Homogeneous crystal nucleation in short polyethylenes

H. Kraack, E. B. Sirota, M. Deutsch

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24 Scopus citations


The homogeneous nucleation of the solid from the melt is studied in low molecular weight (MW) polyethylene samples with a narrow MW distribution and average carbon numbers in the range 38 ≤ n ≤ 144. The measurements employ scanning calorimetry on both emulsified and non-emulsified samples, and low- and high-angle X-ray diffraction. The shortest polyethylenes show undercoolings agreeing well with those of monodisperse n-alkanes of similar chain lengths. The longer samples extrapolate smoothly between the undercoolings measured for monodisperse alkanes and high-MW polyethylenes with n ≥ 654. The results support the earlier conclusions that any transition from a full-molecule nucleation to a 'bundle' nucleation must occur well below n ∼ 25. The absence of significant features around n = 120 where chain folding is expected to set in, implies that it may not occur at the nucleation stage, or may have no significant contribution to the nucleation energetics.

Original languageEnglish
Pages (from-to)8225-8233
Number of pages9
Issue number19
StatePublished - 18 Jun 2001

Bibliographical note

Funding Information:
An important discussion with Sam Safran (Weizmann Institute) which nucleated this, and a preceding study is gratefully acknowledged. We thank Exxon Research and Engineering Co. for financial support of the work at Bar-Ilan University, NSLS and Exxon for beamtime at and use of X10A, and the MINERVA Foundation for a fellowship to H.K.


  • Alkanes
  • Nucleation
  • Polyethylene


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