Blends of poly butylene terephthalate (PBT) and polycarbonate (PC) form a very important class of commercial blends in numerous applications requiring materials with good chemical resistance, impact resistance even at low temperatures, and aesthetic and flow characteristics. PC and PBT are usually blended in a twin screw extruder (TSE). Product melt volume flow rate (MVR) is a property used to monitor product quality while blending the PC/PBT in a twin screw extruder. It is usually measured off line in a quality control laboratory using extrusion plastometer on samples collected discretely during the compounding operation. Typically a target value representing the desired value of the quality characteristics for an in-control process, along with upper and lower control limits are specified. As long as the MVR measurement is within the control limits, the sample is approved and the whole compounded blend is assumed to meet the specification. Otherwise, the blend is rejected. Because of infrequent discrete sampling, corrective actions are usually applied with delay, thus resulting in wasted material. It is important that the produced PC/PBT blend pellets have consistent properties. Variability and fault usually arise from three sources: human errors, feed material variability, and machine operation (i.e. steady state variation). Among these, the latter two are the major ones affecting product quality. The resulting variation in resin properties contributes to increased waste products, larger production cost and dissatisfied customers. Motivated by this, the objective of this project was to study the compounding operation of PC/PBT blend in a twin screw extruder and to develop a feasible methodology that can be applied on-line for monitoring properties of blends on industrial compounding operations employing available extruder input and output variables such as screw speed, material flow rate, die pressure and torque. To achieve this objective, a physics-based model for a twin screw extruder along with a MVR model were developed, examined and adapted for this study, and verified through designed experiments. This dynamic model for a TSE captures the important dynamics, and relates measurable process variables (screw speed, torque, feed rates, pressure etc.) to ones that are not being measured (material holdups and compositions at the partially and filled section along a TSE barrel). This model also provides product quality sensors or inferential estimation techniques for prediction of viscosity and accordingly MVR. The usefulness of the model for inferential MVR sensing and fault diagnosis was demonstrated on experiments performed on a 58 mm co-rotating twin-screw extruder for an industrial compounding operation at a SABIC Innovative Plastics plant involving polycarbonate – poly butylene terephthalate blends. The results showed that the model has the capability of identifying faults (i.e., process deviation from the nominal conditions) in polymer compounding operations with the twin screw extruder. For instance, the die pressure exhibited a change as a function of changes in raw materials and feed composition of PC and PBT. In the presence of deviations from nominal conditions, the die pressure parameters are updated. These die pressure model parameters were identified and updated using the recursive parameter estimation method. The recursive identification of the die pressure parameters was able to capture very well the effects of changes in raw material and/or composition on the die pressure. In addition, the developed MVR model showed a good ability in monitoring product MVR on-line and inferentially from output process variables such as die pressure which enables quick quality control to maintain products within specification limits and to minimize waste production.

In this work, the compounding of polycarbonate (PC) / poly-butylene terephthalate (PBT) blends was studied for the purpose of improving quality of products with reduced wastage and finally to satisfaction of end users. The effect of material rheological characteristics and processing conditions on compounding of PC /PBT was investigated through statistical experiments carried out on a 58 mm twin-screw extruder at SABIC Innovative Plastics Limited (formerly GE Plastics Limited) in Cobourg, Ontario. Melt Volume-Flow Rate (MVR) is the most commonly used property to monitor the quality of products of PC/PBT blends. The MVR was studied with different sampling times and correlations between product properties (melt flow) and processing conditions (screw speed, flow rates) were discussed. The rheological behavior of PC/PBT blends was investigated by dynamic and capillary rheometers. The effects of processing conditions (screw speed, feed rate) on viscosity were measured and it was found that the Cox-Merz rule is not valid for PC/PBT blends. The change of morphology of PC/PBT blends was observed under a scanning electron microscope (SEM) by using different types of samples. Those samples were (i) PC/PBT blends pellets, (ii) PC/PBT blend samples, but collected after completing the rheological tests in the parallel plate rheometer, and (iii) PC/PBT blend samples, but collected after completing the rheological tests in the capillary rheometer. There was evidence that the samples collected after completing the tests in the parallel and capillary rheometer might be degraded due to temperature and time.

