scholarly journals Alumina and Zirconia-Reinforced Polyamide PA-12 Composites for Biomedical Additive Manufacturing

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6201
Author(s):  
Damian S. Nakonieczny ◽  
Frank Kern ◽  
Lukas Dufner ◽  
Magdalena Antonowicz ◽  
Krzysztof Matus
Keyword(s):  
Chemical Composition ◽  
Functional Groups ◽  
Artificial Saliva ◽  
Ceramic Powder ◽  
Mechanical Tests ◽  
Chemical Surface ◽  
Piranha Solution ◽  
Surface Development ◽  
Ceramic Fillers ◽  
Surface Modified

This work aimed to prepare a composite with a polyamide (PA) matrix and surface-modified ZrO2 or Al2O3 to be used as ceramic fillers (CFs). Those composites contained 30 wt.% ceramic powder to 70 wt.% polymer. Possible applications for this type of composite include bioengineering applications especially in the fields of dental prosthetics and orthopaedics. The ceramic fillers were subjected to chemical surface modification with Piranha Solution and suspension in 10 M sodium hydroxide and Si3N4 to achieve the highest possible surface development and to introduce additional functional groups. This was to improve the bonding between the CFs and the polymer matrix. Both CFs were examined for particle size distribution (PSD), functional groups (FTIR), chemical composition (XPS), phase composition (XRD), and morphology and chemical composition (SEM/EDS). Filaments were created from the powders prepared in this way and were then used for 3D FDM printing. Samples were subjected to mechanical tests (tensility, hardness) and soaking tests in a high-pressure autoclave in artificial saliva for 14, 21, and 29 days.

scholarly journals The Effects of Acid Etching on the Morphology and Properties of Medical Grade Alumina and Zirconia Surfaces for Prosthetics

2020 ◽  
Author(s):  
Damian S Nakonieczny ◽  
Zbigniew Kazimierz Paszenda ◽  
Marianna Hundáková Hundáková ◽  
Gabriela Kratošová ◽  
Sylva Holešová ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Zirconia Ceramic ◽  
Ceramic Powders ◽  
Zirconia Ceramics ◽  
Acidic Solutions ◽  
Post Process ◽  
Piranha Solution ◽  
Surface Development ◽  
The Impact ◽  
Medical Grade

Abstract In this study we modify and functionalize the surface of alumina and zirconia ceramics for medical applications using chemical etching with mixtures of sulfuric, nitric, hydrofluoric acids and peroxide. After etching, the impact of processes on surface development, chemical composition, and topography is studied to select the most effective process of surface development. Medical grade alumina and zirconia ceramic powders have been chemically etched with selected three kinds of acidic solutions : 1.sulfuric and nitric acid, 2.sulfuric acid and peroxide, 3.fluoric acid various diluted aqueous solution during the selected time periods. Following heat treatment was performed and the samples characterization were undertaken: morphology and chemical composition , phase composition, functional group determination, and the specific surface area and porosity evaluation.. Comparing the results raised from acidic etching, it was noticed that the use of H2SO4:HNO3 solutions causes sulphur residues in ceramic in the form of sulphates. The application of HF negatively affects the structure of the material and cause agglomeration. The most advantageous modification of ceramic powders was application of piranha solution, the obtaining surface development was achieved, satisfactory degree of agglomeration and post-process pollution.

scholarly journals Electrochemical Evaluation of Surface Modified Free-Standing CNT Electrode for Li–O2 Battery Cathode

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4196
Author(s):  
Ji Hyeon Lee ◽  
Hyun Wook Jung ◽  
In Soo Kim ◽  
Min Park ◽  
Hyung-Seok Kim
Keyword(s):  
Functional Groups ◽  
Atomic Layer ◽  
Free Standing ◽  
Coating Technology ◽  
Oxygen Functional Groups ◽  
Layer Deposition ◽  
Discharge Product ◽  
Effect Of Oxygen ◽  
Surface Modified ◽  
Electrochemical Evaluation

In this study, carbon nanotubes (CNTs) were used as cathodes for lithium–oxygen (Li–O2) batteries to confirm the effect of oxygen functional groups present on the CNT surface on Li–O2 battery performance. A coating technology using atomic layer deposition was introduced to remove the oxygen functional groups present on the CNT surface, and ZnO without catalytic properties was adopted as a coating material to exclude the effect of catalytic reaction. An acid treatment process (H2SO4:HNO3 = 3:1) was conducted to increase the oxygen functional groups of the existing CNTs. Therefore, it was confirmed that ZnO@CNT with reduced oxygen functional groups lowered the charging overpotential by approximately 230 mV and increased the yield of Li2O2, a discharge product, by approximately 13%. Hence, we can conclude that the ZnO@CNT is suitable as a cathode material for Li–O2 batteries.

scholarly journals Evaluation of ionic degradation and slot corrosion of metallic brackets by the action of different dentifrices

