Relaxation nuclear magnetic resonance imaging(R-NMRI)of PDMS/PDPS siloxane copolymer desiccation

摘要

Relaxation nuclear magnetic resonance imaging(R-NMRI)was employed to study the effects of desiccation on SiO_2-filled and unfilled polydimethylsiloxane-polydiphenylsiloxane(PDMS/PDPS)copolymers.Uniform NMR spin-spin relaxation time(T_2)profiles were observed across the sample thickness indicating that the drying process is approximately uniform,and that the desiccation of the silicone copolymer is not a H_2O diffusion limited process.In a P_2O_5 desiccation environment,significant reduction of T_2 was observed for the SiO_2-filled and unfilled copolymer material for desiccation up to 225 days.A very small reduction in T_2 was observed for the unfilled copolymer between 225 and 487 days.The increase in relative stiffness with desiccation was found to be higher for the unfilled copolymer.