151 |
Strategies for building polymers from renewable sources : Using prepolymers from steam treatment of wood and monomers from fermentation of agricultural productsSöderqvist Lindblad, Margaretha January 2003 (has links)
A strategic research area today is development of polymericproducts made from renewable sources. The ways of utilizingrenewable sources studied in this thesis are using 1)prepolymers obtained by steam treatment of wood and 2) monomersobtainable by fermentation of agricultural products. Novel hemicellulose-based hydrogels were prepared by usingprepolymers obtained from steam treatment of spruce.Hemicellulose was first modified with well-defined amounts ofmethacrylic functions. Hydrogels were then prepared by radicalpolymerization with 2-hydroxyethyl methacrylate orpoly(ethylene glycol) dimethacrylate to form hydrogels. Theradical polymerization reaction was carried out in water usinga redox initiator system. The hydrogels were in generalelastic, soft and easily swollen in water. Frequency sweeptests indicated that the hydrogel system displayed prevailingsolid-like behavior. Comparison of the hemicellulose-basedhydrogels with pure poly(2-hydroxyethyl methacrylate)-basedhydrogels showed that it was possible to preparehemicellulose-based hydrogels with properties similar to thoseof pure poly(2-hydroxyethyl methacrylate)-based hydrogels. Polyester-based materials were prepared by using themonomers 1,3- propanediol and succinic acid obtainable byfermentation. α,ω-Dihydroxyterminatedoligomeric polyesters produced by the thermal polycondensationof 1,3-propanediol and succinic acid were chain-extended toobtain sufficiently high molecular weight. Depending on thechain-extension technology adopted, poly(ester carbonate)s orpoly(ester urethane)s were obtained. In the case of poly(estercarbonate)s, the chain-extended products ofα,ω-dihydroxyterminated oligomeric copolyesters werealso produced using 1,3-propanediol/1,4-cyclohexanedimethanol/succinic acid mixtures toimprove thermal and mechanical properties. Segmented poly(esterether carbonate)s fromα,ω-dihydroxyterminated oligo(propylenesuccinate)s and poly(ethylene glycol) were also synthesized toincrease the hydrophilicity. Molecular weights and polydispersity were analyzed by SECfor all materials. Their structures were also identified by NMRspectroscopy (1H NMR and 13C NMR). All characterizations werein agreement with the proposed structures. Thermal parameterswere characterized by DSC. Tensile testing anddynamic-mechanical tests were performed and in additionpreliminary processing trials were carried out in some cases.The results demonstrate the feasibility of using monomersderived from renewable sources to build up new polymericstructures endowed with a variety of physical and mechanicalproperties.
|
152 |
Studies on Poly(N,N-dimethylaminoethyl methacrylate) Composite Membranes for Gas Separation and PervaporationDu, Runhong January 2008 (has links)
Membrane-based acid gas (e.g., CO2) separation, gas dehydration and humidification, as well as solvent dehydration are important to the energy and process industries. Fixed carrier facilitated transport membranes can enhance the permeation without compromising the selectivity. The development of suitable fixed carrier membranes for CO2 and water permeation, and understanding of the transport mechanism were the main objectives of this thesis.
Poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) composite membranes were developed using microporous polysulfone (PSF) or polyacrylonitrile (PAN) substrates. The PDMAEMA layer was crosslinked with p-xylylene dichloride via quaternization reaction. Fourier transform infrared, scanning electron microscopy, adsorption tests, and contact angle measurements were conducted to analyze the chemical and morphological structure of the membrane. It was shown that the polymer could be formed into thin dense layer on the substrates, while the quaternary and tertiary amino groups in the side chains of PDMAEMA offered a high polarity and hydrophilicity.
