Synthesis of Copolymers Based on Benzene and Biphenyl and their Characterization by XRD and DSC

In this work the crystalinity and the thermal transitions of soluble and insoluble in chlorobenzene polyphenylene copolymers (synthesized by oxidative cationic polymerization) were studied. All copolymers had a degree of crystallinity between 44.6 and 66.7 %. With Differential Scanning Calorimentry (DSC) measurements it was found that the copolymers exhibited endothermic peaks in the region 268 up to 286 oC. These peaks in the case of soluble polyphenylenes were attributed to the melting of their crystallites, whereas in the case of insoluble polyphenylenes were attributed to liquid crystal transitions

Εγκληματολογική και ποινική προσέγγιση της διαφθοράς: Το ζήτημα του σκοτεινού αριθμού των εγκλημάτων διαφθοράς. Περιγραφική έρευνα με δευτερογενή στατιστικά δεδομένα

Σκοπός της παρούσας εργασίας είναι να αναδείξει την εγκληματική διάσταση της διαφθοράς, τόσο από τη σκοπιά του ποινικού δικαίου όσο και από εκείνη της Εγκληματολογίας. Ειδικότερα, η ανάλυση ξεκινά με μια προσπάθεια εννοιολόγησης και οριοθέτησης του σύνθετου και περίπλοκου όρου της διαφθοράς. Ύστερα, προχωρά στην μελέτη των επιμέρους παρανόμων πράξεων που συνιστούν εγκλήματα διαφθοράς, μέσα από τις υποδείξεις διεθνών και ευρωπαϊκών κειμένων, αλλά και της συμμορφωμένης προς αυτά εθνικής νομοθεσίας. Έπειτα, γίνεται σύνδεση της διαφθοράς με γνωστές εγκληματολογικές θεωρίες, και ακολουθεί η περιγραφική και συγκριτική παρουσίαση στατιστικών στοιχείων από το σύστημα ποινικής δικαιοσύνης της χώρας μας. Μέσα από την παράθεση αυτών των στατιστικών δεδομένων, η εργασία φιλοδοξεί να αναδείξει το ζήτημα του σκοτεινού αριθμού των εγκλημάτων διαφθοράς και να προτείνει πιθανούς τρόπους αντιμετώπισής του, στο πλαίσιο της αντεγκληματικής πολιτικής.This thesis aims at highlighting the criminal dimension of corruption, under the prism of Criminal Law and Criminology. In particular, it begins with an effort to define and explain the term “corruption”, by presenting relevant definitions and types of the phenomenon. Furthermore, it attempts to examine those unlawful acts which constitute corruption crimes, via the interpretation of international and European legal texts, as well as national legislation that follows their commands. In this dissertation, corruption is also linked to criminological theories of the positivist paradigm in Criminology, aiming at explaining the roots of corruption-related criminality. Finally, official statistical data of the national criminal justice system are presented, in order to signify the issue of the dark figure of corruption crimes and suggest possible means for its combat and interpretation, in the context of criminal policy

Infra-red and vibration tests of hybrid ablative/ceramic matrix technological breadboards for earth re-entry thermal protection systems

A new thermal protection system for atmospheric earth re-entry is proposed. This concept combines the advantages of both reusable and ablative materials to establish a new hybrid concept with advanced capabilities. The solution consists of the design and the integration of a dual shield resulting on the overlapping of an external thin ablative layer with a Ceramic Matrix Composite (CMC) thermo-structural core. This low density ablative material covers the relatively small heat peak encountered during re-entry the CMC is not able to bear. On the other hand the big advantage of the CMC based TPS is of great benefit which can deal with the high integral heat for the bigger time period of the re-entry. To verify the solution a whole testing plan is envisaged, which as part of it includes thermal shock test by infra-red heating (heating flux up to 1 MW/m2) and vibration test under launcher conditions (Volna and Ariane 5). Sub-scale tile samples (100×100 mm2) representative of the whole system (dual ablator/ceramic layers, insulation, stand-offs) are specifically designed, assembled and tested (including the integration of thermocouples). Both the thermal and the vibration test are analysed numerically by simulation tools using Finite Element Models. The experimental results are in good agreement with the expected calculated parameters and moreover the solution is qualified according to the specified requirements.European Comisión Fp7, 283797, HYDR

A novel method for metal–diamond composite coating deposition with cold spray and formation mechanism

