited high storage moduli, a glassy plateau until the onset of flow, and tensile testing revealed a Young’s iii modulus of ~900 MPa for poly(SDE-HD). These properties enable a wide range of working temperatures and environments for electronic applications. Adding complexity to linear liquid crystalline copolyesters, copolymerization with oligomeric hydroxyl-functionalized polyethers afforded segmented liquid crystalline copolyesters. 4,4’-Biphenyl dicarboxylate (BDE), commercially available diols containing 4, 5, 6, 8, or 10 methylene units, and introducing poly(tetramethylene oxide) or a Pluronic® triblock oligoethers in varying weight % were used to synthesize multiple series of segmented copolyesters. Comparing melting transitions as a function of methylene spacer length elucidated the expected even-odd effect and melting temperatures ranged from 150 °C to 300 °C. Furthermore, incorporating the flexible soft segment did not prevent formation of a liquid crystalline morphology. Complementary findings between differential scanning calorimetry and small-angle X-ray scattering confirmed a microphase-separated morphology. Thermomechanical analysis revealed tunable plateau moduli and temperature windows based on both soft segment content and methylene spacer length, and tensile testing showed the strain at break doubled from 75 weight % to 50 weight % hard segment content. The same compositions Young’s moduli decreased from 107 ± 12 MPa at 75 weight % hard segment to 19 ± 1 MPa with 50 weight % hard segment, demonstrating the mechanical trade-off and range of properties possible with small compositional changes. These segmented copolyesters could find use in high-performance applications including electronic and aerospace industries. A two-step synthesis transformed caffeine into a novel caffeine-containing methacrylate (CMA). Conventional free radical copolymerization with a comonomer known to provide a low glass transition temperature (Tg), 2-ethylhexyl methacrylate (EHMA), allowed the investigation of the effect of small amounts of pendant caffeine on polymer properties. Thermal and iv thermomechanical testing indicated CMA incorporation dramatically increased the storage modulus, however, a microphase-separated morphology was not attained. Association of the pendant caffeine groups through non-covalent π-π stacking could present opportunities for novel thermoplastics and it is proposed that placing the pendant group further from the backbone, and potentially increasing the concentration, could aid in promoting microphase-separation. Alkenes are reactive sites for placing functional groups, particularly those required for polyester synthesis. Methyl 9-decenoate (9-DAME), a plant-based fatty acid, provided a platform for novel biodegradable, renewable, polyesters. A formic acid hydration reaction generated an isomeric mixture of AB hydroxyester or AB hydroxyacid monomers for melt polymerization. Thermal analysis elucidated the plant-based polyesters exhibited a single transition, a Tg of about -60 °C. Aliphatic polyesters commonly crystallize, thus the isomeric mixture of secondary alcohols seemed to introduce enough irregularity to prevent crystallization. These polyesters offer an amorphous, biodegradable, sustainable replacement for applications currently using semi-crystalline poly(ε-caprolactone), which is not obtained from renewable monomers and also exhibits a -60 °C Tg. Additional applications requiring low-Tg polymers such as pressure sensitive adhesives or thermoplastic elastomers could also benefit from these novel polyesters. 9-DAME also was transformed into an ABB’ monomer after an epoxidation and subsequent hydrolysis. Successful gelation under melt transesterification conditions provided evidence that the multifunctional monomer could perform as a renewable, biodegradable, branching and/or crosslinking agent. Novel copolyesters comprised of a bromomethyl imidazolium diol and adipic acid demonstrated potential as non-viral gene delivery vectors. Melt polycondensation produced water dispersible polyesters which bound deoxyribonucleic acid at low N/P ratios. The v polyplexes showed stability in water over 24 h and no cytotoxic effect on human cervical cancer cells (HeLa). A luciferase transfection assay revealed the copolyesters successfully underwent endocytosis and released the nucleic acid better than controls. The copolyesters with pendant imidazolium functionality also provided tunable Tgs, -41 °C to 40 °C, and the ability to electrospin into fibers upon blending with poly(ethylene oxide). These additional properties furthered potential applications to include pressure sensitive adhesives and biocompatible antibacterial bandages. / Ph. D.

The effect of process conditions, temperature, time and rate of temperature rise, on the exhaustion of disperse dye on polyester yarn under High-Temperature dyeing conditions was investigated. Two ply spun type Dacron 54 polyester yarn was dyed with Disperse Red 60 in 0.5 g/l dye bath concentration using an Ahiba Texomat Dyeing Apparatus under High-Temperature Dyeing conditions. The dyeing process design used, consists of three levels of dyeing temperature (105°C, 120°C, 135°C), four levels of holding time (0 min, 15 min, 30 min, 60 min) and two levels of rate of temperature rise (1ºC/min, 3°C/min). After the dyeing process, the dye concentration in the yarn was obtained through extraction and measured spectrophotometrically. A factorial analysis of variance (ANOVA) test was used to determine whether or not significant differences existed among dyeing process conditions in regard to the dye uptake of the yarn. If significant differences existed, which parameter of process conditions (temperature, time, rate of temperature rise or their interactions) was responsible. The results of this study indicated that a three-way interaction of temperature, time, and rate of temperature rise was responsible for the differences in dye uptake of the yarn. The dye uptake of the yarn increased by increasing dyeing temperature from 105°C to 120°C for all levels of holding time and rate of temperature rise. However, increasing dyeing temperature from 120°C to 135°C, did not increase dye uptake of the yarn. The dye uptake of the yarn increased by increasing holding time from zero to 15 minutes for dyeing temperature of 120°C. However, increasing holding time from 15 to 60 minutes, did not increase dye uptake of the yarn. At the dyeing temperature of 120°C, a slower rate of temperature rise resulted in greater dye uptake of the yarn. It can be concluded that high temperature dyeing of polyester yarn at 120°C for 15 minutes with a rate of temperature rise of 1°C/min was the optimum dyeing process in achieving full exhaustion. / Master of Science