Improvement in processability of metallocene polyethylene by ultrasound and binary processing aid

Chen, Jinyao; Liu, Xiaolong; Li, Huilin

doi:10.1002/app.24506

Cited by 10 publications

(5 citation statements)

References 23 publications

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“…Ultrasonically aided extrusion also led to an improvement of the elongation at break of LDPE/LLDPE blends 29. An addition of the diatomite/polyethylene glycol mixture to LLDPE led to an increase of the critical shear rate for the onset of sharkskin fracture and, in the presence of ultrasonic treatment, an improvement of the processibility of the LLDPE mixture was reported 30…”

Section: Introductionmentioning

confidence: 87%

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Online ultrasonic film casting of LLDPE and LLDPE/clay nanocomposites

Niknezhad

Isayev

2012

J of Applied Polymer Sci

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Transparent cast films of linear low density polyethylene (LLDPE) with nanoclay up to 10 wt % were prepared in one step process using an ultrasonically assisted compounding extruder operating at various ultrasonic amplitudes combined with film casting machine operating at various take up speeds. Thermal, rheological, morphological, and mechanical properties and gas permeability of these films were studied. Ultrasonic treatment introduced an increase in the complex viscosity and storage modulus and a reduction in the tangent loss of LLDPE/clay nanocomposite melts. Cast films prepared by ultrasonic treatment at an amplitude of 7.5 lm showed the highest mechanical properties in both the machine and transverse directions and the lowest oxygen permeability. X-ray diffraction patterns along with the SEM and TEM images revealed the presence of the exfoliated structure due to the ultrasonic treatment for cast films containing up to 7.5 wt % of clay loading. NMR studies of LLDPE cast films showed an increase of branching due to the ultrasound treatment.

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Section: Introductionmentioning

confidence: 87%

“…A few studies on the effect of ultrasound on pure LLDPE were reported 27–30. In particular, they showed that an ultrasonically aided single screw extrusion improved processing of LLDPE by reducing the die pressure and melt viscosity.…”

Section: Introductionmentioning

confidence: 99%

Online ultrasonic film casting of LLDPE and LLDPE/clay nanocomposites

Niknezhad

Isayev

2012

J of Applied Polymer Sci

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“…Li and coworkers [76] described the use of PEG as a processing aid for extrusion of UHMW PE/PP blend. Li and coworkers [77,78] also report a suppression of sharkskin melt fracture for additives of a binary blend of PEG and diatomaceous earth in amounts from 0.5 to 3 wt%. According to the authors, the blend works synergistically and PEG alone does not suppress sharkskin melt fracture.…”

Section: Peg In Lubricants and Ppamentioning

confidence: 96%

Low viscous hydrophilic processing additives for extrusion of polyethylene at reduced temperatures

Kulikov

Hornung

Wagner

2010

Polymer Engineering & Sci

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Industry is using fluorinated polymer processing additives (PPA) to delay the onset of sharkskin to higher rates of extrusion of PE resins. Yet it is necessary to keep elevated temperatures during extrusion to reduce apparent melt viscosity. We propose to use low viscous PPA made from reacting mixtures of polyethylene glycol with organic polyacids, phosphoric acid, and polyesters of oxiacids of Phosphorus. Surprisingly, extrusion pressures and apparent viscosity with the novel PPA at reduced temperatures are less, than at elevated temperatures. In total, extrusion pressures can be reduced 2-5 times for concentrations of PPA from 0.1 to 0.5 wt%, while sharkskin melt fracture can be eliminated for concentrations of PPA above 0.02 wt%. Extrusion with the novel PPA at reduced temperatures potentially increases productivity, reduces production cost, and allows processing of PE resins of higher MW and highly filled polymer composites.The use of novel PPA is a challenging opportunity to simplify processing of PO resins. The use of low viscous PEG in the composition of PPA with existing machinery has to be combined with changes in the die design for film blowing, blow molding, and pipe extrusion to extract

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“…[2][3][4] Literature on eliminating these flow instabilities have pointed out that mPE could be prepared by the improvement of synthesis techniques, using composite catalyst to produce bimodal or broad molecular weight distribution of mPE, [5][6][7] blending with similar chain structure polymers such as HDPE, LDPE, LLDPE, long chain branched PE, and UHMWPE, [8][9][10][11][12] filling with flow modifier [13][14][15] or amending the processing equipment of polyolefins. 16,17 Mechanochemical modification is an easy and efficient method for improving rheological properties of mPE. When an external force is exerted on the covalent bonds of polymer chains, they will deform and even to breakdown if the external energy is beyond the covalent bond energy, which will produce macroradicals.…”

Section: Introductionmentioning

confidence: 99%

Effect of solid‐state stress induced reaction on morphology and structure of metallocene polyethylene

Zou

Chen

Liang

et al. 2013

J of Applied Polymer Sci

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Metallocene-catalyzed polyethylene (mPE) powder was prepared through a mechanochemical reactor in solid state at ambient temperature. The changes of morphology and structure of mPE were investigated by SEM, FTIR, DSC, viscosimetry, GPC, WAXD, dynamic rheometer, and high pressure capillary rheometer methods. FTIR measurement illustrated that the branching degree of mPE increased after mechanochemical reaction. Combined with the dynamic rheological analysis, it was proved that the rupture and combination of macromolecular chain undergo strong shear resulted in the formation of long chain branches. X-ray diffraction analysis showed that the crystal form of mPE transferred from rhombic to monoclinic system partly, and the crystalline degree increased slightly in the initial mechanochemical reaction period. Viscometer test results exhibited that molecular weight of mPE dropped during the mechanochemical treatment. Rheology measurement indicated that the critical shear rate of the shark-skin failure enhanced and the extruded stands exhibited smooth face for the mPE after mechanochemical treatment.

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Improvement in processability of metallocene polyethylene by ultrasound and binary processing aid

Cited by 10 publications

References 23 publications

Online ultrasonic film casting of LLDPE and LLDPE/clay nanocomposites

Online ultrasonic film casting of LLDPE and LLDPE/clay nanocomposites

Low viscous hydrophilic processing additives for extrusion of polyethylene at reduced temperatures

Effect of solid‐state stress induced reaction on morphology and structure of metallocene polyethylene

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