The solid-liquid interfacial crosslinking of PDMAEMA led to an asymmetric crosslinked network structure, which helped minimize the resistance of the membrane to the mass transport. The interfacially formed membranes were applied to CO2/N2 separation, dehydration of CH4, gas humidification and ethylene glycol dehydration. The membranes showed good permselectivity to CO2 and water. For example, a CO2 permeance of 85 GPU and a CO2/N2 ideal separation factor of 50 were obtained with a PDMAEMA/PSF membrane at 23oC and 0.41 MPa of CO2 feed pressure. At 25oC, the permeance of water vapor through a PDMAEMA/PAN membrane was 5350 GPU and the water vapor/methane selectivity was 4735 when methane was completely saturated with water vapor. On the other hand, the relative humidity of outlet gas was up to 100 % when the membrane was used as a hydrator at 45oC and at a carrier gas flow rate of 1000 sccm. For used for dehydration of ethylene glycol at 30oC, the PDMAEMA/PSF membrane showed a permeation flux of ~1 mol/(m2.h) and a permeate concentration of 99.7 mol% water at 1 mol% water in feed.
This work shows that the quaternary and tertiary amino groups can be used as carriers for CO2 transport through the membrane based on the weak acid-base interaction. In the presence of water, water molecules in the membrane tend to form a water "path" or water "bridge" which also help contribute to the mass transport though the membrane. In addition, CO2 molecules can be hydrated to HCO3-, which reaction can be catalyzed by the amino groups, the hydrated CO2 molecules can transport through the water path as well as the amino groups in the membrane. On the other hand, for processes involving water (either vapor or liquid) permeation, the amino groups in the membrane are also helpful because of the hydrogen bonding effects.
|
153 |
Studies on Poly(N,N-dimethylaminoethyl methacrylate) Composite Membranes for Gas Separation and PervaporationDu, Runhong January 2008 (has links)
Membrane-based acid gas (e.g., CO2) separation, gas dehydration and humidification, as well as solvent dehydration are important to the energy and process industries. Fixed carrier facilitated transport membranes can enhance the permeation without compromising the selectivity. The development of suitable fixed carrier membranes for CO2 and water permeation, and understanding of the transport mechanism were the main objectives of this thesis.
Poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) composite membranes were developed using microporous polysulfone (PSF) or polyacrylonitrile (PAN) substrates. The PDMAEMA layer was crosslinked with p-xylylene dichloride via quaternization reaction. Fourier transform infrared, scanning electron microscopy, adsorption tests, and contact angle measurements were conducted to analyze the chemical and morphological structure of the membrane. It was shown that the polymer could be formed into thin dense layer on the substrates, while the quaternary and tertiary amino groups in the side chains of PDMAEMA offered a high polarity and hydrophilicity.
The solid-liquid interfacial crosslinking of PDMAEMA led to an asymmetric crosslinked network structure, which helped minimize the resistance of the membrane to the mass transport. The interfacially formed membranes were applied to CO2/N2 separation, dehydration of CH4, gas humidification and ethylene glycol dehydration. The membranes showed good permselectivity to CO2 and water. For example, a CO2 permeance of 85 GPU and a CO2/N2 ideal separation factor of 50 were obtained with a PDMAEMA/PSF membrane at 23oC and 0.41 MPa of CO2 feed pressure. At 25oC, the permeance of water vapor through a PDMAEMA/PAN membrane was 5350 GPU and the water vapor/methane selectivity was 4735 when methane was completely saturated with water vapor. On the other hand, the relative humidity of outlet gas was up to 100 % when the membrane was used as a hydrator at 45oC and at a carrier gas flow rate of 1000 sccm. For used for dehydration of ethylene glycol at 30oC, the PDMAEMA/PSF membrane showed a permeation flux of ~1 mol/(m2.h) and a permeate concentration of 99.7 mol% water at 1 mol% water in feed.
