Influence of Short‐Chain Branching of Polyethylenes on the Temperature Dependence of Rheological Properties in Shear

Stadler, Florian J.; Gabriel, Claus; Münstedt, Helmut

doi:10.1002/macp.200700267

Cited by 77 publications

(84 citation statements)

References 27 publications

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“…Thus, the length and distribution of SCB can be tuned to control properties [24][25][26][27][28][29][30][31][32] such as crystallization kinetics, morphology, blend miscibility, mechanical properties of blown or compression molded films such as tear and impact strengths, and resistance to crack growth. Ultimate mechanical properties and crack resistance improve as the length of the side branch increases, possibly because SCB influences morphology and tie-molecule concentration, requiring greater energy to be absorbed to initiate cracks [33].…”

Section: 21mentioning

confidence: 99%

Analytical Rheology of Polymer Melts: State of the Art

Shanbhag

2012

ISRN Materials Science

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The extreme sensitivity of rheology to the microstructure of polymer melts has prompted the development of "analytical rheology," which seeks inferring the structure and composition of an unknown sample based on rheological measurements. Typically, this involves the inversion of a model, which may be mathematical, computational, or completely empirical. Despite the imperfect state of existing models, analytical rheology remains a practically useful enterprise. I review its successes and failures in inferring the molecular weight distribution of linear polymers and the branching content in branched polymers.

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Section: 21mentioning

confidence: 99%

Analytical Rheology of Polymer Melts: State of the Art

Shanbhag

2012

ISRN Materials Science

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“…Experimental details of the sample preparation and measuring techniques used are described in part I of this article series in detail [7] as well as their microstructure. Some rheological data about these samples have been published elsewhere as well [14,15,[30][31][32][33][34][35]. …”

Section: Methodsmentioning

confidence: 98%

Dynamic-mechanical behavior of polyethylenes and ethene/α-olefin-copolymers: Part II. α- and β-relaxation

Stadler

2011

Korean J. Chem. Eng.

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Several ethylene homopolymers and ethene/α-olefin-copolymers with crystallinities ranging between 85 and 12% were characterized by dynamic-mechanical measurements. The occurring relaxations were correlated to the crystallinity of the polymeric materials and to morphology. The α-relaxation, being attributed to interlamellar shear, was found to be around 60 o C with activation energies of about 120 kJ/mol in samples with more than 42 % crystallinity. The β-transition shows a much greater variety among the different samples characterized. Its relaxation temperatures vary between −40 and 10 o C with activation energies between 200 and 400 kJ/mol. The α-and β-relaxation of several quenched samples with crystallinities between 63 and 42 % were found to overlap, thus producing bimodal maxima and different activation energies from the Arrhenius plots. A separation of these overlapping relaxations was only possible by measuring the relaxations over a frequency range of more than three orders of magnitude.

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“…Even the blends prepared by a twin-screw extruder exhibit marked elasticity [20,21], suggesting that the peculiar rheological properties are not attributed to the phase separation and/or poor mixing. Although it has been known that the number of short-chain branches has strong influence on the rubbery plateau modulus [22], flow activation energy [23,24], and the onset shear stress of shark-skin failure [25,26], the effect is not so obvious as compared with the pronounced elastic properties of the blends. On the contrary, the molecular weight, i.e., shear viscosity, of a linear polyethylene plays an important role, on the rheological properties suggesting that entanglement couplings between LDPE and a linear polyethylene are responsible for the anomalous rheological responses [13,17,19].…”

Section: Introductionmentioning

confidence: 95%