This paper describes the application of cold spray to the deposition of a diamond grade pre-coated with Cu and Ni. This is the first time that pre-coated diamond powders are used as the sole feedstock without the addition of binders (ductile phases) in cold spraying. The experimental results showed that it was possible to manufacture thick metal–diamond composite coatings onto an Al alloy substrate with high diamond fraction in the coating and without phase change. Results from this paper also have demonstrated a new methodology for the deposition of metal–diamond/ceramic composite coating with the cold spray technique

A sustainable multi-function biomorphic material for pollution remediation or UV absorption: aerosol assisted preparation of highly porous ZnO-based materials from cork templates

For the first time, highly porous ZnO-based biomorphic materials were synthesised using cork as a natural sustainable template. In the first step, waste cork powder was pyrolysed and converted into inorganic carbon. This template was then infiltrated using a novel approach employing an aerosol of zinc-containing solutions. The infiltrated powders were calcined to convert the precursors into zinc oxide. Depending on temperature, these could form either a ZnO-graphite composite material, or pure ZnO. Their morphology, porosity, microstructure and composition were characterised; their optical band gap energies, ability to adsorb and photodegrade organic pollutants and UV absorption were also assessed. When heated to 350 °C they maintained the 3D porous cork structure, producing a graphite-containing composite material, with both physical adsorption and photocatalytic activity (Eg = 3.19 eV), suitable for environmental remediation. When heated to 700 °C, the powders were pure ZnO (no graphite), and they absorbed in the UV region, hence suitable for use as sunscreen. Doped ZnO ecoceramics were also produced, using silver and aluminium. An addition of 1 mol% Ag improved photocatalysis under solar light. Conversely, adding 2 mol% Al and calcining at 700 °C deactivated photocatalysis, but maintained strong UV absorption, producing a safer sunscreen material (no generation of free radicals). This is the first time that photocatalytic or UV absorption properties of any wood-derived biomorphic material or ecoceramic have been reported.This work wasfinancially supported by the projects HApECOrk,funded by "Fondazione Con il Sud”(project 2015-0243), and“FutureInResearch”APQ Ricerca Regione Puglia. This work was de-veloped within the scope of the project CICECO-Aveiro Institute ofMaterials, FCT (Fundação para a Ciência e a Tecnologia, Portugal) Ref.UID/CTM/50011/2019,financed by national funds through the FCT/MCTES. The authors wish to thank Ms. Stefania D’Amone for the helpwith SEM microscopy. R.C. Pullar thanks FCT grant IF/00681/2015 forsupporting this work, and R.M. Novais wishes to thank FCT projectH2CORK (PTDC/CTM-ENE/6762/2014). The authors also acknowledge Amorim Cork Composites for providing the cork samples.publishe

Comparison of acute and chronic exercise effects in the lipid droplets topography skeletal muscle, following high and low-fat diet in mice

In the modern world, diet patterns high on lipids, sedentary lifestyle and obesity contribute all in the development of metabolic syndrome, which in turn can lead to type 2 diabetes. All the excess fats, that the majority of the population consumes nowadays, are stored as ectopic fat, particularly in the skeletal muscle, a tissue beyond doubt insulin-sensitive. Physical activity has been proposed according to various studies to be the most drastic factor, which can induce changes in skeletal muscle lipid metabolism,as well as different diet models. We hypothesized that different exercise patterns and diet-changes can alter the spatial arrangement in lipid droplets (LDs) in different skeletal muscle fiber types of C57BL/6J mice. Muscle samples from gastrocnemius were collected from 8 groups: sedentary controls fed with a high-fat (HFD, n=10), or a low-fat diet (LFD, n=10), chronic exercise group fed with a high-fat (HFDR, n=10) or a low-fat diet (LFDR, n=10) and acute exercise group that either killed immediately after exercise or 6 hours later following a high-fat (HFD0, n=7 or HFDR6, n=7) or a low-fat diet (LFDR0, n=7 or LFDR6, n=7). Then immunohistochemistry and laser confocal microscopy were used, followed by image analysis. Fiber type LD size showed a significant difference between all groups, apart from the chronic exercise group fed with the low-fat diet and the acute exercise group fed with the high-fat diet and sacrificed 6 hours after exhaustion. Fiber type LD density showed a very significant difference(P<0.001) between all groups. It seems that physical activity with or without the highfat diet, induced changes in size and density of LDs, meaning that those two factors exercise and diet play a critical role in the prevention of metabolic syndrome later on. A precise comprehension of metabolic pathways participating in obesity and metabolic syndrome reinforces the worldwide effort of diminishing or totally eliminate them

