Polymer compositions are described containing a poly(1,4-cyclohexanedimethanol terephthalate) polymer in combination with a white pigment and optionally one or more reinforcing fillers. In accordance with the present disclosure, the composition also contains one or more reactive viscosity stabilizers. In order to prevent against yellowing, the composition is free of various aromatic epoxy resins, such as novolac epoxy resins. The polymer composition has excellent reflectance properties making the composition well suited for producing reflectors for light sources, such as LED assemblies.