Influence of Type and Content of Various Comonomers on Long-Chain Branching of Ethene/α-Olefin Copolymers

Stadler, Florian J.; Piel, C.; Klimke, Katja; Kaschta, Joachim; Parkinson, Matthew; Wilhelm, Manfred; Kaminsky, Werner; Münstedt, Helmut

doi:10.1021/ma0514018

Cited by 123 publications

(155 citation statements)

References 44 publications

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“…Cole-Cole plot of G (ω) v/s G (ω), and van GurpPalmen plot of loss angle δ = tan −1 [G (ω)/G (ω)] v/s the complex modulus |G * (ω)| are other alternatives that are very sensitive to changes in relaxation processes [88,[296][297][298][299][300][301]. For example, Robertson et al [302] used the van GurpPalmen plot and correlated the peak in δ at intermediate frequencies with LCB by appealing to blending rules.…”

Section: Experimental Methodsmentioning

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: Experimental Methodsmentioning

confidence: 99%

Analytical Rheology of Polymer Melts: State of the Art

Shanbhag

2012

ISRN Materials Science

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“…Table 1) was measured by solution NMR using the WALTZ-16-program [16]. For L4, melt-state NMR was used [36,37]. Molar mass measurements were carried out by means of a high temperature size exclusion chromatograph (Waters, 150C) equipped with refractive index (RI) and infra-red (IR) (PolyChar, IR4) detectors.…”

Section: Molecular Characterizationmentioning

confidence: 99%

“…However, the presence of sizable amounts of long-chain branches can also be safely excluded as the reaction conditions, under which F18G was synthesized inhibit the formation of long-chain branches [36]. Also the value of the zero shear-rate viscosity & 0 of about 9100 Pa·s (at 150°C) and the molar mass M w of 140 kg/mol make the presence of a small amount of LCBs very unlikely, as the expected zero shear-rate viscosity & 0 lin at 140 kg/mol is 30 000 Pa·s [38].…”

Section: Rheology 331 Zero Shear-rate Viscosity !mentioning

confidence: 99%

Evidence of intra-chain phase separation in molten short-chain branched polyethylene

Stadler¹

2011

Express Polym. Lett.

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Abstract. Intramolecular phase separation is usually associated with block-copolymers, but the same phenomenon is also obtainable by random-copolymers. In this article, evidence of intramolecular phase separation is reported for a linear octadecene-ethene copolymer, which shows an evolving 'yield point' at a long time and low frequency. This is attributed to a partial phase separation of the long short-chain branches. In creep recovery, this behavior is evident as increasing elastic steady-state creep recovery compliance J e 0 . In contrast to 'normal' block-copolymers, this special polymer has an increase in phase separation with temperature, which is caused by the chemical composition and the short chain segments in the side chain domain, leading to a high surface fraction. Vol.5, No.4 (2011) 327-341 Available online at www.expresspolymlett.com DOI: 10.3144/expresspolymlett.2011 * Corresponding author, e-mail: fjstadler@jbnu.ac.kr © BME-PT length in their paper, as it cannot be determined due to the synthesis method. Such block-copolymers are usually thermorheologically complex [9,14,15]. The group of Bates [9,10], for example, found that below the order-disorder transition temperature, i.e., in the ordered state, the sample behaves like a gel and thermorheologically simple, while in the disordered state, a clear thermorheological complexity is found. The higher the temperature, the less pronounced the long-term relaxation process and, thus, the more similar is the data to a single-phase polymer melt. Recently, it was also proven that pure ethylene-/!-olefin copolymers with very long comonomers (C26) can be phase separating in the solid state, if their comonomer content is sufficiently high [16]. This effect is different from the previous cases, because it only involves one type of chain and, furthermore, occurs on random copolymers. Hence, it is an effect that occurs only on a short length scale, as shown by the fact that the length of the comonomers used were 18 and 26 carbons. Thus, the second phase has to encompass only the maximum of 24 terminal carbons; realistically, 16-20 carbons. This effect had a small trace in X-ray diffraction, which points to a weak side chain crystallization [17,18]. However, it was shown that the samples showing this phase behavior in the solid state [16] did not show it in the melt state, as the samples behaved like normal linear low density polyethylenes (LLDPEs), being only special because of their higher flow activation energy E a , which is the consequence of the side-chain content s c of the comonomer [19,20]. Phase separation in the melt is usually visible by traces of the interfacial tension [21] and different temperature dependencies of the individual blend components and the interfacial processes [22,23]. Hence, if other techniques don't show any trace, e.g., because of too low differences in the electron density in X-ray scattering, rheological behavior can provide a valuable aid to the characterization of phase separation. Recently, molecular dynamics studies revea...

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“…One parameter influencing the lattice dimensions is the weight average molar mass M w (which strongly influences the rheological properties [27] and thus the chain mobility (and also long-chain branches [12,16,34,41])). For this purpose, several HDPEs (defined by the absence of sizable numbers of short-chain branches) -some slightly long-chain branched-were characterized.…”

Section: Influence Of Molar Mass M W and The Cooling Conditions For Nmentioning

confidence: 99%

“…This affinity of metallocene catalysts to incorporate longer -olefins easily also means that they are able to incorporate vinyl terminated chains, thus producing longchain branched materials [7,[12][13][14][15]. Because of the higher probability of a chain termination upon incorporation of a longer -olefin the production of highly SCB LCBmPE proves difficult [16].…”

Section: Introductionmentioning

confidence: 99%

Lattice sizes, crystallinities, and spacing between amorphous chains - characterization of ethene-/ɑ-olefin copolymers with various comonomers and comonomer contents measured by wide angle X-ray scattering

Stadler¹,

Takahashi

Yonetake

2009

E-Polymers

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Ethene-/-olefin copolymers having a wide range of comonomer contents with comonomers between 4 and 26 carbon atoms in length were characterized by wide angle X-ray scattering (WAXS). It was found that the crystallinities matched fairly well with the crystallinities from DSC and volumetric measurements. An increase of the crystal lattice size was found with increasing comonomer content and comonomer length. Both are attributed to the formation of defects around these short-chain branches in the crystal lattice, which widen it. Increasing the cooling time will lead to a more densely packed crystal structure, if the quenched structure is distorted, i.e. if the sample contains comonomer. A higher molar mass M w widens the average space between chains in the amorphous phase as well as the addition of comonomer. The latter finding is explained by the increasing number of chain ends introduced by the comonomer which increases the free volume in the sample because of the worse amorphous packing of the chain ends.

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Influence of Type and Content of Various Comonomers on Long-Chain Branching of Ethene/α-Olefin Copolymers

Cited by 123 publications

References 44 publications

Analytical Rheology of Polymer Melts: State of the Art

Analytical Rheology of Polymer Melts: State of the Art

Evidence of intra-chain phase separation in molten short-chain branched polyethylene

Lattice sizes, crystallinities, and spacing between amorphous chains - characterization of ethene-/ɑ-olefin copolymers with various comonomers and comonomer contents measured by wide angle X-ray scattering

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