scholarly journals Processing of Sr2+ Containing Poly L-Lactic Acid-Based Hybrid Composites for Additive Manufacturing of Bone Scaffolds

2020 ◽  
Vol 7 ◽  
Author(s):  
Priscila Melo ◽  
Raasti Naseem ◽  
Ilaria Corvaglia ◽  
Giorgia Montalbano ◽  
Carlotta Pontremoli ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Additive Manufacturing ◽  
Hybrid Composites ◽  
Homogeneous Distribution ◽  
Fused Filament Fabrication ◽  
Rheological Characterization ◽  
Biodegradable Composite ◽  
Manufacturing Technologies

Biodegradable composite materials represent one of the major areas of investigation for bone tissue engineering due to their tuneable compositional and mechanical properties, which can potentially mimic those of bone and potentially avoid the removal of implants, mitigating the risks for the patient and reducing the overall clinical costs. In addition, the introduction of additive manufacturing technologies enables a strict control over the final morphological features of the scaffolds. In this scenario, the optimisation of 3D printable resorbable composites, made of biocompatible polymers and osteoinductive inorganic phases, offers the potential to produce a chemically and structurally biomimetic implant, which will resorb over time. The present work focuses on the development and process optimisation of two hybrid composite filaments, to be used as feedstock for the fused filament fabrication 3D printing process. A Poly L-lactic acid matrix was blended with either rod-like nano-hydroxyapatite (nano-HA) or nanoparticles of mesoporous bioactive glasses, both partially substituted with strontium (Sr2+), due to the well-known pro-osteogenic effect of this ion. Both inorganic phases were incorporated into Poly L-lactic acid using an innovative combination of processes, obtaining a homogeneous distribution throughout the polymer whilst preserving their ability to release Sr2+. The filament mechanical properties were not hindered after the incorporation of the inorganic phases, resulting in tensile strengths and moduli within the range of cancellous bone, 50 ± 10 MPa and 3 ± 1 GPa. Finally, the rheological characterization of the hybrid composites indicated a shear thinning behaviour, ideal for the processing with fused filament fabrication, proving the potential of these materials to be processed into 3D structures aiming bone regeneration.

Validation of a low-cost selective powder deposition process through the characterization of tin bronze specimens

2021 ◽  
pp. 146442072110319
Author(s):  
Samuel Magalhães ◽  
Manuel Sardinha ◽  
Carlos Vicente ◽  
Marco Leite ◽  
Relógio Ribeiro ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Low Cost ◽  
Deposition Process ◽  
Metal Powders ◽  
Tin Bronze ◽  
Powder Deposition ◽  
Manufacturing Technologies ◽  
The Cost

Additive manufacturing technologies are becoming increasingly popular due to their advantages over traditional subtracting manufacturing technologies. Despite advances in this field, fixed and maintenance costs for additive manufacturing with metals remain high. The introduction of low-cost metal machines in the additive manufacturing market considerably reduces the cost of acquiring and maintaining this type of equipment. This work aims to establish the process requirements for a low-cost selective powder deposition process, and validate it through the production of specimens in the laboratory and evaluate their mechanical properties. Tin bronze specimens were produced under different manufacturing conditions, namely powder dimensions, type of crucible and coke, firing segments and casting strategy. The morphology and chemical composition of the specimens were carried out combining the scanning electron microscopy and energy dispersive X-Ray spectroscopy techniques, respectively. It was observed that crucibles and coke with impurities that react with the metal powders and infill in a reducing atmosphere have influence in the final quality of parts. Tested samples displayed high variability of results which can be correlated with different manufacturing conditions. The selection of the appropriate print parameters led to the manufacture of tin bronze specimens with mechanical properties comparable to those reported in the literature. Overall, low-cost selective powder deposition is a promising technology, if identified manufacturing issues are addressed.

