High‐pressure phases in polymers. V. Crystallization studies of synthetic cis‐polyisoprene

The effects of elevated pressure on the morphology and crystallization kinetics of cis‐polyisoprenes containing 2–2.5% trans units have been determined. Lamellar growth rates of both α and β crystals are enhanced by elevated pressure. The degree of enhancement of α‐crystal rates is much greater resulting in an effective suppression of β growth. Differences in lamellar growth rates between these polymers and cis‐polyisoprene result from different preexponent values. Hedritic or axialitic growth, presumably due to low‐molecular‐weight fractions, is observed in shish‐kebabs present in strained films. The high‐pressure hexagonal phase cannot be grown in these polymers.