Understanding why plastics turn cloudy

When plastics turn cloudy, it’s more than a cosmetic change – it’s an indication about what’s happening at the molecular level.

R&D colleagues at INEOS Styrolution recently explored this phenomenon in depth, and their findings have now been published in Macromolecules, one of the most respected journals in polymer science.

The research began with a real customer question: why did a transparent SBC material like Styrolux^®, Styroflex^® and K-Resin^®  become opaque after storage in warm salt water? The team in Antwerp set out to replicate the exact conditions with thousands of hours of exposure to understand the effect. Machine learning enabled the team to predict long-term performance from early test results, reducing evaluation time in development.

Their investigations revealed that when water interacts with certain polymers, tiny droplets form inside the material. These microscopic droplets scatter light, creating the cloudy appearance. By fine-tuning the chemical structure, the haze was minimised, and the SBC materials remained transparent for longer.

Beyond the scientific recognition, this research helps INEOS Styrolution design better materials – not just SBC, but also MBS (Zylar®) materials that are used in humid or wet environments – from medical devices and transparent packaging to dishwasher-safe consumer goods and electronics.