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The interest on porous ceramics has increased in the last years with the developments in additive manufacturing methods, enabling design of components with complex geometries for membranes, filters, catalytic converters, or biostructures. In this study, porous alumina samples were produced by using different concentrations of poly(methyl methacrylate) (PMMA) as pore‐forming agent (PFA) in a photocurable slurry via vat photopolymerization (VPP). The effect of layer thickness, PMMA particle size, and sintering temperature on the mechanical properties and microstructural features of the samples was investigated as a function of PMMA concentration. It is shown that the mechanical properties of 3D‐printed porous alumina are comparable with those fabricated by conventional processes. The Young modulus, fracture toughness as well as the biaxial strength decreased with increasing weight concentration of PFA (resulting in an increased total porosity). Specially using smaller PMMA particles has a positive effect, resulting in higher Young's modulus as well as fracture toughness. The feasibility of VPP for fabricating novel parts with more complex porosity regions is explored by printing multi‐material samples and porosity‐graded architectures. The counterbalance effect between porosity and mechanical properties may be optimized by tailoring material composition and processing parameters. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the relationship between the fiber distribution and the permeability properties of the hydroentangled nonwoven fabrics in terms of air permeability and porosity. The fiber distribution and web properties of the hydroentangled nonwoven fabrics have significant influence on mechanical and physical performance of the finished products. Control of these properties during production, without physical testing, plays an important role in reducing response time to change the process parameters as well as production costs and material waste. In this study, an artificial intelligence method has been developed to predict the porosity and air permeability properties of hydroentangled nonwoven fabrics from their texture features. For this aim, two image processing algorithms were developed in order to measure the fabric porosity and to extract texture statistical features. For the prediction of the investigated fabric properties, an Artificial Neural Network (ANN) model was built. The investigated samples were composed of Polyester (PES) and Viscose (CV) fiber with different areal weights. High regression values were obtained between predicted and actual values for both porosity and air-permeability properties. According to ANN results, it was revealed that the air permeability and porosity properties of hydroentangled nonwovens can be predicted with high accuracy from their texture images. [ABSTRACT FROM AUTHOR]

A PVDF polymer has very good strength, toughness and piezoelectric properties and is nowadays used as the film in strain sensors, mechanical actuators, energy harvesters and artificial muscles. Furthermore, PVDF polymer is used as the fiber in hollow fiber membranes for filtration applications. This article introduces the manufacturing of solid PVDF fibers by a wet spinning process and investigates the effects of the process parameters (i.e. drawing temperatures and drawing ratios on the first and second bath) on macroscopic properties (i.e. fiber linear density, fiber shape, density, porosity, strength and elongation) of solid wet-spun PVDF fibers. Increasing the drawing ratio at the first region of the wet spinning of the PVDF fiber increases the porosity. However, if the drawing is performed at the second drawing bath, the porosity of the PVDF fibers remains almost same. The slopes of the strength vs. drawing ratio and elongation vs. drawing ratio curves increase if the drawing is performed at the second drawing bath. The drawing ratio at the first bath does not affect the tensile properties of fibers, such as tensile strength and elongation. Information about the relationships between the process parameters and macro properties of PVDF fibers is very important so that PVDF fibers with the required properties can be produced with a wet spinning process by setting the correct process parameters. [ABSTRACT FROM AUTHOR]