Density fluctuations: The nucleation event in isotactic polypropylene crystallization

Terrill, Nicholas J.; Fairclough, J. Patrick A.; Towns-Andrews, Elizabeth; Komanschek, Bernd U.; Young, Robert J.; Ryan, Anthony J.

doi:10.1016/s0032-3861(97)00547-8

Cited by 202 publications

(167 citation statements)

References 17 publications

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“…Despite the scientific significance of the study of the effect of different processing conditions on the final product structure, it is more relevant for polymer industries to understand the structure development during polymer processing and in situ experiments are required. Attempts to perform online polymer processing experiments using synchrotron-based X-ray scattering experiments have already been conducted in the past two decades and ranged from simple crystallization experiments using differential scanning calorimetry (Bras et al, 1995) in combination with dedicated small/wide-angle X-ray scattering (SAXS/WAXS) beamlines (Bras et al, 1993), to more complicated experiments where fiber spinning (Terrill et al, 1998;Kolb et al, 2000) or even reactive processing was used (Elwell et al, 1994). However, previous SAXS/WAXS experiments have been limited to experimental protocols far from the industrial processing conditions as a result of the instrumental limitations.…”

Section: Introductionmentioning

confidence: 99%

Polymer crystallization studies under processing-relevant conditions at the SAXS/WAXS DUBBLE beamline at the ESRF

et al. 2013

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Recent developments on the experimental infrastructure and the acquisition of new detectors on the Dutch-Belgian beamline BM26B at the ESRF offer novel and promising possibilities for synchrotron X-ray experiments in the field of polymer crystallization under processing-relevant conditions. In this contribution, some of the most recent experiments mimicking conditions similar to those relevant for the plastics processing industry are discussed. Simultaneous thermal analysis and wide-angle X-ray scattering (WAXS) experiments, at the millisecond time-frame level, on -nucleated isotactic polypropylene (i-PP) samples subjected to ballistic cooling up to 230 K s À1 , show that the efficiency of the nucleating agent can be suppressed when quenched cooling rates higher than 130 K s À1 are used. In situ WAXS experiments using small-scale industrial equipment during a real film blowing process reveal the dependence of the onset of crystallinity (the so-called freeze line) and the crystal orientation as a function of different take-up and blow-up ratios. In situ small-angle X-ray scattering (SAXS) experiments during high-flow fields reveal the formation of shish and kebab structures in i-PP as a function of the imposed stress. Quantitative analysis of i-PP flow-induced structures is presented. The beamline specifications required to obtain high quality and industrially relevant results are also briefly reported.

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Section: Introductionmentioning

confidence: 99%

Polymer crystallization studies under processing-relevant conditions at the SAXS/WAXS DUBBLE beamline at the ESRF

et al. 2013

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“…Both observed that increasing the haul-off speed of the fibre increased the orientation and lamellar repeat distances, thus the morphology changed from spherulitic to a sheaf-like structures. Further to this, earlier publications by the authors [29][30][31] have detailed SAXS/WAXS studies on extrusion of polypropylene tapes, which concentrated on observing the onset of large-scale ordering prior to any crystalline growth. The onset was revealed by the development of intensity in the SAXS data before crystalline peaks in the WAXS data are observed.…”

Section: Introductionmentioning

confidence: 99%

Effect of processing parameters on the morphology development during extrusion of polyethylene tape: An in-line small-angle X-ray scattering (SAXS) study

Heeley

Gough

Hughes

et al. 2013

Polymer

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Ray scattering (SAXS). AbstractThe in-line development of crystalline morphology and orientation during melt extrusion of low density polyethylene (LDPE) tape at nil and low haul-off speeds has been investigated using Small-Angle X-Ray Scattering (SAXS). The processing parameters, namely haul-off speed and distance down the tape-line have been varied and the resulting crystalline morphology is described from detailed analysis of the SAXS data. Increasing haul-off speed increased orientation in the polymer tape and the resulting morphology could be described in terms of regular lamellar stacking perpendicular to the elongation direction. In contrast, under nil haul-off conditions the tape still showed some orientation down the tape-line, but a shish-kebab structure prevails. The final lamellae thickness (~50 Å) and bulk crystallinity (~20%), were low for all processing conditions investigated, which is attributed to the significant shortchain branching in the polymer acting as point defects limiting lamellae crystal growth.2

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“…In addition to the large-scale correlation length, more sophisticated scattering experiments demonstrated that the system has the following kinetic features [163][164][165][166][167]:…”

Section: Primary Nucleationmentioning

confidence: 99%

A Review on Polymer Crystallization Theories

2016

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Abstract:It is the aim of this article to review the major theories of polymer crystallization since up to now we still have not completely comprehended the underlying mechanism in a unified framework. A lack of paradigm is an indicator of immaturity of the field itself; thus, the fundamental issue of polymer crystallization remains unsolved. This paper provides an understanding of the basic hypothesis, as well as relevant physical implications and consequences of each theory without too much bias. We try to present the essential aspects of the major theories, and intuitive physical arguments over rigorously mathematical calculations are highlighted. In addition, a detailed comparison of various theories will be made in a logical and self-contained fashion. Our personal view of the existing theories is presented as well, aiming to inspire further open discussions. We expect that new theories based on the framework of kinetics with direct consideration of long-range multi-body correlation will help solve the remaining problems in the field of polymer crystallization.

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Density fluctuations: The nucleation event in isotactic polypropylene crystallization

Cited by 202 publications

References 17 publications

Polymer crystallization studies under processing-relevant conditions at the SAXS/WAXS DUBBLE beamline at the ESRF

Polymer crystallization studies under processing-relevant conditions at the SAXS/WAXS DUBBLE beamline at the ESRF

Effect of processing parameters on the morphology development during extrusion of polyethylene tape: An in-line small-angle X-ray scattering (SAXS) study

A Review on Polymer Crystallization Theories

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