Mechanical Behavior of Hydroxyapatite-Chitosan Composite: Effect of Processing Parameters

Three-dimensional hydroxyapatite-chitosan (HA-CS) composites were formulated via solid-liquid technic and freeze-drying. The prepared composites had an apatitic nature, which was demonstrated by X-ray diffraction and Infrared spectroscopy analyses. The impact of the solid/liquid (S/L) ratio and the content and the molecular weight of the polymer on the composite mechanical strength was investigated. An increase in the S/L ratio from 0.5 to 1 resulted in an increase in the compressive strength for HA-CSL (CS low molecular weight: CSL) from 0.08 ± 0.02 to 1.95 ± 0.39 MPa and from 0.3 ± 0.06 to 2.40 ± 0.51 MPa for the HA-CSM (CS medium molecular weight: CSM). Moreover, the increase in the amount (1 to 5 wt%) and the molecular weight of the polymer increased the mechanical strength of the composite. The highest compressive strength value (up to 2.40 ± 0.51 MPa) was obtained for HA-CSM (5 wt% of CS) formulated at an S/L of 1. The dissolution tests of the HA-CS composites confirmed their cohesion and mechanical stability in an aqueous solution. Both polymer and apatite are assumed to work together, giving the synergism needed to make effective cylindrical composites, and could serve as a promising candidate for bone repair in the orthopedic field.

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Three-Dimensional Printed PLA and PLA/PHA Dumbbell-Shaped Specimens: Material Defects and Their Impact on Degradation Behavior

Materials ◽

10.3390/ma13082005 ◽

2020 ◽

Vol 13 (8) ◽

pp. 2005 ◽

Cited By ~ 1

Author(s):

Joanna Rydz ◽

Jakub Włodarczyk ◽

Jennifer Gonzalez Ausejo ◽

Marta Musioł ◽

Wanda Sikorska ◽

...

Keyword(s):

Three Dimensional ◽

Hydrolytic Degradation ◽

Processing Parameters ◽

Polymer Materials ◽

Original Research ◽

Polymer Properties ◽

Subsequent Behavior ◽

And Behavior ◽

The Impact ◽

Printing Direction

The use of (bio)degradable polymers, especially in medical applications, requires a proper understanding of their properties and behavior in various environments. Structural elements made of such polymers may be exposed to changing environmental conditions, which may cause defects. That is why it is so important to determine the effect of processing conditions on polymer properties and also their subsequent behavior during degradation. This paper presents original research on a specimen’s damage during 70 days of hydrolytic degradation. During a standard hydrolytic degradation study of polylactide and polylactide/polyhydroxyalkanoate dumbbell-shaped specimens obtained by 3D printing with two different processing build directions, exhibited unexpected shrinkage phenomena in the last degradation series, representing approximately 50% of the length of the specimens irrespective of the printing direction. Therefore, the continuation of previous ex-ante research of advanced polymer materials is presented to identify any possible defects before they arise and to minimize the potential failures of novel polymer products during their use and also during degradation. Studies on the impact of a specific processing method, i.e., processing parameters and conditions, on the properties expressed in molar mass and thermal properties changes of specimens obtained by three-dimensional printing from polyester-based filaments, and in particular on the occurrence of unexpected shrinkage phenomena after post-processing heat treatment, are presented.

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Strength, Permeability, and Freeze-Thaw Durability of Pervious Concrete with Different Aggregate Sizes, Porosities, and Water-Binder Ratios

Applied Sciences ◽

10.3390/app8081217 ◽

2018 ◽

Vol 8 (8) ◽

pp. 1217 ◽

Cited By ~ 12

Author(s):

Hanbing Liu ◽

Guobao Luo ◽

Haibin Wei ◽

Han Yu

Keyword(s):

