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The effect of specific nucleation on molecular and supermolecular orientation in isotactic polypropylene
Author(s) -
Ščudla Jaroslav,
Eichhorn KlausJochen,
Raab Miroslav,
Schmidt Pavel,
Jehnichen Dieter,
Häußler Liane
Publication year - 2002
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/1521-3900(200208)184:1<371::aid-masy371>3.0.co;2-l
Subject(s) - materials science , tacticity , crystallite , nucleation , differential scanning calorimetry , flattening , polypropylene , composite material , phase (matter) , crystallography , relaxation (psychology) , fourier transform infrared spectroscopy , chemical engineering , polymer , polymerization , thermodynamics , chemistry , organic chemistry , metallurgy , psychology , social psychology , physics , engineering
The molecular and supermolecular orientation, morphology and structural changes observed during cold drawing of injection moulded isotactic polypropylene modified by specific α, and β nucleating agents were studied by polarised photoacoustic FTIR spectroscopy, wide‐angle X‐ray diffraction and differential scanning calorimetry. Significantly lower molecular orientation was found in the core of the β‐nucleated injection moulded specimens as compared to unmodified and α‐nucleated materials. This has been ascribed to the fast growth of the β‐crystallites which inevitably dislocates the flow‐induced orientation within the crystalline regions and in their vicinity. Moreover, it was found that the presence of the developed β‐crystallites distinctly diminishes the efficiency of the orientational solid‐state drawing assessed on both levels of the hierarchical structure (molecular and crystalline). This structural observation is directly connected with macroscopic softening effect of the β‐phase: lowering the yield stress and flattening the neck shoulder. Thus, the interrelation between the microstructural and macroscopic effects of the β‐phase could be described as a feedback process.