This work shows that the quaternary and tertiary amino groups can be used as carriers for CO2 transport through the membrane based on the weak acid-base interaction. In the presence of water, water molecules in the membrane tend to form a water "path" or water "bridge" which also help contribute to the mass transport though the membrane. In addition, CO2 molecules can be hydrated to HCO3-, which reaction can be catalyzed by the amino groups, the hydrated CO2 molecules can transport through the water path as well as the amino groups in the membrane. On the other hand, for processes involving water (either vapor or liquid) permeation, the amino groups in the membrane are also helpful because of the hydrogen bonding effects.
|
154 |
Synthesis And Charaterization Of Multi-hollow Opaque Polymer PigmetsAsmaoglu, Serdar 01 July 2012 (has links) (PDF)
In the present work, a new generation opaque polymer pigment with multihollow structure was synthesized by suspension polymerization of &ldquo / Water-in-Oil-in-Water&rdquo / (W/O/W) emulsion system. Oil phase was methyl methacrylate and ethylene glycol dimethacrylate monomer mixture at 1:1 weight ratio. The dimension and distribution of hollows inside polymer particles are dependent on the size of water droplets which are encapsulated in micelles. For Water-in-Oil (W/O) assembly, a hydrophobic surfactant and hydrophilic co-surfactant (Span 80-Tween 80) combination with a hydrophilic/lipophilic balance (HLB) value between 5-8 was used. The effects of surfactant and co-surfactant composition on the stability of the W/O emulsion and also on the size of water droplets were studied. In addition, the effect of the ultrasonication on the average size of water droplets was investigated.
The hollow size distribution which may possibly give the maximum scattering efficiency was predicted by a mathematical model based on the Mie scattering. The optimum size
distribution for W/O emulsion was obtained at the monomer/surfactant/water ratio of 75.5/9.4/15.1 after ultrasonication for 30 seconds at 80 W power.
The W/O/W emulsion was prepared by dispersing the W/O emulsion in aqueous solution of hydrophilic Triton X-405. The influence of surfactant concentration and mechanical mixing on monomer droplets was investigated by size measurement and optical microscopy. After stabilizing with 1 %w/w polyvinylpyrrolidone (PVP) solution, the W/O/W emulsion was polymerized at 55 ° / C for 20 h. The surface morphology of synthesized polymer pigments was analyzed by scanning electron microscopy (SEM) and the inner hollow structure was confirmed by transmission electron microscopy (TEM). The analysis indicated that multihollow opaque polymer pigments were successfully synthesized.
The opacity, the L*a*b* color, and the gloss properties of polymer pigments were examined by spectrophotometer and glossmeter. The opacity values were assessed by contrast ratio measurements, and the synthesized polymer pigments provided up to 97.3 % opacity (50 %v/v solid content). In addition, the pigments exhibited low gloss values, and yielded matt films.
|
155 |
Stereocomplex poly (methyl methacrylate) fibers and self-reinforced composites and structural color of butterflies and beetles - characterization, replication and mimicryCrne, Matija 12 May 2009 (has links)
Stereocomplex poly(methyl methacrylate) (PMMA) fibers for the purpose of reinforcing PMMA materials were developed. These kinds of composites are known as "self-reinforced" composites. We were successful in producing stereocomplex PMMA fibers with three different methods - wet spinning, gel spinning and electrospinning. Gel spinning and electrospinning produced the most crystalline fibers. Steroecomplex PMMA fibers were further shown to be resistant to high temperature and also to hot monomer solvent during bulk polymerization.
We further describe our efforts in characterization, replication and mimicry of structural color features of butterflies and beetles. We have developed a simple method of characterizing the bidirectional reflectance distribution function of microscopic objects such as butterfly wing scales. We used this method to characterize nanometer sized structural color features resulting from the replication of butterfly Morpho rhetenor, mimickry of butterfly Papilio palinurus and also the native structural color features of iridescent beetle Chrysina gloriosa, which were shown to be cholesteric focal conic defects lined on the surface.