Compressive Strength ◽

Mechanical Strength ◽

Aggregate Size ◽

Pervious Concrete ◽

High Porosity ◽

Range Analysis ◽

Freeze Thaw ◽

Binder Ratio ◽

The Impact ◽

Water Binder Ratio

Pervious concrete (PC), as an environmental friendly material, can be very important in solving urban problems and mitigating the impact of climate change; i.e., flooding, urban heat island phenomena, and groundwater decline. The objective of this research is to evaluate the strength, permeability, and freeze-thaw durability of PC with different aggregate sizes, porosities, and water-binder ratios. The orthogonal experiment method is employed in the study and nine experiments are conducted. The compressive strength, flexural strength, permeability coefficient, porosity, density, and freeze-thaw durability of PC mixtures are tested. Range analysis and variance analysis are carried out to analyze the collected data and estimate the influence of aggregate size, porosity, and water-binder ratio on PC properties. The results indicate that porosity is the most important factor determining the properties of PC. High porosity results in better permeability, but negatively affects the mechanical strength and freeze-thaw durability. PC of 15% porosity can obtain high compressive strength in excess of 20 MPa and favorable freeze-thaw durability of 80 cycles without sacrificing excessive permeability. Aggregate size also has a significant effect on freeze-thaw durability and mechanical strength. Small aggregate size is advantageous for PC properties. PC with 4.75–9.5 mm coarse aggregate presents excellent freeze-thaw durability. The influence of the water-binder ratio on PC properties is not as significant as that of aggregate size and porosity. An optimal mix ratio is required to trade-off between permeability, mechanical strength, and freeze-thaw durability.

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Darmstadt Rotor No. 2, II: Design of Leaning Rotor Blades

International Journal of Rotating Machinery ◽

10.1155/s1023621x03000368 ◽

2003 ◽

Vol 9 (6) ◽

pp. 385-391

Author(s):

Jörg Bergner ◽

Dietmar K. Hennecke ◽

Martin Hoeger ◽

Karl Engel

Keyword(s):

Mechanical Stability ◽

Three Dimensional ◽

Stability Limit ◽

Operating Conditions ◽

Rotor Blades ◽

Navier Stokes ◽

Structural Constraints ◽

Transonic Compressor ◽

Aero Engines ◽

The Impact

For Darmstadt University of Technology's axial singlestage transonic compressor rig, a new three-dimensional aft-swept rotor was designed and manufactured at MTU Aero Engines in Munich, Germany. The application of carbon fiber–reinforced plastic made it possible to overcome structural constraints and therefore to further increase the amount of lean and sweep of the blade. The aim of the design was to improve the mechanical stability at operation that is close to stall.To avoid the hazard of rubbing at the blade tip, which is found especially at off-design operating conditions close to the stability limit of the compression system, aft-sweep was introduced together with excessive backward lean.This article reports an investigation of the impact of various amounts of lean on the aerodynamic behavior of the compressor stage on the basis of steady-state Navier-Stokes simulations. The results indicate that high backward lean promotes an undesirable redistribution of mass flow and gives rise to a basic change in the shock pattern, whereas a forward-leaning geometry results in the development of a highly back-swept shock front. However, the disadvantage is a decrease in shock strength and efficiency.

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Fabrication and Multiscale Structural Properties of Interconnected Porous Biomaterial for Tissue Engineering by Freeze Isostatic Pressure (FIP)

Journal of Functional Biomaterials ◽

10.3390/jfb9030051 ◽

2018 ◽

Vol 9 (3) ◽

pp. 51 ◽

Cited By ~ 3

Author(s):

Mythili Prakasam ◽

Ali Chirazi ◽

Grzegorz Pyka ◽

Anna Prokhodtseva ◽

Daniel Lichau ◽

...

Keyword(s):

