scholarly journals Development of novel biodegradable nanocomposites for bone repair applications

2021 ◽  
Author(s):  
Samin Eftekhari
Keyword(s):  
Thermal Properties ◽  
Mass Loss ◽  
Young’S Modulus ◽  
Bone Repair ◽  
Young's Modulus ◽  
Weight Ratio ◽  
Weight Fraction ◽  
Influential Factor ◽  
Mechanical And Thermal Properties ◽  
Biodegradable Nanocomposites

The main goal of this research is to introduce novel series of biodegradable nanocomposites that closely mimic the characteristics of real bone such as mechanical and thermal properties. These nanocomposites are composed of cotton-sourced cellulose microcrystals (MCC), hydroxyapatite nanoparticles (HA) and Poly L-Lactic Acid (PLLA). A novel fabrication route is used to manufacture MA and MH series of nanocomposites. MA series was developed to find an optimum range for weight fraction of each constituent required for design of the MH series. Evaluation of the thermal properties of MA series showed that increasing of weight ratio of MCC and HA from 0 to 21 Wt% increased the crystallinity up to 38%. Compression test results of them revealed that increasing the weight fraction of MCC or HA from 0 to 21Wt% enhanced the compressive yield stress from 0.127 to 2.2 MPa and the Young’s modulus from 6.6 to 38 MPa. The cytotoxicity assay results showed there was no sign of toxic material affecting on viability of cells. The MH series was designed and fabricated by selecting a narrower range of weight fraction of the constituents. A design of experiments was used to alter the composition of the constituents to assess their contributions and their effect onto the mechanical properties and biodegradation behaviour of the MH series of the nanocomposites. The weight ratio of MCC to HA, the concentration of PLLA, and the porogen content were chosen as varying factors. A model that accurately predicts the optimum parameter setting was created. Analysis of variance statistical analysis showed that the ratio of MCC to HA was the most influential factor affecting the compressive yield and the mass loss, while the porogen content was the most detrimental factor affecting the Young’s modulus of MH series of nanocomposites had no significant effect on their rate of the mass loss. The nanocomposites with highest weight ratio 4 of MCC to HA, showed maximum mechanical strength and the lowest water absorption and the lowest mass loss. It was found two series of nanocomposites was comparable to trabecular bone from a compositional, structural, thermal, mechanical point of view.

scholarly journals Development of novel biodegradable nanocomposites for bone repair applications

2021 ◽  
Author(s):  
Samin Eftekhari
Keyword(s):  
Thermal Properties ◽  
Mass Loss ◽  
Young’S Modulus ◽  
Bone Repair ◽  
Young's Modulus ◽  
Weight Ratio ◽  
Weight Fraction ◽  
Influential Factor ◽  
Mechanical And Thermal Properties ◽  
Biodegradable Nanocomposites

The main goal of this research is to introduce novel series of biodegradable nanocomposites that closely mimic the characteristics of real bone such as mechanical and thermal properties. These nanocomposites are composed of cotton-sourced cellulose microcrystals (MCC), hydroxyapatite nanoparticles (HA) and Poly L-Lactic Acid (PLLA). A novel fabrication route is used to manufacture MA and MH series of nanocomposites. MA series was developed to find an optimum range for weight fraction of each constituent required for design of the MH series. Evaluation of the thermal properties of MA series showed that increasing of weight ratio of MCC and HA from 0 to 21 Wt% increased the crystallinity up to 38%. Compression test results of them revealed that increasing the weight fraction of MCC or HA from 0 to 21Wt% enhanced the compressive yield stress from 0.127 to 2.2 MPa and the Young’s modulus from 6.6 to 38 MPa. The cytotoxicity assay results showed there was no sign of toxic material affecting on viability of cells. The MH series was designed and fabricated by selecting a narrower range of weight fraction of the constituents. A design of experiments was used to alter the composition of the constituents to assess their contributions and their effect onto the mechanical properties and biodegradation behaviour of the MH series of the nanocomposites. The weight ratio of MCC to HA, the concentration of PLLA, and the porogen content were chosen as varying factors. A model that accurately predicts the optimum parameter setting was created. Analysis of variance statistical analysis showed that the ratio of MCC to HA was the most influential factor affecting the compressive yield and the mass loss, while the porogen content was the most detrimental factor affecting the Young’s modulus of MH series of nanocomposites had no significant effect on their rate of the mass loss. The nanocomposites with highest weight ratio 4 of MCC to HA, showed maximum mechanical strength and the lowest water absorption and the lowest mass loss. It was found two series of nanocomposites was comparable to trabecular bone from a compositional, structural, thermal, mechanical point of view.

