Synthesis of Biodegradable β-TCP/PLGA Composites Using Microwave Energy

2006 ◽  
Vol 510-511 ◽  
pp. 758-761 ◽  
Author(s):  
Hyeong Ho Jin ◽  
Sang Ho Min ◽  
Kyu Hong Hwang ◽  
Ik Min Park ◽  
Hong Chae Park ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Young’S Modulus ◽  
Tricalcium Phosphate ◽  
Bending Strength ◽  
In Situ Polymerization ◽  
Young's Modulus ◽  
Microwave Energy ◽  
Microstructure And Mechanical Properties

Biodegradable β-tricalcium phosphate (β-TCP)/poly (lactide-co-glycolide) (PLGA) composites were synthesized by in situ polymerization with microwave energy. The influence of the β-TCP content in β-TCP/PLGA composites on the molecular weight, crystallinity, microstructure, and mechanical properties was investigated. As the molecular weight of composites decreased, the β-TCP content increased up to 10 wt%, while further raising of the β-TCP content above 10%, the molecular weight increased with increasing β-TCP content. This behavior may be ascribed to the superheating effect or nonthermal effect induced by microwave energy. It was found that the bending strength and Young’s modulus of the β-TCP/PLGA composites were proportional to the molecular weight of PLGA. The bending strength of the β-TCP/PLGA composites ranged from 18 to 38 MPa, while Young’s modulus was in the range from 2 to 6 GPa.

Study on Microstructure and Mechanical Properties of Epoxy Resin/Carbon Black Composites Prepared by in Situ Polymerization

2011 ◽  
Vol 109 ◽  
pp. 156-160 ◽  
Author(s):  
Xue Feng Lu ◽  
Pei Qing La ◽  
Xin Guo ◽  
Yu Peng Wei
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Epoxy Resin ◽  
Bending Strength ◽  
In Situ Polymerization ◽  
Resin Matrix ◽  
Condensation Polymerization ◽  
Maximum Value ◽  
Microstructure And Mechanical Properties

Microstructure and mechanical properties of epoxy resin/carbon black composites synthesized by in situ condensation polymerization of monomers in the presence of carbon black particles were investigated. SEM observation showed that carbon black particles were well dispersed in the epoxy resin matrix. The composite with 1 wt. % carbon black had the electrical resistivity of approximately 108.7 Ω•cm. The composites exhibited an a percolation threshold at carbon black content about 4 wt.%, indicating the existence of a path of percolation by connecting carbon black particles. Bending strength dramatically increased to a maximum value of 133.4MPa and then slowly decreased with content of carbon black increasing. Shore hardness increased gradually with content of carbon black and came to 23.3HD at carbon black 10 wt.%.

scholarly journals Effect of Sintering Temperature on Microstructure and Mechanical Properties of Hot-Pressed Fe/FeAl2O4 Composite

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 422
Author(s):  
Kuai Zhang ◽  
Yungang Li ◽  
Hongyan Yan ◽  
Chuang Wang ◽  
Hui Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Hot Press ◽  
Microstructure And Mechanical Properties ◽  
Powder Particles ◽  
Hot Press Sintering ◽  
Sintering Method

An Fe/FeAl2O4 composite was prepared with Fe-Fe2O3-Al2O3 powder by a hot press sintering method. The mass ratio was 6:1:2, sintering pressure was 30 MPa, and holding time was 120 min. The raw materials for the powder particles were respectively 1 µm (Fe), 0.5 µm (Fe2O3), and 1 µm (Al2O3) in diameter. The effect of sintering temperature on the microstructure and mechanical properties of Fe/FeAl2O4 composite was studied. The results showed that Fe/FeAl2O4 composite was formed by in situ reaction at 1300 °C–1500 °C. With the increased sintering temperature, the microstructure and mechanical properties of the Fe/FeAl2O4 composite showed a change law that initially became better and then became worse. The best microstructure and optimal mechanical properties were obtained at 1400 °C. At this temperature, the grain size of Fe and FeAl2O4 phases in Fe/FeAl2O4 composite was uniform, the relative density was 96.7%, and the Vickers hardness and bending strength were 1.88 GPa and 280.0 MPa, respectively. The wettability between Fe and FeAl2O4 was enhanced with increased sintering temperature. And then the densification process was accelerated. Finally, the microstructure and mechanical properties of the Fe/FeAl2O4 composite were improved.