Blends of poly butylene terephthalate (PBT) and polycarbonate (PC) form a very important class of commercial blends in numerous applications requiring materials with good chemical resistance, impact resistance even at low temperatures, and aesthetic and flow characteristics. PC and PBT are usually blended in a twin screw extruder (TSE). Product melt volume flow rate (MVR) is a property used to monitor product quality while blending the PC/PBT in a twin screw extruder. It is usually measured off line in a quality control laboratory using extrusion plastometer on samples collected discretely during the compounding operation. Typically a target value representing the desired value of the quality characteristics for an in-control process, along with upper and lower control limits are specified. As long as the MVR measurement is within the control limits, the sample is approved and the whole compounded blend is assumed to meet the specification. Otherwise, the blend is rejected. Because of infrequent discrete sampling, corrective actions are usually applied with delay, thus resulting in wasted material. It is important that the produced PC/PBT blend pellets have consistent properties. Variability and fault usually arise from three sources: human errors, feed material variability, and machine operation (i.e. steady state variation). Among these, the latter two are the major ones affecting product quality. The resulting variation in resin properties contributes to increased waste products, larger production cost and dissatisfied customers. Motivated by this, the objective of this project was to study the compounding operation of PC/PBT blend in a twin screw extruder and to develop a feasible methodology that can be applied on-line for monitoring properties of blends on industrial compounding operations employing available extruder input and output variables such as screw speed, material flow rate, die pressure and torque. To achieve this objective, a physics-based model for a twin screw extruder along with a MVR model were developed, examined and adapted for this study, and verified through designed experiments. This dynamic model for a TSE captures the important dynamics, and relates measurable process variables (screw speed, torque, feed rates, pressure etc.) to ones that are not being measured (material holdups and compositions at the partially and filled section along a TSE barrel). This model also provides product quality sensors or inferential estimation techniques for prediction of viscosity and accordingly MVR. The usefulness of the model for inferential MVR sensing and fault diagnosis was demonstrated on experiments performed on a 58 mm co-rotating twin-screw extruder for an industrial compounding operation at a SABIC Innovative Plastics plant involving polycarbonate – poly butylene terephthalate blends. The results showed that the model has the capability of identifying faults (i.e., process deviation from the nominal conditions) in polymer compounding operations with the twin screw extruder. For instance, the die pressure exhibited a change as a function of changes in raw materials and feed composition of PC and PBT. In the presence of deviations from nominal conditions, the die pressure parameters are updated. These die pressure model parameters were identified and updated using the recursive parameter estimation method. The recursive identification of the die pressure parameters was able to capture very well the effects of changes in raw material and/or composition on the die pressure. In addition, the developed MVR model showed a good ability in monitoring product MVR on-line and inferentially from output process variables such as die pressure which enables quick quality control to maintain products within specification limits and to minimize waste production.

In this work, the compounding of polycarbonate (PC) / poly-butylene terephthalate (PBT) blends was studied for the purpose of improving quality of products with reduced wastage and finally to satisfaction of end users. The effect of material rheological characteristics and processing conditions on compounding of PC /PBT was investigated through statistical experiments carried out on a 58 mm twin-screw extruder at SABIC Innovative Plastics Limited (formerly GE Plastics Limited) in Cobourg, Ontario. Melt Volume-Flow Rate (MVR) is the most commonly used property to monitor the quality of products of PC/PBT blends. The MVR was studied with different sampling times and correlations between product properties (melt flow) and processing conditions (screw speed, flow rates) were discussed. The rheological behavior of PC/PBT blends was investigated by dynamic and capillary rheometers. The effects of processing conditions (screw speed, feed rate) on viscosity were measured and it was found that the Cox-Merz rule is not valid for PC/PBT blends. The change of morphology of PC/PBT blends was observed under a scanning electron microscope (SEM) by using different types of samples. Those samples were (i) PC/PBT blends pellets, (ii) PC/PBT blend samples, but collected after completing the rheological tests in the parallel plate rheometer, and (iii) PC/PBT blend samples, but collected after completing the rheological tests in the capillary rheometer. There was evidence that the samples collected after completing the tests in the parallel and capillary rheometer might be degraded due to temperature and time.

