Ice-Templated Poly(vinyl alcohol): Enhanced Strength and Low Thermal Conductivity

The freeze-casting technique has been used for a variety of materials to tailor their pore structure. The growing ice crystals act as a template for the subsequent voids present in the body. While it is mostly used for inorganic oxide materials, the method is also applicable to polymers like poly(vinyl alcohol) (PVA). The synthesized materials have an aligned anisotropic pore structure which significantly influences the mechanical behavior and the thermal conductivity. Glutaraldehyde (GA) can be used as a cross-linking agent to reduce the water solubility of the PVA samples. The composition-dependent thermal conductivities are measured, and found to be 0.055-0.078Wm(-1)K(-1) parallel to the freezing direction and 0.048-0.058Wm(-1)K(-1) in the transverse direction. The scaffold-like structure resembling the hydroxyapatite structures in bones yields high strength values in the axial direction well exceeding that of common unsupported building insulation materials.