The Structure and Properties of Films of Siloxane Coupling Agents

The structure of a free film of hydrolysed gamma-glycidoxypropyl-trimethoxy-silane is examined by various techniques. It is particulate rather than continuous in structure and there are residual hydroxy and methoxy groups. These hydroxyl groups are largely inaccessible to exchange with deuterium oxide. The structure suggested is mainly six-membered rings joined by short lengths of—SiO—chains and crosslinked by fusion of rings. The free hydroxyl groups on connected chains are protected by a spiral structure and probably from hydrogen bonds.     

Synthesis of Bismuth(III)Neodecanoate and Its Application to Poly(Vinyl Chloride) as a Thermal Stabilizer

The bismuth(III)neodecanoate (Bi(Ne)₃) was synthesized via the method of co-reaction of bismuth oxide, neodecanoic acid, and acetic anhydride and then characterized by Fourier transform infrared spectroscopy (FTIR) and elemental analysis (EA). The effect of Bi(Ne)₃ as a thermal stabilizer on poly(vinyl chloride) (PVC) was assessed by thermal aging test, Congo red test, conductivity measurement, and thermogravimetric analysis, respectively. The results showed that Bi(Ne)₃ significantly provided PVC with a good initial color and long-term stability. Bi(Ne)₃ played a role in improving the stabilizing efficiency of PVC through absorbing hydrogen chloride (HCl) and displacing labile chlorine atoms in PVC molecular chains.     

Chemical Modification of Poly(Vinyl Chloride) with Ethylene Glycol and its Application in Ion-Chromatography

ABSTRACT

Poly(vinyl chloride) (PVC) has been chemically modified through crosslinking with different molar ratios of sodium ethylene glycoxide in ethylene glycol. The crosslinked PVC was used for coating of silica gel 60 particles and the obtained products were impregnated with tetramethylammonium hydroxide (TMAH). The crosslinking reaction as well as the insertion of TMAH were followed up and quantitatively determined with the aid of FT-IR spectroscopic and elemental analyses. The obtained materials were roughly tested for ion chromatographic separation of different ions. Retention time ( t _R) was determined for lithium, magnesium, strontium, and calcium cations whereas chloride, nitrate, and sulfate were selected as representatives for anions.     

Adhesion of Pure and CaCO3 Filled Latex Films on Poly(ethylene terephthalate)

Adhesion to poly(ethylene terephthalate) of carboxylated styrene-butadiene latex films, filled with calcium carbonate particles, was studied in this work. The acid content (2, 4 or 6 wt%) the degree of crosslinking (25, 50 or 75 wt% of insoluble polymer) of the latex particles, and the percentage of filler (0, 20, 40, 60, 80 or 90wt%) were varied. A peel test at 180° was used.

It was shown that, for the lowest filler percentages (up to 60 wt%), the films were non-porous and adhesion decreased when the peel rate, the percentage of filler, the degree of crosslinking and the acid content increased. Failure was always localized at the film-support interface (except at very low peel rate). At low peel rate, stick-slip was observed. The adhesion lowering can be explained by a decrease of the energy dissipation during peeling due to a reduced mobility of the polymeric chains. At high filler percentage (80 or 90 wt%), the films became porous and the level of adhesion very low. Failure occurred in the bulk of the latex film. The peel rate dependence was reversed; adhesion increased at higher speed. Owing to its marked importance in this system, the mechanism of the stick-slip phenomenon is especially discussed.     

Effect of Surface Energetics of Substrates on Adhesion Characteristics of Poly (p-xylylenes)

In investigating the effect of the surface energetics of substrate materials on the adhesion characteristics of poly(p-xylylene) and poly(chloro-p-xylylene) by the “Scotch Tape” method, it was found that if the substrates had not been preconditioned (treated with argon or a methane plasma), the adhesion was poor. The characteristics of water resistant adhesion that were observed when coated substrates were boiled in 0.9% sodium chloride solution were found to vary from excellent (when the polymer did not peel from the substrate after three cycles of 8 hours of boiling and 16 hours at room temperature) to poor (when the polymer peeled off almost immediately). It was noticed that water resistant adhesion depends on the hydrophobicity of the substrate material (the greater the hydrophobicity, the greater the adhesion) and is not related to the dry adhesive strength of poly(p-xylylene). The oxygen glow discharge treatment of the substrates decreased both the dry and wet adhesive strength of the polymer. The effect of the argon glow discharge treatment depended on the surface energetics of the substrate, and the methane glow discharge treatment increased both the dry and wet adhesive strength of the polymer. These preconditioning processes are discussed in terms of the sputtering of the material from the wall of the reactor in contact with the plasma and the deposition of the plasma polymer of the sputtered material on the substrate surface.     

FT-IR and Temperature-programmed Desorption (TPD) Study of the Adsorption of Probe Molecules Used to Model Epoxy Resin Adhesion to Chromium,Iron and Stainless Steel Substrates

In this study, we investigated the reactivity of chromium, iron, and surface-treated 304L stainless steels (SS) toward molecules representing model epoxy resins. These molecules were ammonia (a basic probe molecule also representative of the hardener amine group), 1,2-epoxybutane (for epoxy groups) and 2(methylamino)ethanol (for the β-amino alcohol resulting from the reaction of epoxy with amine). These molecules were analyzed in the adsorbed state by either FT-IR or temperature-programmed desorption (TPD).

Surface analysis showed that the top surface of the treated 304L samples only contains chromium and iron as metallic elements. The chromium/iron ratio can be varied within a wide range according to the SS surface treatment used. When increasing the SS surface chromium enrichment, we show a simultaneous increase of (i) both density and strength of surface acid sites, (ii) the amount of β-amino alcohol adsorbed. In addition, there is a marked improvement of the epoxy resin/304L bond strength when the SS surface is more chomium-enriched.