High-molecular-weight high-density polyethylene (HMWHDPE)

2007 ◽  
pp. 496-496
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
High Density Polyethylene ◽  
High Density

scholarly journals Applicability of the Cox-Merz Rule to High-Density Polyethylene Materials with Various Molecular Masses

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1218
Author(s):  
Raffael Rathner ◽  
Wolfgang Roland ◽  
Hanny Albrecht ◽  
Franz Ruemer ◽  
Jürgen Miethlinger
Keyword(s):  
Molecular Weight ◽  
Pressure Drop ◽  
High Molecular Weight ◽  
High Density Polyethylene ◽  
Parallel Plate ◽  
Empirical Relationship ◽  
Polymer Processing ◽  
High Density ◽  
Viscosity Data ◽  
Molecular Masses

The Cox-Merz rule is an empirical relationship that is commonly used in science and industry to determine shear viscosity on the basis of an oscillatory rheometry test. However, it does not apply to all polymer melts. Rheological data are of major importance in the design and dimensioning of polymer-processing equipment. In this work, we investigated whether the Cox-Merz rule is suitable for determining the shear-rate-dependent viscosity of several commercially available high-density polyethylene (HDPE) pipe grades with various molecular masses. We compared the results of parallel-plate oscillatory shear rheometry using the Cox-Merz empirical relation with those of high-pressure capillary and extrusion rheometry. To assess the validity of these techniques, we used the shear viscosities obtained by these methods to numerically simulate the pressure drop of a pipe head and compared the results to experimental measurements. We found that, for the HDPE grades tested, the viscosity data based on capillary pressure flow of the high molecular weight HDPE describes the pressure drop inside the pipe head significantly better than do data based on parallel-plate rheometry applying the Cox-Merz rule. For the lower molecular weight HDPE, both measurement techniques are in good accordance. Hence, we conclude that, while the Cox-Merz relationship is applicable to lower-molecular HDPE grades, it does not apply to certain HDPE grades with high molecular weight.

Influence of Processing Aids and Hydroxyapatite as Fillers on Flow Behaviour and Mechanical Properties of Ultra High Molecular Weight Polyethylene/High Density Polyethylene Composites

2011 ◽  
Vol 471-472 ◽  
pp. 827-832 ◽  
Author(s):  
Mazatusziha Ahmad ◽  
Mat Uzir Wahit ◽  
Mohammed Rafiq Abdul Kadir ◽  
Khairul Zaman Mohd Dahlan
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
High Density Polyethylene ◽  
Flexural Modulus ◽  
High Density ◽  
Compression Moulding ◽  
Biomedical Implant ◽  
Bone Properties ◽  
Ultra High Molecular Weight

In this study, blends of ultra high molecular weight polyethylene/high density polyethylene/polyethylene glycol (UHMWPE/HDPE/PEG) and the composites containing Hydroxyapatite (HA) as reinforcement filler were prepared via single screw extruder nanomixer followed by compression moulding. PEG (2phr) was used as processing aid and HA loadings were varied from 10 to 50 phr. HDPE and PEG were introduced to improve the extrudability of UHMWPE. Rheological behavior was studied via capillary rheometer while flexural and izod impact tests were conducted in order to investigate the mechanical properties of the blends and composites. Melt viscosity of the blends was found to decrease with increasing shear rate indicating a pseudoplastic behaviour. Incorporation of PEG shows a synergism effect on the reduction of blends viscosity. Blend of 40% UHMWPE/ 60% HDPE/ 2 phr PEG was chosen as the optimum blend composition with a balance properties in terms of the mechanical properties and processability. The incorporation of HA fillers from 10 to 50 phr into the blend resulted in the increase of flexural modulus and flexural strength with a slight decline of impact strength values. It can be concluded that the composites having adequate strength and modulus within the range of cancellous bone properties were succesfully developed to be used as biomedical implant devices.

scholarly journals High-density polyethylene crystals with double melting peaks induced by ultra-high-molecular-weight polyethylene fibre

