PIPD is a polymer with unusual tensile and compressive strength. Inter and intramolecular H-bonding interactions are thought to be responsible for these properties. PIPD is also known to incorporate water but the quantity, location and orientation of water molecules in the crystal structure have not been precisely identified. This fiber exhibits axial and radial disorder in the relative positioning of polymer chains, so that order is lost after a few repeats. Finally, water affects both the H-bonding and the extent of order. The disorder components are quite substantial and are best treated by the measurement of the coherent differential scattering cross section (DCS) in two dimensions. A Neutron Diffraction Isotopic Substitution Measurement is proposed. A NDIS measurement will help to understand how heat tretment and water content affect hydrogen bonding and the disorder in the fiber.