Optimizing LDPE Foam Film Properties: Skin Layer Control and Dimensional Stability Enhancements

Precise control over skin layer thickness during the supercritical CO₂ foaming process is essential for optimizing the performance and dimensional stability of polymer foam films, particularly for applications in the consumer electronics sector. This study presents a method that combines irradiation cross-linking and flexible constraints to regulate the skin layer thickness and dimensional stability of low-density polyethylene (LDPE) foam films. Irradiation cross-linking significantly enhances the melt strength of LDPE, reducing cell sizes by approximately 25% and improving dimensional stability at an optimal dose of 125 kGy. The application of flexible constraints allows for skin layer thickness adjustment ranging from 25 μm to complete elimination. Notably, the specific energy absorption of LDPE foams without a skin layer increased by 96% compared to foams with a 25.62 μm skin layer. Waterproof performance was also directly correlated with skin layer thickness, with foams lacking a skin layer maintaining waterproof properties for 10 min, while foams with a 25 μm skin layer retained waterproof properties for up to 72 h. The regulation of skin layer thickness facilitates a balance between high specific energy absorption and superior waterproof performance.