On the processability of metallocene-catalysed polyethylene: effects of blending with ethylene–vinyl acetate copolymer

Peón, J; Aguilar, M.; Vega, Juan Francisco; Amo, B. del; Martínez‐Salazar, Javier

doi:10.1016/s0032-3861(02)00941-2

Cited by 18 publications

(13 citation statements)

References 41 publications

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“…We can thus imagine that this critical shear rate is inversely proportional to a characteristic relaxation time. To define this time, we have studied the variation of the critical shear rate with the weight average molecular weight, using data from the literature [6,16,[31][32][33]. On Fig.…”

Section: Expression Of Critical Shear Ratementioning

confidence: 99%

Relationships between molecular structure and sharkskin defect for linear polymers

Allal

Lavernhe

Vergnes

et al. 2006

Journal of Non-Newtonian Fluid Mechanics

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Section: Expression Of Critical Shear Ratementioning

confidence: 99%

Relationships between molecular structure and sharkskin defect for linear polymers

Allal

Lavernhe

Vergnes

et al. 2006

Journal of Non-Newtonian Fluid Mechanics

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“…Various techniques have been used to increase Q for metallocene/MAO‐catalyzed polyolefins. Blending polymers of different molar masses, M W in extruder15–17 requires excessive amounts of energy to attain acceptable homogeneity. Employing multiple polymerization reactors in tandem7, 18–19 is capital‐intensive.…”

Section: Introductionmentioning

confidence: 99%

Gas‐phase olefin polymerization over supported metallocene/MAO catalysts: influence of support on activity and polydispersity

Hammawa

Wanke

2006

Polymer International

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Three catalysts obtained by supporting bis(n‐butylcyclopentadienyl)zirconium dichloride/methylaluminoxane on: (1) porous crosslinked poly(2‐hydroxyethylmethacrylate‐co‐styrene‐co‐divinylbenzene) particles (CAT1); (2) swellable crosslinked poly(styrene‐co‐divinylbenzene) particles (CAT2); and (3) by evaporating the catalyst precursors solution to dry powder, CAT3 were used in gas‐phase polymerization of ethylene, and ethylene/1‐hexene in a 2 L semi‐batch reactor at 80 °C and 1.4 MPa. The average polymerization activities of the three catalysts were 12.3–15.5, 4.2–10.1, and 14.3–62.9 ton PE (mol Zr h)−1 respectively. CAT1 and CAT3 produced polyethylenes with a polydispersity range of 2.3–2.7, while that of CAT2 was 3.5–6.4. The supported catalysts produced polyolefin particles with bulk density of 0.36–0.43 g ml−1, and essentially no fines. Ethylene/1‐hexene co‐polymerization (7 mol m−3 initial 1‐hexene concentration in the reactor) increased polymerization activities and produced lower‐molar‐mass co‐polymers. At 21 mol m−3 1‐hexene the polymerization activities decreased, but the relative amount of the low‐molar‐mass co‐polymer for CAT2 increased, leading to higher polydispersity. Copyright © 2006 Society of Chemical Industry

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“…Martinez-Salazar et al studied the rheological properties of metallocene-catalyzed linear polyethylenes and those of blends prepared with ethylene vinyl acetate copolymer. 22 In the present work we have studied the dynamic mechanical properties of low-density polyethylene (LDPE), high-density polyethylene (HDPE), and the effect of ethylene vinyl acetate copolymer (EVA) blending on various transitions (␣, ␤, and ␥ transitions). Moreover the miscibility of the blends was examined both theoretically and experimentally, and it was correlated with blend morphology examined by scanning electron microscopy (SEM).…”

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confidence: 99%

Dynamic mechanical properties and morphology of polyethylene/ethylene vinyl acetate copolymer blends

et al. 2004

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Dynamic mechanical analysis (DMA) was used to study the miscibility and various transitions (␣, ␤, and ␥ ) in binary blends of ethylene vinyl acetate copolymer (EVA) with low-density polyethylene (LDPE) and high-density polyethylene (HDPE). Addition of a rubbery phase, such as EVA, reduced all the transition temperatures. A peak broadening of tan ␦ was observed with increasing EVA content in the blends. This can be explained by the observed reduction of the crystallinity of the systems. The presence of a single transition peak in the region of glass transition temperature (T g ) has indicated that the blends were miscible. However, morphological investigation by scanning electron microscopy (SEM) revealed the features of a two phase system in which the EVA domains would be dispersed in the polyethylene (PE) phase. The results have demonstrated that DMA is not sensitive enough to study the miscibility of polymeric blends with a similar backbone structures (such as PE and EVA) in view of the small difference in their T g . For such blends, therefore, the use of direct observations, such as microscopic examinations is necessary.

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On the processability of metallocene-catalysed polyethylene: effects of blending with ethylene–vinyl acetate copolymer

Cited by 18 publications

References 41 publications

Relationships between molecular structure and sharkskin defect for linear polymers

Relationships between molecular structure and sharkskin defect for linear polymers

Gas‐phase olefin polymerization over supported metallocene/MAO catalysts: influence of support on activity and polydispersity

Dynamic mechanical properties and morphology of polyethylene/ethylene vinyl acetate copolymer blends

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