|
156 |
Strategies for building polymers from renewable sources : Using prepolymers from steam treatment of wood and monomers from fermentation of agricultural productsSöderqvist Lindblad, Margaretha January 2003 (has links)
<p>A strategic research area today is development of polymericproducts made from renewable sources. The ways of utilizingrenewable sources studied in this thesis are using 1)prepolymers obtained by steam treatment of wood and 2) monomersobtainable by fermentation of agricultural products.</p><p>Novel hemicellulose-based hydrogels were prepared by usingprepolymers obtained from steam treatment of spruce.Hemicellulose was first modified with well-defined amounts ofmethacrylic functions. Hydrogels were then prepared by radicalpolymerization with 2-hydroxyethyl methacrylate orpoly(ethylene glycol) dimethacrylate to form hydrogels. Theradical polymerization reaction was carried out in water usinga redox initiator system. The hydrogels were in generalelastic, soft and easily swollen in water. Frequency sweeptests indicated that the hydrogel system displayed prevailingsolid-like behavior. Comparison of the hemicellulose-basedhydrogels with pure poly(2-hydroxyethyl methacrylate)-basedhydrogels showed that it was possible to preparehemicellulose-based hydrogels with properties similar to thoseof pure poly(2-hydroxyethyl methacrylate)-based hydrogels.</p><p>Polyester-based materials were prepared by using themonomers 1,3- propanediol and succinic acid obtainable byfermentation. α,ω-Dihydroxyterminatedoligomeric polyesters produced by the thermal polycondensationof 1,3-propanediol and succinic acid were chain-extended toobtain sufficiently high molecular weight. Depending on thechain-extension technology adopted, poly(ester carbonate)s orpoly(ester urethane)s were obtained. In the case of poly(estercarbonate)s, the chain-extended products ofα,ω-dihydroxyterminated oligomeric copolyesters werealso produced using 1,3-propanediol/1,4-cyclohexanedimethanol/succinic acid mixtures toimprove thermal and mechanical properties. Segmented poly(esterether carbonate)s fromα,ω-dihydroxyterminated oligo(propylenesuccinate)s and poly(ethylene glycol) were also synthesized toincrease the hydrophilicity.</p><p>Molecular weights and polydispersity were analyzed by SECfor all materials. Their structures were also identified by NMRspectroscopy (1H NMR and 13C NMR). All characterizations werein agreement with the proposed structures. Thermal parameterswere characterized by DSC. Tensile testing anddynamic-mechanical tests were performed and in additionpreliminary processing trials were carried out in some cases.The results demonstrate the feasibility of using monomersderived from renewable sources to build up new polymericstructures endowed with a variety of physical and mechanicalproperties.</p>
|
157 |
Frequency and Voltage-Modulated electrochemical Aflatoxin B1 immunosensor systems prepared on electroactive organic polymer platforms.Owino, Joseph Hasael Odero. January 2008 (has links)
