The oscillating die: A useful concept in polymer extrusion

Casulli, J.; Clermont, Jean‐Robert; Ziegler, A. Von; Mena, B.

doi:10.1002/pen.760302310

Cited by 27 publications

(22 citation statements)

References 6 publications

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“…Throughputs can be increased by increasing pressure, which require more powerful and more expensive equipment, or by increasing the temperature of the melt which reduces viscosity. Experiments with vibrated walls and vibrated dyes show that the slip-stick mechanism responsible for melt instability in annual dyes under high pressure is altered, allowing a large increase of the throughputs (21,(23)(24)(25) and/or a reduction of the required pressure or temperature at identical throughputs. This can be beneficial in the case where a temperature reduction results in a decrease of degradation by oxidation or by chemical decomposition.…”

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confidence: 99%

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Control of polymer properties by melt vibration technology: A review

Ibar¹

1998

Polymer Engineering & Sci

144

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This paper reviews the technology of melt vibration (more specifically at low frequency) to reduce viscosity during processing of plastics and to enhance mechanical px-formance of the solidified parts. The effect of vibration frequency and amplitude on melt viscosity is explained in terms of shear-thinning criteria. The effect of pressure and temperature on shear thinning is also reviewed to predict how these variables interfere with melt vibration. Practical applications of the principles of melt vibration are provided in injection molding, extrusion and compression molding/tliermoforming, from reduction of viscosity to lowering processing temperature and pressure to the elimination of melt defects and weld lines, to the enhancement of mechanical properties, stiffness and strength, by modification of the amorphous and semicrystalline texture and orientational state. Commercially available equipments are reviewed. Results showing the effect of melt vibration durin

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confidence: 99%

“…The throughput in annular dies can be increased by 30% to 50% by the effect of wall vibration (21,(23)(24)(25). Schramm also demonstrated, as early as 1976, that vibrating the nozzles of injection molding machines (20) resulted in higher throughputs and parts with less shrinkage.…”

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confidence: 99%

Control of polymer properties by melt vibration technology: A review

Ibar¹

1998

Polymer Engineering & Sci

144

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“…High-density polyethylene (HDPE) 6100M, with a melt index of 0.15 g/10 min (2308C, 2.16 kg)and a density of 0.954 g/cm 3 , was commercially obtained from Lanzhou Chemical Industry Co. (Lanzhou, China).…”

Section: Methodsmentioning

confidence: 99%

Effect of vibration extrusion on high‐density polyethylene

Gao

Zhang

Chang-sen

et al. 2007

J of Applied Polymer Sci

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A new type of extrusion apparatus with a hydraulic vibration field was self-developed to study the effects of vibration on the rheological behavior, mechanical properties, and morphology of high-density polyethylene (HDPE) during the process of extrusion. In the research, the morphology and mechanical properties of specimens produced by conventional extrusion molding were used for comparison with specimens obtained via vibration extrusion molding. The research showed that the extrusion property of the HDPE melt was improved under a vibration field, and the apparent viscosity decreased. The maximum decrement of the apparent viscosity was 37.98%. The change in the apparent viscosity of the HDPE melt corresponded to the vibration frequency and amplitude, die temperature, and rotational speed of the extruder screw. Both the longitudinal and transverse yield strengths of the HDPE specimens increased under the vibration field. The increment of the longitudinal yield strength (11.5%) was bigger than that of the transverse yield strength (6.9%). According to scanning electron microscopy micrographs, the vibration field made the crystallites orient and become smaller, and the crystal size became more homogeneous.

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“…Likewise, pulsating and oscillating flows are important in the industrial applications such as polymer extrusion using oscillatory dies. The effect of the oscillations on the heat transfer and their interplay with inertia and viscous dissipation in nonNewtonian fluids, such as the dependency of the bulk temperature on frequency and amplitude of the oscillations, has been reported [14][15][16][17][18][19][20][21]. In addition, the use of pulsations has also been of interest in connection with heat, turbulent heat, mass transfer and coating processes [22][23][24].…”

Section: Introductionmentioning

confidence: 99%