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.

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 Polymer Nanocomposites Exploited Under The Arctic Conditions

2016 ◽  
Vol 1 (1) ◽  
pp. 122 ◽  
Author(s):  
A.A. Okhlopkova ◽  
L.A. Nikiforov ◽  
T.A. Okhlopkova ◽  
R.V. Borisova
Keyword(s):  
Molecular Weight ◽  
Mechanical Activation ◽  
High Molecular Weight ◽  
Polymer Matrix ◽  
Planetary Mill ◽  
Layered Silicates ◽  
The Arctic ◽  
Liquid Media ◽  
Arctic Conditions ◽  
Ultra High Molecular Weight

<p>Several technologies of the preparation of nanocomposites based on ultra-high-molecular-weight polyethylene were developed. The first technology is based on mechanical activation of layered silicates with surfactant before addition into polymer matrix. The second technology represents mixing of ultra-high-molecular-weight polyethylene with nanoparticles by joint mechanical activation in a planetary mill. The third technology is based on mixing of ultra-high-molecular-weight polyethylene with nanoparticles in liquid media under continuous ultrasonic treatment. Common features of these technologies are reaching of filler uniform distribution in a polymer matrix and significant improvement in the mechanical properties. Also, supramolecular structure of the composites was studied.</p>

Nano- and Micro-Structural Evolution of UHMWPE by Ion Beam

2007 ◽  
Vol 1020 ◽  
Author(s):  
F. Calzzani ◽  
B. Chhay ◽  
R. Zimmerman ◽  
A. Oztarhan ◽  
D. Ila
Keyword(s):  
Molecular Weight ◽  
Surface Morphology ◽  
High Molecular Weight ◽  
Chemical Structure ◽  
Ion Beam ◽  
Aerospace Industry ◽  
Structural Evolution ◽  
Before And After ◽  
Polyethylene Devices ◽  
Ultra High Molecular Weight

AbstractIt is important to produce uniform nano-patterns with no possibility of surface exfoliation on polyethylene devices used in medical and in aerospace industry. We studied the change in the surface morphology of polyethylene at nanoscale using MeV ion beam. We have investigated the change in the surface morphology before and after ion bombardment. We have made an attempt to change the morphology to produce a uniform surface with reduced cracks and reduced granularity. For this process we have chosen ultra-high-molecular-weight polyethylene (UHMWPE). Coupons of these materials were exposed to various fluences of MeV Ag+ ions. The surface morphology and the change in the chemical structure were studied using scanning micro Raman, FTIR and AFM.

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.

The Effect of Surface Processing on the Protein Adsorption and Tribomechanical Properties of Ultra-High-Molecular Weight Polyethylene

2006 ◽  
Author(s):  
K. S. Kanaga Karuppiah ◽  
Sriram Sundararajan ◽  
Zhi-Hui Xu ◽  
Xiaodong Li
Keyword(s):  
Molecular Weight ◽  
Shear Strength ◽  
Protein Adsorption ◽  
High Molecular Weight ◽  
Interfacial Shear Strength ◽  
Interfacial Shear ◽  
Surface Finishing ◽  
Before And After ◽  
Physiological Fluid ◽  
Ultra High Molecular Weight

Ultra-high molecular weight polyethylene (UHMWPE) is a popular choice for the liner material of the acetabular cup and forms one of the articulating surfaces in total joint replacements (TJRs). Evaluating the tribological characteristics of UHMWPE on immediate contact with the physiological fluid is essential to understand pathways and mechanisms of eventual failure. In this study, the friction response and interfacial shear strength of a UHMWPE - ceramic interface was quantified using atomic force microscopy (AFM) before and after exposure to bovine serum albumin (BSA) solution. A 10% protein solution concentration was used to closely mimic protein levels in human physiological fluid. Medical grade UHMWPE samples with two different surface finishing treatments, milling and melting/reforming were used in the experiments. Friction response as a function of normal load was monitored on a particular area on each sample. Fluorescence microscopy was used to assess the protein adsorption on the test area. The interfacial shear strength of the interface was calculated from the friction data using contact mechanics. Contact angle measurements were also performed on the surfaces to evaluate the surface energies before and after protein adsorption. Correlations between the friction behavior and surface energy of the surfaces are discussed.

