What color's your polymer?

Chemists have known for some time that organic and inorganic pigments added to polymers can affect the tensile strength and other physical properties of the polymer. Now, Rex Kanu of Ball State University and colleague Thomas Spotts, and Michael Chesebrough of Tomken Tool and Engineering, Inc. have extended their earlier work to show that their organic and inorganic pigments can affect the color and stability to ultraviolet of injection-molded polypropylene. They suggest that the pigments act as nucleating agents during the polymer crystallization process. Different pigments result in a different degree of nucleation and so the polymer can be tailored to have particular color and physical properties.