<p>In the presented work, immunosensors for detection of Aflatoxin B1 based on different immobilization platforms were studied. Synthesis of an electroactive hydrogel was also carried out. Aflatoxins are a group of mycotoxins that have deleterious effects on humans and are produced during fungal infection of plants or plant products. Electrochemical immunosensor for the determination of Aflatoxin B1 (AFB1) was developed with anti-aflatoxin B1 antibody immobilized on Pt electrodes modified with polyaniline (PANi) and polystyrene sulphonic acid (PSSA). Impedimetric analysis shows that the electron transfer resistances of Pt/PANi-PSSA electrode, Pt/PANi-PSSA/AFB1-Ab immunosensor and Pt/PANi-PSSA/AFB1-Ab incubated in BSA were 0.458, 720 and 1066 k&Omega / , respectively. These results indicate that electrochemical impedance spectroscopy (EIS) is a suitable method for monitoring the change in electron-transfer resistance associated with the immobilization of the antibody. Modelling of EIS data gave equivalent circuits which showed that the electron transfer resistance increased from 0.458 k&Omega / for Pt/PANi-PSSA electrode to 1066 k&Omega / for Pt/PANi-PSSA/AFB1-Ab immunosensor, indicating that immobilization of the antibody and incubation in BSA introduced an electron transfer barrier. The AFB1 immunosensor had a detection limit of 0.1 mg/L and a sensitivity of 869.6 k &Omega / L/mg.</p>
|
158 |
Η χρήση των εμποτισμένων με φάρμακα μεταλλικών ενδοπροθέσεων στον ουρητήρα πειραματικού μοντέλουΚαλληδώνης, Παναγιώτης 14 February 2012 (has links)
Οι εμποτισμένες με φάρμακα μεταλλικές ενδοπροθέσεις (DES) έχει αποδειχθεί ότι ελαχιστοποιούν την υπερπλασία του ενδοθηλίου των στεφανιαίων αγγείων. Η υπερπλαστική αντίδραση του ουροθηλίου είναι το πιο συχνή επιπλοκή της χρήσης των μεταλλικών ενδοπροθέσεων στον ουρητήρα. Στην παρούσα μελέτη αξιολογήσαμε τις εμποτισμένες με zotarolimus μεταλλικές ενδοπροθέσεις (ZES- Endeavor Resolute, Medtronics Inc, USA) στον ουρητήρα χοίρων και κουνελιών. Μέθοδος: Μία ZES and μία συνήθης μεταλλική ενδοπρόθεση (BMS) τοποθετήθηκαν στον κάθε ουρητήρα 10 χοίρων και 6 κουνελιών. Η τοποθετήση έγινε κυστεοσκοπικά. Αξονική τομογραφία (CT) έγινε για την αξιολόγηση των ουρητήρων του χοίρου και ενδοφλέβιος πυελογραφία (IVP) έγινε για τον ίδιο σκοπό στα κουνέλια. Το πρόγραμμα παρακολούθησης περιλάμβανε CT ή IVP κάθε εβδομάδα για τις επόμενες 4 εβδομάδες για τους χοίρους και 8 εβδομάδες για τα κουνέλια. Σπινθηρογραφήματα νεφρών πριν την τοποθέτηση των ενδοπροθέσεων και κατά την 3 εβδομάδα παρακολούθησης έλαβε χώρα σε όλα τα ζώα. Οπτική τομογραφία συνοχής (OCT) χρησιμοποιήθηκε για την εκτίμηση της κατάστασης του αυλού και τοιχώματος των ουρητήρων που έφεραν τις ενδοπροθέσεις. Ιστοπαθολογική εξέταση των ουρητήρων με τις ενδοπρόθεσεις έγινε με τα παρασκευάσματα να έχουν στερεοποιηθεί σε glycol-methacrylate ρητίνη.
Αποτελέσματα: Υπερπλαστική αντίδραση διαπιστώθηκε και στους δύο τύπους ενδοπροθέσεων. Οι BMS ενδοπροθέσεις αποφράχτηκαν πλήρως σε 7 ουρητήρες χοίρων ενώ οι ουρητήρες των ιδίων ζώων που έφεραν ZES ενδοπρόθεση έφεραν υπερπλαστική αντίδραση αλλά δεν κατέληγαν σε απόφραξη. Δύο ουρητήρες κουνελιών με BMS ενδοπροθέσεις αποφράχτηκαν τελείως ενώ όλες οι ZES ενδοπροθέσεις δε συσχετίστηκαν με απόφραξη του ουρητήρα. Διαπιστώθηκε έκπτωση της λειτουργίας 7 νεφρών χοίρων και 2 κουνελιών που είχαν ουρητήρες με αποφραγμένες ενδοπροθέσεις. Η OCT έδειξε αυξημένη υπερπλαστική αντίδραση σε ουρητήρες που έφεραν BMS ενδοπρόθεση σε σχέση με ZES. Παρόλα αυτά, η ιστοπαθολογική εξέταση έδειξε υπερπλαστική αντίδραση παρούσα σε όλες τις ενδοπροθέσεις αλλά σημαντικά περισσότερη υπερπλαστική αντίδραση στις BMS ενδοπροθέσεις.
