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Aabstract phd thesis

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Aabstract phd thesis
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    Mazandaran University   Faculty of Chemistry   Thesis for PhD of Degree in Polymer Chemistry   Title: Synthesis, characterization and investigation properties of fluorescent and thermally stable new heterocyclic polymer nanocomposites and cure reaction of epoxy resin nanocomposites Supervisor: Dr. Mousa Ghaemy   Advisor: Dr. Moslem Mansour LakourajDr. Sekineh Asghari  Student: Maasoomeh Bazzar   June 2014  93 Abstract In this project, a series of poly (triazole-imide)s (PTAI)s and poly (triazole-amides)s (PTAA)s from five new diamines containing triazole ring in main chain,   substituted diaryl quinoxaline units, flurene and carbazol as pendant and several commercial diacids and dianhydrides were obtained in high yields. All polymers were charactrized using FT-IR and 1 H NMR spectroscopy methods and their optical, thermal, mechanical, solubility, intrinsic viscosity, ion absorption properties and also their morphology were investigated. (PTAIs) were prepared from chemical polymerization in two steps using NMP solvent,  pyridine (Py) and acetic anhydride and also some samples were synthesized from thermal imidization. Viscosity of PTAI (a-e) was in the range of 0.58-0.65 dL/g.T g values were observed in the range of 280-342 °C. These polymers showed good thermal stability with T 10%  in the range of 430-575°C . (PTAAs) were prepared from direct polymerization reaction, using triphenyl phosphite (TPP), NMP solvent, pyridine (Py) and lithium chloride salt (LiCl) and calcium chloride salt (CaCl 2 ). PTAA (a-e) viscosity was observed in the range of dL/g 0.52-0.56. T g  values of PTAAs were in the range of 261-310 °C. These polymers showed good thermal stability, with T 10%  in range of 340-530 °C.   The optical properties of these polymers were studeid. All prepared polymers were amorphous and showed good solubility in polar aprotic solvents. Silicon carbid and Aliminium nitrid nanoparticles modified with epoxy silane coupling agent (mSiC and mAlN) were used for  preparation of PTAA(a-c)/mSiC, PTAA(d-e)/mAlN and PTAI/mSiC nano composites by solution blending method. PTAI(2a)/SiC nanocomposites were preparation by in situe method. Thermal, mechanical, optical, ion absorption and morphology of the nanocomposites were investigated. The results showed uniform dispersion of the nano  particles within polymer matrix through formation of strong chemical and physical bonds. The results are showed; the nanoparticles improved the T g , thermal stability and ion absorption properties of these polymers.   In the second part of study, two series of nanocomposites were prepared by direct mixing of (1) thioglycolic acid stabilized CdS quantum dots (QDs) and epoxy resin, (DGEBA) and fluorescent curing agent, 4,4',4''-(1H-imidazole-2,4,5-triyl)triphenol (ITP), (2) zinc oxid nanoparticles (NZ), DGEBA and fluorescent curing agent, 4,4'-(2-(4-(trifluoromethyl)phenyl)-1H-imidazole-4,5-diyl)diphenol (TFIDO). The resulting materials were investigated in terms of chemical interactions, curing behavior, and  photophysical, thermal, mechanical and fracture properties. The cure kinetics was studied  by using differential scanning calorimetry (DSC). The morphology of cured systems was investigated by using transmission electron microscopy (TEM) and atomic forced microscopy (AFM). The results indicated that addition of QDs and NZ as catalyst to  942 DGEBA/ITP and DGEBA/TFIDO mixture increased the rate of cure reaction by decreasing the activation energy (E a ) and increasing the rate constant values. The thermal stability measured by thermal gravimetrical analysis (TGA) and mechanical properties such as tensile strength and impact of nano composite were superior to that achieved for cured systems. The cured system showed fluorescence emission peak which was shifted towards higher wavelength significantly with addition of QDs and NZ. In the third part of study, the ethylene-propylene random copolymer (EP) was maleated in the presense of different percentage of peroxide. The maleation of EPs was characterized in terms of succinic anhydride (SAH) content and level of SAH clustering along the  polymer backbone by FT-IR. The results shows by increasing the percentage of initiator from 50% to 125% the content of SAH is increased and then started to decrease. The maleated EPs were labeled with fluorescent dye by reacting pyrene-methyl-amine with the SAH moieties randomly attached along the EP copolymer. As a result, the distribution of dyes mimics that of the SAH moieties along the polymer backbone.The pryrene content of labeled samples were calculate by Beer-Lambert equation by using UV-vis absorption of solution of samples. The labeled EP copolymers thus obtained were studied  by steady-state and time-resolved fluorescence techniques in solution. Key words:  Poly(triazol-amide), Poly(triazole-imide), Nano composite, Resin epoxy, quantum dots, ethylene propylene co polymer, time-resolved fluorescence
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