scholarly journals Dynamical mechanical analysis as an assay of cross-link density of orthopaedic ultra high molecular weight polyethylene

2015 ◽  
Vol 45 ◽  
pp. 174-178 ◽  
Author(s):  
Steven D. Reinitz ◽  
Evan M. Carlson ◽  
Rayna A.C. Levine ◽  
Katherine J. Franklin ◽  
Douglas W. Van Citters
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Mechanical Analysis ◽  
Cross Link ◽  
Dynamical Mechanical Analysis ◽  
Link Density ◽  
Cross Link Density ◽  
Ultra High Molecular Weight

Wear Mechanisms of Untreated and Gamma Irradiated Ultra-High Molecular Weight Polyethylene for Total Joint Replacements

2005 ◽  
Vol 127 (2) ◽  
pp. 273-279 ◽  
Author(s):  
J. Zhou ◽  
K. Komvopoulos
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
Wear Mechanisms ◽  
Irradiation Dose ◽  
Cross Link ◽  
Link Density ◽  
Cross Link Density ◽  
Gamma Irradiated ◽  
Ultra High Molecular Weight

Modification of the surface microstructure of ultra-high molecular weight polyethylene (UHMWPE) is essential for improving the wear resistance of orthopedic implants. A common approach is to cross-link the polymer by gamma irradiation. The objective of this study was to examine the tribological behaviors of untreated and gamma irradiated UHMWPE under physiologically relevant contact conditions. Emphasis was placed on the identification of the dominant wear mechanisms in the early stage of polymer wear. The irradiation dose exhibited a strong effect on the tribological properties of UHMWPE sliding against Co–Cr alloy in a bath of bovine serum. Transmission electron microscopy (TEM) and environmental scanning electron microscopy (ESEM) were used to examine the microstructure and morphology of the worn surfaces. Regularly spaced folds with average spacing depending on the irradiation dose (i.e., cross-link density) formed on the wear tracks. Surface folding was related to plastic flow and the degree of mobility of the crystalline lamellae. SEM and TEM results elucidated the roles of the cross-link density and crystalline lamellae in the wear process. Based on the experimental evidence, a deformation model was obtained that provides explanation for the dependence of surface folding on the cross-link density and lamellae reorientation during sliding.

scholarly journals Dynamical mechanical analysis of photocrosslinked hyperbranched urethane acrylates

2004 ◽  
Vol 69 (6) ◽  
pp. 441-453 ◽  
Author(s):  
Enis Dzunuzovic ◽  
Srba Tasic ◽  
Branislav Bozic ◽  
Dragan Babic ◽  
Branko Dunjic
Keyword(s):  
Mechanical Properties ◽  
1H Nmr Spectroscopy ◽  
Dynamic Mechanical Properties ◽  
Mechanical Analysis ◽  
Cross Link ◽  
Dynamical Mechanical Analysis ◽  
Molecular Weights ◽  
Link Density ◽  
Cross Link Density ◽  
Newtonian Behavior

A series of acrylate functionalized samples based on hyperbranched hydroxy-terminated polyesters with different molecular weights and different degrees of acrylation were synthesized. The obtained urethane acrylates were slightly yellow viscose liquids. Their composition was characterized by FTIR and 1H-NMR spectroscopy and their molecular weights were measured by GPC. All the synthesized samples were diluted with 25 wt.% 1,4-butanediol dimethacrylate (BDDM). The rheological properties of the uncured samples and the dynamic mechanical properties of the UV cured samples were examined. All the samples exhibit Newtonian behavior, which indicates the absence of physical entanglements in these polymers. The viscosity increases with increasing number of acrylic groups permolecule. The glass transition temperature of the UV cured samples increases with increasing the number of acrylic groups permolecule. The value of the storage modulus in the rubber-elastic plateau and the cross-link density increase with increasing number of acrylic groups permolecule. The formed networks are inhomogeneous and the residual unsaturation is the highest in the samples with the largest number of acrylic groups per molecule.