Συμπέρασμα: Οι ZES ενδοπροθέσεις στους ουρητήρες χοίρων και κουνελιών δε συσχετίστηκαν με υπερπλαστική αντίδραση που οδηγούσε σε απόφραξη της ενδοπρόθεσης. Αυτές οι ενδοπροθέσεις συσχετίστηκαν με σημαντικά μικρότερη υπερπλαστική αντίδραση συγκριτικά με τις BMS ενδοπροθέσεις ενώ η φλεγμονώδης αντίδραση ήταν παρόμοια και στους δύο τύπους ενδοπροθέσεων. / Drug eluting stents (DES) proved to minimize neointimal hyperplasia in coronary vessels. Hyperplastic reaction is the most common unwelcome event related to the use of metal mesh stents in the ureter. We evaluated the effect of zotarolimus eluting stent (ZES- Endeavor Resolute, Medtronics Inc, USA) in porcine and rabbit ureter.
Methods: A ZES and a bare metal stent (BMS) were inserted in each ureter of 10 pigs and 6 rabbits. The insertion was performed by retrograde approach. Computerized tomography (CT) was used for the evaluation of porcine ureters while intraoperative intravenous pyelography (IVP) for rabbit ureters. The follow-up included CT or IVP every week for the following 4 weeks for pigs and 8 weeks for rabbits. Renal scintigraphies were performed prior to stent insertion and during the 3rd week in all animals. Optical coherence tomography (OCT) has been used for the evaluation of the luminal and intraluminal condition of the stented ureters. Histopathologic examination of the stented ureters embedded in glycol-methacrylate was performed.
Results: Hyperplastic reaction was present in both stent types. BMSs in 7 porcine ureters were completely obstructed while porcine ureters stented with ZES had hyperplastic tissue which did not result in obstruction. Two rabbit ureters stented by BMS were occluded while no ZES was associated with ureteral obstruction. The function of the 7 porcine renal units and the two rabbit units with obstructed stented ureter was compromised. The OCT revealed increased hyperplastic reaction in the ureters stented by BMSs in comparison to ZESs. Although, hyperplastic reaction was present in all cases, pathology examination revealed significantly more hyperplastic reaction in BMSs.
Conclusion: ZESs in the pig and rabbit ureter were not related to hyperplastic reaction resulting in stent occlusion. These stents were related to significantly lower hyperplastic reaction in comparison to BMSs while inflammation rates were similar for both stent types.
|
159 |
Estudo morfol?gico da blenda polim?rica poli(metacrilato de metila)/poli(tereftalato de etileno) reciclado (PMMA/PET)Dantas, Rosanne de Lima Filgueira 17 November 2011 (has links)
Made available in DSpace on 2014-12-17T14:07:01Z (GMT). No. of bitstreams: 1
RosanneLFD_DISSERT.pdf: 2030152 bytes, checksum: fac9b7e6c23b892eb3fd86ea5b5f43bc (MD5)
Previous issue date: 2011-11-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Among the options for plastics modification more convenient, both from a technical-scientific and economic, is the development of polymer blends by processing in the molten state. This work was divide into two stages, with the aim to study the phase morphology of binary blend PMMA / PET blend and this compatibilized by the addition of the poly(methyl methacrylate-co-glycidyl methacrylate-co-ethyl acrylate) copolymer (MMA-GMA-EA). In the first stage is analyzed the morphology of the blend at a preliminary stage where we used the bottle-grade PET in a Haake torque rheometer and the effect of compatibilizer in this blend was evaluated. In the second stage the blend was processed using the recycled PET in a single screw extruder and subsequently injection molding in the shape of specimens for mechanical tests. In both stages we used a transmission electron microscopy (TEM) to observe the morphologies of the samples and an image analyzer to characterize them. In the second stage, as well as analysis by TEM, tensile test, scanning