2013 ◽  
Vol 18 (1) ◽  
pp. 86-93
Author(s):  
Gustavo Antônio Martins Brandão ◽  
Rafael Menezes Simas ◽  
Leandro Moreira de Almeida ◽  
Juliana Melo da Silva ◽  
Marcelo de Castro Meneghim ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Artificial Saliva ◽  
Positive Control ◽  
Negative Control ◽  
Sem Analysis ◽  
Wilcoxon Test ◽  
Surface Polishing ◽  
Aluminium Ion ◽  
Negative Controls

OBJECTIVE: To evaluate the in vitro ionic degradation and slot base corrosion of metallic brackets subjected to brushing with dentifrices, through analysis of chemical composition by Energy Dispersive Spectroscopy (EDS) and qualitative analysis by Scanning Electron Microscopy (SEM). METHODS: Thirty eight brackets were selected and randomly divided into four experimental groups (n = 7). Two groups (n = 5) worked as positive and negative controls. Simulated orthodontic braces were assembled using 0.019 x 0.025-in stainless steel wires and elastomeric rings. The groups were divided according to surface treatment: G1 (Máxima Proteção Anticáries®); G2 (Total 12®); G3 (Sensitive®); G4 (Branqueador®); Positive control (artificial saliva) and Negative control (no treatment). Twenty eight brushing cycles were performed and evaluations were made before (T0) and after (T1) experiment. RESULTS: The Wilcoxon test showed no difference in ionic concentrations of titanium (Ti), chromium (Cr), iron (Fe) and nickel (Ni) between groups. G2 presented significant reduction (p < 0.05) in the concentration of aluminium ion (Al). Groups G3 and G4 presented significant increase (p < 0.05) in the concentration of aluminium ion. The SEM analysis showed increased characteristics indicative of corrosion on groups G2, G3 and G4. CONCLUSION: The EDS analysis revealed that control groups and G1 did not suffer alterations on the chemical composition. G2 presented degradation in the amount of Al ion. G3 and G4 suffered increase in the concentration of Al. The immersion in artificial saliva and the dentifrice Máxima Proteção Anticáries® did not alter the surface polishing. The dentifrices Total 12®, Sensitive® and Branqueador® altered the surface polishing.

Effect of Cellulose Functionalization on Thermal and Mechanical Properties of Epoxy Resin

2017 ◽  
Vol 757 ◽  
pp. 62-67 ◽  
Author(s):  
Kritsanachai Leelachai ◽  
Supissara Ruksanak ◽  
Tarakol Hongkeab ◽  
Supakeat Kambutong ◽  
Raymond A. Pearson ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Diglycidyl Ether ◽  
Cellulose Content ◽  
Thermal And Mechanical Properties ◽  
Chemical Surface ◽  
Pull Out ◽  
Fiber Bridging ◽  
Surface Modified ◽  
Modified Epoxy

In this study, diglycidyl ether of bisphenol A (DGEBA) cured cycloaliphatic polyamine was modified with functionalized celluloses for improved thermal and mechanical properties. Three different types of surface-modified cellulose, polyacrylamide-g-cellulose (PGC), aminopropoxysilane-g-cellulose (SGC), and carboxymethyl cellulose (CMC), were investigated and used as reinforcing agents in epoxy resins. The storage modulus of these modified epoxy systems was found to significantly increase with addition of cellulose fillers (up to 1 wt. % cellulose content). An improved fracture toughness (KIC) was also observed with increasing cellulose loading content with PGC and SGC. Among the surface-modified celluloses, epoxy modified with SGC was found to have the highest fracture toughness followed by PGC and CMC at 1.0 wt.% cellulose addition due to the chemical surface compatibility. The toughening mechanisms of the cellulose/epoxy composites, measured by scanning electron microscopy (SEM), revealed that fiber-debonding, fiber-bridging, and fiber-pull out were responsible for increased toughness.

scholarly journals PENGARUH FLOURIDE TERHADAP SIFAT MEKANIK GIGI TIRUAN BERBAHAN DASAR LIMBAH CANGKANG TELUR AYAM

2019 ◽  
Vol 4 (1) ◽  
pp. 72-77
Author(s):  
Baiq R. S. Yusuf ◽  
Siti Alaa ◽  
Dian W. Kurniawidi ◽  
Susi Rahayu
Keyword(s):  
Functional Groups ◽  
Calcium Oxide ◽  
Mechanical Tests ◽  
Precipitation Method ◽  
Oxide Content ◽  
Distilled Water ◽  
Minimum Standard ◽  
Fluoride Toothpaste ◽  
Egg Shells

The fabrication of dentures from the eggshell has been done using the precipitation method. FTIR and AAS tests were carried out to determine the functional groups and calcium oxide content in egg shells. From the AAS results, the CaO value is 58.33% which is much greater than the minimum standard CaO in dentures. Mechanical tests were carried out on dentures treatment with immersion into distilled water and the results were compared if immersion using fluoride toothpaste. It was found that immersion with fluoride toothpaste can increase the elasticity of dentures by more than 100%.

