Sealing with adhesives

Note The iodine evaporates relatively quickly from the layer after a chromatogram has been removed from the iodine chamber. This evaporation of the iodine can be considerably delayed by covering the chromatogram with a glass plate the edge can also be sealed with adhesive tape, if necessary. Iodine solution can also be used for detection instead of iodine vapor. 

Recrystallized (7 ,R)-2,2"-bis [(5)-1 -(diphenylphosphinyl)ethyl]-1,1 "-biferrocene (1.5 toluene adduct, 918 mg, 0.95 mmol) was placed in a 17 mL screw-capped test tube equipped with a rubber septum. The test tube was evacuated and was charged with nitrogen. After dry benzene (2.5 mL) was added at room temperature, triethylamine (1.1 mL, 7.9 mmol) and trichlorosUane (0.6 mL, 5.9 mmol) were added at 0°C. The rubber septum was quickly replaced with a screw cap, which was tightened up and sealed with adhesive tape. The screw capped test tube was immersed in the oil bath at 100 °C, and the mixture was heated for 10 h. 

A sample is put into a polyethylene tube which is placed into a steel tube, leaving a space for the booster. The tube is sealed with adhesive tape and the mass of the sample is recorded. A booster is placed on the sample, a wood rod with 6.8mm in diameter is inserted into the hole on the booster to enable the insertion of a detonator, and the screw cover is tighted by hand. 

Charge of 10, 20, or 30g of sample are is inserted into a polyethylene tube with a diameter of 23 mm, the bottom of which is sealed with adhesive tape. 

Sealing with adhesives does not provide the long-term hermetic properties associated with seam welding. Some adhesives suppliers report passing a 1 x 10" cc/sec helium leak-rate after 100 hours exposure to 90% RH and 32°C. Others demonstrated reliable use of epoxy-sealed... 

Preparation of polyurethane matrix In a Petri dish, 9.0 g of the polyol of castor oil and 6.0 g of the prepolymer based on MDI were combined to obtain a polyol (castor oil) diisocyanate mass ratio of 1.5 1.0 for all composites. The homogenized mixture was distributed in the mold to fill the entire space of the intermediate plate. Then, the upper plate of the mold was closed and sealed with adhesive tape. After the material was cured for approximately 24 h, the mold was opened. 

It is perhaps worth pointing out that it often takes twice as much force to remove interference-fitted liners whose flanges and registers have been sealed with adhesives as it does to assemble them. This is partly because the adhesive does form a bond (as distinct from its intended role as a sealant) and because of gummy deposits formed in the running engine. 

Pre-treatment of the resin. By the column method, wash about 400 g of the analytical grade resin with about 700 ml of 3.0 N hydrochloric acid and then with 4 or 5 litres of water. Transfer the resin to a 1 litre flask, remove most of the water by decantation and shake the resin thoroughly for several minutes with three succesive 100 ml portions of ethanol. Remove the residual ethanol by repeated washing with water and shake the resin vigorously with 400 ml of 0.5 N sodium hydroxide for about 10 minutes. Decant the slightly turbid solution, wash the resin with water until all suspended fine particles have been removed, and filter on a Buchner funnel. Press the resin between filter papers and store it in a glass stoppered bottle sealed with adhesive tape. 

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