Tissue Engineering ◽

Mechanical Strength ◽

Cell Attachment ◽

Imaging Techniques ◽

Three Dimensional ◽

High Strength ◽

Processing Parameters ◽

Fabrication Technology ◽

Porous Network ◽

Pore Connectivity

Biomaterial for tissue engineering is a topic of huge progress with a recent surge in fabrication and characterization advances. Biomaterials for tissue engineering applications or as scaffolds depend on various parameters such as fabrication technology, porosity, pore size, mechanical strength, and surface available for cell attachment. To serve the function of the scaffold, the porous biomaterial should have enough mechanical strength to aid in tissue engineering. With a new manufacturing technology, we have obtained high strength materials by optimizing a few processing parameters such as pressure, temperature, and dwell time, yielding the monolith with porosity in the range of 80%–93%. The three-dimensional interconnectivity of the porous media through scales for the newly manufactured biomaterial has been investigated using newly developed 3D correlative and multi-modal imaging techniques. Multiscale X-ray tomography, FIB-SEM Slice & View stacking, and high-resolution STEM-EDS electronic tomography observations have been combined allowing quantification of morphological and geometrical spatial distributions of the multiscale porous network through length scales spanning from tens of microns to less than a nanometer. The spatial distribution of the wall thickness has also been investigated and its possible relationship with pore connectivity and size distribution has been studied.

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New Chemicals and Routes for the Preparation of Gelatin/HA Composites using the Wet Precipitation Method

Jurnal Kimia Sains dan Aplikasi ◽

10.14710/jksa.23.2.46-50 ◽

2020 ◽

Vol 23 (2) ◽

pp. 46-50 ◽

Cited By ~ 1

Author(s):

Nur Akbar ◽

Asril Pramutadi Andi Mustari ◽

Atiek Rostika Noviyanti

Keyword(s):

Compressive Strength ◽

Mechanical Strength ◽

Bone Repair ◽

Particle Density ◽

Testing Machine ◽

Precipitation Method ◽

High Mechanical Strength ◽

Wet Precipitation ◽

Universal Testing ◽

Infra Red

Hydroxyapatite (HA) is a material that has many uses in a wide variety of applications such as bone repair, bone implants, and bone drug delivery systems. However, the main weakness of this material is its mechanical strength, which HA is not enough to be directly applied. Gelatin addition is used to improve the mechanical properties that can support material properties for the load-bearing application. This research aimed to obtain gelatin/HA composites with high mechanical strength. This goal is achieved by finding the optimum composite composition (addition of 20, 30, and 40% w/w gelatin), CaO precursors from chicken eggshells, and gradual composite preparation. The preparation of gelatin/HA composites was carried out using the wet precipitation method. The chemical bonding, the compressive strength of HA and gelatin/HA composites, and also morphologies were analyzed by Fourier Transform Infra-Red (FTIR), Universal Testing Machine, and Scanning Electron Microscopy (SEM) respectively. The FTIR spectra show there are chemical bonds between amide and carboxyl in gelatin and Ca2+ in HA. The best compressive strength obtained at the composition of 20% gelatin/HA composite is 99.3 MPa (meanwhile HA is 81.5 MPa). The addition of gelatin to HA increases the particle density; this contributes to the increase in mechanical strength.

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The Effects of Three-Dimensional Ligand Immobilization on Kinetic Measurements in Biosensors

Polymers ◽

10.3390/polym14020241 ◽

2022 ◽

Vol 14 (2) ◽

pp. 241

Author(s):

Elisa Chiodi ◽

Allison M. Marn ◽

Monireh Bakhshpour ◽

Nese Lortlar Ünlü ◽

M. Selim Ünlü

Keyword(s):

