Molecular weight and tacticity effect on morphological and mechanical properties of Ziegler–Natta catalyzed isotactic polypropylenes

Amer, Ismael; Reenen, Albert J. van; Mokrani, Touhami

doi:10.1590/0104-1428.2158

Cited by 13 publications

(12 citation statements)

References 35 publications

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“…Table reports the measured M w and PDI. The M w value is comparable with the viscosity average molecular weight, M v , of an equivalent MFR i ‐PP reported in the literature …”

Section: Methodssupporting

confidence: 87%

Non‐isothermal crystallization of Ziegler Natta i‐PP‐graphene nanocomposite: DSC and new model prediction

et al. 2020

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Crystallization occurs in processing i-PP-GnP nanocomposites, and these nanocomposites have the potential to replace traditional fillers and be used to fabricate advanced materials and technology. Therefore, this subject was comprehensively investigated by applying a recent crystallization model, non-isothermal DSC experiments, Raman spectroscopy, and WAXRD. The multi-layer GnPinduced nucleation and the crystal growth rates were modelled. The overall modelling effort generated new insights, results, and explanations. This study confirmed and elucidated, or refuted several published conclusions. It has also been reported that the present model can pursue differences in catalyst-mediated i-PP backbone defects (stereo and regio) by simulating the relative crystallization profile and determining the crystallization kinetic triplet (n, k o , and E a ). The multiple roles played by GnP were underscored, which exceed what the related literature currently reports. The Raman and XRD work revealed the interaction between GnP and i-PP. The shear-induced dispersion of GnP that occurs during extrusion significantly affected i-PP crystal size distribution. The present approach can also assess the effects of catalyst type and structure, and backbone defect types and their distribution on the non-isothermal crystallization of, in general, polyolefin blends and nanocomposites.

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“…Table reports the measured M w and PDI. The M w value is comparable with the viscosity average molecular weight, M v , of an equivalent MFR i ‐PP reported in the literature …”

Section: Methodssupporting

confidence: 87%

Non‐isothermal crystallization of Ziegler Natta i‐PP‐graphene nanocomposite: DSC and new model prediction

et al. 2020

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“…Nonpolar polymers are characterised by an appropriate range of molecular weights between critical values, whereas polar polymers and polymers containing hydrogen exhibit optimal mechanical properties at low molecular weights [48], [49]. The dielectric films used in capacitors, however, must have sufficient tensile strength to withstand the pressure applied on the film layer when they are rolled tightly to prevent air gap formation.…”

Section: B Mechanical Propertiesmentioning

confidence: 99%

“…Comparing the effects of AC and DC voltage on discharge events shows that the amount of discharge under DC voltage is considerably less than that under the AC voltage on the assumption that the dielectric films have the same properties and are subject to the same measurement conditions [49]. The PD events under both AC and DC voltages heavily depend on the film thickness where a void size inside dielectric relates to the random nature of the polymers.…”

Section: ) Under Ac Voltagementioning

confidence: 99%

Ageing: Causes and Effects on the Reliability of Polypropylene Film Used for HVDC Capacitor

Umran

Wang

2020

IEEE Access

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It is well-known that the high-performance polymeric dielectric films used for high-voltage DC capacitors should have outstanding capabilities in terms of electrical and mechanical properties in order to face harsh operating conditions. Many factors limit the ability of these thin films to face different and growing stresses according to modern electrical requirements. Microstructure properties, additives, impurities, defects formed during manufacturing as well as applied stress types significantly affect the performance of dielectric films and their operational lifetime. This paper presents a comprehensive review of the factors which affect the ageing, degradation and breakdown of metallised polypropylene (PP) capacitors films. The effects of microstructure, surface morphological properties, mechanical properties and defects on the reliability of biaxially oriented polypropylene films (BOPP) are studied. In addition, the phenomena affecting dielectric performance and ageing mechanisms which are induced by electrical, thermal and electrothermal stresses are discussed.

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“…For example, Menyhard et al and Ksmael et al examined the effects of stereoregularity and molecular weight on the physical properties of PPs produced using heterogeneous Ziegler-Natta (ZN) catalysts. [6,7] PP samples with different stereoregularities and molecular weights were prepared using different catalysts or external donors, and their dependence on the physical properties was examined. De Rosa et al and Minami et al prepared PP samples with precisely controlled stereoregularity using diverse molecular catalysts, and showed that their thermal and mechanical properties were correlated with stereo-defects.…”

Section: Introductionmentioning

confidence: 99%

Physical Properties of Isotactic Polypropylene Blended with Less Crystalline Polypropylene

Wada

Kitabayashi

Chammingkwan

et al. 2022

Macro Reaction Engineering

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The physical properties of polymeric materials, which are mixtures of various molecules, are determined by the sum of their contributions. Industrially important isotactic polypropylene (iPP), which is produced using heterogeneous Ziegler–Natta catalysts, shows broader distributions of molecular weight and stereoregularity because of the multisite nature, compared to molecular catalysts. However, systematic studies on the effects of these distributions on physical properties are lacking, especially for variations in stereoregularity. In this study, polypropylene (PP) additives with various molecular weights and stereoregularities (and their distributions) are added to an iPP matrix to clarify the effects of low‐concentration components on the overall physical properties. The results indicate the importance of incorporating the PP additives into the crystal structure of the iPP matrix.

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Molecular weight and tacticity effect on morphological and mechanical properties of Ziegler–Natta catalyzed isotactic polypropylenes

Cited by 13 publications

References 35 publications

Non‐isothermal crystallization of Ziegler Natta i‐PP‐graphene nanocomposite: DSC and new model prediction

Non‐isothermal crystallization of Ziegler Natta i‐PP‐graphene nanocomposite: DSC and new model prediction

Ageing: Causes and Effects on the Reliability of Polypropylene Film Used for HVDC Capacitor

Physical Properties of Isotactic Polypropylene Blended with Less Crystalline Polypropylene

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