The social security obligations of the enterprises and their supervision

This thesis is expected to present, as far as possible, the legal scope in which enterprises in the field of social security now operate, with regard to the IKA ETAM, including all the changes occurred in our country since the economic crisis and beyond. In short, in the context of this thesis, the obligations of enterprises are presented, both substantive and procedural, with most important the obligation of contribution to the financing of the institution through the insurance of their employees, that is why a detailed description of the insurance of specific categories of employee, that cause interest and concern, both nationally and globally, is made selectively. Furthermore, the key elements of the current domestic financing system are being explored, which is based primarily on employers and employees contributions, although it needs additional aid through state contributions. This also has greatly an impact on the phenomenon of contribution evasion, which is developed immediately below, which puts at risk the very viability of the institution, due to the forms and dimensions it assumes. On the other hand, this thesis attempts to presents thoroughly the supervision of the enterprises in terms of the proper and timely payment of the statutory contributions, with a detailed reference of its species, but also with an extensive record of the possible effects it implies, namely the issue of imputations, the repayment of undue payments and the criminal and personal liability of the liable persons. Subsequently, the reform of the collection of social security contributions is presented, with a view to the establishment of the ΚΕΑΟ, and the existing settlements for the debts on the part of the employer are demonstrated, through a detailed description of the conditions and the procedure for settling debts, the consequences of settlements and the reasons for the loss of settlements. In conclusion, the possibilities of defending the interests of employers, both at the administrative level, by applying for treatment to the Local Administrative Commission, and by means of litigation, following appeals, are presented.Με την εν λόγω διατριβή προσδοκάται να παρουσιαστεί, όσο το δυνατόν εκτενέστερα, το νομικό φάσμα, στο οποίο κινούνται και δρουν πλέον οι κοινές επιχειρήσεις στο πεδίο της κοινωνικής ασφάλισης, αναφορικά πάντα με το τ. ΙΚΑ-ΕΤΑΜ, συμπεριλαμβανομένων και όλων των μεταβολών που επήλθαν στην χώρα μας από την οικονομική κρίση και μετέπειτα. Εν ολίγοις, στα πλαίσια της παρούσας διατριβής παρατίθενται οι υποχρεώσεις των κοινών επιχειρήσεων, τόσο οι ουσιαστικού περιεχομένου, όσο και οι διαδικαστικού τύπου, με προέχουσα όμως αυτήν της συμβολής τους στη χρηματοδότηση του θεσμού μέσω της ασφάλισης των εργαζομένων τους, εξού πραγματοποιείται επιπροσθέτως επιλεκτικά και κάποια εκτενής περιγραφή της ασφάλισης συγκεκριμένων κατηγοριών απασχολούμενων που παρουσιάζουν ενδιαφέρον και προβληματισμό, τόσο σε εθνικό, όσο και σε παγκόσμιο επίπεδο. Περαιτέρω, ερευνώνται τα βασικά στοιχεία του ισχύοντος εγχώριου συστήματος χρηματοδότησης, το οποίο στηρίζεται μεν πρωτίστως στις εισφορές των εργοδοτών και των εργαζομένων, χρήζει όμως επιπλέον ενίσχυσης μέσω της κρατικής συμβολής. Σε αυτό συμβάλλει κατά πολύ και το φαινόμενο της εισφοροδιαφυγής που αναπτύσσεται αμέσως κατωτέρω και το οποίο θέτει σε διακινδύνευση την ίδια τη βιωσιμότητα του θεσμού, λόγω των μορφών και διαστάσεων που προσλαμβάνει. Από την άλλη, επιχειρείται η διεξοδική ανάδειξη του ζητήματος του ελέγχου των επιχειρήσεων ως προς την ορθή και εμπρόθεσμη καταβολή των οριζομένων από τον νόμο εισφορών, με λεπτομερειακή αναφορά των ειδών του, αλλά και με την αναλυτική καταγραφή των ενδεχόμενων επιπτώσεων που αυτός επιφέρει, ήτοι την έκδοση καταλογιστικών πράξεων, την επιστροφή των αχρεωστήτως καταβληθέντων, καθώς και την ποινική και προσωπική ευθύνη των υπόχρεων προσώπων. Ακολούθως, προβάλλεται η συντελεσθείσα μεταρρύθμιση της είσπραξης των εισφορών κοινωνικής ασφάλισης, ενόψει της σύστασης του Κ.Ε.Α.Ο., και καταδεικνύονται οι ισχύουσες ρυθμίσεις των οφειλών από πλευράς του εργοδότη με εκτενέστατη απεικόνιση των προϋποθέσεων και της διαδικασίας υπαγωγής σε αυτές, των συνεπειών της υπαγωγής και των λόγων απώλειας της ρύθμισης. Εν κατακλείδι, παρουσιάζονται οι δυνατότητες προάσπισης των συμφερόντων των εργοδοτών τόσο σε διοικητικό επίπεδο, με την άσκηση αίτησης θεραπείας ενώπιον της Τοπικής Διοικητικής Επιτροπής, όσο και μέσω της δικαστικής επίλυσης των διαφορών, κατόπιν υποβολής προσφυγής και ενδίκων μέσων