scholarly journals Study the Effect of Different Percentages of Natural (Orange Peels and Date Seeds) and Industrial Materials (Carbon and Silica) on the Mechanical and Thermal Properties of Polymeric Reinforced Composites

2018 ◽  
Vol 14 (4) ◽  
pp. 16-23
Author(s):  
Haydar Abed Dahad ◽  
Sameh Fareed Hasan ◽  
Ali Hussein Alwan
Keyword(s):  
Thermal Conductivity ◽  
Composite Material ◽  
Thermal Properties ◽  
Young’S Modulus ◽  
Weight Ratio ◽  
Mechanical And Thermal Properties ◽  
Orange Peels ◽  
Industrial Materials ◽  
Flexural Tests ◽  
Natural Composite

Mechanical and thermal properties of composites, consisted of unsaturated polyester resin, reinforced by different kinds of natural materials (Orange peels and Date seeds) and industrial materials (carbon and silica) with particle size 98 µm were studied. Various weight ratios, 5, 10, and 15 wt. % of natural and industrial materials have been infused into polyester. Tensile, three-point bending and thermal conductivity tests were conducted for the unfilled polyester, natural and industrial composite to identify the weight ratio effect on the properties of materials. The results indicated that when the weight ratio for polyester with date seeds increased from 10% to 15%, the maximum Young’s modulus decreased by 54%. When the weight ratio was 5%, the maximum Young’s modulus, yield stress and ultimate tensile stress occurred in the polyester with date seeds. The results of tensile and flexural tests showed that the natural composite material has a higher strength than the industrial material. While the results of flexural tests manifested that the maximum improvement in the flexural strength is obtained for orange peels at 5 wt. %, where the maximum increasing percentage is 153.4% than pure polyester. The thermal conductivity of orange peels decreased to the half value when the weight ratio increased from 10% to 15%. The thermal conductivity for polyester with orange peels was greater than the thermal conductivity of polyester with date seeds with maximum percentage occurred at weight ratio 10% is 14.4%, but the thermal conductivity of the industrial composite material was higher than the natural composite material. Finally, the date seeds composite was a good insulator and it had a reduced heat transfer rate in comparison to the rest of the samples, also the maximum variation of temperature with time occurred in date seeds composite.

scholarly journals Effect of Defects on the Mechanical and Thermal Properties of Graphene

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 347 ◽  
Author(s):  
Maoyuan Li ◽  
Tianzhengxiong Deng ◽  
Bing Zheng ◽  
Yun Zhang ◽  
Yonggui Liao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Strain Rate ◽  
Young’S Modulus ◽  
Fracture Strength ◽  
Fracture Strain ◽  
Young's Modulus ◽  
Pristine Graphene ◽  
Mechanical And Thermal Properties

In this study, the mechanical and thermal properties of graphene were systematically investigated using molecular dynamic simulations. The effects of temperature, strain rate and defect on the mechanical properties, including Young’s modulus, fracture strength and fracture strain, were studied. The results indicate that the Young’s modulus, fracture strength and fracture strain of graphene decreased with the increase of temperature, while the fracture strength of graphene along the zigzag direction was more sensitive to the strain rate than that along armchair direction by calculating the strain rate sensitive index. The mechanical properties were significantly reduced with the existence of defect, which was due to more cracks and local stress concentration points. Besides, the thermal conductivity of graphene followed a power law of λ~L0.28, and decreased monotonously with the increase of defect concentration. Compared with the pristine graphene, the thermal conductivity of defective graphene showed a low temperature-dependent behavior since the phonon scattering caused by defect dominated the thermal properties. In addition, the corresponding underlying mechanisms were analyzed by the stress distribution, fracture structure during the deformation and phonon vibration power spectrum.

