Elongational viscosity of LDPE with various structures: employing a new evolution equation in MSF theory

Abbasi, Mahdi; Ebrahimi, Nadereh Golshan; Nadali, Mahdi; Esfahani, Masood K.

doi:10.1007/s00397-011-0572-z

Cited by 28 publications

(23 citation statements)

References 43 publications

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“…In the case of polydisperse branched polymer melts, the original MSF model [Wagner et al (2001)] has the advantage that the nonlinear parameters have a specific physical meaning associated with the structure of the polymer [Wagner et al (2001); Wagner et al (2004); Rol on-Garrido and Wagner (2007); Abbasi et al (2012)]. This version of the MSF model has been applied to describe quantitatively and simultaneously nonlinear shear and elongational flows of LDPE with a minimum number of parameters [Rol onGarrido et al (2009)].…”

Section: Introductionmentioning

confidence: 99%

Increase of long-chain branching by thermo-oxidative treatment of LDPE: Chromatographic, spectroscopic, and rheological evidence

Rolón-Garrido¹,

Zatloukal²,

Wagner³

2013

Journal of Rheology

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SynopsisLow-density polyethylene was thermo-oxidatively degraded at 170 C, i.e., degraded in the presence of air, by a one thermal cycle (1C) treatment during times between 30 and 90 min, and by a two thermal cycles (2C) treatment, i.e., after storage at room temperature, an already previously degraded sample was further degraded during times between 15 and 45 min. Characterization methods include gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy, as well as linear and nonlinear rheology. A reduction of molar mass was detected for all degraded samples by GPC, as well as an increase of the high molar mass fraction of the 1C sample degraded for the longest time. Intrinsic viscosity measurements indicate also a reduction of molar mass with increasing degradation times for both 1C and 2C samples. Thermo-oxidation is confirmed for 1C and 2C samples by analyzing specific indices in FTIR. Linear viscoelasticity seems to be in general only marginally affected by thermo-oxidative exposure, while the enhanced strain-hardening effect observed in uniaxial extension experiments presents a clear evidence for an increased long-chain branching (LCB) content in both 1C and 2C samples. Elongational viscosity data were analyzed by the molecular stress function (MSF) model as well as the Wagner-I model, and for both models, quantitative description of the experimental data for all samples was achieved by fit of only one nonlinear model parameter. Time-deformation separability was confirmed for all samples degraded, 1C as well as 2C, for cumulative degradation times of up to 90 min. The characterization by GPC was confronted with the characterization obtained from nonlinear rheology. It can be stated that elongational rheology is a powerful method to detect structural a) Author to whom correspondence should be addressed; electronic mail: victor.h.rolongarrido@tu-berlin.de

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Section: Introductionmentioning

confidence: 99%

Increase of long-chain branching by thermo-oxidative treatment of LDPE: Chromatographic, spectroscopic, and rheological evidence

Rolón-Garrido¹,

Zatloukal²,

Wagner³

2013

Journal of Rheology

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“…Several viscoelastic models can describe the growth of stress during the uniaxial elongation of polymeric melts. By generalizing the Doi-Edwards model to the Molecular Stress Function (MSF) a successful prediction of the rheological behavior of linear and long-chain branched polymer melts in transient uniaxial constant extension-rate experiments is possible [33][34][35]. In the MSF model, the relative tension of the macromolecular chain in a tube segment of diameter, a, at time, t, is expressed by a Molecular Stress Function: t ′ represents the time when the tube was created with equilibrium tube diameter a 0 .…”

Section: Rheological Characterization Of the Blendsmentioning

confidence: 99%

Melt rheology of linear and long-chain branched polypropylene blends

Maroufkhani

Ebrahimi

2015

Iran Polym J

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“…MSF(molecular stress function) theory suggests that tube stretching is a function of deformation history rather than deformation rate [22,27]. It was revealed that by using Zatloukal's novel orifice die design corrected Cogswell model is more precise in uniaxial extensional viscosity prediction than Binding [28] and Gibson models for highly branched and slightly branched polymer melts [12].…”

Section: Introductionmentioning

confidence: 98%

“…Yang et al [19] used a melt-spinning technique for melt-strength and extensional viscosity of low-density polyethylene and poly(butylenes succinate) blends. Extensional viscosity is widely used in polymer branching study, especially for LDPE [20][21][22] and fluorothermoplastics [17]. Different models have been proposed for calculation of extensional viscosities.…”

Section: Introductionmentioning

confidence: 99%