Molecular Weight ◽

Three Dimensional ◽

The Other ◽

Low Molecular Weight ◽

Surface Binding ◽

Kinetic Measurements ◽

Advantages And Disadvantages ◽

Affinity Constants ◽

Other Hand ◽

The Impact

The field of biosensing is in constant evolution, propelled by the need for sensitive, reliable platforms that provide consistent results, especially in the drug development industry, where small molecule characterization is of uttermost relevance. Kinetic characterization of small biochemicals is particularly challenging, and has required sensor developers to find solutions to compensate for the lack of sensitivity of their instruments. In this regard, surface chemistry plays a crucial role. The ligands need to be efficiently immobilized on the sensor surface, and probe distribution, maintenance of their native structure and efficient diffusion of the analyte to the surface need to be optimized. In order to enhance the signal generated by low molecular weight targets, surface plasmon resonance sensors utilize a high density of probes on the surface by employing a thick dextran matrix, resulting in a three-dimensional, multilayer distribution of molecules. Despite increasing the binding signal, this method can generate artifacts, due to the diffusion dependence of surface binding, affecting the accuracy of measured affinity constants. On the other hand, when working with planar surface chemistries, an incredibly high sensitivity is required for low molecular weight analytes, and furthermore the standard method for immobilizing single layers of molecules based on self-assembled monolayers (SAM) of epoxysilane has been demonstrated to promote protein denaturation, thus being far from ideal. Here, we will give a concise overview of the impact of tridimensional immobilization of ligands on label-free biosensors, mostly focusing on the effect of diffusion on binding affinity constants measurements. We will comment on how multilayering of probes is certainly useful in terms of increasing the sensitivity of the sensor, but can cause steric hindrance, mass transport and other diffusion effects. On the other hand, probe monolayers on epoxysilane chemistries do not undergo diffusion effect but rather other artifacts can occur due to probe distortion. Finally, a combination of tridimensional polymeric chemistry and probe monolayer is presented and reviewed, showing advantages and disadvantages over the other two approaches.

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Calcium Phosphate Cement Modified with Sodium Citrate for Bone Repair

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.197-198.151 ◽

2011 ◽

Vol 197-198 ◽

pp. 151-155 ◽

Cited By ~ 1

Author(s):

Xiao Peng Qi

Keyword(s):

Compressive Strength ◽

Calcium Phosphate ◽

Mechanical Strength ◽

Calcium Phosphate Cement ◽

Bone Repair ◽

Sodium Citrate ◽

High Strength ◽

The Self ◽

Hydration Reaction ◽

Citrate Concentration

An injectable calcium phosphate cement (CPC) modified with sodium citrate was developed in the present study. The effects of sodium citrate concentration on the injectability, mechanical strength, and the self-setting properties of CPC were systematically investigated. The addition of sodium citrate significantly improved injectability and compressive strength of CPC. The specimens have an injectability of 93% and compressive strength of 36.43 ± 2.64 MPa at 15 wt% sodium citrate concentration, compared to injectability of 75% and compressive strength of 23.15 ± 2.12 MPa of the specimens without sodium citrate. XRD spectra indicated that addition of sodium citrate did not change the hydration reaction of CPC and the reaction product was mainly poorly crystallized hydroxyapatite. In conclusion, CPC developed in this work exhibited excellent injectability and high strength, which should be a promising material for bone repair.

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Multi-Layer Computational Modeling of Selective Laser Sintering Processes

Volume 2A: Advanced Manufacturing ◽

10.1115/imece2014-37535 ◽

2014 ◽

Cited By ~ 4

Author(s):

Daniel Moser ◽

Scott Fish ◽

Joseph Beaman ◽

Jayathi Murthy

Keyword(s):

Selective Laser Sintering ◽

Three Dimensional ◽

Processing Parameters ◽

Laser Sintering ◽

Incomplete Fusion ◽

Temperature History ◽

Powder Layer ◽

Large Temperature ◽

Powder Bed ◽

The Impact

Selective laser sintering (SLS) is an additive manufacturing technique able to rapidly create parts directly from a CAD model using a laser to selectively fuse successive layers of powder. However, defects can arise in SLS parts due to incomplete fusion of the powder layers or thermal stresses introduced by large temperature gradients during the part build. Accurate models of the SLS process are needed to ensure that high quality parts are produced and to allow new materials and designs to be used without requiring extensive experimentation. Most existing models of the SLS process are very narrowly focused, predicting the temperature history of a single powder layer after a single laser pass or examining the impact of a few processing parameters on the properties of the produced part. A model capable of predicting a complete temperature history during an entire part build does not yet exist. Therefore, a new thermal model able to simulate multiple powder layers is proposed. A transient, three-dimensional, finite volume model is developed and implemented in ANSYS Fluent. A domain of cells representing multiple layers of an SLS build is initialized, some with the properties of air and some with the properties of powder, depending on cell location. A Gaussian heat source representing the laser is applied to the top layer of powder cells. The center of the Gaussian is varied with time along an established path to simulate the motion of the laser along the powder bed. At all times the three-dimensional heat equation is solved to produce a temperature profile of the powder bed. When the laser completes a full scan of the powder layer, the air cells directly above the powder layer are re-initialized as powder cells and re-set to an initial temperature, representing the addition of a new powder layer. The process is repeated for each new layer. Temperature history results from the model are validated against experimental data available in the literature and good agreement is obtained. As the model accounts for multiple powder layers, it can be used to simulate an entire part build and predict the impact of any of the SLS processing parameters on part quality and thus enable better control and optimization of the SLS process.