Rheological characterization of biocompatible associative polymer hydrogels with crystalline and amorphous endblocks

2006 ◽  
Vol 21 (8) ◽  
pp. 2118-2125 ◽  
Author(s):  
Sarvesh K. Agrawal ◽  
Naomi Sanabria-DeLong ◽  
Gregory N. Tew ◽  
Surita R. Bhatia
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Elastic Modulus ◽  
Block Length ◽  
Rheological Characterization ◽  
Precise Control ◽  
Order Of Magnitude ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

Control over mechanical properties of hydrogels is of primary importance for the use of these materials in drug delivery and tissue engineering applications. We demonstrate here that crystallinity and block length of poly(lactide) (PLA) can be used to tune the elastic modulus of associative network gels of poly(lactide)–poly(ethylene oxide)–poly(lactide) over several orders of magnitude. Polymers made with crystalline L lactic acid blocks formed very stiff hydrogels at 25 wt% concentration with an elastic modulus that was almost an order of magnitude higher than hydrogels of polymers with a similar molecular weight but containing amorphous D/L-lactic acid blocks. The relaxation behavior and crosslink density of gels are also significantly influenced by crystallinity of PLA and are again a function of PLA block length. Using these variables we can design new tailor-made materials for biomedical applications with precise control over their structure and mechanical properties.

Preparation and Characterization of Polycaprolactone / Graphene / Zinc Oxide Composites

2021 ◽  
Vol 877 ◽  
pp. 21-26
Author(s):  
Shuai Yuan ◽  
Lin Yuan ◽  
Chen Gao ◽  
Xue Fei Hu ◽  
Chin San Wu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Zinc Oxide ◽  
Soil Test ◽  
Scanning Electron Micrographs ◽  
Biodegradation Rate ◽  
Biodegradable Composite ◽  
Buried Soil ◽  
Oxide Composites ◽  
Scanning Electron

Biodegradable composite from polycaprolactone (PCL) and Graphene/zinc oxide (Graphene/ZnO) is studied. The Graphene/ZnO content is at 0.5%, 1.5% in PCL. Neat PCL and composites were characterized by microstructure, mechanical properties and thermal properties. Scanning electron micrographs show that the additive has agglomerated in PCL/Graphene/ZnO. Agglomeration of the filler results in reduced tensile properties of the composite. The result from XRD indicates Graphene/ZnO can improve the crystallinity of PCL. According to the results of buried soil test and analysis, Graphene/ZnO can reduce the biodegradation rate of PCL and make the material more durable. This new biodegradable composite material can be used as a new environmentally friendly material.

Effect of graphite and silicon carbide fillers on mechanical properties of PA6 polymer composites

2017 ◽  
Vol 37 (6) ◽  
pp. 547-557 ◽  
Author(s):  
Sekaran Sathees Kumar ◽  
Ganesan Kanagaraj
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Polymer Composites ◽  
Interfacial Adhesion ◽  
Hybrid Composites ◽  
Fracture Morphology ◽  
Tensile Fracture ◽  
Injection Molded ◽  
The Individual

Abstract In this paper, the combined effect of different weight percentages of silicon carbide (SiC) and graphite (Gr) reinforcement on the mechanical properties of polyamide (PA6) composite is studied. Test specimens of pure PA6, 85 wt% PA6+10 wt% SiC+5 wt% Gr and 85 wt% PA6+5 wt% SiC+10 wt% Gr are prepared using an injection molding machine. The tensile, impact, hardness, morphology and thermal properties of the injection molded composites were investigated. The obtained results showed that mechanical properties, such as tensile and impact strength and modulus of the PA6 composites, were significantly higher than the pure PA6, and hybridization with silicon carbide and graphite further enhanced the performance properties, as well as the thermal resistance of the composites. The tensile fracture morphology and the characterization of PA6 polymer composites were observed by scanning electron microscope (SEM) and Fourier transform infrared spectroscopic methods. SEM observation of the fracture surfaces showed the fine dispersion of SiC and Gr for strong interfacial adhesion between fibers and matrix. The individual and combined reinforcing effects of silicon carbide and graphite on the mechanical properties of PA6 hybrid composites were compared and interpreted in this study. Improved mechanical properties were observed by the addition of small amount of SiC and Gr concurrently reinforced with the pure PA6. Finally, thermogravimetric analysis showed that the heat resistance of the composites tended to increase with increasing silicon carbide and graphite content simultaneously.

