Abstract:Effect of gamma irradiation on high density polyethylene/hydroxyapatite (HDPE/HA) composites prepared by solution was studied. Melt flow index (MFI) showed a strong increase with radiation due to some decalin remnant. The evaluation of the mechanical behavior showed an increase in the Young's modulus and resistance at break values attributed to the HA addition. Elongation at break decrease strongly. Radiation did not produce any significant changes on crystallization temperatures. Crystallinity of the polymer … Show more
“…On the other hand when HA is added to the polymer, the material viscosity increases and hence resistance to flow increases. Similar results have been also obtained where the MFI decreases due to irradiation and presence of HA for HDPE/HA (20:80) [ 29 ]. Figure 2 Effects of HA and Gamma radiation on the HDPE melt flow index (MFI).…”
Section: Resultssupporting
confidence: 84%
“…This weight loss mainly occurred in the range of 433-495°C with negligible change at temperature higher than 505°C. Also, the improvements in the nanocomposite thermal stability due to irradiation can be attributed to the reduction of chain mobility which occurred as a positive effect due to gamma irradiation [ 29 ]. Figure 6 Thermogravimetric analyses of HDPE and its nanocomposite (a) Effect of HA ratio (b) Effect of Irradiation Dose.…”
BackgroundHigh Density Polyethylene (HDPE) is one of the most often used polymers in biomedical applications. The limitations of HDPE are its visco-elastic behavior, low modulus and poor bioactivity. To improve HDPE properties, HA nanoparticles can be added to form polymer composite that can be used as alternatives to metals for bone substitutes and orthopaedic implant applications.MethodIn our previous work (BioMedical Engineering OnLine 2013), different ratios of HDPE/HA nanocomposites were prepared using melt blending in a co-rotating intermeshing twin screw extruder. The accelerated aging effects on the tensile properties and torsional viscoelastic behavior (storage modulus (G’) and Loss modulus (G”)) at 80°C of irradiated and non-irradiated HDPE/HA was investigated. Also the thermal behavior of HDPE/HA were studied. In this study, the effects of gamma irradiation on the tensile viscoelastic behavior (storage modulus (E’) and Loss modulus (E”)) at 25°C examined for HDPE/HA nanocomposites at different frequencies using Dynamic Mechanical Analysis (DMA). The DMA was also used to analyze creep-recovery and relaxation properties of the nanocomposites. To analyze the thermal behavior of the HDPE/HA nanocomposite, Differential Scanning Calorimetry (DSC) was used.ResultsThe microscopic examination of the cryogenically fractured surface revealed a reasonable distribution of HA nanoparticles in the HDPE matrix. The DMA showed that the tensile storage and loss modulus increases with increasing the HA nanoparticles ratio and the test frequency. The creep-recovery behavior improves with increasing the HA nanoparticle content. Finally, the results indicated that the crystallinity, viscoelastic, creep recovery and relaxation behavior of HDPE nanocomposite improved due to gamma irradiation.ConclusionBased on the experimental results, it is found that prepared HDPE nanocomposite properties improved due to the addition of HA nanoparticles and irradiation. So, the prepared HDPE/HA nanocomposite appears to have fairly good comprehensive properties that make it a good candidate as bone substitute.
“…On the other hand when HA is added to the polymer, the material viscosity increases and hence resistance to flow increases. Similar results have been also obtained where the MFI decreases due to irradiation and presence of HA for HDPE/HA (20:80) [ 29 ]. Figure 2 Effects of HA and Gamma radiation on the HDPE melt flow index (MFI).…”
Section: Resultssupporting
confidence: 84%
“…This weight loss mainly occurred in the range of 433-495°C with negligible change at temperature higher than 505°C. Also, the improvements in the nanocomposite thermal stability due to irradiation can be attributed to the reduction of chain mobility which occurred as a positive effect due to gamma irradiation [ 29 ]. Figure 6 Thermogravimetric analyses of HDPE and its nanocomposite (a) Effect of HA ratio (b) Effect of Irradiation Dose.…”
BackgroundHigh Density Polyethylene (HDPE) is one of the most often used polymers in biomedical applications. The limitations of HDPE are its visco-elastic behavior, low modulus and poor bioactivity. To improve HDPE properties, HA nanoparticles can be added to form polymer composite that can be used as alternatives to metals for bone substitutes and orthopaedic implant applications.MethodIn our previous work (BioMedical Engineering OnLine 2013), different ratios of HDPE/HA nanocomposites were prepared using melt blending in a co-rotating intermeshing twin screw extruder. The accelerated aging effects on the tensile properties and torsional viscoelastic behavior (storage modulus (G’) and Loss modulus (G”)) at 80°C of irradiated and non-irradiated HDPE/HA was investigated. Also the thermal behavior of HDPE/HA were studied. In this study, the effects of gamma irradiation on the tensile viscoelastic behavior (storage modulus (E’) and Loss modulus (E”)) at 25°C examined for HDPE/HA nanocomposites at different frequencies using Dynamic Mechanical Analysis (DMA). The DMA was also used to analyze creep-recovery and relaxation properties of the nanocomposites. To analyze the thermal behavior of the HDPE/HA nanocomposite, Differential Scanning Calorimetry (DSC) was used.ResultsThe microscopic examination of the cryogenically fractured surface revealed a reasonable distribution of HA nanoparticles in the HDPE matrix. The DMA showed that the tensile storage and loss modulus increases with increasing the HA nanoparticles ratio and the test frequency. The creep-recovery behavior improves with increasing the HA nanoparticle content. Finally, the results indicated that the crystallinity, viscoelastic, creep recovery and relaxation behavior of HDPE nanocomposite improved due to gamma irradiation.ConclusionBased on the experimental results, it is found that prepared HDPE nanocomposite properties improved due to the addition of HA nanoparticles and irradiation. So, the prepared HDPE/HA nanocomposite appears to have fairly good comprehensive properties that make it a good candidate as bone substitute.
