s/so = a0× ta1×(1 + a2 ×t) , where t = 1 - T/Tc and Tc is the critical temperature, and so = 1 N/m.
s/so = exp(A)×{1 - ( T / Tc )}n, where so = 1 N/m
ln(s/so) = a1 + åai ×Tri-1×ln(1-Tr) , where the summation is from i = 2 to nTerms -1
Tr = T/Tc, Tc is the critical temperature, and so = 1 N/m
s/so = åai ×(1 - T/Tc)i, where the summation is from i = 1 to nTerms, and so = 1 N/m