Rheological behaviors of a series of hyperbranched polyethers

Miao, Xuepei; Guo, Yan-shuang; He, Li; Meng, Yan; Li, Xiaoyü

doi:10.1007/s10118-015-1707-y

Cited by 12 publications

(12 citation statements)

References 48 publications

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“…The rheological properties of 3- star and 4- star -PVC are shown in Figure . The variation of complex viscosities η* with frequency at different temperatures is consistent with Newtonian behavior over the covered frequency range and suggests that both the 3- star and 4- star -PVC stars comprise largely unentangled chains that undergo rapid molecular motion even at about room temperature. , …”

Section: Resultssupporting

confidence: 64%

“All-PVC” Flexible Poly(vinyl Chloride): Nonmigratory Star-Poly(vinyl Chloride) as Plasticizers for PVC by RAFT Polymerization

Sun

Mi²,

et al. 2021

Macromolecules

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Xanthate-mediated RAFT polymerization has been used to prepare 3-star and 4-star-poly(vinyl chloride) (star-PVC) with a number average molar mass (M n ) in the range of 1 to 7 kg mol −1 . The T g of star-PVC reduces with molar mass and with the number of arms. The star-PVC have substantially lower glasstransition temperatures (T g ) than that of linear PVC of similar M n , with the T g of low-molar mass 4-star-PVC being −7.4 °C. The star-PVC are effective in lowering the T g of blends with commercial PVC when added at 10−30 wt % PVC. When added even at 10 wt %, they are effective in improving the ductility of PVC with an elongation at break (EB) of ∼350% (4-star-PVC) and ∼300% (3star-PVC) relative to commercial PVC, which is substantially higher than that for PVC conventionally plasticized with 30 wt % dioctyl phthalate under similar conditions (EB ∼160%). Importantly, the star-PVC, despite their low molar mass, do not migrate from the PVC blends when tested under standard conditions. The performance of the star-PVC as non-migratory plasticizers for PVC demonstrates the potential for an "all-PVC" flexible PVC.

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Section: Resultssupporting

confidence: 64%

“All-PVC” Flexible Poly(vinyl Chloride): Nonmigratory Star-Poly(vinyl Chloride) as Plasticizers for PVC by RAFT Polymerization

Sun

Mi²,

et al. 2021

Macromolecules

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“…The ratio χ between the pressure drop simulated based on PPR data p ppr and the experimental data p exp was calculated by χ = p ppr p exp (16) The ratio C between the pressure drop simulated based on HPCR data p HPCR and the experimental data was calculated by C = p HPCR P exp (17) The results are given in Table 6. The ratio ɕ between the pressure drop simulated based on HPCR data and the experimental data was calculated by The ratio ɕ between the pressure drop simulated based on HPCR data and the experimental data was calculated by The results for Materials 1 and 2 show that the CFD simulations using PPR data overestimate the pressure drop, whereas the simulations based on HPCR data are in good accordance with the experiments.…”

Section: Comparison Of Pipe-head Simulations With Measured Rheology Curvesmentioning

confidence: 99%

“…Since then, the Cox-Merz rule has been investigated in the context of other polymers and was found to apply to various linear and branched polymers [ 10 , 11 , 12 ]. However, several research groups have reported that the Cox-Merz relation does not hold for some polymers (e.g., concentrated suspensions compounds, highly branched polymers, polymer blends, thermoplastic elastomers, functionalized polymers and in some cases high-molecular-weight polymers) [ 13 , 14 , 15 , 16 , 17 , 18 ]. For example, Snijkers and Vlassopoulos [ 19 ] found that the Cox-Merz relation did not apply to certain well-defined branched polymers they studied.…”

Section: Introductionmentioning

confidence: 99%

Applicability of the Cox-Merz Rule to High-Density Polyethylene Materials with Various Molecular Masses

et al. 2021

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The Cox-Merz rule is an empirical relationship that is commonly used in science and industry to determine shear viscosity on the basis of an oscillatory rheometry test. However, it does not apply to all polymer melts. Rheological data are of major importance in the design and dimensioning of polymer-processing equipment. In this work, we investigated whether the Cox-Merz rule is suitable for determining the shear-rate-dependent viscosity of several commercially available high-density polyethylene (HDPE) pipe grades with various molecular masses. We compared the results of parallel-plate oscillatory shear rheometry using the Cox-Merz empirical relation with those of high-pressure capillary and extrusion rheometry. To assess the validity of these techniques, we used the shear viscosities obtained by these methods to numerically simulate the pressure drop of a pipe head and compared the results to experimental measurements. We found that, for the HDPE grades tested, the viscosity data based on capillary pressure flow of the high molecular weight HDPE describes the pressure drop inside the pipe head significantly better than do data based on parallel-plate rheometry applying the Cox-Merz rule. For the lower molecular weight HDPE, both measurement techniques are in good accordance. Hence, we conclude that, while the Cox-Merz relationship is applicable to lower-molecular HDPE grades, it does not apply to certain HDPE grades with high molecular weight.

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“…[13][14][15][16][17][18][19][20][21] Among them, the more compact conformation and three-dimensional spheroidal shape of the star polymer give it special physical-chemical properties, [22,23] such as smaller hydrodynamic volume and diffusion coefficient, lower viscosity, low glass transition temperature, and high functionality. [24][25][26] Whittaker et al synthesized Nisopropylacrylamide (NIPAM) star polymers through the use of an 4-arm RAFT agent. The lower critical solution temperature (LCST) transitions of these star-shaped PNIPAM were significantly depressed by the presence of the hydrophobic star core.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of star-shaped polyzwitterions with adjustable UCST and fast responsiveness by a facile RAFT polymerization

Sun

et al. 2020

Polym. Chem.

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Rheological behaviors of a series of hyperbranched polyethers

Cited by 12 publications

References 48 publications

“All-PVC” Flexible Poly(vinyl Chloride): Nonmigratory Star-Poly(vinyl Chloride) as Plasticizers for PVC by RAFT Polymerization

“All-PVC” Flexible Poly(vinyl Chloride): Nonmigratory Star-Poly(vinyl Chloride) as Plasticizers for PVC by RAFT Polymerization

Applicability of the Cox-Merz Rule to High-Density Polyethylene Materials with Various Molecular Masses

Synthesis of star-shaped polyzwitterions with adjustable UCST and fast responsiveness by a facile RAFT polymerization

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