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J. Janicki, S. Rabiej, A. Włochowicz

Synchrotron investigations of polyethylene materials nanostructures

Polimery 2004, No 4, 248


Summary

Nanostructures of polyethylene materials were investigated, at real time in the processes of crystallization and melting, with using of SAXS or DSC methods. The following polyethylene materials were investigated: homogeneous copolymers of ethylene/1-alkene (propene, butene, octene), standard linear polyethylene (PE-L), high-density polyethylene (PE-HD) and low-density polyethylene (PE-LD). The term "homogeneous copolymers" concerns copolymers obtained with using of metalocene or vanadium based catalysts. Except the narrow molecular weights distributions they show constant content of co-monomers units in the chains and statistically identical distribution of these units in the each chain. Theoretical base as well as the methodology of the calculations of the results were described in details. There were presented mathematical dependences describing: correlation function, invariant [i.e. full scattering power of a material], thickness of crystalline lamellae and amorphic layers as well as mass degree of crystallinity. Changes of crystallinity degree (wc), invariant (Q), long period values (Lp), thickness of crystalline lamellae (Lc) or amorphic layers (La) proceeding in the wide range of temperature (from -40°C to +120°C) were discussed. The mechanism of lamella systems' melting was explained, taking into consideration the significant Lp changes versus temperature and constant thickness of crystalline lamellae.


Keywords: homogeneous copolymers of ethylene/1-alkene, polyethylene, SAXS, DSC, nanostructure, melting, crystallization


J. Janicki, S. Rabiej, A. Włochowicz

Synchrotron investigations of polyethylene materials nanostructures