A literatura corrente possui informações limitadas sobre o projeto da área de troca térmica de tanques com jaqueta, serpentina helicoidal, serpentina espiral e chicana tubular vertical, em operação com fluidos não-Newtonianos. A presente tese teve por objetivo principal analisar a transferência de calor, potência consumida e ampliação de escala em tanques com impulsores mecânicos na agitação de fluidos não-Newtonianos com duas superfícies de transmissão de calor, chicana tubular vertical e serpentina em espiral. O trabalho também visou fornecer métodos de ampliação de escala de tanques com agitação para fluidos não-Newtonianos que sigam o modelo reológico da lei das potências. A unidade experimental contemplou dois tanques de acrílico, com volume de 10 litros e 50 litros, respectivamente, chicanas tubulares verticais e serpentina em espiral. Os impulsores mecânicos utilizados foram o axial com 4 pás inclinadas a 45° e o radial turbina com 6 pás planas. Como fluidos utilizaram-se soluções aquosas de carboximetilcelulose (0,5%, 1,0% e 1,5%), solução aquosa de carbopol 940 (1,5%), solução aquosa de sacarose (50%) e água. Todos os experimentos foram conduzidos em batelada. Com os dados obtidos, empregou-se o uso de regressões para a obtenção da Equação de Nusselt, as quais forneceram valores de coeficiente de determinação ajustados entre 0,83 e 0,89 com Reynolds no intervalo de 20 a 405000, Prandtl na faixa de 4 a 6400 e índice reológico do modelo da lei das potências entre 0,45 e 1,00. Observou-se que no aquecimento realizado com a chicana tubular vertical, o impulsor radial forneceu coeficientes de convecção 20% acima quando comparado com o impulsor axial, entretanto o consumo de potência foi cerca de 66% maior em relação ao impulsor axial. No caso da serpentina espiral, o impulsor axial promoveu coeficientes de convecção por volta de 15% superiores em relação ao impulsor radial com um consumo de potência 65% menor. Desse modo, em processos em que não é necessária uma elevada turbulência, recomenda-se o uso do impulsor axial com a serpentina espiral, porém, se o processo demandar uma turbulência significativa, deve-se usar o impulsor radial com a chicana tubular vertical. Em uma última análise, os modelos não-lineares obtidos para ampliação de escala forneceram erros entre 11% e 20% na predição da rotação no tanque industrial, os quais são válidos para Reynolds modificados de Metzner e Otto (1957) na faixa de 20 a 4000 e para fluidos não-Newtonianos pseudoplásticos com índices reológicos entre 0,45 e 1,00. / Current literature has limited information on the design of the thermal exchange area of tanks with jacket, helical coil, spiral coil and vertical tuber baffle, in operation with non-Newtonian fluids. The main purpose of this thesis was to analyze heat transfer, power consumption and scale-up in tanks with mechanical impellers in the agitation of non-Newtonian fluids with two heat transfer surfaces, vertical tube baffle and spiral coil. The work also aimed to provide methods of scale-up tank scale with agitation for non-Newtonian fluids that follow the rheology model of the law of powers. The experimental unit included two acrylic tanks, with a volume of 10 liters and 50 liters, respectively, vertical tube baffles and spiral coil. The mechanical impellers used were the 45° pitched blade turbine (PBT) and the Rushton turbine (RT). Aqueous solutions of carboxymethylcellulose (0.5%, 1.0% and 1.5%), aqueous solution of carbopol 940 (1.5%), aqueous solution of sucrose (50%) and water were used as fluids. All the experiments were conducted in batch. With the obtained data, we used the regressions to obtain the Nusselt Equation, which provided coefficient of determination values adjusted between 0.83 and 0.89 with Reynolds in the range of 20 to 405000, Prandtl in the range of 4 to 6400 and rheological index of the power law model between 0.45 and 1.00. It was observed that in the heating performed with the vertical tube baffle, the RT provided convection coefficients 20% higher when compared to the axial impeller, however the power consumption was about 66% higher in relation to the PBT. In the case of the spiral coil, the PBT promoted convection coefficients around 15% higher than the RT with 65% lower power consumption. Thus, in processes where high turbulence is not required, it is recommended to use the PBT with the spiral coil, but if the process requires significant turbulence, the RT must be used with the vertical tubular chassis. In a final analysis, the nonlinear models obtained for scaling provided errors between 11% and 20% in the prediction of rotation in the industrial tank, which are valid for Metzner and Otto (1957) modified Reynolds in the range of 20 to 4000 and for non-Newtonian pseudoplastic fluids with rheological indexes between 0.45 and 1.00.