A combination of the methods of Gardner and Prony is used for the qualitative and quantitative analysis of
solid-state free induction decay (1H NMR) curves of isotactic polypropylene, recorded at 40, 60, 80, and 100
°C at constant time intervals. These multicomponent decay curves contain information about the physicochemical structure of the polymer sample: each component is characterized by a specific model function
containing a spin−spin relaxation time T
2 and an intensity as parameters depending on the properties and
amount of the corresponding phase. The number of phases is still an unanswered question. Each FID curve
is analyzed by using an improved method of Gardner et al. in order to reveal the number of phases, to predict
the best fitted model function, and to estimate the T
2 value of each component. The quantification of the
parameters (T
2 and fraction) with Prony's improved method is discussed. The presence of an intermediate
phase is unambiguously demonstrated. The influence of temperature on the physicochemical structure of the
polymer is examined. The precision of the computed parameters is discussed for the analyses of three
consecutively measured FID curves of isotactic polypropylene at 60 °C.