The Effect of Binder Loading on the Pore Size of 3D Printed PMMA

Binder jetting is known to produce porous objects by depositing the binder selectively layer by layer on a powder bed. In this study, the pore size of printed parts and the correlating mechanical properties are investigated on a commercially available PMMA powder binder system. Pore sizes are measured via capillary flow porometry and mechanical properties via tensile tests. Porometry indicates that the pore size stays at a constant level of 22 µm at 5 to 10 wt% binder loading before decreasing to 6 µm at loadings of 30 wt% or higher. The results were compared with the mechanical testing and related to the agglomerate strength model of Rumpf. The highlights of the article are the application of a binder jetted part as a filter and the identification of a close relationship between porosity and mechanical strength, similar to phenomena in agglomeration science.

Optimasi Parameter Mesin 3D Bioprinter dengan Response Surface Method

This research uses material polymethylmethacrylate (PMMA) and hydroxyapatite (HA). The composition of PMMA: MMA is 1: 1 with the ratio composition of HA to PMMA powder is 0.50: 1 (w/w). The composition will be printed with a 3D Bioprinter that has 1.5 mm nozzle. The parameters of the 3D Bioprinter`s tested are perimeter speed with a range of 20 mm/s, 30 mm/s and 40 mm/s, infill speed with a range of 50 mm/s, 60 mm/s, and 70 mm/s, and fill density with a range of 40 mm/s, 50 mm/s and 60 mm/s. These parameters were optimized using response surface method with Minitab software 17. The design of specimens to be printed with a 3D Bioprinter machine using ASTM D638 Type 1. This design will be tested with dimensional measurement and tensile strength. The result of this study is indicated the optimal point at 31.15 mm/s for the perimeter speed`s parameter, 58.84 mm/s for the infill speed`s parameter and 64% for the fill density`s parameter. Dimension of the design is added with a scale of 1: 1.02 mm for length`s dimensions, 1: 1.08 mm for width`s dimensions, 1: 1.09 mm for narrow width`s dimensions and 1: 1.17 mm for thick`s dimensions.

Comparison of Design Method for Making Composite of (PMMA/HA/Sericin)

Biomaterial components (PMMA/HA/Sericin) are composite biomaterial that have complemented each other, which HA is able to improve the mechanical properties, biocompatible and osteoconductivity. PMMA has the ability biocompatible with human tissue and easy manipulated, while sericin can improve cell viability. Analysis of the composite composition is important to do more in depth, but the design method in the analysis of research also has significant impact in generating research output and prediction output. Analysis of the design method to determine the method of designing the optimal research was needed. This research used 3 factors: Poly methyl methacrylate (PMMA) powder (with concentration of 40% to 60%), Hydroxyapatite (HA) powder (with concentration of 10% to 25%) and Sericin (with concentration of 0.16% to 0.32%). This research is done to identify the effect of individual components of the composite and analyze the design method to obtain the best of diametral tensile strength (DTS) with a small error. The result of two methods was found that the 2k factorial design method give higher DTS (PHS401032 = 25.49MPa) than that of Taguchi method (PHS601532 = 24.82MPa). The error of 2k Factorial design method between validation and model prediction is 0.27%, which smaller than Taguchi method (7.45%).

Influences of NBR/Al2O3/YSZ as Fillers for PMMA Composite on the Thermal Properties

The aim of this study is to investigate the effect of nitrile butadiene rubber (NBR as impact modifier) together with Al2O3/YSZ (toughening) as different filler ratios in PMMA material on the DSC thermal properties. PMMA matrix without fillers was mixed between PMMA powder and 0.5 wt.% of BPO and fixed at 7.5 wt.% of NBR particles with different ratios of filler (1, 3, 5, 7 and 10 wt.%) of Al2O3/YSZ mixture filler by (1:1 ratio). The TGA data were shown that the PMMA composite have better thermal stability compared to unreinforced PMMA matrix. While, DSC curves shows slightly similar in Tg value. DSC results also indicated the presence of unreacted monomer content for both reinforced and unreinforced PMMA composites. As conclusion of this study, the reinforced PMMA composites are improved in thermal stability compared to unreinforced PMMA matrix.

Using MicroCT to Visualize Nanofluid Droplet Sorption Profiles in Unsaturated Porous Media

Liquid droplet sorption in unsaturated porous media is an important process for a wide range of applications. However, visualizing droplet sorption is difficult due to the opaque nature of porous media used in most of the applications. In this study, microCT is used to characterize the sorption profiles of single/multiple nanofuid droplets in PMMA powder beds. The microCT scan results reveal that the region of the powder bed saturated with nanofluid has a substantially higher gray scale value than that in the unsaturated region, thus enabling the visualization of the sorption profile. It also shows that nanoparticles enhance the visualization of the sorption profiles as they tend to accumulate and stay near the wetting front even after water evaporation.

Modification of Rubber Particles and Ceramic Fillers on PMMA Denture Base Materials

The purpose of this study is to investigate the effect of nitrile butadiene rubber (NBR) particles and ceramic fillers on the density of PMMA denture base materials. The denture base was prepared based on the mixture of PMMA powder and MMA liquid. The density of the denture base has been modified by adding three different ratios of nitrile rubber (5, 7.5 and 10 wt %), three types of ceramic fillers (Al2O3, YSZ and SiO2, respectively) fixed at 5 wt %, 0.5% of benzoyl peroxide (PBO) and ethylene glycol dimethacryate (10 wt% EGDMA). The powder/liquid (P/L) was mixed by 2.5:1 g ratio. At 10 wt% of NBR the denture base density has reduced to 50%. Furthermore, the addition of ceramic fillers together with NBR particles has also reduced the denture base density. The density data was statistically analysed by on-way (ANOVA) and the values were significantly effect when addition of rubber particles in PMMA denture base composite (p < 0.05).Therefore, the density issue can be easily adjusted in retention and stability of denture base in the patient mouth.

Comparative Study of the Synthesis Condition for Orthodontic Polymethylmethacrylate Powder

The aim was to investigate particles of poly (methylmethacrylate)(PMMA) prepared by suspension polymerization using different concentration of a stabilizer and by varying of the agitation speed at 300, 400, and 500 rpm. Particle size distribution (PSD), and morphology of the PMMA powders were observed and compared with commercial orthodontic PMMA powder. The experimental results indicated that the increasing the agitation speed tends to decrease the particles size at 0.08 wt % stabilizer.