Effect of secondary zone dimensions on melt fracture manifestations of high density polyethylene

1987 ◽  
Vol 26 (6) ◽  
pp. 543-547 ◽  
Author(s):  
A. Cohen
Keyword(s):  
High Density Polyethylene ◽  
High Density ◽  
Melt Fracture ◽  
Secondary Zone

scholarly journals Comparative Analysis of the Effect of Organoclay, Boron Nitride, and Fluoropolymer on the Rheology and Instabilities in the Extrusion of High Density Polyethylene

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
A. A. Adesina ◽  
M. S. Nasser ◽  
I. A. Hussein
Keyword(s):  
Comparative Analysis ◽  
Boron Nitride ◽  
High Density Polyethylene ◽  
Pressure Fluctuations ◽  
High Density ◽  
Melt Fracture ◽  
Distortion Factor ◽  
Stick Slip ◽  
Apparent Shear Rate ◽  
The Individual

The effect of different processing additives on the extrusion instabilities of high density polyethylene (HDPE) was investigated. The concentration of each processing additive was fixed at 0.05 wt%. Organoclay, boron nitride, and fluoropolymer reduced transient shear and extensional viscosities of HDPE melt. Drop in extrusion pressure occurred during the extrusion experiment. The initial loss of glossiness in HDPE was restored with the addition of these additives. However, the fluoropolymer did not succeed in eliminating the stick-slip fracture. Despite the inclusion of the processing additives, gross-melt fracture in HDPE reappeared at apparent shear rate of 141 s−1. Both moment and distortion factor methods of analyses were employed and their findings support the observed visual trends of the extrudate surface. The quantifying tools indicated that combined organoclay and fluoropolymer reduced the pressure fluctuations and its performance surpassed that of the individual additives.

Experimental study of the melt fracture behavior of filled high-density polyethylene melts

2013 ◽  
Vol 54 (2) ◽  
pp. 364-377 ◽  
Author(s):  
Francesco Baldi ◽  
Francesco Briatico-Vangosa ◽  
Anika Franceschini
Keyword(s):  
Experimental Study ◽  
High Density Polyethylene ◽  
Fracture Behavior ◽  
High Density ◽  
Melt Fracture ◽  
Polyethylene Melts

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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