Glass Network Modification

Uchino, T., Sakka, T., Ogata, Y., and Iwasaki, M. (1992) Changes in the Stmcture of Alkali-Metal Silicate Glasses with the type of Network Modifer Cation An ab initio Molecular Orbital Study, J. Phys. Chem., 96,2455-2463. 

The glass ceramics have densities around 2.5 g/cm, therefore, the penetration depth of space electrons and protons is only a few millimetres. Network modifications resulting in changed material properties affect the performance of glass ceramics only if they are exposed directly to space and mounted on the outside of the spacecraft. However, in this case as above only the first millimetres of the glass ceramics are concerned. 

TaUe-2. Glass Transition Temperatures of Epoxy Networks after Modification with Siloxane Oligomers... 

PVA, close to 80°C. The polymer chains become mobile at the glass transition, allowing a partial re-organization of the nanotubes in the matrix and a modification of the conducting network. The polymer mobility allows some relaxation in the structure with possible better intertube contacts and loss of nanotube alignment which favors the contact probability. Both mechanisms can explain improvements of conductivity at the glass transition of the polymer. 

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