Mechanism and Prevention of Winter Discoloration of Light-Colored PVC Exterior Trim

In recent years, trends towards monochromatic styling have increased the use of body side moldings matched to panel paint colors. These moldings can be painted to match, but are increasingly using pigmented flexible poly (vinyl chloride) to improve durability and reduce part cost. Even complicated “special effect” colors like metallics and pearlescents are now matched in pigmented vinyl. However, after several winters in severe climates like the Great Lakes region, some white moldings were observed to be noticeably yellowed. Since white is the most popular choice of car buyers, this is particularly troubling. The effect proved to be difficult to consistently reproduce in laboratory experiments.