Division, Spring$eld, Massachusetts 011 01 synopsisA number of phenyl polyesters have been synthesized to furnish molecules whose backbones rearrange under ultraviolet irradiation to an o-hydroxybenzophenone structure.This photochemical Fries rearrangement produces ultraviolet opacity in the irradiated film while maintainiig visual transparency. Thin coatings of these polyesters completely protect substrates ordinarily sensitive to ultraviolet light. Spectroscopic analysis of various rearranged films and coatings clearly shows that the o-hydroxybenzophenone polymer formed is concentrated at the irradiated surface of the original polyester coating as a "skin". Such a skin, formed in situ during the irradiation, functions to protect both the original polyester coating as well as the coated substrate from degradation by ultraviolet irradiation. Furthermore, a significant "healing" mechanism appears inherent in these coatings, for as the exposed skin ultimately degrades under extended ultraviolet irradiation, more of the underlying polyester layer apparently rearranges to compensate for the loss. Thus the clear coating functions both as a protective skin and a rearrangeable reservoir. Modified structures of the polyesters have been prepared which possess, in addition to their protective fdm properties, a useful solubility spectrum and a good solution shelf life.
With the increasing use of graphite/epoxy materials in primary and secondary structures, it has become apparent that specifications which can assure material consistency are required. While numerous analytical methods have been developed for graphite/epoxy materials, their relation to processing behavior has not been established. The development of the new material specification involved the use of new analytical methods as well as the design of a batch acceptance processability laminate to determine the suitability of the batch for constructing a large laminate with a specified process cycle. Material acceptance or rejection is based on chemical composition and mechanical and physical properties, including viscosity profiles and performance of the processability laminate.
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