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Due to the complexity of its matrix, more efficient methods have been studied for the determination of pesticide residues in maize. The use of QuEChERS method coupled to low temperature clean up technique has showed advantages to reduce lipids during sample preparation in matrix with high fat content. It was optimized and validated in this study a multiresidue method for the determination of pesticides in maize employing QuEChERS and GC-MS/MS. The extraction procedure was optimized though the factorial design, and consisted in weighing 2.5 g of sample and adding 10 mL of ultrapurified water followed by vortex shaking for 1 min. After this, It was added 10 mL of acetonitrile and the tube was stirred for 1 h in a platform shaker at 200 rpm. Partition step was performed using 1 g of NaCl and 6 g of MgSO4, followed by manual shaking for 1 min and centrifugation at 3400 rpm for 8 min, at 10 ºC. An aliquot of 4 mL of the extract was transferred to a 15 mL tube for clean up step at low temperature for 12 h around -20 ºC. Finally, another clean up stage was realized applying dispersive SPE, 1 mL of the extract was transferred to a tube containing 150 mg of MgSO4, 50 mg of C18 and 50 mg of PSA followed by shaking and centrifugation. The final extract was filtered and analyzed by GC-MS/MS. Analytical parameters evaluated in this work were linearity of the analytical curve, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy and matrix effect for the 12 compounds studied. The method showed efficient, with recovery results in a range of 55.3 to 110.1% in the spiked levels of concentration of 40, 100 and 200 μg kg-1 and RSD ≤ 20%. Values of instrument LOD and LOQ were 1.5 and 5.0 μg L-1, respectively. Method LOQ was 100 μg kg-1 for most compounds. Thereby, It was concluded that the proposed method demonstrated to be adequate for the analysis of most pesticide residues studied in maize, since the parameters evaluated were in according to the limits required for chromatographic methods validation applied in residues analysis. / Devido à complexidade da sua matriz, métodos mais eficientes para a determinação de resíduos de agrotóxicos em milho têm sido estudados. O uso do método QuEChERS, juntamente com a técnica de precipitação a baixa temperatura tem apresentado vantagens para a redução de lipídios durante o preparo de amostra de matrizes com alto teor de gordura. Neste estudo, otimizou-se e validou-se um método multirresíduo para determinação de agrotóxicos em milho empregando QuEChERS e GC-MS/MS. O procedimento de extração, otimizado através de planejamento fatorial, constituiu na pesagem de 2,5 g da amostra, adição de 10 mL de água purificada, seguida de agitação em vórtex por 1 min e posterior adição de 10 mL de acetonitrila seguindo de agitação em agitador pendular por 1 h a 200 rpm. A partição utilizando sais foi realizada com 1 g de NaCl e 6 g de MgSO4 e agitação manual por 1 min, seguida de centrifugação a 3400 rpm por 8 min a 10 ⁰C. Uma alíquota de 4 mL do extrato foi retirada e transferida para um tubo de 15 mL para a etapa de limpeza do extrato a baixa temperatura por 12 h a aproximadamente -20 ⁰C. Após, efetuou-se a etapa final de limpeza do extrato com SPE dispersiva onde retirou-se 1 mL deste extrato e transferiu-se para um tubo contendo 150 mg de MgSO4, 50 mg de C18 e 50 mg de PSA, repetindo a agitação por 1 min e centrifugação a 3400 rpm por 8 min. O extrato final foi filtrado e analisado por GC-MS/MS. Os parâmetros analíticos avaliados neste trabalho foram a linearidade da curva analítica, limite de detecção (LOD), limite de quantificação (LOQ), precisão, exatidão e efeito matriz para os 12 compostos estudados. O método demonstrou-se eficiente, com resultados de recuperação na faixa de 55,3 a 110,1% nos níveis de fortificação 40, 100 e 200 μg kg-1 e com RSD ≤ 20%. Os valores de LOD e LOQ do instrumento foram de 1,5 e 5,0 μg L-1, respectivamente, e o valor de LOQ do método foi de 100 μg kg-1para a maioria dos compostos. Desta forma, conclui-se que o método otimizado mostrou-se adequado para análise da maioria dos resíduos de agrotóxicos estudados em milho, pois os parâmetros avaliados encontram-se dentro dos limites exigidos para validação de métodos cromatográficos aplicados a análise de resíduos.

