Hydrated Calcium Silicate and Poly(vinyl alcohol): Nuclear Spin Propagation across Heterogeneous Interfaces

Spin-diffusion NMR techniques were applied to the description of a heterogeneous interphase of composite materials formed by the hydration of calcium orthosilicate and poly(vinyl alcohol) (MDF cements). Hydrogen relaxation times were measured by magnetization transfer to 29 Si and 13 C atoms and indicate the degree of interaction between the organic and inorganic phases. Magnetization diffusion through the interfaces, measured by T 1H and T 1 ρ H relaxation times, seems effective, showing that the phases are intimately mixed and restricted defective regions are interposed between the bulk organic and the inorganic phases. On the other hand, some components of the hydrogen relaxation times, observed in both the 13 C and the 29 Si domain, identify an extended interphase. The distances travelled by the magnetization in homogeneous domains of the polymer are limited, being confined to the 4−90 nm range.