Theoretical correlation of linear and non-linear rheological symptoms of long-chain branching in polyethylenes irradiated by electron beam at relatively low doses

Entezam, Mehdi; Abbasi, Mahdi; Ahmadi, Mostafa

doi:10.1007/s00397-017-1029-9

Cited by 19 publications

(26 citation statements)

References 56 publications

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“…One of the most appropriate methods to find which one of the two other phenomena could be predominant during EOC irradiation is the rheological studies in the linear viscoelastic regime. 26,37 Figure 1(a)-(c) shows the complex viscosity (ɳ * ), storage modulus (G ' ), and loss modulus (G " ) versus angular frequency (ω) for EOC-0 and EOC-20 samples. Both samples show a power-law rheological behavior in whole the range of frequency.…”

Section: Irradiation Effect On the Properties Of Eocmentioning

confidence: 99%

“…Irradiation of the raw materials of POs, using ionizing beams such as electron and gamma, could be one of the appropriate and interesting methods to modify their molecular characteristics and physico-mechanical properties. 22,[24][25][26] In fact, irradiation could be considered a method to obtain new grades of POs. 27,28 However, how irradiation affects the properties of POs is significantly depended on the irradiation process conditions, including dose, temperature, and atmosphere of irradiation.…”

Section: Introductionmentioning

confidence: 99%

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Irradiation processing of immiscible PP/EOC blend: Morphology control and processability modification

Hassan

Entezam

2020

J of Applied Polymer Sci

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In this study, applying electron beam irradiation method at a relatively lowirradiation dose (20 kGy) under the air atmosphere to prepare injectable polypropylene (PP)/ethylene-octene copolymer (EOC) blends with fine morphology and appropriate performance was investigated. For this purpose, an extrusion PP grade with an EOC grade suitable to improve its impact resistance was melting blended. Gel content and rheological measurements revealed long-chain branching is predominant phenomenon occurring during the irradiation process of EOC. Blend irradiation resulted in changing its melt flow index proper for injection molding. A fine morphology obtained for the unirradiated blend was preserved for the irradiated blend. Moreover, irradiation thermally stabilized the blend morphology. Blends linear viscoelastic behavior discussed by proper rheological models revealed the existence of interfacial interactions and a reduction of the interfacial tension between irradiated blend phases. No significant effect of irradiation on the crystallization characteristics of EOC and the blend was observed. The satisfying impact resistance of the irradiated blend was near to that of the unirradiated blend, although its tensile mechanical properties were less.

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Section: Irradiation Effect On the Properties Of Eocmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Irradiation processing of immiscible PP/EOC blend: Morphology control and processability modification

Hassan

Entezam

2020

J of Applied Polymer Sci

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“…However, short reaction time and the inherent non‐polar structure of polyolefins limit the control over the final polymer properties. Specifically, such processes are accompanied by inevitable side‐reactions like chain scission or branching . Lastly, the reactive co‐polymer approach, which has been recently developed by Chung and his co‐workers, is based on using special reactive co‐monomers or chain transfer agents .…”

Section: Introductionmentioning

confidence: 99%

“…Specifically, such processes are accompanied by inevitable side-reactions like chain scission or branching. [14] Lastly, the reactive co-polymer approach, which has been recently developed by Chung and his co-workers, is based on using special reactive comonomers or chain transfer agents. [7] Such reactive comonomers, like borane-containing monomers, p-vinyl styrene and p-methylstyrene, can be simply copolymerized with olefinic monomers in the presence of the commercially available Ziegler−Natta and metallocene catalyst.…”

Section: Introductionmentioning

confidence: 99%

A mechanistic study on the synthesis of branched functional polyethylene through reactive co‐polymer approach

Jandaghian

Ahmadjo

Mortzavi

et al. 2020

Applied Organom Chemis

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The reactive co‐polymer approach is one of the most promising techniques for the synthesis of functional polyolefins. Following this concept, 1‐hexene and p‐methylstyrene are co‐polymerized in the presence of a generic Brookhart‐type catalyst. The microstructures of the co‐polymers imply the tendency of p‐methylstyrene co‐monomers to place at the end of the structural branches formed by the chain walking reaction. The molar masses of the co‐polymers decrease, not only at higher levels of co‐monomer but surprisingly by decreasing reaction temperature. A mechanism consisting of a highly stable η3 metal–benzyl intermediate, which is quantitatively approved by density functional theory calculations, can delicately justify all the aforementioned observations. A series of the produced co‐polymers is selectively functionalized by maleic anhydride at the benzylic position of p‐methylstyrene, under very mild reaction conditions. Such a reactive intermediate opens the path for the introduction of different types of functionalities in polyolefins. Namely, the grafted co‐polymers were further functionalized by a triazole ring, which provides a transient supramolecular network through intermolecular hydrogen bonding.

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“…It has been reported that nucleation of the cell depends on the critical size of the rubber particles and its total surface within the matrix [38,39]. Conversely, cell growth depends on the composition of the polymer matrix [40]. Kim et al [38] proved that the final morphology of polypropylene blend foams is influenced by the size and overall surface area of the dispersed rubber particles.…”

Section: Introductionmentioning

confidence: 99%

Cell structure-impact property relationship of polypropylene/thermoplastic elastomer blend foams

Heidari¹,

Fasihi²

2019

Express Polym. Lett.

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The purpose of the present study was to investigate the effect of cellular structure on the impact strength of polypropylene/polyolefin elastomers blend foams produced by the continuous extrusion process. To create different cell sizes, two chemical blowing agents were employed: azodicarbonamide and sodium bicarbonate. Sodium bicarbonate created foams with bigger cell size and cell wall thickness than azodicarbonamide. The impact strength of the neat and blend foams were studied and correlated to the foam properties and structure. It was observed that the impact strength of blend foams was directly related to the concentration of polyolefin elastomers (POE). Increasing POE by up to 30 wt% increased the foam impact strength by more than 400%. On the other hand, Increasing POE content caused the cell size and cell wall thickness to be reduced. Moreover, an attempt has been made to establish a relationship between the impact strength and cellular structural parameters. It was found that in the blend foams with higher cell wall thickness the rough fracture of the cell walls was intensified and in turn, the impact strength of the foams improved further.

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Theoretical correlation of linear and non-linear rheological symptoms of long-chain branching in polyethylenes irradiated by electron beam at relatively low doses

Cited by 19 publications

References 56 publications

Irradiation processing of immiscible PP/EOC blend: Morphology control and processability modification

Irradiation processing of immiscible PP/EOC blend: Morphology control and processability modification

A mechanistic study on the synthesis of branched functional polyethylene through reactive co‐polymer approach

Cell structure-impact property relationship of polypropylene/thermoplastic elastomer blend foams

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