Mechanical properties study of micro‐ and nano‐hydroxyapatite reinforced ultrahigh molecular weight polyethylene composites

Radiation crosslinked ultrahigh molecular weight polyethylene (X-UHMWPE) powder was prepared by g-ray irradiation under nitrogen atmosphere with a dose of 50-200 kGy at a dose rate of 7 kGy/h and further annealing in vacuum at 120 8C for 4 h. The crosslinked powder was characterized by FT-IR spectroscopy, gel content, and hot-press molding. Then, X-UHMWPE was added to pristine UHMWPE to prepare a composite with 0-25 wt % filler. The morphology, wear resistance, and tensile property of the composite were investigated. Using X-UHMWPE as a filler could sufficiently improve the wear resistance of the composite. Adding 25 wt % X-UHMWPE (dose: 150 kGy) improved wear resistance by 130% and retained approximately 90% tensile strength and 70% ductility. Wear-resistant and ductile UHMWPE composite may be potentially used for artificial joint replacement and engineering devices. The proposed route is useful in fabricating UHMWPE material with excellent comprehensive performance or functional polymer composite. INTRODUTIONUHMWPE is a polymer with numerous outstanding properties such as chemical inertness, excellent biocompatibility, good mechanical properties, and widely used in medical and engineering applications. Several unsatisfactory mechanical properties of this polymer are its poor creep-resistance and yield strength. Although UHMWPE exhibits better wear resistance than many other polymers, prolonged use of medical devices made from this polymer used as artificial joint produced debris in the human body. 1 This phenomenon shortens the lifetime of the device and induces pain to the patient. 2,3 Therefore, improving the wear resistance of UHMWPE is still urgent for its application as artificial organ and in engineering devices. Physical blending 4 and radiation crosslinking 5 are two useful methods for improving the wear resistance of UHMWPE. 6,7 Many fillers, such as carbon black, carbon fibers, 8,9 carbon nanotubes (CNTs), 7,10 and Al 2 O 3 , have been added to UHMWPE for physical blending to improve the wear resistance of this polymer. 11 However, dispersion compatibility remains a problem in most cases primarily because of the remarkable difference in chemical structure and surface energy. In addition, the chemical and physiological toxicity of the added material are important in vivo. For instance, 0.1 wt % CNTs in polyethylene can reduce the 80% wear of polyethylene, 12 but this supplementation can even induce cancer in vivo. 13 Therefore, these composites have not been used clinically. Polyethylene blends with other types of polyethylene exhibit better compatibility and lower physiological toxicity than blends with other materials. [14][15][16] This blending method can be used to improve the mechanical properties of UHMWPE. 15,17 Radiation crosslinking can obviously alter the chemical and crystal structures of UHMWPE. This process increases the molecular weight and induces the formation of crosslinking networks. These characteristics sufficiently improve the mechanical properties of UHMWPE such as creep resistanc...

Section: Resultssupporting

confidence: 88%

More wear‐resistant and ductile UHMWPE composite prepared by the addition of radiation crosslinked UHMWPE powder

Wang

Zhang

et al. 2016

“…With small amount of fillers with high aspect ratio the entire polymer is converted into an interfacial polymer with desirable properties . They do exhibit excellent mechanical properties on comparison with those of microcomposites, even with small quantity of nanofillers. They also exhibit increased thermal, chemical, and electrical properties.…”

Section: Introductionmentioning

confidence: 99%

Mechanical and thermal properties of modified kaolin clay/unsaturated polyester nanocomposites

George

Kochimoolayil

Narakathra

2015

The improvement in thermal and mechanical properties of Nanocomposites prepared with unsaturated polyester (UP) as polymer matrix and various loadings of amino‐modified nano kaolinite clay as filler has been studied. Mechanical stirring and ultrasonication resulted in better dispersion of the clay. For curing polyester resin, cobalt naphthenate was used as accelerator and MEKP as initiator. Dynamic Mechanical Analysis (DMA) was carried out to find storage and loss modulus. Thermal stability was found through thermogravimetric analysis and the evaluation of structure and morphology of the nanocomposites were done through XRD, SEM, and TEM. Nanocomposite with 3 phr of amino modified clay has shown higher storage modulus and an improved thermal stability of UP/clay nanocomposites has been established. Tensile strength and toughness of the composite have been found to achieve maximum values at 1 phr of clay and the storage modulus has had an improvement of 38% compared to neat UPR. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43245.

“…Although the shrinkage cannot be measured or observed in this investigation, the shrinkage of the fibers remains a consequence of small changes in polymer morphology with temperature elevation. Previous work has shown that the UHMWPE fibers used in this experiment undergo an alpha‐relaxation above 80 °C, but degradation may be accelerated at higher temperatures. The statement is further confirmed by remarkably different morphology of the fiber prepared under different temperature.…”

Section: Resultsmentioning

confidence: 94%

“…Initially, the bend deformation of resin matrix was the dominant damage of the laminate, corresponding to the lower slope of load–displacement curves. With the increasing of indenter's displacement, the slope of the curves obviously increased, indicating that the dominant damage transformed to the stretch of UHMWPE fibers and matrix and interfacial debonding between fibers and matrix . Eventually, the load on the laminate decreased.…”

Section: Resultsmentioning

confidence: 99%

Experimental and simulated investigation of temperature distribution of UHMWPE laminated composites during hot pressing process

Zeng

Guo

et al. 2017

In this article, the influence of molding temperature on the mechanical properties and ballistic impact behavior of the ultrahigh molecular weight polyethylene (UHMWPE) laminated composites has been investigated. The results demonstrate that with the temperature increasing from 80 to 120 °C, the tensile strength decreases while the interlaminar bonding strength increases. The UHMWPE laminated composites manufactured by hot pressing of 75 layers UHMWPE fabrics show excellent ballistic performance when the molding temperature reaches 120 °C, indicating that dominant failure mechanism of the UHMWPE laminated composites are delamination, the fiber tension as well as bulging. Furthermore, a numerical model has been proposed to predict the temperature distribution of the UHMWPE laminated composites for a better understanding of the effect of molding temperature on the ballistic performance. The results show that the simulated results and experimental data are in good agreement. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45874.