Effect of Ce Substitution on Mechanical and Thermal Properties of Tetragonal YSZ: First-Principles Calculations

2015 ◽  
Vol 1120-1121 ◽  
pp. 73-84
Author(s):  
Lei Jin ◽  
Pei Zhong Li ◽  
Guo Dong Zhou ◽  
Wei Gao ◽  
Jiang Ning Ma ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Sound Velocity ◽  
Young’S Modulus ◽  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Young's Modulus ◽  
Mechanical And Thermal Properties ◽  
Ce Substitution

The effect of impurity Ce on the mechanical and thermal properties of tetragonal ZrO2 stabilized by rare earth element Y (YSZ) have been studied using first principles density functional theory within generalized gradient approximation (GGA) for the exchange correlation potential. The predicted elastic constants indicate that YSZ and Ce doped YSZ (CeYSZ) are mechanically stable structures. And then the numerical estimates of bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, sound velocity and minimum thermal conductivity were performed using the calculated elastic constants and analyzed for the first time. The values of sound velocity from different orientations are also reported. The agreement between the results of the available experiments and our calculations was satisfactory. Our calculated results indicate that Young’s modulus, hardness, mean sound velocity and minimum thermal conductivity of YSZ can be decreased by Ce substitution. The reasons are from the “softened” Ce-O bond strength using bond population and relative volume change under external hydrostatic pressure. Chemical bonding nature was also analyzed from the density of states and electron density difference.

Natural Rubber-Whisker Alumina Fiber Composite Materials for Mechanical and Thermal Insulation Applications

2018 ◽  
Vol 789 ◽  
pp. 221-225
Author(s):  
Nattapol Dedruktip ◽  
Wasan Leelawanachai ◽  
Nuchnapa Tangboriboon
Keyword(s):  
Thermal Conductivity ◽  
Tensile Strength ◽  
Thermal Properties ◽  
Natural Rubber ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Curing Temperature ◽  
Mechanical And Thermal Properties ◽  
Alumina Fiber ◽  
Elongation At Break

Alumina fiber is a ceramic material used as a dispersed phase or filler to reinforce the mechanical and improve thermal properties of natural rubber via vulcanization process at curing temperature 150°C. The amount of alumina fiber added in natural rubber was varied from 0 to 50 phr on 100 phr of natural rubber in a sulfur curing system. Adding 10 phr alumina fiber affects to obtain the best natural rubber composite samples having good mechanical and thermal properties. Tensile strength, elongation at break, Young’s modulus and thermal conductivity of adding 10 phr whisker alumina fiber encoded NR-Al-10 are equal to 14.38±1.95 MPa, 1038.4±41.45%, 545.63±25.67 MPa and 0.2376±0.0003 W/m.K, respectively, better than those of pure natural rubber compounds without adding alumina fiber. Tensile strength, elongation at break, Young’s modulus and thermal conductivity of natural rubber without adding alumina fiber are equal to 14.06±6.03 MPa, 949.41±52.15%, 496.32±8.54 MPa and 0.2500±0.0003 W/m.K, respectively.

Development of fiber-reinforced polypropylene with NaOH pretreated rice and coffee husks as fillers: Mechanical and thermal properties

2019 ◽  
Vol 33 (9) ◽  
pp. 1269-1291 ◽  
Author(s):  
Vianney Andrew Yiga ◽  
Sinja Pagel ◽  
Michael Lubwama ◽  
Stefan Epple ◽  
Peter Wilberforce Olupot ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Filler Material ◽  
Filler Materials ◽  
Mechanical And Thermal Properties ◽  
Fiber Reinforced ◽  
Rice Husks ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics

Incorporation of agricultural wastes as fillers in fiber-reinforced plastics is gaining momentum in plastics engineering research. In this study, fiber-reinforced polypropylene (PP) with rice and coffee husks as filler material were developed. The effect of alkali (sodium hydroxide) pretreatment of the husks on mechanical and thermal properties of developed PP biocomposites was observed. Filler material loading was varied from 0% to 20% for rice husks and 0% to 10% for coffee husks. A twin-screw extruder was used for compounding the PP matrix with rice and coffee husk filler materials. Tensile strengths and percentage elongation results varied from 27.4 to 37.4 MPa and 2.4% to 70.3% (unmodified coffee husks), 31.1 to 37.4 MPa and 5% to 70.3% (unmodified rice husks), 30.7 to 37.4 MPa and 5.3% to 70.3% (modified coffee husks), and 30.7 to 37.4 MPa and 4.8% to 70.3% (modified rice husks). Young’s modulus ranged between 1656 and 2247.8 MPa for biocomposite PP samples with unmodified filler material. Young’s modulus ranged between 1740 and 2160 MPa after alkali treatment of the filler material. Charpy impact strengths ranged from 1.2 to 4 kJ/m2 and 3.1 to 19.6 kJ/m2 for samples containing unmodified and modified filler material, respectively. Thermogravimetric analysis showed that an increase in filler content resulted into delayed weight loss at high degradation temperatures. The results suggest that these developed fiber-reinforced plastics can be used in applications requiring high thermal stability and good mechanical properties.

Effect of Sc, Y, Yb, Hf, Ce on Mechanical and Thermal Properties of La2Zr2O7: First-Principles Calculations

2015 ◽  
Vol 1120-1121 ◽  
pp. 85-93 ◽  
Author(s):  
Lei Jin ◽  
Pei Zhong Li ◽  
Chun Zhu Jiang ◽  
Guo Dong Zhou ◽  
Hai Bin Zhou ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Sound Velocity ◽  
Young’S Modulus ◽  
Debye Temperature ◽  
Elastic Constants ◽  
First Principles ◽  
Young's Modulus ◽  
Elastic Stiffness ◽  
Mechanical And Thermal Properties

In order to achieve better understanding of the effect of dopant (Sc, Y, Yb, Hf and Ce) on elastic stiffness and thermal properties of La2Zr2O7. The related calculations were performed using the first principles methods. The predicted elastic constants indicate that La2Zr2O7 and oxidations-La2Zr2O7 (oxidations refer to Sc2O3, Y2O3, Yb2O3, HfO2 and CeO2) are mechanically stable structures. And then the numerical estimates of bulk modulus, shear modulus, Young’s modulus were performed using the calculated elastic constants. After these mechanical properties are obtained, sound velocity, Debye temperature and theoretical minimum thermal conductivity of La2Zr2O7 and oxidations-La2Zr2O7 are calculated and analyzed in detail. The available experimental results and our calculations are basically satisfactory. The calculated results indicate that Young’s modulus, mean sound velocity, Debye temperature and minimum thermal conductivity of La2Zr2O7 can be decreased by dopants. CeO2 has extraordinary ability to decrease thermal conductivity in these dopant oxidations.

scholarly journals CHEMICALLY CHITOSAN MODIFIED WITH METHYL METHACRYLATE AND ITS EFFECT ON MECHANICAL AND THERMAL PROPERTIES OF POLYPROPYLENE COMPOSITES

2013 ◽  
Vol 13 (2) ◽  
pp. 114-121 ◽  
Author(s):  
Faisal Amri Tanjung ◽  
Salmah Husseinsyah ◽  
Kamarudin Hussin ◽  
Iqmal Tahir
Keyword(s):  
Tensile Strength ◽  
Thermal Properties ◽  
Methyl Methacrylate ◽  
Young’S Modulus ◽  
Fourier Transforms ◽  
Young's Modulus ◽  
Filler Loading ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Pp Composites

Effects of methyl methacrylate on the properties of chitosan-filled polypropylene (PP) composites has been investigated. Mechanical and thermal properties of the composites were analyzed according to ASTM D 638-91, thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). The results showed that tensile strength of PP composites decreased upon the addition of chitosan, while Young's modulus improved. At a similar filler loading, the treated PP/chitosan composites were found to have higher tensile strength and Young's modulus as compared with the untreated composites. Thermal analysis results showed that thermal stability and crystallinity of the treated composites were higher than the untreated ones. Scanning electron microscopy (SEM) and Fourier transforms infrared (FTIR) studies revealed less detached filler from matrix on tensile surface of the treated composites as an evidence of enhanced filler-matrix interfacial adhesion due to formation of ester-bridge between the chitosan and the methyl methacrylate.