Processing and exploitation of engineering polymers from waste of electrical and electronic equipment

The aim of the present thesis is the study of blends consisted of engineering polymers, which are found in the recycling stream of electrical and electronic equipment, and, moreover, the upgrading of their properties by the fabrication of polymer nanocomposites with montmorillonite and graphene. The preparation of the blends and the corresponding nanocomposites took place in a twin-screw extruder. In particular, the processing conditions, the rheological properties, the morphology and the thermomechanical properties of poly(acrylonitrile-butadiene-styrene)’s (ABS) blends with polycarbonate (PC) and polypropylene (PP) were investigated. The effect on the blends’ properties as well as on those of their nanocomposites produced by compatibilizers based on: i) ABS grafted with maleic anhydride (ABS-g-MAH) and ii) PP grafted with maleic anhydride (PP-g-MAH) was also examined.The blending of ABS with the polar PC leads to the improvement of the drawbacks which characterize each one of these polymers separately. Specifically, the ABS/PC blends can be processed at lower temperatures than those of pure PC and their extrusion becomes easier. Moreover, they present improved thermal stability and better mechanical performance in comparison with pure ABS. Also, the ABS/PC blends exhibit higher values of melt flow index (MFI), modulus of elasticity and storage modulus (Gʹ) compared to the pure components. The maximum synergistic action is recorded in the proportion 50/50 w/w and is probably attributed to the interactions which are developed between the PC phase and the SAN phase of ABS at this composition. The ABS/PC blends are characterized by partial miscibility, which permits the fairly uniform dispersion of PC particles in the ABS-rich blends, while chains with low molecular weight of one polymer emigrate in the phase of the other polymer. This emigration restricts the friction between the polymeric chains and facilitates their free movement. The existence of ABS-rich regions where PC chains are involved and vice versa, was quantified by the application of Fox’s equation in the experimental results of glass transition temperature (Tg), which was estimated by the dynamic mechanical analysis (DMA).Regarding the effect of addition of ABS-g-MAH to the ABS/PC systems, it decreases the values of MFI, due to a possible chemical reaction between the anhydride groups of ABS-g-MAH and the hydroxyl end groups of PC. Furthermore, the addition of ABS-g-MAH to the ABS/PC blends has as a consequence the completion of their thermal degradation at lower temperatures and in one stage at all the investigated proportions. Also, the addition of ABS-g-MAH reduces the modulus of elasticity of ABS/PC blends and the storage modulus of PC-rich, ABS/PC blends.In the nanocomposites of ABS/PC blends, two structures were observed by X-ray diffraction analysis (XRD): mixed intercalated/exfoliated and microcomposite structure. The second one is formed at much lower percentage and is ascribed to the degradation of surfactant on the clay or to its transfer from the clay to the matrix or/and to the change of the surrounding tension during the melt exfoliation.Regarding the effect of the incorporation of organically modified clay to the ABS/PC blends, a decrease of MFI values and significant increase of modulus of elasticity and storage modulus is observed, as well as an increase of loss modulus of SAN phase of ABS, because of the restriction of mobility of the polymeric chains by the clay nanoplatelets, the interactions between the organic modification of clay and the polar groups of polymeric components and the better miscibility between the ABS and PC achieved by the incorporation of organoclay. In addition, the incorporation of organoclay to the PC-rich, ABS/PC blends affects the mechanism of their thermal degradation, which is analyzed in two steps in the reinforced blends. The organically modified montmorillonite hinders the thermal degradation of PC phase, due to the formation of a protective layer in the ABS/PC interface or due to the creation of new paths of the degradation reaction, as a result of the “labyrinth” and “barrier” effects caused by the nanoplatelets. The improved thermal stability causes an increase of their char residue and a