Abstract: An improved optical light pipe for side-lit uses is formed from a core/cladding combination, optionally with a transparent jacket, where the core is preferably a cured acrylic polymer and the cladding is preferably a fluorocarbon polymer containing a very low level of fine particles which scatter the light uniformly along the length of the piping. Further light enhancement can be obtained with low levels of glass fibers or glass microspheres also present in the cladding. Chopped glass fibers alone at low levels in the cladding are useful for back-lit applications. The light pipe so formed is useful in signs, underwater outlines, corridor lighting in theaters, and similar uses.

Abstract: Acrylic light pipe as described in Bigley et al., U.S. Pat. Nos. 5,406,641 and 5,485,541, has adequate thermal stability for many purposes. It has been found that improved thermal stability, as reflected in color formation, can be imparted by adjusting the polymerization conditions to produce the uncured core polymer of the core/clad construction with a much reduced terminal vinyl content, preferably below 0.5 vinyl groups/1000 monomer units.