Toughness Of Polyethylene Research Articles

Ultra‐high enhancement in the toughness of polyethylene by exfoliated natural clay nanosheets

ABSTRACTThe full exfoliation of inorganic natural clay was engineered in a nonpolar polyethylene following a novel method without the involvement of any chemical modification to the surface of silicate layers. Tensile results showed that the toughening effect was dependent of strain rates, and the toughness of polyethylene was substantially improved by nearly five times with 0.5 wt % natural clay nanosheets at a strain rate of 0.15 s−1. Toughening mechanism was also discussed based on this new exfoliated system. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41314.

Role of the Amorphous Morphology in Physical Properties of Ultra High Molecular Weight Polyethylene

The role of amorphous layer in the physical properties of ultra high molecular weight polyethylene (UHMWPE) was investigated. It revealed that the thicker amorphous layer would promote the toughness of polyethylene, but make a negative effect on the rigidity of the polymer. Furthermore, it would be easier for semicrystalline polymers with less entangled chains to bring out the interlamellar slippage that would absorb more energy during the deformation. Finally, promotion of the physical properties of UHMWPE was also achieved with the assistant of nano-modification and an excellent relativity between the physical properties and the amorphous thickness (la) was obtained.

J044013 第一原理計算と粗視化分子動力学法によるポリエチレンの化学劣化が耐久性に与える影響([J044-01]ソフトマター・イノベーション(1))

J044013 第一原理計算と粗視化分子動力学法によるポリエチレンの化学劣化が耐久性に与える影響([J044-01]ソフトマター・イノベーション(1))

A mechanistic approach for determining plane-stress fracture toughness of polyethylene

A new mechanistic approach is used to characterize resistance of polyethylene to deformation and fracture in double-edge-notched tensile test. The new approach considers all three mechanisms involved in the fracture process, i.e. for fracture surface formation, shear plastic deformation, and necking, and can be used to determine values of specific energy consumption for each mechanism. This is different from the conventional approach, known as essential work of fracture (EWF), which does not consider the difference between shear plastic deformation and necking. Results from the new approach for a polyethylene copolymer show that specific energy density for fracture surface formation is about half of that determined from the EWF approach, and specific energy density for necking is very close to that determined from simple tensile test. The latter provides some support for validity of the new approach in characterizing fracture behaviour of polyethylene when accompanied by large deformation and necking. The paper also points out crack growth conditions that have to be met for valid application of the EWF approach and shows that such conditions are not met when deformation and necking occur in polyethylene.

Mechanical Reinforcement of Polyethylene Using Polyethylene‐Grafted Multiwalled Carbon Nanotubes

AbstractThe incorporation of carbon nanotubes to a polymer generally improves the stiffness and strength of the polymer, but the ductility and toughness of the polymer are compromised in most cases. Here we report the mechanical reinforcement of polyethylene (PE) using polyethylene‐grafted multiwalled carbon nanotubes (PE‐g‐MWNTs). The stiffness, strength, ductility and toughness of PE are all improved by the addition of PE‐g‐MWNTs. The grafting of PE onto MWNTs enables the well‐dispersion of nanotubes in the PE matrix and improves MWNT/PE interfacial adhesion. The grafting was achieved by a reactive blending process through melt blending of PE containing 0.85 wt % of maleic anhydride and amine‐functionalized MWNTs. The reaction between maleic anhydride and amine groups, as evidenced by X‐ray photoelectron spectroscopy and Raman spectroscopy, leads to the grafting of PE onto the nanotubes.

Three-Dimensional Characterization of the Microstructure of Bioglass/Polyethylene Composite by X-Ray Microtomography

A Bioglass® reinforced polyethylene (Bioglass®/polyethylene) composite has been prepared, which combines the high bioactivity of Bioglass® and the toughness of polyethylene. The spatial distribution of Bioglass® particles within the composite is important for the performance of composites in-vivo. Recent developments in X-ray microtomography (XμT) have made it possible to visualize internal and microstructural details with different X-ray absorbencies, nondestructively, and to acquire 3D information at high spatial resolution. In this study, the volume fraction and 3D spatial distribution of Bioglass® particles has been acquired quantitatively by XμT. The information obtained provides a foundation for understanding the mechanical and bioactive properties of the Bioglass®/polyethylene composites.

Wear and toughness of crosslinked polyethylene for total knee replacements: A study using a simulator and small‐punch testing

Severe loading and complex kinematics in total knee replacement make wear performance and toughness of the polyethylene in tibial inserts important. We investigated wear of crosslinked polyethylene using a knee simulator and measured toughness using small-punch testing. GUR1050 rods were gamma-irradiated in air at doses from 0 to 200 kGy, annealed in nitrogen, and machined into tibial inserts. The simulator was run to 4 million cycles, and wear rates determined from weight loss. Wear rate decreased by 54, 78, and 95% as radiation dose increased from 50 to 75 to 100 kGy, respectively. At every dose, toughness was significantly less after simulator testing, but the difference between control and wear-tested polyethylene, considered to be due to fatigue damage accumulation, was smallest at 50 kGy. The simulator-tested polyethylene that received 35 to 75 kGy had slightly higher toughness than equivalent material that received no irradiation. However, the toughness of simulator-tested polyethylene that received 150 and 200 kGy was lower than that of the simulator-tested polyethylene that received no irradiation. Our results suggest that an optimal irradiation dose may exist for crosslinked polyethylene for use in TKR and that the optimum dose would be less than the 100 kGy or more that are used in some current crosslinked polyethylene for hip replacement.