electron microscopy (SEM) and atomic force microscopy (AFM) was performed to correlate the morphology with the mechanical properties. The samples used in morphological analyzes were sliced by cryo-ultramicrotomy technique for the analysis by TEM and the analysis by SEM and AFM, we used the flat face of the block after cut cryogenic. It was found that the size of the dispersed phase decreased with the addition of MMA-GMA-EA in blends prepared in a Haake. In the tensile test, the values of maximum tensile strength and modulus of elasticity is maintained in a range between the value of pure PMMA the pure PET, while the elongation at break was influenced by the composition by weight of the PMMA mixture. The coupling agent corroborated the results presented in the blend PMMA / PETrec / MMA-GMA-EA (80/15/5 %w/w), obtained by TEM, AFM and SEM. It was concluded that the techniques used had a good morphologic correlation, and can be confirmed for final analysis of the morphological characteristics of the blends PMMA / PET / Entre as op??es de modifica??o de pl?sticos mais convenientes, tanto do ponto de vista t?cnico-cient?fico como econ?mico, encontra-se o desenvolvimento de blendas polim?ricas por meio de processamento no estado fundido. Este trabalho foi dividido em dois est?gios, tendo como objetivo o estudo da morfologia de fases da blenda bin?ria PMMA/PET e desta compatibilizada pela adi??o do copol?mero poli(metacrilato de metila-co-metacrilato de glicidila-co-acrilato de etila) (MMA-GMA-EA). No primeiro est?gio analisou-se a morfologia da blenda e avaliou-se o efeito do compatibilizante, onde foi usado o PET grau garrafa em um re?metro de torque Haake. J? no segundo est?gio a blenda foi processada empregando desta vez o PET reciclado em uma extrusora monorosca, e posteriormente, moldada por inje??o em forma de corpos de prova para ensaios mec?nicos. Nos dois est?gios utilizou-se a microscopia eletr?nica de transmiss?o (MET) para observar as morfologias das amostras e um analisador de imagens para caracteriz?-las. No segundo estagio, al?m da an?lise por MET, foi realizado ensaio de tra??o, microscopia eletr?nica de varredura (MEV) e microscopia de for?a at?mica (MFA), buscando correlacionar a morfologia com as propriedades mec?nicas. As amostras utilizadas nas an?lises morfol?gicas foram fatiadas por meio da t?cnica crio-ultramicrotomia para na an?lise por MET e para as an?lises por MEV e por MFA, foi utilizada a face plana do tarugo p?s-corte criog?nico. Verificou-se que o tamanho da fase dispersa diminui em fun??o da adi??o do copol?mero MMA-GMA-EA nas blendas preparadas no re?metro Haake. No ensaio de tra??o, os valores de resist?ncia m?xima sob tra??o e m?dulo de elasticidade mantiveram-se em um patamar entre o valor de PMMA puro e do PET puro, enquanto que o alongamento na ruptura mostrou-se influenciada pela composi??o em massa de PMMA na mistura. O agente compatibilizante corroborou nos resultados apresentados da blenda PMMA/PETrec /MMA-MGA-EA (80/15/5), obtidos por MET, MFA e MEV. Concluiu-se que as t?cnicas morfol?gicas utilizadas apresentaram uma boa correla??o e corroboraram para an?lise final das caracter?sticas morfol?gicas das blendas PMMA/PET
|
160 |
Processamento e caracteriza??o da blenda poli (metacrilato de metila) (PMMA) elastomerico e poli (tereftalato de etileno) (PET) p?s-consumoReinaldo, Jucikl?cia da Silva 23 August 2013 (has links)
Made available in DSpace on 2014-12-17T14:07:12Z (GMT). No. of bitstreams: 1
JucikleciaSR_DISSERT.pdf: 18878091 bytes, checksum: 13af0d90d6b4b0980975e46b7393cd8c (MD5)
Previous issue date: 2013-08-23 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This work studied the immiscible blend of elastomeric poly(methyl methacrylate)
(PMMA) with poly(ethylene terephthalate) (PET) bottle grade with and without the