decrease of their gross calorific value.The combined addition of ABS-g-MAH and organoclay to the ABS/PC blends improves the exfoliation of polymeric chains between the organoclay nanoplatelets and facilitates the opening of clay galleries, as the microcomposite structure, which corresponds to low percentage in the nanocomposites of non-compatibilized blends, is absent after the addition of ABS-g-MAH. This behavior is attributed to some interactions between the hydroxyl groups of organic modification of reinforcement filler and the anhydride groups of compatibilizer. The incorporation of clay in the compatibilized, PC-rich, ABS/PC blends results in the thermal degradation taking place in two stages and the thermal degradation of PC phase being completed at higher temperatures compared to those of pure blends, but at lower temperatures compared to those of non-compatibilized, reinforced blends. Moreover, the incorporation of clay nanoplatelets to ABS-rich compatibilized blends improves the modulus of elasticity, which, however, remains lower than that of non-compatibilized nanocomposites. The combined addition of ABS-g-MAH and clay increases, also, the storage modulus of ABS/PC blends, which is lower than that of the non-compatibilized nanocomposites.The incorporation of graphene nanoplatelets to the non-compatibilized and compatibilized ABS/PC blends decreases their onset degradation temperature and maximum rate degradation temperature, at all the investigated proportions and mainly at pure PC, whereas an upward trend is observed for the char residue. The graphene, also has a favorable effect on the thermal degradation mechanism of PC-rich, ABS/PC blends and mainly on that of PC-phase, as the thermal degradation is completed at higher temperatures, in both non-compatibilized and compatibilized blends. Therefore, the graphene sheets contribute to the thermal stability of these blends, due to their increased thermal stability and their special, planar morphology, which permits to them to act as a barrier to the mass transport of volatiles produced during the thermal degradation, while they restricts\ at the same time the movement of polymeric chains which extended nearby. The graphene has a positive effect on the modulus of elasticity of 30/70 w/w ABS/PC blend.Then, the study of ABS was expanded to its hybrid systems with the non-polar PP. During the processing of blends, it was observed that the addition of PP to ABS improves its processability, whereas it makes feasible its extrusion at lower temperatures and decreases the torque during extrusion. The ABS/PP blends present MFI values and tensile strength similar to those of pure PP, because of the lack of miscibility between their components. Despite the lack of miscibility, the dispersion of ABS particles in the continuous PP phase is relatively uniform. The trend of PP to form the continuous phase, even in the ABS-rich blends, is attributed to its lower viscosity.Furthermore, the addition of PP to ABS improves its thermal stability. It is remarkable that the 30/70 w/w ABS/PP blends show higher maximum rate degradation temperature (Tpeak), which is higher even than that of pure PP.As reported in the related literature, the addition of ABS affects the non-isothermal crystallization of PP. In particular, an increase of β-PP phase content is recorded, which obtains the highest value at 30 wt% ABS concentration. Further increase of ABS content in the blend causes the formation of large ABS domains which hinder the β-PP crystallization. In addition, the ABS accelerates the isothermal crystallization of PP, as observed mathematically by the significant increase of constant K of Avrami’s equation and by the decrease of t1/2. Also, it enhances the modulus of elasticity, which increases as the ABS loading in the blend increases.The incorporation of organically modified montmorillonite in the ABS/PP blends causes a decrease of MFI values of the ABS-rich blends, due to the better chemical affinity with ABS in comparison with PP. Moreover, it improves the miscibility between ABS and PP, as it reduces the average size of the dispersed phase. The better chemical affinity of clay with ABS is confirmed by XRD analysis. In accordance with this analysis, microcomposite structure is formed in pure PP, whereas in ABS/PP blends two types of structures are achieved: mixed