The present invention concerns compounds of general formula :in which the substituents are as described herein. Aqueous dispersions and coatings comprising these reaction products are also disclosed. By burning at least a portion of the flammable fluid in the first chamber, the fluid in the first chamber and the second chamber is discharged out through the first vent opening, thereby inflating the air bag. The cross section of the I-beam may be varied according to height, width or thickness of one or more of its members as it extends between the load acceptance and load transfer structures.