Mechanical Properties of Pyrolytic "SiOCN" Thin Coatings

1993 ◽  
Vol 308 ◽  
Author(s):  
Sandrine Bec ◽  
André Tonck ◽  
Jean-Luc Loubet
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Ceramic Coatings ◽  
Optical Observation ◽  
Thin Coatings ◽  
Polymer Precursors ◽  
Polymeric State

ABSTRACTPyrolysis of polymer precursors (polysilazane) is a technologically and economically interesting way to produce thin ceramic coatings. However, many cracks appear and decohesion occurs during pyrolysis when the ceramic coatings (SiOCN) are thicker than 0.5 micrometers. In order to understand these cracking phenomena, the coatings are mechanically characterized by nanoindentation at different stages of the pyrolysis heat treatment.During pyrolysis, the cracking temperature is detected by in-situ optical observation. The thickness of the coatings varies during pyrolysis from 3 micrometers at the polymeric state to 1 micrometer at the ceramic state. The coatings' properties, hardness and Young's modulus are evaluated after heat treatment, taking into account the substrate's influence. A large variation of these properties occurs at the cracking temperature. Both the hardness and the Young's modulus are multiplied by a factor of 10. By analysing these results, we show that cracking is correlated with the evolution of the coatings' mechanical properties during the transformation.

Microstructure and Mechanical Properties of Porous Titanium Based on Controlling Young's Modulus

2017 ◽  
Vol 46 (8) ◽  
pp. 2041-2048 ◽  
Author(s):  
Xu Guangsheng ◽  
Kou Hongchao ◽  
Liu Xianghong ◽  
Li Fuping ◽  
Li Jinshan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Porous Titanium ◽  
Microstructure And Mechanical Properties

Degradation Behaviors of β-TCP/PLGA Composites Prepared with Microwave Energy

2007 ◽  
Vol 342-343 ◽  
pp. 205-208 ◽  
Author(s):  
Hong Chae Park ◽  
Hyeong Ho Jin ◽  
Yong Taek Hyun ◽  
Won Ki Lee ◽  
Seog Young Yoon
Keyword(s):  
Molecular Weight ◽  
In Situ Polymerization ◽  
Morphological Changes ◽  
Microwave Energy ◽  
Degradation Behavior ◽  
Soaking Time ◽  
Biodegradable Scaffolds ◽  
Degradation Behaviors ◽  
Sbf Solution

The β-tricalcium phosphate (β-TCP)/ poly(lactide-co-glycolide) (PLGA) composites for biodegradable scaffolds in bone tissue engineering were synthesized by in situ polymerization with microwave energy. The degradation behavior of β-TCP/PLGA composite was investigated by soaking in simulated body fluid (SBF) for 4 weeks. The molecular weight of the β-TCP/PLGA composites decreased with soaking time until week 2, whereas the loss rate of molecular weight reduced after week 2. The incubation time was needed for the degradation of the β-TCP, indicating that the β-TCP should be detached from the PLGA matrix and then degraded into SBF solution. The studies of mass loss of the composites with the soaking time revealed that the degradation behavior of PLGA would be processed with the transformation from the polymer to the oligomer followed by the degradation. Morphological changes, whisker-like, due to transformation and degradation of polymer in the composites were observed after week 2. On the basis of the results, it found that the degradation behavior of β-TCP/PLGA composites was influenced by the β-TCP content in the composite and the degradation rate of the composite could be controlled by the initial molecular weight of PLGA in the composite.

