Crystallization and Melting of Oriented Parent–Daughter Lamellae in Sheared Isotactic Poly(propylene)

Andrew Phillips; Peng-wei Zhu; Chitiur Hadinata; Graham Edward

doi:10.1071/CH10080

RESEARCH FRONT

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Crystallization and Melting of Oriented Parent–Daughter Lamellae in Sheared Isotactic Poly(propylene)

Andrew Phillips ^A ^C , Peng-wei Zhu ^A , Chitiur Hadinata ^B and Graham Edward ^A

+ Author Affiliations

- Author Affiliations

^A Department of Materials Engineering, Co-operative Research Centre for Polymers, Monash University, Clayton, Vic. 3800, Australia.

^B Autodesk Pty Ltd, 259-261 Colchester Road, Kilsyth, Vic. 3137, Australia.

^C Corresponding author. Email: andyphil21@gmail.com

Australian Journal of Chemistry 63(8) 1179-1188 https://doi.org/10.1071/CH10080
Submitted: 12 February 2010 Accepted: 18 March 2010 Published: 10 August 2010

Abstract

Alpha isotactic poly(propylene) (α-iPP) exhibits a form of lamellar branching that is unique among semicrystalline polymers, where the branches have a distinct orientation relationship with the original crystalline lamellae. This is termed a parent–daughter relationship (PD). By allowing the structure to crystallize in an oriented form, a bimodal orientation of lamellae is developed and the individual contributions of PD lamellae can be observed using wide-angle X-ray scattering (WAXS). The present study investigated oriented PD lamellae during flow-induced crystallization and subsequent melting using time resolved rheo-WAXS. During crystallization the planes of the daughter lamellae were observed to curve towards the flow direction as they grew from their parent lamellae. This was explained by the influence of neighbouring daughter lamellae confining their growth direction. Oriented daughter lamellae were found to melt ~5°C lower than oriented parent lamellae, which provides a new explanation for the multiple melting behaviour observed in the melting thermograms of sheared α-iPP.

Acknowledgements

This work was performed at the Powder Diffraction beamline at the Australian Synchrotron, Victoria, Australia and the Australian National Beamline Facility (ANBF) with support from the Australian Synchrotron Research Program, which is funded by the Commonwealth of Australia under the Major National Research Facility Program. The assistance from Dr Jan Ilavasky at the Advanced Photon Source Argonne National Laboratory for modifying the Nika software package was greatly appreciated. The authors also acknowledge George Theodossiou at the Monash Centre for Electron Microscopy (MCEM) for his invaluable assistance in preparing the SEM images.

References

Crystallization and Melting of Oriented Parent–Daughter Lamellae in Sheared Isotactic Poly(propylene)

Abstract

Acknowledgements

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