“…The results indicated that the modulus of elasticity in tension and tensile strength increased with increasing the radiation dose while the fracture strain decreased. Albano et al [ 22 ] studied the effect of gamma irradiation on properties of HDPE/HA composites prepared by solution. Results indicated strong increase in MFI with radiation dose while remarkable decrease in the crystallinity and melting temperature of HDPE/HA composites.…”
BackgroundThe replacement of hard tissues demands biocompatible and sometimes bioactive materials with properties similar to those of bone. Nano-composites made of biocompatible polymers and bioactive inorganic nano particles such as HDPE/HA have attracted attention as permanent bone substitutes due to their excellent mechanical properties and biocompatibility.MethodThe HDPE/HA nano-composite is prepared using melt blending at different HA loading ratios. For evaluation of the degradation by radiation, gamma rays of 35 kGy, and 70 kGy were used to irradiate the samples at room temperature in vacuum. The effects of accelerated ageing after gamma irradiation on morphological, mechanical and thermal properties of HDPE/HA nano-composites were measured.ResultsIn Vitro test results showed that the HDPE and all HDPE/HA nano-composites do not exhibit any cytotoxicity to WISH cell line. The results also indicated that the tensile properties of HDPE/HA nano-composite increased with increasing the HA content except fracture strain decreased. The dynamic mechanical analysis (DMA) results showed that the storage and loss moduli increased with increasing the HA ratio and the testing frequency. Finally, it is remarked that all properties of HDPE/HA is dependent on the irradiation dose and accelerated aging.ConclusionBased on the experimental results, it is found that the addition of 10%, 20% and 30% HA increases the HDPE stiffness by 23%, 44 and 59% respectively. At the same time, the G’ increased from 2.25E11 MPa for neat HDPE to 4.7E11 MPa when 30% HA was added to the polymer matrix. Also, significant improvements in these properties have been observed due to irradiation. Finally, the overall properties of HDPE and its nano-composite properties significantly decreased due to aging and should be taken into consideration in the design of bone substitutes. It is attributed that the developed HDPE/HA nano-composites could be a good alternative material for bone tissue regeneration due to their acceptable properties.
“…In contrast, no measurable influence of the 25 kGy irradiation dose was observed on the properties of HDPE−HA composites. 65 Considering the lower viscosity of HDPE compared to that of UHMWPE, the addition of an appropriate amount of HDPE to UHMWPE is expected to enhance the processibilty, by reducing the melt viscosity. 51 Furthermore, we have recently demonstrated that the dispersion of GO and interfacial adhesion between GO and HDPE can be improved by immobilizing PE onto GO sheets.…”
Osteolysis
and aseptic loosening due to wear at the articulating
interfaces of prosthetic joints are considered to be the key concerns
for implant failure in load-bearing orthopedic applications. In an
effort to reduce the wear and processing difficulties of ultrahigh-molecular-weight
polyethylene (UHMWPE), our research group recently developed high-density
polyethylene (HDPE)/UHMWPE nanocomposites with chemically modified
graphene oxide (mGO). Considering the importance of sterilization,
this work explores the influence of γ-ray dosage of 25 kGy on
the clinically relevant performance-limiting properties of these newly
developed hybrid nanocomposites in vitro. Importantly, this work also
probes into the cytotoxic effects of the wear debris of different
compositions and sizes on MC3T3 murine osteoblasts and human mesenchymal
stem cells (hMSCs). In particular, γ-ray-sterilized 1 wt % mGO-reinforced
HDPE/UHMWPE nanocomposites exhibit an improvement in the oxidation
index (16%), free energy of immersion (−12.1 mN/m), surface
polarity (5.0%), and hardness (42%). Consequently, such enhancements
result in better tribological properties, especially coefficient of
friction (+13%) and wear resistance, when compared with UHMWPE. A
spectrum of analyses using transmission electron microscopy (TEM)
and in vitro cytocompatibility assessment demonstrate that phagocytosable
(0.5–4.5 μm) sterilized 1 mGO wear particles, when present
in culture media at 5 mg/mL concentration, induce neither significant
reduction in MC3T3 murine osteoblast and hMSC growth nor cell morphology
phenotype, during 24, 48, and 72 h of incubation. Taken together,
this study suggests that γ-ray-sterilized HDPE/UHMWPE/mGO nanocomposites
can be utilized as promising articulating surfaces for total joint
replacements.
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