Prediction of the onset of extrudate distortion in polyethylenes from rheological data

1976 ◽  
Vol 16 (9) ◽  
pp. 626-637 ◽  
Author(s):  
F. P. Smith ◽  
R. Darby
2021 ◽  
Vol 36 (1) ◽  
pp. 69-78
Author(s):  
M. Gupta

Abstract A combined flow, thermal and structural analysis is employed to simulate post-die extrudate distortion in different profile dies. All four factors which can cause extrudate distortion, namely, nonuniform exit velocity distribution, extrudate shrinkage, extrudate draw down, and deformed shape of the calibrator or sizer profile, are simulated. To analyze the effect of exit velocity variation on extrudate distortion, the parameterized geometry of a simple profile die is optimized using an extrusion die optimization software. The simulation results presented for a bi-layer profile die successfully demonstrate how gradually changing profile shape in successive calibrators/sizers can be used to simplify the die design for extrusion of complex profiles. The predicted extrudate shape and layer structure for the bi-layer die are found to accurately match with those in the extruded product.


2018 ◽  
Vol 30 (1) ◽  
pp. 21-28 ◽  
Author(s):  
Sangmo Kim ◽  
Junghaeng Lee ◽  
Sihyun Kim ◽  
Kwang Soo Cho

Author(s):  
Michael Greaves ◽  
Mana Mende ◽  
Jiacheng Wang ◽  
Wenji Yang ◽  
Suelen Barg

AbstractAmong 2D materials, MXenes (especially their most studied member, titanium carbide) present a unique opportunity for application via colloidal processing, as they are electrically conductive and chemically active, whilst still being easily dispersed in water. And since the first systematic study of colloidal MXene rheology was published in 2018 (Rheological Characteristics of 2D Titanium Carbide (MXene) Dispersions: A Guide for Processing MXenes by Akuzum, et al.), numerous works have presented small amounts of rheological data which together contribute to a deeper understanding of the topic. This work reviews the published rheological data on all MXene-containing formulations, including liquid crystals, mixtures and non-aqueous colloids, which have been used in processes such as stamping, patterning, 2D and 3D printing. An empirical model of aqueous titanium carbide viscosity has been developed, and recommendations are made to help researchers more effectively present their data for future rheological analysis. Graphic abstract


2018 ◽  
Vol 24 (2) ◽  
pp. 321-332 ◽  
Author(s):  
Joseph Bartolai ◽  
Timothy W. Simpson ◽  
Renxuan Xie

Purpose The weakest point in additively manufactured polymer parts produced by material extrusion additive manufacturing (MEAM) is the interface between adjacent layers and deposition toolpaths or “roads”. This study aims to predict the mechanical strength of parts by utilizing a novel analytical approach. Strength predictions are made using the temperature history of these interfaces, polymer rheological data, and polymer weld theory. Design/methodology/approach The approach is validated using experimental data for two common 3D-printed polymers: polycarbonate (PC) and acrylonitrile butadiene styrene (ABS). Interface temperature history data are collected in situ using infrared imaging. Rheological data of the polycarbonate and acrylonitrile butadiene styrene used to fabricate the fused filament fabrication parts in this study have been determined experimentally. Findings The strength of the interfaces has been predicted, to within 10% of experimental strength, using polymer weld theory from the literature adapted to the specific properties of the polycarbonate and acrylonitrile butadiene styrene feedstock used in this study. Originality/value This paper introduces a novel approach for predicting the strength of parts produced by MEAM based on the strength of interfaces using polymer weld theory, polymer rheology, temperature history of the interface and the forces applied to the interface. Unlike methods that require experimental strength data as a prediction input, the proposed approach is material and build orientation agnostic once fundamental parameters related to material composition have been determined.


2018 ◽  
Vol 50 (2) ◽  
pp. 114-123
Author(s):  
Ana Paula Stafussa ◽  
Valéria Rampazzo ◽  
Rubens Rosario Fernandes ◽  
Admilson Teixeira Franco ◽  
Evandro Bona ◽  
...  

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