The design of biomaterials, historically initiated and developed by physicians and engineers, in the last decades has slowly shifted toward a more biochemical based approach. For the replacement, repair and regeneration of tissues scientists are now focusing on materials that stimulate specific biological response at the molecular level. These biomaterials have already shown interesting applications in cell proliferation, differentiation, and extracellular matrix production and organization when the material modifications are designed to elicit specific interactions with cell integrins. In the present work we propose the application of this strategy for the development of blood-compatible materials. We first identified, in the coagulation cascade a key enzyme that constitute a valuable biological target for the development of anti-thrombogenic compounds. Piperazinyl-amide derivatives of N-alfa-(3-trifluoromethyl-benzenesulfonyl)-L-arginine were synthesized as graftable thrombin inhibitors. These inhibitors provided a spacer arm for surface grafting and a fluorine tag for XPS (X-ray photoelectron spectroscopy) detection. The possible disturbance of biological activity due to a variable spacer-arm fixed on the N-4 piperazinyl position was evaluated in vitro against human alfa-thrombin, in silico by molecular modelling and via X-ray diffraction study. Selected inhibitors, having inhibition potency in the mM range, were grafted on polyesters surface via wet chemistry and photochemical activation treatments. Wet chemistry surface grafting was performed by specific hydroxyl chain-ends activation and resulted in bioactive molecules fixation of 20-300pmol/cm2. The photochemical grafting was performed using a molecular clip providing an aromatic azide, for nitrene insertion into a polymer, and an activated ester for grafting of tag compounds. This grafting technique resulted in a dramatic increase in fixed bioactive signals (up to nmol/cm2). The material blood-compatibilization induced by the surface fixation of the inhibitors, was measured by a static blood clot weight measurement test. The wet chemistry grafting technique resulted in moderate blood-compatibilization while by the photochemical grafting method important decrease in surface blood clot formation was observed. In the latter case, the blood response to material contact was found to be strongly affected by the polyester surface photo-degradation induced by the activation treatment.

The design of biomaterials, historically initiated and developed by physicians and engineers, in the last decades has slowly shifted toward a more biochemical based approach. For the replacement, repair and regeneration of tissues scientists are now focusing on materials that stimulate specific biological response at the molecular level. These biomaterials have already shown interesting applications in cell proliferation, differentiation, and extracellular matrix production and organization when the material modifications are designed to elicit specific interactions with cell integrins. In the present work we propose the application of this strategy for the development of blood-compatible materials. We first identified, in the coagulation cascade a key enzyme that constitute a valuable biological target for the development of anti-thrombogenic compounds. Piperazinyl-amide derivatives of N-alfa-(3-trifluoromethyl-benzenesulfonyl)-L-arginine were synthesized as graftable thrombin inhibitors. These inhibitors provided a spacer arm for surface grafting and a fluorine tag for XPS (X-ray photoelectron spectroscopy) detection. The possible disturbance of biological activity due to a variable spacer-arm fixed on the N-4 piperazinyl position was evaluated in vitro against human alfa-thrombin, in silico by molecular modelling and via X-ray diffraction study. Selected inhibitors, having inhibition potency in the mM range, were grafted on polyesters surface via wet chemistry and photochemical activation treatments. Wet chemistry surface grafting was performed by specific hydroxyl chain-ends activation and resulted in bioactive molecules fixation of 20-300pmol/cm2. The photochemical grafting was performed using a molecular clip providing an aromatic azide, for nitrene insertion into a polymer, and an activated ester for grafting of tag compounds. This grafting technique resulted in a dramatic increase in fixed bioactive signals (up to nmol/cm2). The material blood-compatibilization induced by the surface fixation of the inhibitors, was measured by a static blood clot weight measurement test. The wet chemistry grafting technique resulted in moderate blood-compatibilization while by the photochemical grafting method important decrease in surface blood clot formation was observed. In the latter case, the blood response to material contact was found to be strongly affected by the polyester surface photo-degradation induced by the activation treatment.

