The first polyester fibers were produced by reacting ethylene glycol and either terephthalic acid or one of its esters to give poly(ethylene terephthalate). This polymer is still used to make thin films (Mylar) and textile fibers (Dacron and Fortrel).
This stamp also may be used for mailing items weighing up to 2-ounces. These Forever stamps will always be equal in value to the applicable price for the price category printed on them, at the time of use. The initial price and value for this stamp is 71 cents, effective May 31.
 A forever stamp is a stamp that is valued (sold and cancelled)  at the current local letter rate of postage. For example, if the  current cost of local postage is 50 cent â¦ s, the forever stamp is  valued at 50 cents.ffectively, yes. Strictly speaking, a forever stamp is only one that bears the word Forever, but like the forever stamp, the Breast Cancer Research stamp is good for 1 oz f â¦ irst class US postage at any time, regardless of the price when you bought it.