Mechanical and Thermal Properties of Rubber Toughened Poly(Lactic Acid)

2015 ◽  
Vol 1125 ◽  
pp. 222-226 ◽  
Author(s):  
Mohd Shaiful Zaidi Mat Desa ◽  
Azman Hassan ◽  
Agus Arsad ◽  
Nor Nisa Balqis Mohammad
Keyword(s):  
Tensile Strength ◽  
Lactic Acid ◽  
Thermal Properties ◽  
Impact Strength ◽  
Natural Rubber ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Poly Lactic Acid ◽  
Mechanical And Thermal Properties ◽  
Rubber Blends

The effect of rubber toughening on mechanical and thermal properties of poly (lactic acid) (PLA) was investigated by using three types of rubbers; natural rubber (NR), epoxidized natural rubber (ENR) and core-shell rubber (CSR). The PLA/rubber blends were prepared by melt blending in a counter-rotating twin-screw extruder, where the rubber content for all blends was kept at 5 wt%. It was found that the addition of the rubbers increased the impact strength for all blends as compared to pure PLA. On the other hand, all PLA/rubber blends showed notable decrease of Young’s modulus especially for PLA/NR blend which decreased by 72% than pure PLA. Similarly, significant decrease of tensile strength was also observed for all PLA/rubber blends. PLA/ENR blend showed a morebalance mechanical properties with fairly significant improvement of impact strength and moderate decrease of tensile strength, Young’s modulus and elongation at break. In general, PLA/NR blend showed the highest overall impact strength, while the PLA/CSR showed the highest tensile strength and Young’s modulus among the blends. Thermal analysis revealed that the Tg of PLA decreased with incorporation of the three types of rubbers with NR showing the largest decrease. This study indicates that NR, ENR and CSR are effective in enhancing toughness of PLA

A Novel Packing Hollow Dodecahedron Model to Study the Mechanical and Thermal Properties of Stocastic Metallic Foams

2021 ◽  
Author(s):  
Rui Dai ◽  
Beomjin Kwon ◽  
Qiong Nian
Keyword(s):  
Thermal Properties ◽  
Physical Properties ◽  
Three Dimensional ◽  
Weight Ratio ◽  
High Strength ◽  
Specific Area ◽  
Deposition Process ◽  
Metallic Foam ◽  
Thermal Testing ◽  
Mechanical And Thermal Properties

Abstract Stochastic foam with hierarchy order pore structure possesses distinguished physical properties such as high strength to weight ratio, super lightweight, and extremely large specific area. These exceptional properties make stochastic foam as a competitive material for versatile applications e.g., heat exchangers, battery electrodes, automotive components, magnetic shielding, catalyst devices and etc. Recently, the more advanced hollow cellular (shellular) architectures with well-developed structure connections are studied and expected to surpass the solid micro/nanolattices. However, in terms of theoretical predicting and studying of the cellular foam architecture, currently no systematic model can be utilized to accurately capture both of its mechanical and thermal properties especially with hollow struts due to complexity induced by its stochastic and highly reticulate nature. Herein, for the first time, a novel packing three-dimensional (3D) hollow dodecahedron (HPD) model is proposed to simulate the cellular architecture. An electrochemical deposition process is utilized to manufacture the metallic foam with hollow struts. Mechanical and thermal testing of the as-manufactured foams are carried out to compare with the HPD model. HPD model is proved to accurately capture both the topology and the physical properties of stochastic foam at the similar relative density. Particularly, the proposed model makes it possible to readily access and track the physical behavior of stochastic foam architecture. Accordingly, this work will also offer inspiration for designing an efficient foam for specific applications.

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