scholarly journals Suitability of Recycled PLA Filament Application in Fused Filament Fabrication Process

2021 ◽  
Vol 15 (4) ◽  
pp. 491-497
Author(s):  
Tomislav Breški ◽  
Lukas Hentschel ◽  
Damir Godec ◽  
Ivica Đuretek
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Polylactic Acid ◽  
Design Of Experiment ◽  
Experimental Approach ◽  
Manufacturing Processes ◽  
Support Structures ◽  
Fused Filament Fabrication ◽  
Layer Height ◽  
Printing Parameters

Fused filament fabrication (FFF) is currently one of the most popular additive manufacturing processes due to its simplicity and low running and material costs. Support structures, which are necessary for overhanging surfaces during production, in most cases need to be manually removed and as such, they become waste material. In this paper, experimental approach is utilised in order to assess suitability of recycling support structures into recycled filament for FFF process. Mechanical properties of standardized specimens made from recycled polylactic acid (PLA) filament as well as influence of layer height and infill density on those properties were investigated. Optimal printing parameters for recycled PLA filaments are determined with Design of Experiment methods (DOE).

Impact of quasi-isotropic raster layup on the mechanical behaviour of fused filament fabrication parts

2021 ◽  
pp. 095400832110419
Author(s):  
Lovin K John ◽  
Ramu Murugan ◽  
Sarat Singamneni
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Mechanical Strength ◽  
Process Parameters ◽  
Mechanical Behaviour ◽  
Fused Filament Fabrication ◽  
Anisotropic Behaviour ◽  
Oriented Samples ◽  
Weak Interlayer ◽  
Special Concern

The development of fused filament fabrication has extended the range of application of additive manufacturing in various areas of research. However, the mechanical strength of the fused filament fabrication–printed parts were considerably lower than that of parts fabricated by other conventional methods, owing to the observed anisotropic behaviour and formation of voids by weak interlayer diffusion. Intense studies on the effect of design and process parameters of the printed parts on the mechanical properties have been done, whereas studies on the effect of build orientations and raster patterns needs special concern. The main aim of this work is to fabricate parts printed using quasi-isotropic laminate arrangement of rasters, achieved by a raster layup of [45/0/−45/90]s, and to compare their mechanical properties with those of the commonly used 0°/90° (cross) and 45°/−45° (crisscross) raster oriented parts. The quasi-isotropic–oriented samples were observed with improved mechanical behaviour in tensile, compressive, flexural and impact tests compared to the commonly employed raster orientations.

Variance Quantification of Different Additive Manufacturing Processes for Acoustic Meta Materials

2021 ◽  
Vol 263 (4) ◽  
pp. 2708-2723
Author(s):  
Manuel Bopp ◽  
Arn Joerger ◽  
Matthias Behrendt ◽  
Albert Albers
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Production Process ◽  
Laser Scanning ◽  
Mode Shapes ◽  
Manufacturing Processes ◽  
3D Laser Scanning ◽  
Fused Filament Fabrication ◽  
Manufacturing Techniques ◽  
Different Levels

Many concepts for acoustic meta materials rely on additive manufacturing techniques. Depending on the production process and material of choice, different levels of precision and repeatability can be achieved. In addition, different materials have different mechanical properties, many of which are frequency dependent and cannot easily be measured directly. In this contribution the authors have designed different resonator elements, which have been manufactured utilizing Fused Filament Fabrication with ABSplus and PLA, as well as PolyJet Fabrication with VeroWhitePlus. All structures are computed in FEA to obtain the calculated Eigenfrequencies and mode shapes, with the respective literature values for each material. Furthermore, the dynamic behavior of multiple instances of each structure is measured utilizing a 3D-Laser-Scanning Vibrometer under shaker excitation, to obtain the actual Eigenfrequencies and mode shapes. The results are then analyzed in regards to variance between different print instances, and in regards to accordance between measured and calculated results. Based on previous work and this analysis the parameters of the FEA models are updated to improve the result quality.

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