scholarly journals Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 1: characterizing molecular weight

2020 ◽  
Vol 92 (9) ◽  
pp. 1469-1483
Author(s):  
Clive Bucknall ◽  
Volker Altstädt ◽  
Dietmar Auhl ◽  
Paul Buckley ◽  
Dirk Dijkstra ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Quality Control ◽  
High Molecular Weight ◽  
Relaxation Times ◽  
Tensile Tests ◽  
Compact Tension ◽  
Fatigue Tests ◽  
International Standards ◽  
Hencky Strain ◽  
Ultra High Molecular Weight

AbstractThe aim of this project was to study the efficacy of current methods of quality control and quality assurance for ultra-high molecular weight polyethylene (UHMWPE) products, and find improvements where possible. Intrinsic viscosity (IV) tests were performed on three grades of polyethylene with weight average relative molar masses $̅{M}$w of about 6 × 105, 5.0 × 106 and 9.0 × 106. Results from three laboratories showed substantial scatter, probably because different methods were used to make and test solutions. Tensile tests were carried out to 600 % extension at 150 °C under both constant applied load and constant Hencky strain rate, on compression mouldings made by a leading manufacturer of ultra-high molecular weight polyethylene. They gave low values of $̅{M}$w, suggesting incomplete entanglement at ‘grain boundaries’ between powder particles. Results from conventional melt-rheology tests are presented, and their relevance to quality control and assurance is discussed. Attempts to calculate molecular weights from these data met with limited success because of extended relaxation times. Suggestions are made for improving international standards for IV testing of UHMWPE, by investigating the various factors that can cause significant errors, and by introducing methods for checking the homogeneity (and hence validity) of the solutions tested. Part 2 addresses characterization of crystallinity and structure. Part 3 covers mechanical properties, and Part 4 focuses on the sporadic crack propagation behaviour exhibited by all three grades of UHMWPE in fatigue tests on 10 mm thick compact tension specimens.

Mechanical and thermal behaviors of ultra-high molecular weight polyethylene triaxial braids: the influence of structural parameters

2018 ◽  
Vol 89 (16) ◽  
pp. 3362-3373 ◽  
Author(s):  
Shenglei Xiao ◽  
Charles Lanceron ◽  
Peng Wang ◽  
Damien Soulat ◽  
Hang Gao
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Mechanical Characteristics ◽  
Structural Parameters ◽  
Tensile Tests ◽  
Tensile Behavior ◽  
Experimental Database ◽  
Strength And Deformation ◽  
Braiding Angle ◽  
Ultra High Molecular Weight

Recently, triaxial braids made from ultra-high molecular weight polyethylene (UHMWPE) have been recognized as one of the most popular composite reinforcements in the aerospace and defense fields. To further explore the mechanical characteristics of this material, a detailed experimental study on tensile behavior is reported in this paper. The triaxial braids show a “double-peak” phenomenon in tensile strength and deformation, caused by axial yarns and the in-plane shearing of bias yarns. The evolution of the braiding angle, measured during these tensile tests, is discussed according to the braiding parameters (initial braiding angle, number of axial yarns). Using the high conductivity properties of the UHMWPE material, the temperature caused by inter-yarn friction during tensile tests is also studied. This temperature is related to the evolution of the braiding angle. The temperature increases with the increasing number of axial yarns and decreases with increasing braiding angle. This study provides an experimental database on the influence of braiding parameters on the tensile behavior of triaxial braids.

scholarly journals Photodegradation of UHMWPE Compounded with Annatto and Beetroot Extracts

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Alexandre Rangel de Sousa ◽  
Géssica Patrícia Dornas ◽  
Isadora Cota Carvalho ◽  
Renata Francisca da Silva Santos
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Polymer Matrix ◽  
Spectroscopic Characterization ◽  
Tensile Tests ◽  
Neat Polymer ◽  
Before And After ◽  
The Stability ◽  
The One ◽  
Ultra High Molecular Weight

We observed the anti-UV action of beetroot extract in an ultra-high molecular weight (UHMWPE) matrix. The beetroot extract and the one prepared from annatto seed also acted efficiently as pigment to the same polymeric matrix. Neat UHMWPE and UHMWPE compounded with annatto and beet extract were compression molded and tensile specimens were obtained from the molded plates and submitted to UV radiation for up to 42 days. Tensile tests were performed and it was observed that the beet extract had a stabilizing action in the polymer compared to neat polymer and the one with annatto extract. Complementary analyses showed good homogenization of the extracts through the polymer matrix indicating the possibility of use as pigment, although the annatto extract appeared to be very unstable under irradiation. Spectroscopic characterization helped to explain the stability of the extracts before and after molding.