Mechanical Properties Of Cu-Based Composites with in Situ Formed Ultrafine Filaments

1981 ◽  
Vol 12 ◽  
Author(s):  
J. Bevk ◽  
W. A. Sunder ◽  
G. Dublon ◽  
David E. Cohen
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Young’S Modulus ◽  
Size Dependence ◽  
Young's Modulus ◽  
Plastic Properties ◽  
Young’S Moduli ◽  
Lattice Softening

ABSTRACTElastic and plastic properties of in situ Cu-based composites with Nb, V, and Fe filaments are reviewed. The evidence is presented for a pronounced size dependence of both the ultimate tensile strength and the Young's moduli. In composites with the smallest filaments (d∼50–200Å) and filament densities as high as 1010/cm2 dislocation density reaches values of 1013 cm/cm3. The yield stress of these samples increases dramatically over the predictions based on the “rule of mixtures” and their ultimate tensile strength approaches the estimated theoretical strength of the material (∼2.7GPa). The observed decrease of Young's modulus as a function of inverse wire diameter in the as-drawn composites is attributed to lattice softening due to high density of extended lattice defects. Upon annealing, Young's modulus increases by as much as 100% and exceeds the maximum values calculated from bulk elastic constants. Possible mechanisms leading to modulus enhancement and to related changes in magnetic and superconducting behavior of in situ composites are discussed.

Mechanical Properties and Microstructure of PMMA-ZrO2 Nanocomposites for Dental CAD/CAM

2013 ◽  
Vol 785-786 ◽  
pp. 533-536 ◽  
Author(s):  
Shi Bao Li ◽  
Yi Min Zhao ◽  
Jian Feng Zhang ◽  
Cheng Xie ◽  
Dong Mei Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bending Strength ◽  
In Situ Polymerization ◽  
Zirconia Ceramics ◽  
Sem Images ◽  
The Matrix ◽  
Cad Cam ◽  
Organic Resin

A novel PMMA-ZrO2 composite (PZC) was prepared by resin infiltrated to ceramic method. The composite mechanical properties were evaluated and correlated to its microstructure. Partially sintered zirconia ceramics (PSZC) were made by isostatic pressing and partially sintering. Subsequently, the PZC was prepared by vacuum infiltrating prepolymerized MMA into PSZC, followed by in-situ polymerization. When PSZC-70% was used as the matrix, the bending strength, elastic modulus, and fracture toughness of the prepared composite i.e PZC-70% were 202.56±12.09 MPa, 58.71±3.98 GPa, and 4.60±0.26 MPa·m1/2, corresponding to 25.69%, 23.31%, and 169.01% improvement, respectively, in comparison with the control matrix. Among them, the fracture toughness improvement was the most prominent. According to SEM images of the fracture surfaces, each pore of zirconia skeleton was filled by organic resin contributing to the bending strength improvement. These weak interfaces between zirconia skeleton and organic resin absorbed energy and terminated the growth of microcracks which might be responsible for significant improvement in fracture toughness. This PZC material is anticipated to be a new member of the dental CAD/CAM family.

Microstructure Formation Mechanism of (Al2O3+TiB2+Al3Ti)/Al Composites Fabricated by Reactive Hot Pressing

2007 ◽  
Vol 353-358 ◽  
pp. 1439-1442 ◽  
Author(s):  
Gui Song Wang ◽  
Lin Geng
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Formation Mechanism ◽  
Hot Pressing ◽  
Young's Modulus ◽  
Microstructure Formation ◽  
Sem And Tem ◽  
Reactive Hot Pressing ◽  
Tib2 Particles

The two (Al2O3+TiB2+Al3Ti)/Al composites were fabricated from Al-B2O3-TiO2 and Al-B-TiO2 raw powders by reactive hot pressing, respectively. The microstructure of in situ two composites was analyzed by OM, SEM and TEM. The results showed that coarse Al3Ti blocks with several tens of micrometers size were formed during hot pressing. The equiaxed Al2O3 particulates and hexagonal TiB2 particulates with finer sizes were formed in the composites simultaneously. The microstructure formation mechanism of (Al2O3+TiB2+Al3Ti)/Al composites were discussed. The results showed that Al2O3 reinforcements were formed on the surface of TiO2 or B2O3 powder and TiB2 particles were formed on B or B2O3 powders. The formation of coarse Al3Ti block is result from continuous diffusion of Ti in liquid Al during reactive hot pressing. In addition, there are fine Al3Ti precipitates exist in the composite fabricated from Al-B-TiO2 powders. This contributes to the improved mechanical properties in terms of yield and ultimate stresses and Young’s modulus of the composite.