2018 ◽  
Vol 5 (7) ◽  
pp. 180394 ◽  
Author(s):  
Weijun Miao ◽  
Hao Zhu ◽  
Tianchen Duan ◽  
Hongbing Chen ◽  
Feng Wu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
High Density Polyethylene ◽  
Fibre Composite ◽  
Crystal Form ◽  
High Density ◽  
Scanning Calorimetry ◽  
Orthorhombic Crystal ◽  
Fibre Composites ◽  
Ultra High Molecular Weight

High-density polyethylene (HDPE)/ultra-high-molecular-weight polyethylene (UHMWPE) fibre composites were prepared via solution crystallization to investigate the components of epitaxial crystal growth on a highly oriented substrate. Scanning electron microscopy morphologies of HDPE crystals on UHMWPE fibres revealed that the edge-on ribbon pattern crystals that were formed initially on UHMWPE fibres converted afterwards to a sheet shape as crystallization progressed. Wide-angle X-ray diffraction confirmed that the polymer chain oriented along the fibre axis and the orthorhombic crystal form of HDPE remained unchanged in HDPE/UHMWPE fibre composite systems. The thermal behaviour of the fibre composites measured by differential scanning calorimetry showed double melting peaks, the nature of which, as disclosed by partial melting experiments, is ascribed to bilayer components existing in the induced crystals: the inner layer is composed of more regularly folded chain crystals induced by UHMWPE fibres, and the outer layer formed on the inner one with a thinner and lower ordered crystal structure.

Study of the Nature of the Influence of some Oligophosphonates on the Rheological Properties of High-Density Polyethylene

2021 ◽  
Vol 899 ◽  
pp. 606-612
Author(s):  
Abubekir Kh. Shaov ◽  
Asya N. Beslaneeva ◽  
Gennady B. Shustov ◽  
Albina M. Altueva
Keyword(s):  
Molecular Weight ◽  
Rheological Properties ◽  
High Molecular Weight ◽  
High Density Polyethylene ◽  
Functional Group ◽  
High Density ◽  
Low Molecular Weight ◽  
Phosphorus Containing ◽  
Cyclic Compounds

High molecular weight compounds with organophosphorus backbones are usually obtained by polycondensation of phosphorus-containing monomers, leading, most often, to products of low molecular weight at low yields. This fact is explained [1] by several reasons: a decrease in the reactivity of the second functional group of the monomer after the first one has reacted; the possibility of the formation of cyclic compounds; hydrolytic instability of the phosphorus-heteroatom bond (usually P-O, P-N), etc.

Natural fiber-reinforced high-density polyethylene composite hybridized with ultra-high molecular weight polyethylene

2019 ◽  
Vol 53 (15) ◽  
pp. 2119-2129 ◽  
Author(s):  
Haibin Ning ◽  
Selvum Pillay ◽  
Na Lu ◽  
Shaik Zainuddin ◽  
Yongzhe Yan
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
High Molecular Weight ◽  
Hybrid Material ◽  
High Density Polyethylene ◽  
Natural Fiber ◽  
High Density ◽  
Low Density ◽  
Fiber Reinforced ◽  
Ultra High Molecular Weight

A great deal of research and development work has been recently conducted on natural fiber-reinforced polymer matrix composite for its abundancy, low density, excellent damping characteristic, and good mechanical properties. However, the low strength of natural fiber composite has limited its use to only low stress applications. The purpose of this work is to develop a natural fiber hybrid material with both enhanced strength and failure strain using a novel approach and study the effect of the processing temperature on its microstructure and performance. High-strength ultra-high molecular weight polyethylene fabrics are co-molded onto the surfaces of a kenaf fiber high-density polyethylene-based composite material by single-step compression molding. The status of the ultra-high molecular weight polyethylene fabrics at different processing temperatures is investigated using microscopic analysis. The tensile strength and impact strength of the hybrid material are evaluated. It is found that its tensile strength is increased by more than 90% with only 8% ultra-high molecular weight polyethylene fiber reinforcement added and its low density is maintained.

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