Two-step foaming

Diester/Ether Diol of Tetrabromophthalic Anhydride. This material [77098-07-8] is prepared from TBPA in a two-step reaction. First TBPA reacts with diethylene glycol to produce an acid ester. The acid ester and propylene oxide then react to give a diester. The final product, a triol having two primary and one secondary hydroxyl group, is used exclusively as a flame retardant for rigid polyurethane foam (53,54). 

The smallest increases in foam capacity occurred at pH 6.7. Percentages of protein in the soluble fractions varied at this pH. Foam capacity and stability improved and decreased, respectively, at this pH as the salt content of the suspension was increased. The two-step pH adjustment (23) of 6.7 to 4.0 to... 

Suspensions of field pea flour at pH 6.7 and 8.2 (including the two-step adjustment) contained similar high quantities of soluble protein at pH 4.0, most of the protein was Insoluble. Foam capacity of suspensions was higher at pH 8.2 than at 4.0 and 6.7. The two-step pH adjustment did not improve foam capacity over that of the one-step change as shown with the soybean and peanut products. The foam produced at pH 4.0 was thinner than those at pH 6.4 and 8.2 the latter three products had similar consistencies. 

The final action required is reheating the molded part at which time the plastic softens and the gas expands to form a closed-cell foam. With this technique it is possible to produce foams with densities as low as 2 lb/ft3, although the usual range is 10 to 50 lb/ft3. Because of this two-step procedure the process is much slower than the foaming procedure for open-cell foams. Close cell use includes athletic mats and marine flotation products. 

Whether obtained by one- or two-step pH adjustment, at pH 8.2 the percentages of protein in soluble extracts were among the the highest observed In the study, yet Increases In foam volume were not as great as those observed at pH 1.5 or 4.0. 

Foam stability showed little variation among suspensions at pH 1.5 and 4.0, remaining between 35% and 45% (Figure 7). The largest variations In stability were noted among suspensions at pH 6.7 and 8.2, and after the two-step adjustment to pH 6.7. Increasing the amount of salt In the suspension at these pH values decreased foam stability. The suspensions adjusted from pH 6.7 to 4.0 to 8.2 exhibited similar foam capacity and stability, regardless of salt concentration. 

Two-Step Process. A mixture composed of 100 g of 4,4 -diphenylmethane diisocyanate and 1.1 g of l-phenyl-3-methyl-l-phospholene oxide is stirred for 3 minutes at room temperature. After carbon dioxide is evolved 4.0 g of 2,4,6-tris(dimethylaminomethyl) phenol is added into the reaction mixture. The mixture generates a reaction exotherm and expands to form a foamed product. After curing at 125°C for one hour, the resultant foam is colorless and posesses low friability. 

The pH-value of the medium was adjusted with aqueous ammonia solution to 5.6 The sterilization was carried out in two steps as described above. The fermentation was continued for 7 days under aeration of 1 litre/litre/minute and stirring with 280 R.P.M. at 24°C, with systematic addition of foam-inhibitors. 

In the next two steps the residential upholstered furniture questions should be resolved. The second destination is an appropriate open flame composite assessment test along with an improved UFAC cigarette resistance test. The third destination will be development of a foam that meets UFAC labeling test requirements and replaces their construction approach. 

The coalescence of disperse systems, such as foams and emulsions, and the contact of air bubbles with solid particles, e.g. in the process of flotation, takes place in two steps. The first is characterised by a flocculation of the system, the formation of thin liquid films with an equilibrium thickness. In the second step the film becomes thin enough for the interparticular attractions to overcome the film state so the two separated interfaces form a new interface. The situation where a small bubble attaches a liquid interface is shown in Fig. 2D. 1. 

Devolatilization (7) This is a two-step operation under high vacuum, to remove lights components such as unreacted styrene and diluent, which is enhanced with the addition of a foaming agent in the... 

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