Rheology and crystallization behavior of polypropylene and high‐density polyethylene in the presence of a low molar mass polyethylene

Michael, Robert; Fulchiron, René; Cassagnau, Philippe

doi:10.1002/pcr2.10078

Cited by 3 publications

(14 citation statements)

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“…Due to a large viscosity ratio, low molar wax addition induces a dilution effect of the backbone polymer strongly decreasing its viscosity [ 39 ], [ 40 ]. Robert et al studied paraffin wax miscibility in both PP and HDPE at the molten state via viscoelasticity measurements [ 36 ]. They developed a model based on the comparison between polymer/wax viscosity behaviors and generalized Carreau–Yasuda equation in order to conclude on blends homogeneity.…”

Section: Resultsmentioning

confidence: 99%

“…In fact, considering an entangled regime of HDPE or PP chains, the zero shear viscosity of the homogeneous blend η 0 can be expressed as a function of the backbone polymer viscosity η 0P , its content in the blend φ , and a factor relative to the free volume correction with temperature (Equation (3))

. The latter can be expressed as a function of the temperature, the universal gas constant, and activation energies of the blend and the polymer [ 36 ].

…”

Section: Resultsmentioning

confidence: 99%

“…They also investigated the effect of crystallization on PP/wax and HDPE/wax morphology with polarized light measurements. It was shown that low molar mass component was rejected in interspherulitic regions during PP crystallization [ 36 ]. DSC measurements have also been used in the literature to investigate structure of PE/wax and PP/wax blends after crystallization [ 41 , 42 ].…”

Section: Resultsmentioning

confidence: 99%

“…In this study, HDPE/wax and PP/wax blends presenting weight ratios of 90/10, 80/20, and 35/65 were investigated. Based on the work of Robert et al, experimental viscosities were measured and compared to generalized Carreau–Yasuda equation by applying factors of

and

on the frequencies and viscosities, respectively [ 36 ].…”

Section: Resultsmentioning

confidence: 99%

“…Using a rheological model developed by Robert et al [ 36 ] and detailed in the next section, viscosity measurements were used to investigate waxes miscibility in HDPE and PP in molten conditions. Those particular tests were realized on neat polymer/wax blends with increasing wax proportions ( Table 3 ).…”

Section: Methodsmentioning

confidence: 99%

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Impact of Polymer Binders on the Structure of Highly Filled Zirconia Feedstocks

et al. 2020

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The impact of polypropylene and high-density polyethylene backbone binders on the structure of organic matrix, feedstock, and ceramic parts is investigated in terms of morphology in this paper. The miscibility of wax with polyethylene and polypropylene is investigated in the molten state via a rheological study, revealing wax full miscibility with high-density polyethylene and restricted miscibility with polypropylene. Mercury porosimetry measurements realized after wax extraction allow the characterization of wax dispersion in both neat organic blends and zirconia filled feedstocks. Miscibility differences in the molten state highly impact wax dispersion in backbone polymers after cooling: wax is preferentially located in polyethylene phase, while it is easily segregated from polypropylene phase, leading to the creation of large cracks during solvent debinding. The use of a polyethylene/polypropylene ratio higher than 70/30 hinders wax segregation and favors its homogeneous dispersion in organic binder. As zirconia is added to organic blends containing polyethylene, polypropylene, and wax, the pore size distribution created by wax extraction is shifted towards smaller pores. Above zirconia percolation at 40 vol%, the pore size distribution becomes sharp attesting of wax homogeneous dispersion. As the PP content in the organic binder decreases from 100% to 0%, the pore size distribution is reduced of 30%, leading to higher densification ability. In order to ensure a maximal densification of the final ceramic, polyethylene/polypropylene ratios with a minimum content of 70% of high-density polyethylene should be employed.

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Section: Resultsmentioning

confidence: 99%

. The latter can be expressed as a function of the temperature, the universal gas constant, and activation energies of the blend and the polymer [ 36 ].

…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

and

on the frequencies and viscosities, respectively [ 36 ].…”

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Impact of Polymer Binders on the Structure of Highly Filled Zirconia Feedstocks

et al. 2020

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Multivariable Rheological Models for Commercial Polypropylene with High Molar Masses

Castor

Fialho

Oechsler

et al. 2023

Macro Reaction Engineering

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This work investigates the fitting performance of conventional rheological models and the development of multivariable rheological models to reproduce experimental rheological data of different industrial grades of linear isotactic polypropylene (iPP) having high mass average molar masses, Mm (164–404 kg mol−1), at three temperature values (180–220 °C) over a wide range of shear rates (10−1–104 s−1). A shear thinning behavior is found in all investigated conditions. However, a low shear rate primary Newtonian plateau for a short shear rate range is only identified for the smallest Mm among those investigated, and for higher Mm such primary plateaus are even found at shorter shear rate range. Among the investigated models, only Cross and Carreau–Yasuda models are effective to reproduce the data for a specific PP grade. Two modified models are proposed that incorporate three variables. In the modified Cross Model, it has been shown that the characteristic time (λ) between the Newtonian plateau at the low shear rates and the shear‐rate range with shear‐thinning behavior depends exponentially on the Mm, and it does not depend on the temperature. Both proposed models fit very well with the experimental data with shear thinning behavior for a wide range of Mm.

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Experimental study on the effect of molecular weight and chemical composition distribution on the mechanical response of high‐density polyethylene

Jani¹,

Sepahi²,

Afzali³

et al. 2022

Polymer Engineering & Sci

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This article aims to appraise the effect of microstructure comprising molecular weight distribution and chemical composition distribution on the mechanical properties of high-density polyethylene (HDPE). HDPE resins were synthesized using several titanium-magnesium-supported Ziegler-Natta catalysts in the industrial gas phase reactor under the same polymerization condition. Gel permeation chromatography and crystallization elution fractionation (CEF) were conducted on the resins to characterize the molecular weight and comonomer distribution. Crystallization, thermal and rheological behavior were evaluated following differential scanning calorimetry, polarization light microscopy, and rheometric mechanical spectrometry. The resins with higher soluble fraction in trichlorobenzene below 80 C (highly branched low molecular weight chains) exhibited longer crystallization time based on the crystallization kinetic obtained from the Avrami model. Rheological determination of the molecular weight between entanglements (M e ) and the average lamella thickness based on the Gibbs-Thomson equation revealed that the entanglement density and impact strength decreased, and the average lamella thickness increased with an increase in the ratio of CEF eluted fraction below 80 C to the crystallizable fraction in the range of 80-90 C.

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Rheology and crystallization behavior of polypropylene and high‐density polyethylene in the presence of a low molar mass polyethylene

Cited by 3 publications

References 71 publications

Impact of Polymer Binders on the Structure of Highly Filled Zirconia Feedstocks

Impact of Polymer Binders on the Structure of Highly Filled Zirconia Feedstocks

Multivariable Rheological Models for Commercial Polypropylene with High Molar Masses

Experimental study on the effect of molecular weight and chemical composition distribution on the mechanical response of high‐density polyethylene

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