Summary: A new crystal morphology (δ form) of poly(3‐hydroxypropionate) (PHP) is found in cast and melt‐crystallized PHPs with low molecular weight, in which the PHP chains possibly adopt a 21 helix rather than the trans conformation found in the β or γ form. The fusion temperature‐ and the crystallization temperature‐dependent polymorphism are responsible for the dual morphologies and the unique growth kinetics of spherulites in the melt‐crystallized PHPs.
a) A dual‐morphology developed at 70 °C in PHP films after melting at 117 °C and b) that formed during cooling at a rate of 1 °C · min−1 from 130 °C.
