Rheological characterization and modeling of linear and branched metallocene polypropylenes prepared by reactive processing

Pivokonský, Radek; Zatloukal, Martin; Filip, Petr; Tzoganakis, Costas

doi:10.1016/j.jnnfm.2008.06.001

Cited by 24 publications

(19 citation statements)

References 22 publications

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“…This can be counterbalanced by applying a non-affine motion term f GS in the PTT-XPP model. The detailed comparison of the XPP and PTT-XPP models can be found in [7,8,23].…”

Section: Ptt and Ptt-xpp Modelsmentioning

confidence: 99%

The role of the Gordon–Schowalter derivative term in the constitutive models—improved flexibility of the modified XPP model

2015

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Constitutive models that complete the set of equations describing the flow of polymer melts should respect objective thermodynamics and stability conditions ensuring their validity in the whole range of possible deformation flow. However, in practice, a very good description of flow situations can be achieved with the models not complying with the physical assumptions in all respects. Analogously to the term characterizing yield stress in empirical viscoplastic models, the term represented by the Gordon-Schowalter (GS) derivative in the differential constitutive models contributes to better fitting the experimental data, especially shear thinning. Efficiency of the recently presented modified eXtended Pom-Pom model (just one non-linear parameter per mode) implementing the GS derivative term (one additional nonaffine motion parameter per mode) is improved (documented on LDPE, HDPE, and polyvinyl butyral (PVB) materials), and a comparison with the exponential Phan-Tien-Tanner (PTT) and PTT-XPP models (a priori containing the GS derivative term) are presented.

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“…This can be counterbalanced by applying a non-affine motion term f GS in the PTT-XPP model. The detailed comparison of the XPP and PTT-XPP models can be found in [7,8,23].…”

Section: Ptt and Ptt-xpp Modelsmentioning

confidence: 99%

The role of the Gordon–Schowalter derivative term in the constitutive models—improved flexibility of the modified XPP model

2015

Self Cite

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“…Thereby, the macro-radicals that are extremely unstable at high temperature can further undergo β-scission to achieve lower molecular weight chains or react with the PP and multifunctional monomer to form hyperbranched structure. The β-chain scission is, therefore, the main factor during the branching process, causing the degradation of PP with a negative effect on polymer rheological properties [12,13]. Hence, limiting the β-chain scission is very important for this purpose.…”

Section: Introductionmentioning

confidence: 99%

Preparation and rheology characterization of branched polypropylene during reactive extrusion process

Mohebbi

Ebrahimi

2015

Iran Polym J

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“…In order to stabilize the polymer processing, it is very important to understand all possible structural changes of the particular polymer due to thermal degradation. It has been shown that rheology can be used as the powerful tool to understand degradation of different polymers due to its sensitivity to very small changes in the molecular structure of polymers as well as to understand their molecular structure via utilization of advanced constitutive equations, which are based on the molecular arguments [1][2][3][4][5][6][7][8][9][10]. With the aim to extend the knowledge in this area, thermal stability of branched polypropylene was investigated in this work by using basic rheological tool and methodologies.…”

Section: Introductionmentioning

confidence: 99%

Investigation of thermal degradation of branched polypropylene via rheology

Drábek

Zatloukal

2015

AIP Conference Proceedings

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Abstract. In this work, virgin as well as thermally degraded branched polypropylenes were investigated by using rotational and Sentmanat extensional rheometers. Based on the shear and extensional rheology data it was deduced that both chain scission and chain branching takes place during thermal degradation of the tested polypropylene. It was found that simple phenomenological constitutive equations such as Generalized Newtonian law and modified White Metzner model can be used to describe the measured steady state shear and uniaxial extensional viscosity data as well as for the simple quantification of the extensional strain hardening via their model parameters.

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Rheological characterization and modeling of linear and branched metallocene polypropylenes prepared by reactive processing

Cited by 24 publications

References 22 publications

The role of the Gordon–Schowalter derivative term in the constitutive models—improved flexibility of the modified XPP model

The role of the Gordon–Schowalter derivative term in the constitutive models—improved flexibility of the modified XPP model

Preparation and rheology characterization of branched polypropylene during reactive extrusion process

Investigation of thermal degradation of branched polypropylene via rheology

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