intercalated/exfoliated structure and microcomposite structure at lower percentage. Furthermore, in ABS/PP blends higher dispersion is noted by increasing the PP content, due to the decrease of viscosity caused by its addition. The decrease in viscosity facilitates the movement of polymeric chains and the opening up mechanisms of clay galleries.Also, the incorporation of montmorillonite nanoplatelets in PP-rich, ABS/PP blends results in the completion of their thermal degradation at slightly higher temperatures and in the increasing trend of limiting oxygen index (LOI).In addition, the incorporation of clay nanoplatelets to pure PP increases the percentage of β-PP phase and slightly accelerates its isothermal crystallization, causing doubling of K constant of Avrami’s equation and a slightly decrease of t1/2. This reveals their action as heterogeneous nucleating agents. However, the addition of clay in ABS/PP blends reduces the β-PP content and retards the isothermal crystallization of PP phase, maybe due to the effective dispersion of nanoplatelets in the polymeric matrix, promoted by the presence of polar ABS and the interactions between them. These interactions constrain the action of clay particles as heterogeneous nucleating agents of PP. The improved dispersion of clay platelets in ABS/PP blends has as a consequence their action as an impediment in the diffusion of PP chains, which tend to be organized in crystals.Moreover, the incorporation of clay to ABS/PP blends greatly improves the modulus of elasticity and the storage modulus at all studied proportions, except for that of pure PP, due to the lack of polarity and the non-effective dispersion of nanoplatelets.The combined addition of compatibilizer and clay to ABS/PP blends decreases the flow rate to a higher extent than the predictable based on the blend’s composition, maybe due to chemical interactions between the organic modification of montmorillonite and the anhydride group of compatibilizer. The simultaneous incorporation of PP-g-MAH and clay leads to the highest improvement of miscibility between the components of ABS/PP blend. Also, the addition of compatibilizers facilitates the opening of nanoplatelets in PP-rich, ABS/PP blends and mainly in pure PP, due to the introduction of the polar anhydride groups. This behavior has as a consequence the compatibilized nanocomposites of PP to present higher modulus of elasticity than that of non-compatibilized. However, in the compatibilized ABS/PP blends, the increase of modulus of elasticity caused by the incorporation of clay is lower than the corresponding of non-compatibilized blends. Also, the combined addition of compatibilizer and reinforcing filler increases the storage modulus during the dynamic mechanical analysis in torsion of ABS/PP blends.The results from the upgrading of ABS/PP blend, and mainly of pure PP, with the incorporation of graphene are of particular interest. Specifically, the thermal stability of pure PP is improved and the non-isothermal crystallization is accelerated, due to the action of graphene particles as heterogeneous nucleating agents for the α-PP phase. The isothermal crystallization of pure PP is also greatly accelerated with the addition of graphene, as shown by the increase of K constant of Avrami’s equation by two orders of magnitude and by the reduction of t1/2. Furthermore, the incorporation of graphene’s nanoplatelets increases its tensile strength and significantly improves its modulus of elasticity. The enhancement of the properties of reinforced PP is attributed to the intermolecular CH-π interactions between the i-PP and the graphene.In ABS/PP blends, the graphene does not present a compatibilizing effect, as it increases the size of dispersed ABS phase in the continuous PP phase. However, the favorable effect of graphene in these blends consists of the increase of char residue during their thermal degradation and in the great increase of modulus of elasticity. The dispersion of graphene nanoplatelets protects the adjacent PP chains and restricts their movement. Moreover, the non-isothermal crystallization of their PP-phase is accelerated but to a lower extent in comparison with that of pure PP. During the isothermal crystallization of PP phase of the reinforced with graphene blends, the existence of ABS causes its slight delay compared to that of graphene/PP