Cataloged from PDF version of article.The crystallization behaviour of different commercial grades of isotactic polybutene-1
was investigated and an experimental set-up was designed for this research study. The
experimental set-up constructed provides both fast-cooling of the sample and the recording of
the growth of spherulites as a real time movie. The radial growth rate of the spherulites were
observed to be higher for the grades with higher molecular weights. The results were found to
fit to the Lauritzenn-Hoffman crystallization theory, and this theory is used to calculate the
lateral surface free energy, σ, and fold surface free energy, σe. The lateral surface free energy
was found to be 10.4 erg/cm2
for all the grades investigated. The fold surface free energy
calculated to be between 15.5 to 17.4 erg/cm2
. The fold surface free energies and the
crystallization rates do not exhibit any dependence on the molecular weight of the polymer.
The polymer containing nucleating agents has the highest crystallization rate. It was observed
that the likelihood of deviation from spherical shape is greater for the grades with lower
molecular weights.Erdem, Hacı BayramM.S
