Shrinkage and viscoelastic behavior of alternative substrates for magnetic tapes

Viscoelastic and shrinkage characteristics of alternative substrates for magnetic tapes are presented. The substrates evaluated include two polyesters (PET and PEN), an aromatic polyamide (ARAMID), a polyimide (PI), and poly(benzoxazole) or PBO. Thicknesses of the films range from 14.4 /spl mu/m for PET to 4.4 /spl mu/m for ARAMID. Results are also presented for ultra-thin magnetic tapes which use PET, PEN, or ARAMID as substrates. Based on their creep behavior (and relative cost), PEN or ARAMID appear to be suitable alternative substrates to PET.