Polycarbonate as a Lightweight Alternative to Automotive Glass

Coated polycarbonate shows potential for movable side windows in automobiles, boasting high visibility after weathering.

Weight reduction is a key driver in automotive design. Reducing vehicle weight reduces fuel consumption and greenhouse gas emissions. Many automakers use plastic parts to achieve vehicle weight reduction. In the case of window glass, researchers investigate plastic use, with safety at the forefront of their minds.

You can also read: How Do Polymer Innovations Enhance Automotive Performance?

What Makes up Traditional Window Glass?

Automakers typically use laminated and tempered glass in automotive applications. Plastic windows are uncommon due to cost and safety regulations, but some vehicles have, for example, plastic quarter-side windows. Laminated glass consists of two or more layers of glass held together by polyvinyl butyral (PVB). This prevents the glass from shattering in an accident. Side and rear windows are commonly comprised of tempered glass. In the case of an accident, it shatters in small pieces instead of shards to prevent harming passengers.

An Alternative Window Glazing

Polycarbonate (PC) interests researchers and manufacturers in automotive window glazing. Polymeric glazings can reduce window weight by up to 50% compared to glass with equivalent thickness. In addition, they provide exceptional optical clarity, shatter resistance, design flexibility, and lower manufacturing costs. Automotive glass is integral to passenger safety, and evaluating an alternative requires many considerations. Accidents are not the only consideration for auto manufacturers. Material degradation under regular use can lead to poor visibility. PC lacks abrasion resistance and weathering performance, but clear silicone-based hard coats offer a solution.

They applied a corona discharge treatment between the layers to optimize adhesion. They compared the two hard-coated plastic samples to uncoated PCs and glass. The researchers used the Bayer, Steel Wool, and Taber tests to investigate the coated PC’s abrasion resistance.

Rigorous Testing for Outdoor Conditions

Automobiles undergo rigorous testing to ensure they can withstand real outdoor conditions. To simulate these conditions, the researchers used a combination of tests. These tests exposed the samples to high intensity UV, humidity, water, and temperature cycles. Additionally, the researchers subjected the samples to salt spray testing.

Dual layer hard coated (DLHC) PC showed the best performance throughout testing. This research demonstrated that a corona discharge treatment was sufficient between the hard coat and the PC. This approach eliminated the need for a primer resin between layers. Finally, the DLHC PC has potential for use in movable side windows, offering a lightweight alternative to glass.