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

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dc.title Increase of long-chain branching by thermo-oxidative treatment of LDPE: Chromatographic, spectroscopic, and rheological evidence en
dc.contributor.author Rolón-Garrido, Víctor Hugo
dc.contributor.author Zatloukal, Martin
dc.contributor.author Wagner, Manfred Hermann
dc.relation.ispartof Journal of Rheology
dc.identifier.issn 0148-6055 Scopus Sources, Sherpa/RoMEO, JCR
dc.date.issued 2013
utb.relation.volume 57
utb.relation.issue 1
dc.citation.spage 105
dc.citation.epage 129
dc.type article
dc.language.iso en
dc.publisher Society of Rheology en
dc.publisher American Institute of Physics (AIP) en
dc.identifier.doi 10.1122/1.4763567
dc.relation.uri http://www.journalofrheology.org/resource/1/jorhd2/v57/i1/p105_s1?isAuthorized=no
dc.subject Damping function en
dc.subject Elongational flow en
dc.subject Fourier transform infrared spectroscopy en
dc.subject FTIR en
dc.subject Gel permeation chromatography en
dc.subject GPC en
dc.subject Low-density polyethylene en
dc.subject MSF model en
dc.subject Rheology en
dc.subject Strain hardening en
dc.subject Thermo-oxidative degradation en
dc.subject Wagner-I model en
dc.description.abstract Low-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 90min, 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 45min. 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 90min. 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 changes due to thermo-oxidative degradation, especially the formation of enhanced LCB. It has the further advantage that experimental data can be quantified by a single nonlinear model parameter of constitutive equations like the MSF or the Wagner-I model. © 2013 The Society of Rheology. en
utb.faculty Faculty of Technology
dc.identifier.uri http://hdl.handle.net/10563/1003060
utb.identifier.obdid 43869889
utb.identifier.scopus 2-s2.0-84870974490
utb.identifier.wok 000312240900005
utb.identifier.coden JORHD
utb.source j-scopus
dc.date.accessioned 2013-01-01T22:29:26Z
dc.date.available 2013-01-01T22:29:26Z
dc.rights.access openAccess
utb.contributor.internalauthor Zatloukal, Martin
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