Mechanical Properties of Nanoparticle Hydroxyapatite/gelatin Constructs

2007 ◽  
Vol 1063 ◽  
Author(s):  
Steven Fox ◽  
Inessa Stanishevskaya ◽  
Shafiul Chowdhury ◽  
Shane Catledge ◽  
Andrei Stanishevsky
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Bending Strength ◽  
Young's Modulus ◽  
Bone Microarchitecture ◽  
Bone Substitutes ◽  
Mechanical Analysis ◽  
Model Material ◽  
Bending Modulus ◽  
Nanoparticle Dispersions

ABSTRACTBone consists of up to 70% mostly nanocrystalline hydroxyapatite (HA), and the rest is mostly collagen. One can suggest that synthetic nanoHA/collagen composites could potentially be the closest materials to resemble the bone microarchitecture and prepare resorbable bone substitutes and scaffolds. However, the data on the mechanical properties and property/structure relationships of HA/collagen composites are still scarce. It can be explained, in part, by the high cost of collagen and substantial amounts of materials needed for many tests. However, gelatin is cheap, has many properties similar to collagen, and can be used as a model material for the mechanical testing of HA-based composites. In this study, we report the results of an investigation of some mechanical properties of HA/gelatin composites with 0 to 80% HA nanoparticle (size 15-60 nm) loading by weight. The HA nanoparticle dispersions were mixed with gelatin in trifluoroethanol or in water in different ratios and placed in Teflon molds to produce the sheets with the thickness in the range of 0.4 – 1.0 mm. Nanoindentation technique was used to determine the Young's modulus and hardness. Bending tests were performed using dynamic mechanical analysis with the amplitudes in the 1 – 50 micron range at 1 Hz. The values of Young's modulus (1 – 20 GPa), hardness (70 – 500 MPa) and bending modulus (0.3 – 2.4 GPa) were obtained. The highest values of the Young's modulus and hardness of these composite materials were achieved for 40% – 60% HA content by weight, which was close to the values for similar HA/collagen composites. However, the maximum bending strength was observed for 20 – 35% HA content. We discuss further the observed trends of the mechanical properties and their dependence on other factors such as the test conditions, sample geometry, and HA particle size.

Properties of Cu-TiB2 Composites Fabricated by In-Situ Liquid Melt Mixing Process

2006 ◽  
Vol 15-17 ◽  
pp. 215-219 ◽  
Author(s):  
J.H Yun ◽  
J.H. Kim ◽  
J.S. Park ◽  
Young Do Park ◽  
Yong Ho Park ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Mixing Process ◽  
Melt Mixing ◽  
Maximum Value ◽  
S Model ◽  
Good Agreement

A Cu-TiB2 composite was successfully fabricated by in-situ liquid mixing process, and its microstructure, mechanical properties as well as electrical conductivity were evaluated. For Cu-2vol.%TiB2 composite, the hardness was as high as 5GPa and the Young’s modulus was 130GPa. And hardness and Young’s modulus of Cu-6vol.%TiB2 composite was 5.6Gpa and 138GPa, respectively. With the increase of the TiB2 content, hardness and Young’s modulus of Cu-10vol.%TiB2 composite were 20 and 12%, respectively, which was higher than that of Cu-2vol.%TiB2 composite. Young’s modulus of the Cu-TiB2 composite in this paper was in good agreement with the prediction by Hashin-Shtrikman (H-S) model. Furthermore, the electrical conductivity of the Cu-TiB2 composite showed its maximum value of about 78%IACS and decreased with the increase of the TiB2.

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