Rheometry of polymer melts using processing machines

Friesenbichler, Walter; Neunhäuserer, Andreas; Đuretek, Ivica

doi:10.1007/s13367-016-0016-5

Cited by 10 publications

(7 citation statements)

References 16 publications

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“…Effects of viscous heating must be corrected when viscosity measurements are done using a temperature correction method presented in Ref. . The simulation led to the conclusion that relatively high injection speeds are necessary to fill the features.…”

Section: Discussionmentioning

confidence: 99%

A review on microfabrication of thermoplastic polymer‐based microneedle arrays

Aar

Brouwer

2019

Polymer Engineering & Sci

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This article will provide an overview of recent developments for microneedles made using injection molding and hot embossing techniques for active transdermal drug delivery. Microneedle arrays are developed for pain‐free and efficient drug delivery without using a cold chain. The focus of this article will be on the use of engineering thermoplastics and microneedle manufacturing techniques including patterning. Recent developments demonstrate that commercialization of polymer‐based microneedle systems is feasible. POLYM. ENG. SCI., 59:877–890, 2019. © 2019 Society of Plastics Engineers

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Section: Discussionmentioning

confidence: 99%

A review on microfabrication of thermoplastic polymer‐based microneedle arrays

Aar

Brouwer

2019

Polymer Engineering & Sci

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“…However, in injection molding of thin-walled parts, wall shear rates can significantly exceed 1000

and intense viscous heating arises, thus resulting in a severely reduced viscosity [ 5 ]. For a simulation of such injection molded parts, an excellent description of the rheological behavior of viscous polymer melts relies on an experimentally measured shear viscosity that is free of the large errors introduced by undesirable effects, such as the temperature deviations due to viscous heating [ 3 , 6 , 7 , 8 , 9 , 10 ] or the pressure dependence of viscosity [ 11 , 12 , 13 , 14 ]. Capillary rheometry provides an efficient access to high-shear-rate flow properties relevant for processing.…”

Section: Introductionmentioning

confidence: 99%

“…The standard methods for interpreting capillary rheometer data to determine the shear viscosity are, however, based on the isothermal flow condition. Because of the highly viscous nature of polymer melts and their low thermal conductivities, experimental and computational evidences for appreciable fluid temperature rises of

due to viscous heating have been reported in the literature for various materials in die flows [ 3 , 4 , 6 , 7 , 8 , 13 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ], therefore viscous heating can be a disturbing factor in viscosity measurements.…”

Section: Introductionmentioning

confidence: 99%

“…To address viscous heating in capillary or slit flows, it is possible to measure the temperature rise of the fluid in the flow channels by means of various experimental techniques [ 4 , 15 , 16 , 17 , 18 , 19 , 21 , 22 , 23 ]. The effects of viscous heating can also be analyzed by means of theoretical calculations of temperature profiles [ 1 , 3 , 4 , 7 , 8 , 9 , 13 , 14 , 16 , 17 , 20 , 21 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. In principle, the temperature rises obtained from either of the two approaches can be combined with a viscous heating correction method to retrieve the equivalent viscosity for isothermal flow [ 7 , 15 , 33 ].…”

Section: Introductionmentioning

confidence: 99%

“…The effects of viscous heating can also be analyzed by means of theoretical calculations of temperature profiles [ 1 , 3 , 4 , 7 , 8 , 9 , 13 , 14 , 16 , 17 , 20 , 21 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. In principle, the temperature rises obtained from either of the two approaches can be combined with a viscous heating correction method to retrieve the equivalent viscosity for isothermal flow [ 7 , 15 , 33 ]. Because of the coupling of the momentum and energy equations, the only way to obtain detailed temperature distributions in the general case is to numerically solve the governing equations along with the appropriate boundary conditions.…”

Section: Introductionmentioning

confidence: 99%

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Retrieving Equivalent Shear Viscosity for Molten Polymers from 3-D Nonisothermal Capillary Flow Simulation

Wen¹,

Wang²,

Cyue³

et al. 2021

Polymers

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For highly viscous polymer melts, considerable fluid temperature rises produced by viscous heating can be a disturbing factor in viscosity measurements. By scrutinizing the experimental and simulated capillary pressure losses for polymeric liquids, we demonstrate the importance of applying a viscous heating correction to the shear viscosity, so as to correct for large errors introduced by the undesirable temperature rises. Specifically, on the basis of a theoretical derivation and 3-D nonisothermal flow simulation, an approach is developed for retrieving the equivalent shear viscosity in capillary rheometry, and we show that the shear viscosity can be evaluated by using the average fluid temperature at the wall, instead of the bulk temperature, as previously assumed. With the help of a viscous Cross model in analyzing the shear-dominated capillary flow, it is possible to extract the viscous heating contribution to capillary pressure loss, and the general validity of the methodology is assessed using the experiments on a series of thermoplastic melts, including polymers of amorphous, crystalline, and filler-reinforced types. The predictions of the viscous model based on the equivalent viscosity are found to be in good to excellent agreement with experimental pressure drops. For all the materials studied, a near material-independent scaling relation between the dimensionless temperature rise (Θ) and the Nahme number (Na) is found, Θ ~ Na0.72, from which the fluid temperature rise due to viscous heating as well as the resultant viscosity change can be predicted.

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Quality monitoring and control for plasticization of acrylonitrile‐butadiene‐styrene regrind polymer in injection molding

Chen,

Wong,

Huang

2023

Polymer Engineering & Sci

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To meet net‐zero carbon emissions in injection molding, it is desirable to use regrind polymers in plastic parts fabrication. However, the quality of regrind polymer differs from virgin polymer due to the effects of temperature, pressure, and shear stress in the prior molding process. Consequently, the molded components differ in quality compared to those made from virgin material. This study investigates the feasibility of enhancing the quality consistency of regrind plastic components by controlling melt quality in plasticization. The evaluation of melt quality involves extracting two quality metrics from the pressure signal (i.e., the peak pressure and the pressure integral). They are then used to adjust the plasticization parameters as required to ensure that the weight and dimensions of the final regrind parts approach those of parts produced using virgin polymer. The experimental results show that the pressure integral effectively indicates the quality variation of the molded part during the injection molding of regrind polymer. Notably, by adjusting the back pressure, the quality of the molded part closely resembles that of the part made from virgin feedstock after six shots.

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Rheometry of polymer melts using processing machines

Cited by 10 publications

References 16 publications

A review on microfabrication of thermoplastic polymer‐based microneedle arrays

A review on microfabrication of thermoplastic polymer‐based microneedle arrays

Retrieving Equivalent Shear Viscosity for Molten Polymers from 3-D Nonisothermal Capillary Flow Simulation

Quality monitoring and control for plasticization of acrylonitrile‐butadiene‐styrene regrind polymer in injection molding

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