Relationship between Life, Load and Rotation Speed of UHMWPE Bearing under Dry Rolling Contact Fatigue

2013 ◽  
Vol 683 ◽  
pp. 77-81 ◽  
Author(s):  
Shintaro Hazeyama ◽  
Shunsuke Oyama ◽  
Katsuyuki Kida ◽  
Takashi Honda ◽  
Koshiro Mizobe ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Rotation Speed ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Fatigue Tests ◽  
Rolling Contact ◽  
Wear Loss ◽  
Bearing Life ◽  
Ultra High Molecular Weight

The polymer bearings have been widely used in recent years. In this study, ultra-high-molecular-weight-polyethylene (UHMWPE) is investigated. In order to investigate the relation between the lives, loads and rotation speeds, rolling contact fatigue tests were conducted. It was found that rotation speed related to the bearing life and wear loss.

scholarly journals Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 3: deformation, wear and fracture

2020 ◽  
Vol 92 (9) ◽  
pp. 1503-1519
Author(s):  
Clive Bucknall ◽  
Volker Altstädt ◽  
Dietmar Auhl ◽  
Paul Buckley ◽  
Dirk Dijkstra ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Dominant Factor ◽  
Stress Strain ◽  
Entanglement Density ◽  
Wide Range ◽  
And Performance ◽  
Ultra High Molecular Weight

AbstractThree grades of polyethylene, with weight-average relative molar masses, ${\bar{M}}_{\text{W}}$, of approximately 0.6 × 106, 5 × 106, and 9 × 106, were supplied as compression mouldings by a leading manufacturer of ultra-high molecular weight polyethylene (UHMWPE). They were code-named PE06, PE5, and PE9, respectively. Specimens cut from these mouldings were subjected to a wide range of mechanical tests at 23 °C. In tensile tests, deformation was initially elastic and dominated by crystallinity, which was highest in PE06. Beyond the yield point, entanglement density became the dominant factor, and at 40 % strain, the rising stress–strain curves for PE5 and PE9 crossed the falling PE06 curve. Fracture occurred at strains above 150 %. Differences in stress–strain behaviour between PE5 and PE9 were relatively small. A similar pattern of behaviour was observed in wear tests; wear resistance showed a marked increase when ${\bar{M}}_{\text{W}}$ was raised from 0.6 × 106 to 5 × 106, but there was no further increase when it was raised to 9 × 106. It is concluded that the unexpected similarity in behaviour between PE5 and PE9 was due to incomplete consolidation during moulding, which led to deficiencies in entanglement at grain boundaries; they were clearly visible on the surfaces of both tensile and wear specimens. Fatigue crack growth in 10 mm thick specimens was so severely affected by inadequate consolidation that it forms the basis for a separate report – Part 4 in this series.

Effect of New Pocket Design on the Failure of Thrust UHMWPE Bearings in Dry Condition

2016 ◽  
Vol 703 ◽  
pp. 192-196 ◽  
Author(s):  
Koshiro Mizobe ◽  
Naoki Fujimura ◽  
Yuji Kashima ◽  
Katsuyuki Kida
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Fatigue Tests ◽  
Rolling Contact ◽  
Thermoplastic Polymer ◽  
Ultra High Molecular Weight

We developed a retainer with a new kind of design. This retainer has pockets with angles which we think could improve wear durability. We used ultra high molecular weight polyethylene (UHMWPE) because it is a tough thermoplastic polymer with self-lubrication ability. We performed rolling contact fatigue tests and found that wear durability was improved compared with the standard bearings.

Using Isostatic Pressing Techniques to Mold Uhmwpe

1995 ◽  
Vol 394 ◽  
Author(s):  
Joel Higgins ◽  
David Schroeder
Keyword(s):  
Molecular Weight ◽  
Quality Control ◽  
High Molecular Weight ◽  
Bearing Material ◽  
Isostatic Pressing ◽  
Manufacturing Methods ◽  
Particulate Debris ◽  
And Performance ◽  
Ultra High Molecular Weight

Ultra High Molecular Weight Polyethylene (UHMWPE) has been and is currently the standard for bearing material used in the orthopedic industry. The components are produced using a variety of manufacturing methods, many of which can have an effect on the longevity and performance of the device. Recently there has been extensive research into the causes of loosening of orthopedic devices. One area that has been targeted as a cause for loosening is reactions to particulate debris from the bearing surfaces of these appliances. As biological reactions to particulate become better understood, there has been an increased emphasis on the quality of the UHMWPE forms used for orthopedic bearing surfaces. Due to this increased awareness, various manufacturing and quality control improvements have been made throughout the industry.

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