In this work, EPDM rubber was compounded with increasing amount of filler (FEF N 550 type carbon black), process oil (saturated mineral oil), vulcanizing agent [di (t-butylperoxy) diisopropyl benzene, i.e., BBPIB] and diene [5-ethylidenebicyclo(2.2.1)-hept-2-ene, i.e., ENB] in order to investigate mechanical and rheological properties. Effect of Increasing amount of filler was investigated by using FEF N 550 type carbon black in 35, 70, 87.5, 105 phr. Decrease in scorch times of vulcanization reactions, ts2 (25, 21, 19, and 18 s, respectively) and slight increase in rate constants for vulcanization reactions (0.0270, 0.0274, 0.0301 and 0.0302 s-1, respectively) were explained in terms of nature of semi-active filler. Effect of increasing amount of process oil was investigated by using saturated mineral oil (TUDALEN 3909) in 15, 30, 45 phr. Scorch time for vulcanization reaction and rate constants were measured as 95, 103, 97 s and 0.0277, 0.0274, 0.0291 s-1, respectively. Effect of increasing amount of vulcanizing agent was investigated by using BBPIB (PERKADOX 14/40 MB-gr) in 2.5, 5, 7.5, 10 phr. The compound with 5 phr vulcanizing agent gave optimum rheometer data, crosslink density,, ultimate tensile strength, hardness, deflection and damping. Vulcanization reaction rate constant reached 0.0335 s-1 with 7.5 phr vulcanizing agent. Effect of increasing ENB ratio was investigated by using 4 different EPDM with ENB ratios 5.0, 5.6, 7.5, 8.9%. With two different cure systems, compounds with 5.6 and 7.5% ENB ratio gave optimum results. Vulcanization cure time, reaction rate constant and compression set properties changed in irregular manner.

SELENOPHENE DERIVATIVES FOR ELECTROCHROMIC APPLICATIONS Aydemir, Kadir M.S., Department of Chemistry Supervisor: Prof. Dr. Levent Toppare February 2008, 60 pages A novel selenophene-based monomer / 1,4-di(selenophen-2-yl) benzene (DSB), synthesized via Stille coupling reaction of 1,4 dibromobenzene and tributyl (2-selenophenyl) stannane and corresponding conducting homopolymer (Poly (DSB)) was electrochemically synthesized in the presence of tetrabutylammoniumhexafluorophosphate (TBAPF6) as the supporting electrolyte in dichloromethane. The resulting conducting polymer was characterized by Cyclic Voltammetry (CV), Fourier Transform Infra Red Spectrometry (FTIR) and Ultraviolet&ndash / Visible Spectrometry (UV-Vis Spectrometry). Spectroelectrochemistry analysis and kinetic studies of Poly (DSB) revealed &ndash / * transition (max) at 340 nm with almost zero percent transmittance (T%) concurrently with striking and rapid (0.6 s) absorbance change at near infrared region (1250 nm) with 35% percent transmittance, indicating that Poly (DSB) is a very suitable near infrared electrochromic material. Copolymer of selenophene with ethylenedioxythiophene (EDOT) was potentiostatically synthesized. Poly (selenophene-co-EDOT) was characterized by Cyclic Voltammetry, FTIR and UV-Vis Spectrometry. During spectroelectrochemistry studies, &ndash / * transition (max) was observed at 555 nm with a switching time of 1.4 s and 39% transmittance. Polaron and bipolaron bands were observed at 851 nm and 1299 nm, respectively. Switching time at 1299 nm was 1.8 s with a percent transmittance of 72. Copolymer of DSB with EDOT (Poly (DSB-co-EDOT)) was synthesized and characterized. max, polaron and bipolaron bands were observed at 457 nm, 696 nm and 1251 nm, respectively. A rapid switching time (0.2 s) with 12% transmittance was observed at 696 nm. At the near infrared region (1251 nm), satisfactory percent transmittance (35%) and a moderate switching time (1.75 s) were observed.

ABSTRACT A GLOW IN THE DARK: SYNTHESIS AND ELECTROPOLYMERIZATION OF CHEMILUMINESCENT THIOPHENE DERIVATIVES Asil, Demet M.Sc., Department of Chemistry Supervisor : Prof. Dr. Ahmet M. &Ouml / nal Co-Supervisor: Assist. Prof. Dr. Atilla Cihaner September 2008, 63 Pages Two novel chemiluminescent monomers, 2,3-dihydrothieno(3,4-d)pyridazine-1,4-dione (T-Lum) and 5,7-di-thiophen-2-yl-2,3-dihydro-thieno[3,4-d]pyridazine-1,4-dione (TTT-Lum), were synthesized. The reaction between T-Lum and TTT-Lum in alkaline solution with H2O2 gave chemiluminescence which can be catalyzed using Fe(III) ion. Owing to its sensitivitiy towards Fe(III) ion / T-Lum and TTT-Lum can be promising materials to detect bloodstains in the application of forensic science instead of luminol which gave response to a large family of metallic cations beside Fe(III). Also, TTT-Lum, which is based on a terthienyl system, was electropolymerized and its corresponding polymer (PTTT-Lum) was obtained via repetitive cycling or constant potential electrolysis in both 0.1 M LiClO4 dissolved in acetonitrile containing 5% of BF3-Et2O by volume and neat BF3- Et2O solution. In addition, PTTT-Lum, soluble in alkaline water, was synthesized successfully without breaking the pyridazinedione unit (chemiluminescent unit), as proved by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Electrochemical Luminescence (ECL) measurements. Thus, PTTT-Lum, bearing chemiluminescent unit, can be a good candidate to be used as a sensor in near future. Furthermore, the PTTT-Lum film has a very stable and well-defined reversible redox couple as well as electrochromic behavior during p-doping process. The polymer film has also a band gap of 1.74 eV with an absorption band in its neutral state at 536 nm. Finally, PTTT-Lum film was found to be electrochemiluminescence active, maintaining its activitiy over 1000 cycles.

