Infrared absorption has been applied to the process of adsorption, desorption, and degassing of trimethyl-borate on porous high-silica glass. Theadsorbate was shown to react with the silanol and siloxane surface groups at room temperature to form =Si-OCH3 and =B-0CH3 as well as CH30H which after high temperature degassing left ~S i O H a n d =BOH on thesurface.Canadian Journal o f Chemistry, 46, 3517 (1968) Introduction Many workers (1, and references cited therein) have studied the problem of methanol adsorption on silica gel, aerogel, porous highsilica glass, and silica-alumina gels, probably all with borosilicate-like "Pyrex" glass apparatus. It was brought to our attention (2) during a report on the infrared (i.r.) and electron spin resonance (e.s.r.) studies of methanol (3) on porous high-silica glass that methanol, during storage, is known to dissolve boron from borosilicate glass and form trimethyl-borate (4). We, therefore, undertook a study of the trimethylborate glass system to determine its possible effect on our methanol study.
The electron spin resonance (e.s.r.) spectra of 'CH,, 'CHO, H and/or D, and possibly 'CH,OH or ' C H 2 0 D were found by the ultraviolet (u.v.1 photolysis of methanol -OH or -OD on porous highsilica glass at 77 OK. These e.s.r. spectra resemble the results of the u.v. photolysis of X-irradiated methanol indicating that some perturbation andlor sensitization occurred in the n~olecules by the glass surface. The absence of e.s.r. spectra from the same systems on the acid-leached glass, on the totally fluorinated glass, or on the totally -OH covered glass suggests that (i) the co-existence of surface contaminants, such as Al and Zr and not B, and some of surface -OH could be responsible for producing these free radicals, and (ii) the methanols adsorbed on these glass surfaces are stabilized against U.V. photolysis.
In two previous papers the stress-strain-time relations with respect to variables of temperature, concentration, and pH were given for attapulgite suspension in water, in terms of rheopexy (dilatancy) and thixotropy. Stress relaxation and script S-like curves showing both thixotropy and rheopexy were determined at various temperatures. Yield-point viscosities for the rheopectic and thixotropic curves showed activation energies of about 1 and 2 kcal, respectively. In the present paper Eyring's rate theory of viscosity is briefly discussed in terms of the well known generalized-viscosity equation η= ∑ i=1iXiβiαisinh−1βiṡβiṡ, which is applied successfully to given flow curves. A new method for determining the parameter βi is discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.