Influence of Al2O3/ Y-TSZ Mixture as Filler Loading on the Radiopacity of PMMA Denture Base Composites

AbstractThe radiopacity of alumina/yttrium stabilizer zirconia (Al2O3/Y-TSZ) particles with nitrile butadiene rubber (NBR) dispersed in PMMA denture base material has been investigated. PMMA matrix without filler was prepared from PMMA powder with 0.5% benzoyl peroxide (PBO) as the control material. The similar PMMA matrix was mixed with Al2O3/Y-TSZ (1:1) together with NBR particles as the reinforcement. The amount of NBR was fixed at 7.5wt %, however, Al2O3/Y-TSZ varied from 1 to 10wt %, respectively. Samples with 4mm thickness for each composition were irradiated using 60 KV, 10mA, 0.4 s to examine their radiopacity. This radiopacity was compared to radiopacity of aluminum plate which having the same thickness. The result shows that the radiopacity (i.e. the lower optical density the higher radiopacity) of reinforced PMMA matrix slightly increased from 1.40 to 1.05, respectively, with the increased of filler loading compared to unreinforced PMMA matrix

The effect of polymeric template density and solid loading on the properties of ceramic foam

This paper studies the effect of various polymeric foam template densities and solid loadings on the properties of ceramic foam. The study was based on six different polymeric foam templates with densities ranging from 13.4 to 37.8 kg/m3. The templates were impregnated in ceramic slurry with solid loading ranging from 15 to 60 wt. %. Effects of polymeric foam template density and solid loading quantity were evaluated based on porosity, density and mechanical properties of resulted ceramic foam. It was found that the density, porosity and flexural strength of ceramic foam seem to be independent from the template densities when the solid loading is less than 35 wt. %. For the given solid loading, i.e < 35 wt. %, the density and flexural strength are less than 1100 kg/m3 and 6 MPa, respectively, and porosities are higher than 40 %. The polymer replication method is a versatile method for the production of ceramic foams. It will allow the production of any desired properties of ceramic foam through a simple modification route

Modeling the tensile stress–strain response of carbon nanotube/polypropylene nanocomposites using nonlinear representative volume element

This paper presents a finite element model for predicting the mechanical behavior of polypropylene (PP) composites reinforced with carbon nanotubes (CNTs) at large deformation scale. Existing numerical models cannot predict composite behavior at large strains due to using simplified material properties and inefficient interfaces between CNT and polymer. In this work, nonlinear representative volume elements (RVE) of composite are prepared. These RVEs consist of CNT, PP matrix and non-bonded interface. The nonlinear material properties for CNT and polymer are adopted to solid elements. For the first time, the interface between CNT and matrix is simulated using contact elements. This interfacial model is capable enough to simulate wide range of interactions between CNT and polymer in large strains. The influence of adding CNT with different aspect ratio into PP is studied. The mechanical behavior of composites with different interfacial shear strength (ISS) is discussed. The success of this new model was verified by comparing the simulation results for RVEs with conducted experimental results. The results shows that the length of CNT and ISS values significantly affect the reinforcement phenomenon