Small‐angle X‐ray scattering of isotactic poly(4‐methyl‐1‐pentene)

Although the crystalline phase of poly(4‐methyl‐1‐pentene) (P4MP) is less dense than the amorphous phase, the density difference is very small at room temperature. This makes it difficult to study the fine structure of P4MP by small‐angle x‐ray scattering (SAXS). It has therefore not been clear whether a so‐called superlattice, or long‐spacing structure, is formed in P4MP as in other synthetic polymers. However, it is found that raising the temperature increases the density difference sufficiently to make SAXS study feasible, and the existence of the long‐spacing structure of P4MP is indicated. Annealing studies reveal two characteristic temperatures of 170 and 200°C: above 170°C the long‐spacing structure is formed with an abrupt increase of crystallinity, and at 200°C the structure is further developed.