Stretchable Waterproof Composite Material for Cast Padding

The patent uses a composite material structure consisting of a hydrophobic foam core layer sandwiched between two hydrophobic film layers. This composite construction combines the water-blocking properties of hydrophobic materials with the stretchability of the film and foam components, achieving both waterproof performance and elastic deformation capability.

The patent employs thin hydrophobic film layers that provide both waterproof protection and flexibility. These films can deform elastically to accommodate stretching while maintaining their water-resistant barrier function, resolving the contradiction between rigidity for water blocking and flexibility for stretching.

The patent incorporates elastic and stretchable materials that can dynamically adjust to different limb sizes and shapes. The material transitions from a static, uniform state during application to a dynamically adapted state that conforms to the variable geometry of the limb while maintaining waterproof integrity.

The patent changes the physical parameters of the padding material by incorporating components with different elastic moduli and stretch ratios. The hydrophobic foam and film layers are designed with specific mechanical properties that allow the material to stretch uniformly across variable limb diameters without bunching or wrinkling.

The patent converts the traditionally harmful water absorption property of cotton into a beneficial hydrophobic effect by selecting hydrophobic materials for the foam and film layers. This eliminates water absorption while retaining stretchability, transforming a disadvantage into an advantage by repelling water rather than absorbing it.

The patent replaces homogeneous cotton material with a composite structure of hydrophobic foam and film layers. This composite achieves the stretchability of cotton-like materials while eliminating water absorption through the inherent hydrophobic properties of the synthetic materials used.