Experimental procedures, glass

The SFA, originally developed by Tabor and Winterton [56], and later modified by Israelachvili and coworkers [57,58], is ideally suited for measuring molecular level adhesion and deformations. The SFA, shown schematically in Fig. 8i,ii, has been used extensively to measure forces between a variety of surfaces. The SFA combines a Hookian mechanism for measuring force with an interferometer to measure the distance between surfaces. The experimental surfaces are in the form of thin transparent films, and are mounted on cylindrical glass lenses in the SFA using an appropriate adhesive. SFA has been traditionally employed to measure forces between modified mica surfaces. (For a summary of these measurements, see refs. [59,60].) In recent years, several researchers have developed techniques to measure forces between glassy and semicrystalline polymer films, [61-63] silica [64], and silver surfaees [65,66]. The details on the SFA experimental procedure, and the summary of the SFA measurements may be obtained elsewhere (see refs. [57,58], for example.). 

The experimental procedure consisted of casting the varnish on glass plates by means of a spreader bar having an 0-102 mm (0 004 in) gap this produced a wet film 0-051 mm (0-002 in) thick that yielded a dried film of 0-025 mm (0-001 in). This standard thickness was used throughout and resistances are quoted in cm. The cast films were dried for 48 h in a glove box followed by a further 48 h in an oven at 65°C. 

The absorption rates of CO2 were measured in such non-aqueous solvents as toluene, NMP, and DMSO with GMA concentration ranging Ifom 0.5 to 3 kmol/m in a semi-batch flat-stirred agitated vessel constructed of pyrex glass of 0.075 m inside diameter and of 0.13 m in height. The apparatus and the experimental procedure are the same as those described by... 

The nonlinearity of the sample was analyzed using the experimental procedure described in Section 3.3 The polarization of the fundamental beam of a YAG laser was continuously varied by means of a quarter waveplate, and the intensity of the second-harmonic signal was measured as a function of the rotation angle of the quarter waveplate. The obtained polarization pattern were then fitted to Eq. (42), which yields the relative values of the expansion coefficients /, g, and h. The experimental results for the transmitted, glass-side-incidence, s-polarizcd signal are shown in Figure 9.20. 

Experimental Procedure. A schematic diagram of experimental apparatus is shown in Figure 2. About ten of cylindrical glass bottles enclosed samples of same composition were set in a thermostatic air chamber. The samples melted perfectly by holding for about 2h at... 

Catalytic experiments were performed in a fixed bed glass tubular reactor at atmospheric pressure and at reaction temperature of 450 and 482°C for n-heptane and gas-oil, respectively. Details on the experimental procedure have already been published (7). 

Page numbers in bold-faced type refer to experimental procedures. Numbers followed by an asterisk refer particularly to qualitative organic analysis. Numbers followed by a dagger t refer to apparatus with ground glass joints. Numbers followed by a double dagger refer to reaction mechanisms. 

Experimental Procedure. The resin is washed with appropriate solvents and a small portion (ca. 1-5 mg) is transferred to a small glass tube. To this tube are added three drops of each of the reagent solutions A and B. The tube is then heated at 100° for 3 min. A negative test, indicating the absence of free primary amines, is communicated by a yellow or orange-pink solution and naturally colored beads. A positive test is indicated by a dark blue or purple solution and beads. Variations in the darkness of the solution reflect variations in amine concentration while variations in... 

Experimental Procedure. The resin is washed with MeOH and a small portion (1-3 mg) is transferred to a small glass tube. To this tube is added acetaldehyde (primary or secondary amines) or acetone (secondary amines) (200 pi) followed by the chloranil solution (50 pi). The solution is shaken at room temperature for 5 min. The presence of free amines is indicated by a green- or blue-colored solution. Negative samples register as yellow, amber, or brown. 

Experimental Procedure. A solution of p-anisaldehyde (26 //I) in the first reagent (1 ml) is made. A small portion (1-3 mg) of resin is transferred to a small glass tube and washed with MeOH. To this tube is added the previous Et0H/H2S04/H0Ac solution (500 pi). The solution is heated in a sand bath at 110° for 4 min. The presence of free aldehydes is indicated by orange- to burgundy-colored beads. 

In the LSE, a glass-type equipment is used and the extractions with chloroform, methanol and n-hexane are carried out. The LSE is usually takes about 12 hours with 5 g of each sample. Since we discussed elsewhere the experimental procedures of both the SFE and the LSE, we omit here further descriptionsfl, 2],... 

While the dilatometer method is the preferred method of determining the glass transition temperature, it is a rather tedious experimental procedure and measurements of Tg are often made in a differential scanning calorimeter (DSC). In this instrument (18), the heat flow into or out of a small (10-20 mg) sample is measured as the sample is subjected to a programmed linear temperature increase (typically 10 C/min). The heat flow is proportional to the specific heat of the sample. At the glass transition, there is an increase in the heat flow into the sample due to the increase in specific heat at this point. Values obtained in this manner are only a few degrees higher than the dilatometer values. 

The polysiloxanes were characterized by Fourier transform-IR (FTIR) spectroscopy, H and Si NMR spectrometry, and by GPC. AC conductivities of the polymer electrolytes were measured under dry helium by using an automatic capacitance bridge (General Radio Corporation). Glass transition (Tg) and melt (TJ temperatures were recorded on a differential scanning calorimeter (Perkin Elmer DSC-4). More detailed experimental procedures are published elsewhere (9, 12). 

Filtration is the physical separation of a solid from a liquid and is a process encountered in experimental procedures such as gravimetric analysis (p. 139), recrystallization (p. 92), and solvent drying (p. 41). In principle, the mixture of the solid and liquid is passed through a porous material, filter paper or if sintered glass, and the solid is trapped on the porous material while the liquid passes through. 

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