nanocomposite. From the application of Avrami’s equation, it is found that the addition of 30 wt% ABS to graphene/PP nanocomposite causes reduction K constant by one order of magnitude and doubling of t1/2. It is worth noting that the incorporation of graphene nanoplatelets in ABS/PP induces increasing trend of the dielectric constant without increase of dielectric loss modulus.In conclusion, the nanoparticles of organically modified clay and graphene upgrade the thermal stability of PC-phase and PP-phase in their respective blends with ABS and offer significant improvement in their modulus of elasticity. The different effect on the crystallization of PP and the hindrance by the graphene in the development of β-PP form in its blends with ABS affects accordingly the properties which depend on this morphological feature. By studying the conditions of processing, it is concluded that graphene is appropriate for the preparation of ABS blends with polymers with high melting temperatures, whereas the organoclay is more effective in ABS blends with polymers characterized by lower processing temperatures.The investigated engineering polymers (ABS, PC and PP), as well as their blends, represent a category of thermoplastics polymers with widespread and high added value use in the field of electrical and electronic applications. The upgrading of their properties with the addition of reinforcing fillers with nano- dimensions has already shown interesting results. The originality of the research which was carried out as part of the present thesis lies in the following: The effect of incorporation of organically modified clay on the processing conditions (extrusion, injection), structure, morphology and thermomechanical properties of ABS/PP blends was examined. The literature is very poor regarding this topic and the present thesis contributes to the enlargement of knowledge on this field. The incorporation of graphene to ABS/PC and ABS/PP blends was studied and its effect on their processing conditions (extrusion), as well as on their thermomechanical properties was investigated. The compatibilizing effect of organoclay on ABS/PC and ABS/PP blends was revealed. Comparison between the effects on ABS/PC and ABS/PP blends of conventional compatibilizers and their combined addition with mineral reinforcing nanofillers was carried out and the appropriate concentrations for optimal synergy of the components of the prepared polyblends were specified. Mathematical models were applied to fit the results of thermogravimetric analysis of ABS/PC blends and a physical model which describes the mechanism of their thermal degradation was proposed. The energy exploitation of ABS/PC and ABS/PP blends and their nanocomposites, with recovery of thermal energy through burning was examined and it was associated with the proposed mechanism of thermal degradation. The effect of the ABS, alone and in combination with organoclay or graphene, on non-isothermal and isothermal crystallization of PP was investigated and a kinetic study of the latter was carried out. Moreover, the effect of the above factors on β-crystal form of PP was studied.The originality of these points of the thesis is demonstrated by the fact that the results have been published in international scientific journals and presented in refereed conferences.Σκοπός της παρούσας διδακτορικής διατριβής είναι η μελέτη μιγμάτων μηχανολογικών πολυμερών που συναντώνται στο ρεύμα ανακύκλωσης του ηλεκτρικού και ηλεκτρονικού εξοπλισμού και της αναβάθμισης των ιδιοτήτων μέσω της παρασκευής νανοσυνθέτων τους με μοντμοριλλονίτη και γραφένιο. Η παρασκευή των μιγμάτων και των αντίστοιχων νανοσυνθέτων αυτών, έλαβε χώρα σε δικόχλιο σύστημα εκβολής εργαστηριακής κλίμακας. Συγκεκριμένα μελετήθηκαν οι συνθήκες παρασκευής, οι ρεολογικές ιδιότητες, η μορφολογία και οι θερμομηχανικές ιδιότητες σε μίγματα συμπολυμερούς ακρυλονιτριλίου-βουταδιενίου-στυρενίου (ABS) με πολυανθρακικά (PC) και πολυπροπυλένιο (PP). Εξετάσθηκε επίσης η επίδραση στις ιδιότητες των μιγμάτων και των νανοσυνθέτων τους, συμβατοποιητών με βάση (i) ABS τροποποιημένο με μαλεϊκό ανυδρίτη (ABS-g-MAH) και (ii) PP τροποποιημένο με μαλεϊκό ανυδρίτη (PP-g-MAH).