G. C. East

Synthesis and characterization of some disulfonyl azides as potential crosslinking agents for textile fibers

The syntheses of 1,6-hexanedisulfonyl azide, 1,10-decanedisulfonyl azide, 1,3-benzenedisulfonyl azide, 1,5-naphthalenedisulfonyl azide, 2,6-naphthalenedisulfonyl azide, and 4,4′-biphenyldisulfonyl azide are described in this article. The compounds are characterized according to their melting temperature, infrared spectra, mass spectra, and carbon-13 and proton nuclear magnetic resonance spectra, with the intention of assessing their potential as crosslinking agents for textile fibers.

Titanium Dioxide Particle-induced Alkaline Degradation of Poly(ethylene Terephthalate): Application to Medical Textiles

Titanium dioxide induced degradation of bright high-tenacity poly(ethylene terephthalate) (PET:2GT) used in medical applications was investigated under both relaxed and stressed conditions. It was found that successive layers of the polymers were removed by hydrolysis as weight loss (%) was linear with the treatment time. However, owing to the presence of titanium dioxide, tenacity loss occurred and, therefore, at a given time of hydrolysis treatment, the breaking load loss (%) was greater than the weight loss (%). Scanning electron microscopy of the hydrolyzed PET showed that surface pitting occurred due to the presence of titanium dioxide. Larger pits formed on the surface of the stressed fibers than on the relaxed fibers. The findings suggest that the failure of numerous PET (Dacron) grafts, which have been responsible for many deaths, is due to the penetration of hydroxyl ions through the surface defects caused by titanium dioxide.

Composition of the Brown Material from Oxidized Nylon 6

The dark compounds which are formed during the thermal oxidation of nylon 6 have been isolated and analyzed, mainly by thin-layer chromatography. The structures of the dark substances have been tentatively proposed, having assumed that the chemical principles that have been elucidated for the oxidation of pyrrolidine are equally valid for the oxidation of nylon. The ideas that have been developed differ from earlier ideas about the formation of brown materials, in that they are not necessarily based on the formation of derivatives of pyrrole. The new concepts account for the formation of polymers of variable molecular weight which may contain chromophores of variable length and of slightly different chemical compositions.

The reaction of t-butyl chloride with “living” poly-α-methylstyryl sodium in tetrahydrofuran

Abstract The solid reaction products obtained from the reaction between α-methylstyryl sodium “living” ends in tetrahydrofuran with t-butyl chloride, at ambient temperatures, have been separated by TLC and examined by UV, IR and NMR spectroscopy. Apart from the expected elimination and substitution products, a new grouping, absorbing UV radiation at 315 nm. is found in the polymer. IR and UV data suggest that the new grouping is of a quinonoid type structure. Several mechanisms, in explanation of the overall reaction, are discussed in the light of these results.

The effect of spin finishes on hydrolysis rates of medical grade polyester

PURPOSE The rate of alkaline hydrolysis of medical grade poly(ethylene terephthalate) of grey, scoured, and solvent extracted samples have been studied to understand their degradation behavior during surface modification which is used to produce antithrombus grafts. METHODS The changes in properties were examined using weight loss, mechanical properties loss and infrared spectrum. RESULTS It was found that the rate of hydrolysis of grey sample was always slower than the scoured, and solvent extracted samples. The slower rate of degradation of the grey polyester is attributed to the presence of spin finishes in the polyester biomaterials. Further, different scouring methods also gave samples with varying rates of hydrolysis. This is due to the different spin finish removal efficiency of different scouring procedures. The weight loss (%) of the solvent extracted samples were the largest which demonstrated that the solvent extraction technique is perhaps the best to remove spin finish from the polyester. CONCLUSIONS Thus, these results serve as foundation for polyester biomaterials which are hydrolyzed before implantation in order to improve the protein binding capabilities to minimize thrombosis.

Fibers from urea–formaldehyde resins

The preparation of fibers from aqueous urea–formaldehyde resins has been investigated; a dry spinning process has been developed based on the extrusion of catalyzed resin into a drying chamber at 180–220°C, producing a multifilament yarn at spinning speeds of up to 600 m/min. A range of UF filaments was produced with diameters between 10–70 μm; the tenacities of spun filaments were 6–10 cN/tex, initial moduli were 220–340 cN/tex, and elongation at break was 4–10%. The best tensile properties resulted from conditions that produced the smallest diameter fibers. Postspin heat treatment improved the tenacity to 14 cN/tex and the elongation to 20%. Spinnability improved with increased viscosity of the spinning solution and increased cell temperature, while tenacity and elongation increased with increasing cell temperature and spinning stretch. A correlation was found between TGA weight loss (between 105 and 200°C) and fiber tenacity.

Kinetics of the Reaction of Poly-α-methylstyryl Sodium and Potassium with t-Butyl Chloride in Dioxane

Abstract The kinetics of the reaction of “living” poly-α-methylstyrene with t-butyl chloride has been studied spectrophotometrically in dioxane for the counterions sodium and potassium. The reactions are found to be precisely first-order with respect to both species. The Arrhenius parameters are determined for the overall ion-pair reaction with t-butyl chloride; the living ends have been shown to exist largely in the form of contact ion-pairs. The gaseous products of the reactions are quantitatively estimated by GLC analysis, and in the case of the sodium-initiated system, Arrhenius parameters are recovered for the elimination reaction. A tentative mechanism is advanced to explain the kinetic data.