Influence of the particle size of the MgCl2 support on the performance of Ziegler catalysts in the polymerization of ethylene to ultra-high molecular weight polyethylene and the resulting polymer properties

2017 ◽  
Vol 55 (16) ◽  
pp. 2679-2690 ◽  
Author(s):  
An Philippaerts ◽  
Richard Ensinck ◽  
Nicolas Baulu ◽  
Astrid Cordier ◽  
Kersten Woike ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
High Molecular Weight ◽  
Polymer Properties ◽  
Ultra High Molecular Weight

scholarly journals Particle morphology, structure and properties of nascent ultra-high molecular weight polyethylene

2020 ◽  
Vol 7 (8) ◽  
pp. 200663
Author(s):  
Wenyang Zhang ◽  
Zhengwen Wu ◽  
Hanjun Mao ◽  
Xinwei Wang ◽  
Jianlong Li ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
High Molecular Weight ◽  
Liquid Paraffin ◽  
Particle Morphology ◽  
Particle Growth ◽  
Structure And Properties ◽  
Uhmwpe Particle ◽  
Ultra High Molecular Weight ◽  
Polymerization Method

The effects of particle morphology on the structure and swelling/dissolution and rheological properties of nascent ultra-high molecular weight polyethylene (UHMWPE) in liquid paraffin (LP) were elaborately explored in this article. Nascent UHMWPE with different particle morphologies was prepared via pre-polymerization technique and direct polymerization. The melting temperature and crystallinity of UHMWPE resins with different particle morphologies were compared, and a schematic diagram was proposed to illustrate the mechanism of UHMWPE particle growth synthesized by pre-polymerization method and direct polymerization. The polymer globules in the nascent UHMWPE prepared by using pre-polymerization technique are densely packed and a positive correlation between the particle size and the viscosity-averaged molecular weight can be observed. The split phenomenon of particles and the fluctuation in the viscosity of UHMWPE/LP system prepared by direct polymerization can be observed at a low heating rate and there is no correlation between particle size and viscosity-averaged molecular weight.

Polymer Composite Materials Based on Ultra High Molecular Weight Polyethylene Matrix Filled by Alumina Powders

2014 ◽  
Vol 1040 ◽  
pp. 124-129 ◽  
Author(s):  
O.V. Kovalevskaia ◽  
Y.I. Gordeev ◽  
Arthur K. Abkaryan
Keyword(s):  
Molecular Weight ◽  
Experimental Investigation ◽  
Particle Size ◽  
Composite Materials ◽  
High Molecular Weight ◽  
Polymer Composite ◽  
Polymer Composite Materials ◽  
Polyethylene Matrix ◽  
Microstructure And Properties ◽  
Ultra High Molecular Weight

The paper presents the results of experimental investigation of formation microstructure and properties of ultra high molecular weight polyethylene (UHMW-PE), modified by ceramics А12О3 particles by different particle size and method of obtaining.

scholarly journals Conventional Ultra-high Molecular Weight Polyethylene versus Highly Cross-linked Polyethylene from Semi-constrained, Fixed-bearing Total Ankle Arthroplasty Systems

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0010
Author(s):  
Oliver Schipper ◽  
Steven Haddad ◽  
Spencer Fullam ◽  
Robin Pourzal ◽  
Markus Wimmer
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Wear Rate ◽  
High Molecular Weight ◽  
Particle Shape ◽  
Total Ankle Arthroplasty ◽  
Fixed Bearing ◽  
Ankle Arthroplasty ◽  
The Mean ◽  
Ultra High Molecular Weight

Category: Ankle Arthritis Introduction/Purpose: The aim of this study was to compare the polyethylene wear rate, particle size, and particle shape of primary semi-constrained, fixed-bearing, bone-sparing total ankle arthroplasty using conventional ultra-high molecular weight polyethylene (CPE) versus highly cross-linked polyethylene (HXLPE) by applying a level walking input using a joint simulator. Methods: Two fixed-bearing total ankle replacement systems with different types of polyethylene liners were tested: 1.) CPE sterilized in ethylene oxide, and 2.) HXLPE sterilized with gas plasma after electron beam irradiation. Three implants for each design underwent wear testing using gravimetric analysis over 5 million simulated walking cycles. A fourth implant was used as a load soak control. Equivalent circle diameter (ECD) and equivalent shape ratio (ESR) were computed to determine particle size and particle shape, respectively. Results: The mean wear rate from 1.5-5 million cycles (MC) was 2.0±0.3mg/MC for HXLPE and 16.7±1.3mg/MC for CPE (P < 0.001). The total number of particles per cycle generated for HXLPE and CPE were 0.17x106 particles/cycle and 0.53x106 particles/cycle, respectively (P < 0.001). The mean ECD of HXLPE particles (0.22 ±0.11μm) was significantly smaller than the mean ECD of CPE particles (0.32±0.14μm) (P<0.001). HXLPE particles were significantly more round than CPE particles (P<0.001). Conclusion: HXLPE liners had a significantly lower wear rate and produced significantly fewer and rounder particles than CPE liners. The results of this study suggest that HXLPE has more favorable wear characteristics for total ankle arthroplasty.

Microstructures of ultra high molecular weight polyethylene by SEM

1995 ◽  
Vol 53 ◽  
pp. 500-501
Author(s):  
H. C. Wang ◽  
C. Sung ◽  
J. Hamilton
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Particle Size ◽  
High Molecular Weight ◽  
Optical Transmission ◽  
Transmission Microscopy ◽  
Orthopedic Applications ◽  
Ultra High Molecular Weight ◽  
Fractured Surface ◽  
Small Holes

Ultra high molecular weight polyethylene (UHMWPE) is widely used in many orthopedic applications because of its good mechanical properties and excellent biocompatability. Mechanical properties are related to its ultra-high molecular weight, but the presence of defects in morphology will cause a decrease in these properties. The aim of this study was to characterize the microstructure and microchemistry of so-called “fusion defects”, observed by optical transmission microscopy, using SEM along with EDXS analysis. The fractured surface of UHMWPE was also studied.Defects similar to those found in commercially prepared UHMWPE were detected in the hot-pressed and extruded samples prepared at U-Mass Lowell using GUR 412. They consist of holes or cavities and sometimes appear to be circular in shape and are composed of variously sized small holes. The size of the defects is around 100 μm in diameter which is similar to the particle size of the raw powders.

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