Conducting polypyrrole (PPy) nanoparticles were synthesized via microemulsion polymerization system. The characterization of PPy nanoparticles was done by Fourier transform infrared spectrometer (FTIR) and scanning electron microscope (SEM). Nanocomposites were prepared by melt-mixing of polypyrrole with polypropylene (PP) and processed with injection molding. The amount of PPy in nanocomposites varied in the range of 1-20% by weight. The effect of PPy nanoparticles on mechanical, electrical properties and thermal stability of nanocomposites were investigated. Tensile test has revealed that increasing amount of PPy increased the strength and the stiffness of the nanocomposite while limiting the elongation of PP. Thermal gravimetric analysis has showed that incorporation of PPy nanoparticles has improved the thermal stability of the nanocomposites. Four probe conductivity measurement has exhibited that increasing amount of PPy nanoparticles increases the conductivity of nonconductive PP up to 2,4.10-4 Scm-1. In order to improve the dispersion of PPy in PP, sodium dodecylsulphate was used as dispersant. The same techniques were used to characterize nanocomposites containing 2% by weight dispersant. Composites prepared with dispersant have exhibited improvement in some mechanical and thermal properties and involved smaller dimension PPy nanoparticles.

This thesis aims to investigate the effects of gamma radiation on the properties of polycarbonate, an engineering thermoplastic which has a wide range of applications. A commercial grade polycarbonate resin, after being shaped into the required specimen forms by injection molding, was irradiated with different doses up to 180 kGy. Tensile strength was found to decrease with increasing dose. The lowest values of tensile modulus, flexural modulus and flexural strength were obtained at 96 kGy, which is also the dose at which molecular weight values showed a minimum. No remarkable changes in Shore D hardness values and NMR spectra were observed. The ATR-FTIR spectra showed that irradiation was effective on carbonyl groups in the structure. The glass transition temperatures of the specimens irradiated up to the maximum dose were lower than those of the non-irradiated specimens. The onset of weight loss at lower temperatures and steeper weight loss behavior in the TGA curves indicated decreasing thermal stability of the polymer with increasing dose.

Thesis (Ph. D.)--School of Textile and Fiber Engineering, Georgia Institute of Technology, 2004. Directed Haskell W. Beckham. / Includes bibliographical references.

The optimisation of ligand-macromolecule interactions is fundamental to the design of therapeutic agents. The GRID method is a procedure for determining energetically favourable ligand binding sites on molecules of known structure using an empirical energy potential. In this thesis, it has been extended, tested, and then applied to the design of anti-influenza agents. In the GRID method, the energy of a hydrogen-bond is determined by a function which is dependent on the length of the hydrogen-bond, its orientation at the hydrogen-bond donor and acceptor atoms, and the chemical nature of these atoms. This function has been formulated in order to reproduce experimental observations of hydrogen-bond geometries. The reorientation of hydrogen atoms and lone-pair orbitals on the formation of hydrogen-bonds is calculated analytically. The experimentally observed water structures of crystals of four biological molecules have been used as model systems for testing the GRID method. It has been shown that the location of well-ordered waters can be predicted accurately. The ability of the GRID method to assist in the assignment of water sites during crystallographic refinement has been demonstrated. It has also been shown that waters in the active site of an enzyme may be both stabilized and displaced by a bound substrate. Ligands have been designed to block the highly conserved host cell receptor site of the influenza virus haemagglutinin in order to prevent the attachment of the virus to the host cells. The protein was mapped energetically by program GRID and specific ligand binding sites were identified. Ligands, which exploited these binding sites, were then designed using computer graphics and energy minimization techniques. Some of the designed ligands were peptides and these were synthesised and assayed. Preliminary results indicate that they may possess anti-influenza activity.

No description available.