Brominated flame retardants (BFRs) are chemicals used in e.g. electronic equipment, textiles and plastics for the prevention of fire. Over recent decades, concern has been raised regarding some heavily used BFRs, since the levels in the environment have been increasing. In the present thesis, persistent, bioaccumulative, and toxic (PBT) properties were studied for a structurally varied set of BFRs selected to represent more than 60 organic BFRs. The studied BFRs include: 2,4,4'-tribromodiphenyl ether (BDE 28), 2,2',3,4,4',5',6-heptabromodiphenyl ether (BDE  183), decabromodiphenyl ether (BDE 209), hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBPA), tetrabromobisphenol A 2-hydroxyethyl ether (TBBPA OHEE), 2,4,6-tribromophenol (246BrPh), 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), and hexabromobenzene (HxBrBz). It is likely that soil will act as a sink for BFRs. Therefore, studies of BFRs were performed on persistence in soil, and on bioaccumulation from soil in the earthworm Eisenia fetida. Large variation in the biodegradability in soil among the tested BFRs was observed. The studied brominated diphenyl ethers (BDE 28 and BDE 209) were very persistent under both aerobic and anaerobic conditions, while 246BrPh and TBECH degraded quickly in both aerobic and anaerobic soil. The bioaccumulation in earthworm from soil was high for HxBrBz, TBECH and for tested brominated diphenyl ethers with 4-6 bromine atoms (BDE 47, BDE 99, and BDE 153). Bioaccumulation was also studied in zebrafish after dietary exposure to a mixture of BFRs. It was shown that several metabolites were formed and retained in zebrafish, which highlights the importance of also searching for and identifying persistent degradation products. Maternal transfer was shown for all BFRs present in the female zebrafish. This shows that zebrafish young (fry) are exposed to these BFRs at approximately the same concentrations as female zebrafish during the early-life stages, when fish are usually most sensitive to organic contaminants. Toxicity of individual BFRs and a BFR mixture was studied in Nitocra spinipes using a silica gel-based system. Highest toxicities were observed for BDE 28, TBBPA, and TBBPA OHEE. In the mixture toxicity study, simultaneous exposure to low concentrations (individually causing no significant effect) of six BFRs significantly affected the survival of Nitocra spinipes. The results from the PBT studies presented in the thesis and literature data were compared with the criteria for PBT classification, as set in the European REACH legislation. Further, some BFRs with physico-chemical properties similar to those of identified PBTs were suggested to be prioritized for future PBT testing.

Αντικείμενο της παρούσας διατριβής αποτέλεσε η μελέτη μιγμάτων αλειφατικών/αρωματικών πολυεστέρων. Αρχικά υπήρχε η πρόθεση να επικεντρωθούμε στη μελέτη της βιοαποικοδόμησης μίγματος ενός αλειφατικού και ενός αρωματικού πολυεστέρα. Για τη διερεύνηση όμως της αναμειξιμότητάς τους εστιάσαμε στην έμμεση μελέτη του μοριακού προσανατολισμού μονοαξονικά εφελκυσμένων μιγμάτων αλειφατικών/αρωματικών πολυεστέρων, με τη χρήση πολωμένων φασμάτων δόνησης. Πιο συγκεκριμένα, εξετάστηκε η σύγχρονη παρουσία σ’ ένα μόνο πολωμένο φάσμα Raman της μη-συμβατικής συμπεριφοράς της δόνησης τάσης της χαρακτηριστικής ομάδας του καρβονυλίου (C=O) των αρωματικών πολυεστέρων με την αντίστοιχη συμβατική συμπεριφορά της ίδιας ομάδας των αλειφατικών πολυεστέρων. Μετά από πολλές προσπάθειες διαφόρων παρεμφερών μιγμάτων στα οποία παρουσιάστηκαν διάφορα προβλήματα, κυρίως αναμειξιμότητας, καταλήξαμε στο μίγμα του βιοαποικοδομήσιμου αλειφατικού πολυεστέρα L-PLA με τον αρωματικό πολυεστέρα PBT. Παρασκευάστηκαν φιλμ των ομοπολυμερών L-PLA και PBT καθώς και του μίγματος L-PLA/PBT, με ανάμιξη των συστατικών σε τήγμα και στη συνέχεια μορφοποίησή τους σε υδραυλική θερμοπρέσα. Για τον προσδιορισμό των θερμικών ιδιοτήτων