Rheological characterisation of a high-density polyethylene with a multi-mode differential viscoelastic model and numerical simulation of transient elongational recovery experiments

1999 ◽  
Vol 38 (1) ◽  
pp. 48-64 ◽  
Author(s):  
F. Langouche ◽  
B. Debbaut
Keyword(s):  
Numerical Simulation ◽  
High Density Polyethylene ◽  
Viscoelastic Model ◽  
High Density ◽  
Multi Mode

scholarly journals Modelling of Elongational Flow of HDPE Melts by Hierarchical Multi-Mode Molecular Stress Function Model

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3217
Author(s):  
Leslie Poh ◽  
Esmaeil Narimissa ◽  
Manfred H. Wagner
Keyword(s):  
Stress Function ◽  
High Density Polyethylene ◽  
High Density ◽  
Molecular Characteristics ◽  
Chain Branching ◽  
Data Set ◽  
Long Chain Branching ◽  
Molecular Stress Function ◽  
Multi Mode ◽  
Long Chain

The transient elongational data set obtained by filament-stretching rheometry of four commercial high-density polyethylene (HDPE) melts with different molecular characteristics was reported by Morelly and Alvarez [Rheologica Acta 59, 797–807 (2020)]. We use the Hierarchical Multi-mode Molecular Stress Function (HMMSF) model of Narimissa and Wagner [Rheol. Acta 54, 779–791 (2015), and J. Rheology 60, 625–636 (2016)] for linear and long-chain branched (LCB) polymer melts to analyze the extensional rheological behavior of the four HDPEs with different polydispersity and long-chain branching content. Model predictions based solely on the linear-viscoelastic spectrum and a single nonlinear parameter, the dilution modulus GD for extensional flows reveals good agreement with elongational stress growth data. The relationship of dilution modulus GD to molecular characteristics (e.g., polydispersity index (PDI), long-chain branching index (LCBI), disengagement time τd) of the high-density polyethylene melts are presented in this paper. A new measure of the maximum strain hardening factor (MSHF) is proposed, which allows separation of the effects of orientation and chain stretching.

Numerical simulation of crystallization in high density polyethylene extrudates

2000 ◽  
Vol 40 (11) ◽  
pp. 2356-2373 ◽  
Author(s):  
K. M. Pillai ◽  
S. G. Advani ◽  
A. Benard ◽  
K. I. Jacob
Keyword(s):  
Numerical Simulation ◽  
High Density Polyethylene ◽  
High Density

Composition and Surface Topography Effects on Apatite-Forming Ability of Ceramic-Polymer Composites

2003 ◽  
Vol 774 ◽  
Author(s):  
Susan M. Rea ◽  
Serena M. Best ◽  
William Bonfield
Keyword(s):  
Surface Topography ◽  
High Density Polyethylene ◽  
High Density ◽  
Apatite Layer ◽  
Biologically Active ◽  
Human Blood Plasma ◽  
Apatite Formation ◽  
Polyethylene Matrix ◽  
Composite Surface ◽  
X Ray

AbstractHAPEXTM (40 vol% hydroxyapatite in a high-density polyethylene matrix) and AWPEX (40 vol% apatite-wollastonite glass ceramic in a high density polyethylene matrix) are composites designed to provide bioactivity and to match the mechanical properties of human cortical bone. HAPEXTM has had clinical success in middle ear and orbital implants, and there is great potential for further orthopaedic applications of these materials. However, more detailed in vitro investigations must be performed to better understand the biological interactions of the composites and so the bioactivity of each material was assessed in this study. Specifically, the effects of controlled surface topography and ceramic filler composition on apatite layer formation in acellular simulated body fluid (SBF) with ion concentration similar to those of human blood plasma were examined. Samples were prepared as 1 cm × 1 cm × 1 mm tiles with polished, roughened, or parallel-grooved surface finishes, and were incubated in 20 ml of SBF at 36.5 °C for 1, 3, 7, or 14 days. The formation of a biologically active apatite layer on the composite surface after immersion was demonstrated by thin-film x-ray diffraction (TF-XRD), environmental scanning electron microscopy (ESEM) imaging and energy dispersive x-ray (EDX) analysis. Variations in sample weight and solution pH over the period of incubation were also recorded. Significant differences were found between the two materials tested, with greater bioactivity in AWPEX than HAPEXTM overall. Results also indicate that within each material the surface topography is highly important, with rougher samples correlated to earlier apatite formation.

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