PEG Cross-Linked Alginate Hydrogels with Controlled Mechanical Properties

1998 ◽  
Vol 530 ◽  
Author(s):  
Petra Eiselt ◽  
Jon A. Rowley ◽  
David J. Mooney
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Molecular Weight ◽  
Elastic Modulus ◽  
Cell Transplantation ◽  
Cross Linking ◽  
Cross Link ◽  
Link Density ◽  
A Cell ◽  
Cross Link Density

AbstractReconstruction of tissues and organs utilizing cell transplantation offers an attractive approach for the treatment of patients suffering from organ failure or loss. Highly porous synthetic materials are often used to mimic the function of the extracellular matrix (ECM) in tissue engineering, and serve as a cell delivery vehicle for the formation of tissues in vivo. Alginate, a linear copolysaccharide composed of D-mannuronic acid (M) and L-guluronic acid (G) units is widely used as a cell transplantation matrix. Alginate is considered to be biocompatible, and hydrogels are formed in the presence of divalent cations such as Ca2+, Ba2+ and Sr2+. However, ionically cross-linked alginate gels continuously lose their mechanical properties over time with uncontrollable degradation behavior. We have modified alginate via covalent coupling of cross-linking molecules to expand and stabilize the mechanical property ranges of these gels. Several diamino PEG molecules of varying molecular weight (200, 400, 1000, 3400) were synthesized utilizing carbodiimide chemistry. Sodium alginate was covalently cross-linked with these cross-linking molecules, and mechanical properties of the resulting hydrogels were determined. The elastic modulus of the cross-linked alginates depended on the molecular weight of the cross-linking molecules, and ranged from 10-110 kPa. The theoretical cross-link density in the hydrogels was also varied from 3 to 47% (relative to the carboxylic groups in the alginate) and the mechanical properties were measured. The elastic modulus increased gradually and reached a maximum at a cross-link density of 15%. In summary, covalently coupled hydrogels can be synthesized which exhibit a wide range of mechanical properties, and these materials may be useful in a number of tissue engineering applications.

The Effect of Lightning Strikes on Bismaleimide Composites by Dynamic Mechanical Analysis

2011 ◽  
Vol 179-180 ◽  
pp. 449-454
Author(s):  
Dong Bing Geng ◽  
Hong Jun Guo ◽  
San Qing Zhang
Keyword(s):  
Glass Transition ◽  
Dynamic Mechanical Analysis ◽  
Mechanical Analysis ◽  
Cross Link ◽  
Lightning Strikes ◽  
Dynamic Mechanical ◽  
Lightning Current ◽  
Link Density ◽  
Cross Link Density ◽  
Composite Samples

In this paper, a new method that has shown significant potential to characterize lightning strikes damage which is couple with dynamic mechanical analysis. The composite samples used in this work are based on carbon fiber/bismaleimide system. The analysis of the dynamic mechanical data demonstrate the glass transition temperature of the composites increased as a function of increasing lightning current , simultaneity with the presence ofpotential damage, whichare result in higher network cross-link density and the incipent degradation of the polymer matrix.

Investigation on the structure, cross-link, and oxidation index of ultra high molecular weight polyethylene acetabular liners

2018 ◽  
Vol 101 (1-4) ◽  
pp. 235-241 ◽  
Author(s):  
Gabriel Bertoli ◽  
Izabelle M. Gindri ◽  
Patrícia O. Cubillos ◽  
Carlos R. M. Roesler ◽  
Gean V. Salmoria
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cross Link ◽  
Oxidation Index ◽  
Ultra High Molecular Weight

Shape Memory Behavior of Ultra-High Molecular Weight Polyethylene

2012 ◽  
Vol 1403 ◽  
Author(s):  
Sergey Kaloshkin ◽  
Aleksey Maksimkin ◽  
Maria Kaloshkina ◽  
Mihail Zadorozhnyy ◽  
Margarita Churyukanova
Keyword(s):  
Molecular Weight ◽  
Shape Memory ◽  
High Molecular Weight ◽  
Shape Memory Polymers ◽  
Mechanical Analysis ◽  
Stress Recovery ◽  
Recovery Stress ◽  
Activation Temperature ◽  
Recovery Strain ◽  
Ultra High Molecular Weight

ABSTRACTShape memory effect in pure ultra-high molecular weight polyethylene (UHMWPE) has been studied using dynamic mechanical analysis. Temperature dependencies of properties that define functional characteristics of shape memory polymers (SMP) such as recovery stress, recovery strain and activation temperature of transition were determined for UHMWPE. The recovery stress in UHMWPE deformed by 200% achieved rather high values, up to 7 MPa.

Effect of Carbon Coating on the Properties of Gamma Irradiated Ultra-High-Molecular-Weight Polyethylene Specimens

2000 ◽  
Vol 28 (3-4) ◽  
pp. 445-449 ◽  
Author(s):  
Debi P. Mukherjee ◽  
Alan L. Ogden ◽  
R. H. Mayeux ◽  
U. Siriwardane ◽  
H. R. Patel
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Carbon Coating ◽  
Gamma Irradiated ◽  
Ultra High Molecular Weight
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