use of compatibilizer agent, poly(methyl methacrylate-co-glycidyl methacrylate -
co-ethyl acrylate) (MGE). The characterizations of torque rheometry, melt flow
index measurement (MFI), measuring the density and the degree of cristallinity
by pycnometry, tensile testing, method of work essential fracture (EWF),
scanning electron microscopy (SEM) and transmission electron microscopy
(TEM) were performed in pure polymer and blends PMMA/PET. The rheological
results showed evidence of signs of chemical reaction between the epoxy group
MGE with the end groups of the PET chains and also to the elastomeric phase of
PMMA. The increase in the concentration of PET reduced torque and adding
MGE increased the torque of the blend of PMMA/PET. The results of the MFI also
show that elastomeric PMMA showed lower flow and thus higher viscosity than
PET. In the results of picnometry observed that increasing the percentage of PET
resulted in an increase in density and degree crystallinity of the blends
PMMA/PET. The tensile test showed that increasing the percentage of PET
resulted in an increase in ultimate strength and elastic modulus and decrease in
elongation at break. However, in the phase inversion, where the blend showed
evidence of a co-continuous morphology and also, with 30% PET dispersed
phase and compatibilized with 5% MGE, there were significant results elongation
at break compared to elastomeric PMMA. The applicability of the method of
essential work of fracture was shown to be possible for most formulations. And it
was observed that with increasing elastomeric PMMA in the formulations of the
blends there was an improvement in specific amounts of essential work of
fracture (We) and a decrease in the values of specific non-essential work of
fracture (βWp) / Neste trabalho ? estudada a blenda imisc?vel poli(metacrilato de metila) (PMMA)
elastom?rico com poli(tereftalato de etileno) (PET) grau garrafa com e sem o uso
do agente compatibilizante, poli(metacrilato de metila-co-metacrilato de glicidilaco-
acrilato de etila) (MGE). As caracteriza??es de reometria de torque, medida
de ?ndice de fluidez (MFI), determina??o da densidade e do grau de cristalinidade
por picnometria, ensaio de tra??o uniaxial, m?todo do trabalho essencial fratura
(EWF), microscopia eletr?nica de varredura (MEV) e microscopia eletr?nica de
transmiss?o (MET), foram realizadas nos pol?meros puros e nas blendas
PMMA/PET. Os resultados reol?gicos apresentaram ind?cios de rea??o qu?mica
entre o grupo ep?xi do MGE com os grupos finais de cadeias do PET e, tamb?m,
com a fase elastom?rica do PMMA. O aumento na concentra??o de PET reduziu
o torque e a adi??o do MGE aumentou o torque da blenda PMMA/PET. Os
resultados de MFI mostraram tamb?m que, o PMMA elastom?rico apresentou
menor fluidez e, consequentemente, maior viscosidade que o PET. Nos
resultados de picnometria observou-se que, o aumento da porcentagem de PET
proporcionou um aumento na densidade e no grau de cristalinidade das blendas
PMMA/PET. Os ensaios de tra??o mostraram que, o aumento da porcentagem
de PET proporcionou um aumento na resist?ncia m?xima e no m?dulo de
elasticidade e uma diminui??o no alongamento na ruptura. Entretanto, na
invers?o de fase, onde a blenda apresentou ind?cios de uma morfologia cocont?nua
e tamb?m, com 30% de fase dispersa PET e compatibilizada com 5%
de MGE, verificaram-se resultados expressivos de alongamento na ruptura em
rela??o ao PMMA elastom?rico. A aplicabilidade do m?todo do trabalho
essencial de fratura mostrou-se poss?vel para a maioria das formula??es.
Observou-se ainda que, com o aumento do PMMA elastom?rico nas formula??es
das blendas, ocorreu uma melhoria nos valores do trabalho essencial espec?fico
de fratura (We) e uma redu??o nos valores do trabalho n?o essencial espec?fico
de fratura (βWp)
|
Page generated in 0.065 seconds