Strengthening of Dense Bioceramic Samples Using Bioresorbable Polymers – A Statistical Approach

Author(s):  
Sergey V. Dorozhkin ◽  
T. Ajaal

Mechanical properties of bioceramics are poor and need to be improved for biomedical applications. In order to do this, bioceramics may be strengthened by bioresorbable polymers. In this study, the mechanical properties of poly(ε-caprolactone), PCL, coated dense bioceramic pellets made of silica-contained calcium phosphates were studied and analyzed using a statistical experimental design in conjunction with Taguchi methods for optimization. The aim of this experimental work was to maximize the pellet flexural strength and minimize the amount of deposited PCL. The most important factors affecting the strengthening of the ceramic pellets were evaluated. Four independent processing variables (a removal technique of an excess polymer solution, concentration of PCL in the solution, a heat treatment temperature and the number of dipping) with three levels of variability were tested using an L9 (34) orthogonal array. A statistical experimental design using the analysis of means and orthogonal array was applied to optimize the responses of these variables. The optimal conditions for achieving the maximal flexural strength of the coated pellets at the minimal amount of the deposited PCL were determined. A high quality dense bioceramic pellets with ~ 10.5 MPa flexural strength and ~ 80 μm thickness (~ 21 mg weight) of the deposited PCL coating were manufactured as a result.

2009 ◽  
Vol 20 (3) ◽  
pp. 205-210 ◽  
Author(s):  
Ivone L. Santana ◽  
Edméa Lodovici ◽  
Jivaldo R. Matos ◽  
Igor S. Medeiros ◽  
Caroline L. Miyazaki ◽  
...  

The aim of this study was to verify the influence of an experimental heat treatment (170ºC/10 min) using a casting furnace on the mechanical properties (hardness and flexural strength) of 2 commercial direct resin composites (TPH Spectrum and Filtek P60) compared to a commercial indirect resin system (BelleGlass). Heat treatment temperature was determined after thermal characterization by thermogravimetry (TG) and differential scanning calorimetry (DSC). Data was analyzed by ANOVA and Tukey's test at 5% significance level. There was statistical significance for the main factor heat treatment (p=0.03) and composite (p=0.02), for flexural strength. For Knoop hardness, only the main factor composite was statistically significant (p=0.00). P60 presented higher hardness than TPH. No statistically significant correlation between mechanical properties tested was detected. Based on these results, it was possible to conclude that heat treatment influenced flexural strength of direct composites, while it was not observed for hardness. The association of direct composites with a simple post-cure heat treatment may be an alternative for current indirect composite systems, although more studies are needed to verify other properties of the composites for this application.


2012 ◽  
Vol 455-456 ◽  
pp. 645-649 ◽  
Author(s):  
He Yi Ge ◽  
Jian Ye Liu ◽  
Xian Qin Hou ◽  
Hua Shi Liu ◽  
Dong Zhi Wang

The effects of nano-ZrO2, ZrO2fiber and sintering additives on the mechanical properties of Al2O3ceramic composite were investigated by means of orthogonal experimental design. Meanwhile, the effect of environmental temperature on flexural strength of Al2O3ceramic composite was tested. XRD and SEM were used to analyze the microstructure. The results showed that the content of ZrO2fiber had the greatest effect on flexural strength and fracture toughness, followed by the content of nano-ZrO2. Nano-ZrO2made the crystalline grains of Al2O3smaller. ZrO2fiber pulled out from Al2O3matrix could consume energy of crack and increase the flexual strength and toughness of ceramic composite.


2012 ◽  
Vol 1373 ◽  
Author(s):  
V. Nicolau ◽  
N. Bertoneri ◽  
J. Scarello ◽  
D. Estenoz

ABSTRACTThis work studies the synthesis of styrene copolymers obtained from the reaction between isophthalic unsaturated polyester resins and styrene with the aim of improving the mechanical properties of sheet moulding compounds (SMC), specifically their flexibility and impact resistance.The experimental work involves the experimental design; the SMC synthesis with different concentrations of 4 additives (methylmethacrylate; diethylenglycol, dioctilphthalate, and a commercial flexible resin); and the mechanical characterization including measurements of load-deflection curves; flexural strength (FS), flexural modulus (FM) and impact resistance (IR).


2014 ◽  
Vol 788 ◽  
pp. 580-587
Author(s):  
Yuan Lu ◽  
Jing Long Li ◽  
Jian Feng Yang ◽  
Qiang Zheng Jing ◽  
Jing Jing Li ◽  
...  

The co-continuous AlN composites with different Al contents were fabricated through the squeeze casting of porous AlN preform with varied porosities obtained by carbothermal reduction. The effects of volume fraction of Al phase and the heat treatment temperature on the mechanical properties of composites were investigated. The change of the mechanical properties of composites with the Al content was in line with the mixed rule. With an increase in the Al content, the fracture toughness increased, the Vickers hardness and the flexural strength decreased. The toughen mechanism of composites included ductile rupture and microcrack toughening. The avoiding of excessive interface reaction between AlN and Al was beneficial to the mechanical properties of composites. With an increase in the heat treatment temperature, the stress and the dislocation due to mismatch in the coefficients of thermal expansion increased, the fracture toughness decreased, the vickers hardness and the flexural strength increased.


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