των υλικών χρησιμοποιήθηκε η τεχνική Διαφορικής Θερμιδομετρίας Σάρωσης (DSC). Δοκίμια των ομοπολυμερών και του μίγματος εφελκύστηκαν μονοαξονικά σε θερμοκρασίες μεγαλύτερες από τη μετάβαση υάλου τους και ο προσανατολισμός τους εκτιμήθηκε με τη χρήση πολωμένων φασμάτων Raman. Σε κάθε περίπτωση, επειδή παρά τις πολλές προσπάθειες δεν ήταν δυνατό κυρίως και πάλι λόγω προβλημάτων αναμειξιμότητας να συνεχιστεί μια τέτοια μελέτη και στο επίπεδο της βιοαποικοδόμησης ενός αλειφατικού και ενός αρωματικού πολυεστέρα, αποφασίσαμε να συνεχίσουμε με ένα αναμείξιμο σε κάθε αναλογία μίγμα, ενός βιοαποικοδομήσιμου και ενός μη-αποικοδομίσιμου πολυμερούς. Το μίγμα αυτό των πολυμερών ήταν το PCL/PVC με το οποίο και συνεχίστηκε και ολοκληρώθηκε η παρούσα διατριβή εξειδίκευσης. Το ενδιαφέρον επικεντρώθηκε στη μελέτη μιγμάτων PCL/PVC διαφόρων συστάσεων, δύο πολυμερών τα οποία είναι αναμίξιμα σε όλο το εύρος των αναλογιών τους. Το ομοπολυμερές του αλειφατικού πολυεστέρα PCL και τα μίγματα που προέκυψαν μελετήθηκαν ως προς τις θερμικές τους ιδιότητες και χαρακτηρίστηκαν φασματικά με Raman. Επιπλέον, επιχειρήθηκε η μελέτη της βιοαποικοδόμησης τόσο της PCL όσο και των μιγμάτων της με PVC, μετά από εμβάπτιση σε φυσιολογικό ορό για χρονικό διάστημα άνω των 3 μηνών. Για τον προσδιορισμό των θερμικών ιδιοτήτων των μιγμάτων PCL/PVC και του ομοπολυμερούς PCL χρησιμοποιήθηκε η τεχνική DSC, στη συνέχεια χαρακτηρίστηκαν με τη δονητική φασματοσκοπία Raman ενώ ακολούθησαν πειράματα Χρωματογραφίας Διαπιδύσεως μέσω Πηκτής (GPC) και Δυναμικής Σκέδασης Φωτός (DLS) ώστε να προσδιοριστεί η βιοαποικοδόμηση των υλικών. Η βιοποικοδόμηση των PCL/PVC και κατ’ επέκταση της PCL μελετήθηκε υπό διαφορετικές συνθήκες (θερμοκρασίας, χρόνου, συγκέντρωσης) και σε διαφορετικό βαθμό. / The aim of this dissertation was the study of aliphatic/aromatic copolyesters. At the beginning, the main purpose was to investigate the biodegradation behavior of an aliphatic/aromatic polyester blend. In order to examine the miscibility of the two polymers comprising the blend we have studied the molecular orientation of melt blends utilizing polarized vibrational spectroscopy. After plenty of essays on resembling blends and due to the problems that we have faced (mainly miscibility problems) we decided to study the polymer blend of the biodegradable aliphatic polyester Poly(L-lactic acid) (L-PLA) and the aromatic polyester Poly(butylene terephthalate) (PBT). In particular, the interest centered to the peculiar and unexpected behavior of the C=O stretching carbonyl Raman band of the aromatic polyesters (in case PBT) comparing to the corresponding conventional behavior of the aliphatic polyesters, (in case L-PLA). L-PLA/PBT blends were prepared through reaction extrusion (melt mixing). Films prepared by melt pressing have been uniaxially hot drawn. Polarized laser Raman spectroscopy has been used to estimate the molecular orientation of drawn films of L-PLA and PBT homopolymers and L-PLA/PBT polymer blends. The crystallization behavior of the samples was investigated by using a differential scanning calorimeter (DSC). Finally, the polymers L-PLA and PBT have found to be partially miscible so we took the decision of studying another totally miscible blend consisted of PCL and PVC, a mixture of an aliphatic biodegradable polyester and a non-biodegradable thermoplastic polymer. Blends of PCL and PVC are under development with various potential applications in view, including controlled delivery of agrichemicals, and it is important to investigate their biodegradation behavior. The thermal properties of the homopolymer PCL and PVC blends were investigated under nitrogen by using DSC. Samples of the homopolymer PCL and PCL/PVC blends were placed in glass bottles with serum for more than 3 months. Raman Spectroscopy, Gel Permeation Chromatography and Dynamic Light Scattering have been used to estimate the biodegradation of the samples.