Chemistry Commons^™

Investigation Of The Synthesis And Polymerization Behavior Of Vinyl Benzoate, Selim Mehmet Erhan

Dissertations

The goal of this study is to present a method that gives higher conversions and molecular weights for the polymerization of vinyl benzoate than obtained in previous investigations.

Polyvinyl benzoate has benzene rings attached to the backbone chain, therefore is hard and rigid. This is a characteristic which has a large application area. However previous studies in polymerizing vinyl benzoate with bulk and solution polymerizations reported low yields and troublesome crosslinking, which has limited its application. Emulsion polymerization method has the advantage of giving high polymerization rates together with high molecular weights, and therefore was chosen as the method for …

Gas Permeation Measurements On Small Polymer Specimens, Karen S. Burns

Chemistry & Biochemistry Theses & Dissertations

Mass spectrometry was used to measure oxygen and nitrogen permeabilities while polarography was used to measure oxygen permeabilities for several contact lens materials. Applicable sample holders were designed and fabricated to accommodate curved and flat specimens with surface areas of 0.5 cm² and 1.0 cm² and thicknesses between 0.025 mm and 0.500 mm. A prepared standard was used to calibrate the mass spectrometric analyses.

The oxygen permeability values determined by mass spectrometry were significantly greater than those determined by polarography. This was attributed to the phase boundary phenomena and the limiting oxygen permeance of water inherent in the …

Investigation Of Complex Formation By Oligomers Of Cytosine And Guanosine, Steven Roberts Davis

Chemistry & Biochemistry Theses & Dissertations

Duplex formation between oligo(C:G) _n where n=3 to 4 was shown not to occur under conditions favorable for duplex formation between poly G and poly C. Instead, a stable guano sine self-structure was found to form which a T_m of 50°C for (Gp)₃ and 80°C for (Gp)₄ at strand concentrations of 10^-5M in 1M NaCl. Neither a duplex nor a self-structure formed in the absence of salt.

Oligomers of guanosine and cytosine were obtained by basic hydrolysis and separated according to chain length using DEAE Sephadex column chromatography. Separation of cytosine oligomers with chain lengths …

Studies Of Radiation Effects In Three High Polymers, Heidi Rene-Mitchell Ries

Physics Theses & Dissertations

Three high polymers, Mylar®, Ultem®, and Kapton®, were irradiated to total doses of 1, 5, and 9.5 gigarad using 1-MeV electrons. The glass transition temperatures (T_g) of the materials before and after irradiation were measured using an AC electrical dissipation factor technique. From the T_g data, it was found that the electron radiation at these total doses results in net chain scissioning in Mylar and net crosslinking in Ultem, while self-mending is predominant in Kapton. The dielectric constant was measured before and after irradiation, but no significant changes due to irradiation were observed. Electron paramagnetic resonance (EPR) …

Interaction Of Calcium With Hema/Maa Copolymers., Michael R. Van De Mark, N. D. Lian, M. Brandon, E. C. Eckstein

Chemistry Faculty Research & Creative Works

Polymeric materials based upon 2-hydroxyethyl methacrylate (HEMA) have been extensively used, especially in biomedical applications. Several reports have appeared in the literature during the past 20 years regarding the behavior of these materials upon exposure to body fluids. The results of these studies have ranged from good biocompatibility to calcification. The presence of methacrylic acid (MAA), in HEMA-based copolymers gives rise to a swelling transition at pH 7. The present study relates the swollen volume of HEMA/MAA gels to the concentrations of calcium salts at a pH where the MAA is ionized, as would occur for implanted gels. This swollen …