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The Influence of Processing Parameters on the Void Content and Compressive Strength of Carbon Fibre-Epoxy Laminates

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.275.243 ◽

2011 ◽

Vol 275 ◽

pp. 243-246

Author(s):

Xiao Wen Yuan ◽

S. Bickerton ◽

Samuel Bradley ◽

Arry Tapiheroe ◽

John Little

Keyword(s):

Compressive Strength ◽

Carbon Fibre ◽

Void Fraction ◽

Processing Parameters ◽

Positive Pressure ◽

Void Content ◽

Processing Parameter ◽

The Impact ◽

Carbon Fibre Composites

This research addresses the influence of various processing parameters on the post cure quality of carbon fibre composites. Four processing parameters were investigated in the study, in terms of their impact on void content and overall compressive strength. The first parameter distinguishes between laminates cured in a vacuum oven and those cured in an autoclave under high positive pressure. The second parameter describes the impact on voids of differing fibre architectures, comparing a unidirectional fibre structure to that of woven cloth. Thirdly, the influence of compaction during manufacture is analysed and lastly, variation in cure temperature was tested to determine its effect on final laminate quality. The quality of the cured laminate samples was assessed from visual inspection, and in terms of compressive strength and void fraction calculated by Micro-CT X-ray Tomography. The results show that autoclave-cured samples feature significant quality improvements in terms of void fraction and compressive strength when compared to oven-cured samples. Unidirectional laminates incur higher sensitivity to void inclusion than cloth laminates due to the influence of fibre wrinkling. Compaction has no effect on laminate strength; it does however reduce variability in certain cases. Temperature affects different fibre structures in different ways, these being highly dependent on curing method. Finally, it was discerned that curing by autoclave was the dominant processing parameter. Thus, regardless of other manufacturing techniques, the autoclave samples featured almost zero voids and were consequently of the highest quality.

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Effect of combined drink cans and steel fibers on the impact resistance and mechanical properties of concrete

JOURNAL OF MECHANICAL ENGINEERING AND SCIENCES ◽

10.15282/jmes.14.2.2020.15.0527 ◽

2020 ◽

Vol 14 (2) ◽

pp. 6734-6742

Author(s):

A. Syamsir ◽

S. M. Mubin ◽

N. M. Nor ◽

V. Anggraini ◽

S. Nagappan ◽

...

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Compressive Strength ◽

Reinforced Concrete ◽

Impact Resistance ◽

Fiber Reinforced Concrete ◽

Steel Fibers ◽

Fiber Reinforced ◽

Indirect Tensile ◽

The Impact

This study investigated the combine effect of 0.2 % drink cans and steel fibers with volume fractions of 0%, 0.5%, 1%, 1.5%, 2%, 2.5% and 3% to the mechanical properties and impact resistance of concrete. Hooked-end steel fiber with 30 mm and 0.75 mm length and diameter, respectively was selected for this study. The drinks cans fiber were twisted manually in order to increase friction between fiber and concrete. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the strength performance of concrete, especially the compressive strength, flexural strength and indirect tensile strength. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the compressive strength, flexural strength and indirect tensile strength by 2.3, 7, and 2 times as compare to batch 1, respectively. Moreover, the impact resistance of fiber reinforced concrete has increase by 7 times as compared to non-fiber concretes. Moreover, the impact resistance of fiber reinforced concrete consistently gave better results as compared to non-fiber concretes. The fiber reinforced concrete turned more ductile as the dosage of fibers was increased and ductility started to decrease slightly after optimum fiber dosage was reached. It was found that concrete with combination of 2% steel and 0.2% drink cans fibers showed the highest compressive, split tensile, flexural as well as impact strength.

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