This study was undertaken to prepare polystyrene (PS)/montmorillonite (MMT) nanocomposites by different methods, including melt intercalation, in-situ polymerization and masterbatch methods. The in-situ polymerization method consisted of dispersing the styrene monomer into the galleries of MMT followed by subsequent polymerization. The PS/MMT nanocomposites formed by melt intercalation method were prepared on a twin-screw extruder. The masterbatch method was in fact a two-step process. As the first step, a high clay content composite of polystyrene (masterbatch) was prepared by in-situ polymerization, and then the prepared masterbatch was diluted to desired compositions with commercial polystyrene in a twin-screw extruder.The structural, thermal and mechanical properties of the nanocomposites were examined. X-Ray diffraction (XRD) analysis showed that the d-spacing of the in-situ formed nanocomposites containing 0.73 and 1.6 wt. %organoclay increased from 32.9 &amp / #506 / to 36.3 and 36.8 &amp / #506 / respectively, indicating intercalation while the dspacing of the other prepared materials remained nearly unchanged compared to pure organoclay. At low clay content, (&lt / 1 wt.%), in-situ formed nanocomposites showed the best improvement in mechanical properties including tensile, flexural, impact strength and Young&rsquo / s modulus. In all the three methods, the addition of organoclay increased the Young&rsquo / s modulus compared to neat resin, but the maximum improvement was 88.5 %, obtained at 0.73 wt. % organoclay in the in-situ formed material. In-situ polymerization method did not prove to be efficient at high clay loadings in terms of mechanical properties. At high clay loadings, the effects of the three methods on promoting mechanical properties were not significantly different from each other. The glass transition temperature increased from 105.5 oC in the pure polystyrene to 108.4 oC in the in-situ formed nanocomposite at 0.73 wt % organoclay due to the restricted mobility of the polymer chains within the organoclay layers.

Elastic fibres, a major component of many connective tissues, are composed of an amorphous elastin core surrounded by fibrillin - containing microfibrils. The function of these microfibrils appears to require the co - ordinated interactions of fibrillins with a range of extracellular matrix ( ECM ) macromolecules including, latent transforming growth factor - β ( TGF - β ) binding proteins ( LTBPs ). LTBPs share a high degree of structural similarity to fibrillins, since they both contain unique 8 - cysteine motifs. Of the four members of the LTBP family, LTBPs - 1, - 3 and - 4 covalently bind to latent forms of TGF - β. LTBP - 1 has been shown to interact with the N - terminal domains of fibrillin - 1 and - 2 and LTBP - 4 interacts with the N - terminal domains of fibrillin - 1, suggesting that fibrillin - containing microfibrils may act as TGF - β stores and localise latent TGF - β complexes to the ECM. LTBP - 2 differs from other members of the LTBP family since it does not covalently bind latent TGF - β. However, LTBP - 2 strongly co - localises with fibrillin - containing microfibrils in a number of tissues suggesting that LTBP - 2 could have a structural role associated with these elements presumably independent of TGF - β storage, or could act to mediate specific microfibril - ECM interactions. To understand more about the function of LTBP - 2, this study involved screening for potentially important molecular interactions of LTBP - 2 with fibrillins and a variety of ECM proteins. Human recombinant LTBP - 2 ( r - LTBP - 2 ) was cloned, expressed and purified using a mammalian cell culture system. Solid phase binding assays were used to screen for interactions between r - LTBP - 2 and continguous fragments of fibrillin - 1 and - 2 as well as MAGPs, tropoelastin, collagens and proteoglycans. A cation dependant interaction was found between the C - terminal domains of LTBP - 2 and the N - terminal domains of fibrillin - 1, but not with the analogous region of fibrillin - 2. Thus, LTBP - 2 seems to have an exclusive role associated with fibrillin - 1 - containing microfibrils. Further studies found that the C - terminal region of LTBP - 2 competes with LTBP - 1 for binding to fibrillin - 1, suggesting that the binding site for LTBP - 2 on fibrillin - 1 is the same or in close proximity to that for LTBP - 1. Immunohistochemical analysis of LTBP - 1 and - 2 within developing human aorta indicated that both LTBPs co - localised with fibrillin - 1. However, the two LTBPs did have distinct distribution patterns in relation to each other, in that LTBP - 2 was found throughout the medial layer whereas LTBP - 1 was mainly located in patches of the outer medial layer. No regions of strong co - localisation of the two LTBPs were found. Thus, these findings suggest that LTBP - 2 could indirectly modulate the presence of TGF - β upon the fibrillin - containing microfibrils by competing for binding with the LTBP- 1 / TGF - β complex to these structures. Other binding studies showed a cation independent interaction between r - LTBP - 2 and an as yet unidentified component of a crude bovine collagen - IV extract. Since collagen - IV is a major component of basement membranes, an interaction between r - LTBP - 2 and a protein within this bovine collagen - IV preparation suggests LTBP - 2 may have a further function involving a basement membrane component. It will be interesting to determine if LTBP - 2 acts as a bridging molecule between basement membrane structures and fibrillin - containing microfibrils or if it has another function independent of these microfibrils. / Thesis (Ph.D.)--School of Medical Sciences, 2006.