https://doi.org/10.1351/goldbook.D01573
The fractions of
triads
in a regular vinyl polymer
that are of the mm, rr and mr = rm types, respectively. In cases where triad analysis is not attainable, the diad isotacticity and diad syndiotacticity may be defined as the fractions of diads
in a regular vinyl polymer that are of the m and r types, respectively. (m = meso
; r = racemic
).