Η ανάμειξη του ABS με το πολικό PC επιτρέπει τη βελτίωση των αδυναμιών που εμφανίζει μεμονωμένα το καθένα από αυτά τα πολυμερή. Συγκεκριμένα, τα μίγματα ABS/PC μπορούν να μορφοποιηθούν σε περιοχή χαμηλότερων θερμοκρασιών από ότι το PC και η εκβολή τους καθίσταται ευκολότερη. Παράλληλα, παρουσιάζουν βελτιωμένη θερμική σταθερότητα και καλύτερη μηχανική συμπεριφορά συγκριτικά με το ABS. Ακόμη, τα μίγματα ABS/PC εμφανίζουν υψηλότερες τιμές δείκτη ροής τήγματος (MFI), μέτρου ελαστικότητας και μέτρου αποθήκευσης (Gʹ) από τις αντίστοιχες των καθαρών συστατικών τους. Η μέγιστη συνεργιστική δράση αντιστοιχεί στην αναλογία 50/50 w/w και πιθανόν οφείλεται σε αλληλεπιδράσεις που λαμβάνουν χώρα μεταξύ της φάσης του PC και της φάσης του SAN του ABS για τη συγκεκριμένη σύσταση. Τα μίγματα ABS/PC χαρακτηρίζονται από μερική συμβατότητα, η οποία επιτρέπει την αρκετά ομοιόμορφη διασπορά των σωματιδίων PC στα πλούσια σε ABS μίγματα, ενώ συμβαίνει και μετανάστευση αλυσίδων χαμηλού μοριακού βάρους του ενός πολυμερούς στη φάση του άλλου, η οποία περιορίζει τις τριβές μεταξύ των αλυσίδων του πολυμερούς και διευκολύνει την ελεύθερη κίνησή τους. Η ύπαρξη περιοχών πλούσιων σε ABS, όπου εμπεριέχονται αλυσίδες PC και αντίστροφα, ποσοτικοποιήθηκε με την εφαρμογή της εξίσωσης του Fox στα πειραματικά αποτελέσματα της Tg, όπως προσδιορίσθηκαν από τη δυναμομηχανική ανάλυση (DMA).Όσον αφορά την επίδραση της προσθήκης ABS-g-MAH στα συστήματα ABS/PC, φαίνεται ότι ελαττώνει τις τιμές του MFI, εξαιτίας πιθανής χημικής αντίδρασης μεταξύ των άνυδρων ομάδων του ABS-g-MAH και των ακραίων υδροξυλομάδων του PC. Επιπλέον, η προσθήκη ABS-g-MAH στα μίγματα ABS/PC επιφέρει ολοκλήρωση της θερμικής τους αποδόμησης σε μικρότερες θερμοκρασίες και την πραγματοποίησή της σε ένα στάδιο σε όλες τις εξεταζόμενες αναλογίες. Επίσης, η παρουσία ABS-g-MAH μειώνει το μέτρο ελαστικότητας των μιγμάτων ABS/PC και το μέτρο αποθήκευσης των πλούσιων σε PC, ABS/PC μιγμάτων.Στα νανοσύνθετα των μιγμάτων ABS/PC, με την τεχνική περίθλασης ακτίνων Χ (XRD), εντοπίσθηκαν δύο δομές: μεικτή εμφωλιασμένη/διεσπαρμένη καθώς και δομή μικροσυνθέτου, σε πολύ χαμηλότερο όμως ποσοστό, λόγω της αποδόμησης της οργανικής τροποποίησης της ορυκτής αργίλου κατά την παρασκευή των νανοσυνθέτων ή της μεταφοράς της από την ορυκτή άργιλο στη μήτρα ή/και της μεταβολής των τοπικών τάσεων κατά τη διεργασία του εμφωλιασμού με τήξη.Σχετικά με την επίδραση της ενσωμάτωσης οργανικά τροποποιημένης ορυκτής αργίλου στα μίγματα ABS/PC, διαπιστώνεται ότι επέρχεται μείωση του MFI και σημαντική αύξηση του μέτρου ελαστικότητας και του μέτρου αποθήκευσης, καθώς και αύξηση του μέτρου απωλειών της φάσης του SAN του ABS, εξαιτίας του περιορισμού της κινητικότητας των πολυμερικών αλυσίδων από τα διεσπαρμένα αργιλικά νανοπλακίδια, καθώς και λόγω των αλληλεπιδράσεων που αναπτύσσονται μεταξύ της οργανικής τροποποίησης της αργίλου και πολικών ομάδων των πολυμερικών συστατικών και της καλύτερης συμβατότητας των ABS και PC που επιτυγχάνεται παρουσία της αργίλου.Επιπλέον, η παρουσία της ορυκτής αργίλου στα πλούσια σε PC, ABS/PC μίγματα επηρεάζει καθοριστικά το μηχανισμό θερμικής αποδόμησης, ο οποίος στα ενισχυμένα μίγματα αναλύεται περαιτέρω σε δύο στάδια. Ο οργανικά τροποποιημένος μοντμοριλλονίτης φαίνεται να παρεμποδίζει τη θερμική αποδόμηση της φάσης του PC, πιθανόν λόγω του σχηματισμού ενός προστατευτικού στρώματος στη διεπιφάνεια ABS/PC ή της δημιουργίας νέων διαδρομών της αντίδρασης αποδόμησης, εξαιτίας της επίδρασης των φαινομένων «λαβυρίνθου» και «φράγματος» που οφείλονται στα νανοπλακίδια. Ως αποτέλεσμα της βελτιωμένης θερμικής σταθερότητας, παρατηρήθηκε αύξηση του υπολείμματος καύσης και μείωση της θερμογόνου δύναμης στα μίγματα αυτά.Η συνδυασμένη χρήση ABS-g-MAH και ορυκτής αργίλου στα μίγματα ABS/PC βελτιώνει τον εμφωλιασμό των πολυμερικών αλυσίδων μεταξύ των αργιλικών νανοπλακιδίων και επιτρέπει τη διάνοιξη σε μεγαλύτερο ποσοστό των πλακιδίων της αργίλου, αφού η μικροσύνθετη δομή, η οποία είναι παρούσα σε μικρό βαθμό στα νανοσύνθετα των μη συμβατοποιημένων μιγμάτων, σχεδόν απουσιάζει μετά την προσθήκη του ABS-g-MAH. Η συμπεριφορά αυτή οφείλεται, ενδεχομένως, στην αλληλεπίδραση μεταξύ των υδροξυλομάδων της οργανικής τροποποίησης του μέσου ενίσχυσης και των ομάδων ανυδρίτη του συμβατοποιητή. Η ενσωμάτωση της αργίλου στα συμβατοποιημένα, πλούσια σε PC, ABS/PC μίγματα οδηγεί στην πραγματοποίηση της θερμικής αποδόμησης σε δύο στάδια και στην ολοκλήρωση της θερμικής αποδόμησης της φάσης του PC σε υψηλότερες θερμοκρασίες από τις αντίστοιχες για τα καθαρά μίγματα, αλλά σε μικρότερες θερμοκρασίες από την αντίστοι