Surface Modifaction of Ultra High Molecular Weight Polyethylene by Low Energy DC Plasma Discharge

1998 ◽  
Vol 544 ◽  
Author(s):  
M. S. Hargreaves ◽  
D. S. Hussey ◽  
R. E. Leuchtner
Keyword(s):  
Molecular Weight ◽  
Contact Angle ◽  
High Molecular Weight ◽  
Tensile Axis ◽  
Plasma Processing ◽  
Polar Polymers ◽  
Dc Discharge ◽  
Before And After ◽  
Ultra High Molecular Weight ◽  
Polar Polymer

AbstractSurface effects produced by plasma processing Ultra High Molecular Weight polyethylene (UHMW) were examined. The goal was to enhance adhesion of UHMW to a variety of polar polymers. This research focussed on enhancing adhesion to polyurethane. UHMW samples were immersed in a DC discharge and subjected to various processing conditions. The background gases experimented with were oxygen, nitrogen, and argon, and the pressure was varied between 6-67 Pa. The processing time, discharge current and discharge potential were also varied. A polar polymer (polyurethane) was subsequently applied to the processed UHMW samples and the tensile strength of the bonds was measured. Standard dogbone specimens were fabricated, and the polymer interfaces placed in the middle of the gage section and oriented normal to the tensile axis. The specimens were tested to failure in displacement control at an approximate strain rate of 0.2% per sec. In general, significant enhancement in yield strength was observed over unprocessed samples, where essentially no bonding occurred. Samples subjected to plasma processing in oxygen showed the strongest adhesion, while those in argon were almost as good, followed by nitrogen.The contact angle of water on the processed UHMW samples ranged from about 45° to less than 2°, while unprocessed samples had a contact angle of about 70°. These data correlated with the yield tests. XPS was used to examine the composition of the UHMW surfaces before and after plasma processing with oxygen. It is believed that the plasma etched off surface layers, creating unsaturated carbon bonds that can chemically react with polar polymer groups. Precast, processed UItMW surfaces were found to be reactive for periods of up to one week. Optimum conditions of plasma processing were identified, and will be discussed in light of the chemistry occurring at the interface.

Development of Composite Materials Based on Ultrahigh-Molecular Weight Polyethylene and Thermally Expanded Graphite

2019 ◽  
Vol 945 ◽  
pp. 374-378
Author(s):  
O.V. Gogoleva
Keyword(s):  
Molecular Weight ◽  
Composite Materials ◽  
High Molecular Weight ◽  
Polymer Composite ◽  
Polymer Matrix ◽  
Expanded Graphite ◽  
Necessary Condition ◽  
Thermally Expanded Graphite ◽  
Stress Strain ◽  
Ultra High Molecular Weight

In connection with the huge range of ultra-high molecular weight polyethylene (UHMWPE) grades, the choice of a particular brand is a difficult task. Rational choice of the polymer matrix is a necessary condition for the increase in reliability and service life of products, and consequently, for the efficiency of using these composite materials. The given article presents the results of tests on stress-strain properties of GUR-2122, 4113, 4120, 4130, 4150, 4170 and GHR-8020 ultra-high molecular weight polyethylene grades. GUR-4150 UHMWPE is chosen as the polymer matrix on the base of the test results. It is shown that the friction coefficient of the polymer composite material is reduced even with the modification of UHMWPE with nanodispersed thermally expanded graphite (TEG) in amount of 0.001-0.5 mass%. It is established that the rate of mass wear decreases by 3-4.3 while maintaining the stress-strain properties of the composites at the level of the initial UHMWPE. Polymer composite materials with an improved set of performance indicators are developed.

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