Pebax-1657 mixed matrix membrane containing surface modified multi-walled carbon nanotubes for gas separation

RSC Advances ◽  
2016 ◽  
Vol 6 (83) ◽  
pp. 79563-79577 ◽  
Author(s):  
S. A. Habibiannejad ◽  
A. Aroujalian ◽  
A. Raisi
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Functional Groups ◽  
Gas Separation ◽  
Mixed Matrix Membrane ◽  
Mixed Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
Surface Modified ◽  
Walled Carbon Nanotubes

In this study different functional groups on the surface of carbon nanotube enhanced the performance of Pebax 1657/MWNTs.

scholarly journals A Review on Surface-Functionalized Cellulosic Nanostructures as Biocompatible Antibacterial Materials

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Mandana Tavakolian ◽  
Seid Mahdi Jafari ◽  
Theo G. M. van de Ven
Keyword(s):  
Surface Modification ◽  
In Vivo Studies ◽  
Hydroxyl Groups ◽  
Chemical Surface ◽  
Antibacterial Materials ◽  
Chemical Surface Modification ◽  
Reactive Groups ◽  
Surface Modified ◽  
The Relationship

Abstract As the most abundant biopolymer on the earth, cellulose has recently gained significant attention in the development of antibacterial biomaterials. Biodegradability, renewability, strong mechanical properties, tunable aspect ratio, and low density offer tremendous possibilities for the use of cellulose in various fields. Owing to the high number of reactive groups (i.e., hydroxyl groups) on the cellulose surface, it can be readily functionalized with various functional groups, such as aldehydes, carboxylic acids, and amines, leading to diverse properties. In addition, the ease of surface modification of cellulose expands the range of compounds which can be grafted onto its structure, such as proteins, polymers, metal nanoparticles, and antibiotics. There are many studies in which cellulose nano-/microfibrils and nanocrystals are used as a support for antibacterial agents. However, little is known about the relationship between cellulose chemical surface modification and its antibacterial activity or biocompatibility. In this study, we have summarized various techniques for surface modifications of cellulose nanostructures and its derivatives along with their antibacterial and biocompatibility behavior to develop non-leaching and durable antibacterial materials. Despite the high effectiveness of surface-modified cellulosic antibacterial materials, more studies on their mechanism of action, the relationship between their properties and their effectivity, and more in vivo studies are required.

scholarly journals Soil Organic Carbon Chemical Functional Groups under Different Revegetation Types Are Coupled with Changes in the Microbial Community Composition and the Functional Genes

Forests ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 240 ◽  
Author(s):  
Jiaojiao Deng ◽  
Wenxu Zhu ◽  
Yongbin Zhou ◽  
You Yin
Keyword(s):  
Microbial Community ◽  
Chemical Composition ◽  
Organic Carbon ◽  
Functional Groups ◽  
Soil Microbial Community ◽  
Coniferous Forests ◽  
Functional Genes ◽  
Broadleaf Forest ◽  
Soil Microbial ◽  
Molecular Compounds

Different revegetatiom types can affect the chemical composition of soil organic carbon (SOC), soil microbial community and the functional genes related to carbon cycle. However, the relationships between SOC chemical functional groups and soil microbial communities and the functional genes remains poorly unclear under different revegetation types. Using the solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, we examined changes in the SOC chemical composition of five soils (0–10 cm depth) from Larix gmelinii Rupr. (LG), Pinus koraiensis Sieb. (PK), Quercus mongolica Fisch. (QM), Juglans mandshurica Maxim. (JM), and conifer-broadleaf forest (CB). And the soil microbial community genes related to metabolism of macro-molecular compounds were determined via whole genome shotgun based on Illumina HiSeq. Our results indicated that broadleaf forests (JM, QM) had increased the contents of soil total carbon (C), total nitrogen (N), dissolved organic carbon (DOC), and microbial biomass carbon (MBC), compared with coniferous forests (LG, PK) and the conifer-broadleaf forest (CB). While, the coniferous forests generated a lower O-alcoxyl C, a higher alkyl C, and the ratio of alkyl C/O-alkyl C than broadleaf forests. A total of four kingdoms were identified via whole metagenome shotgun sequencing, including eight archaea, 55 bacteria, 15 eukaryota, and two viruses, giving a total 80 phyla. The contents of alkyne C, phenolic C, methoxyl C, COO/NC=O, and alkyl C were strong related to the composition of soil microbial community and their contents illuminated a major part of the variation in soil microbial composition. We detected seven corresponding macro-molecular compounds of different organic carbon functional group, and 244 genes related to metabolism across all samples, and soil total C, total N, and DOC could be the main factors for microbial functional gene composition. Interestingly, the relative abundances of different SOC chemical functional groups, the phylogenetic distance for microbes, the genes of C cycling based on the KEGG database, and the relative abundance of genes related to metabolism of macro-molecular compounds of different SOC chemical functional groups under different revegetation types all could be divided into three groups, including PK plus LG, JM plus QM, and CB. Our results also illustrated that variations in SOC chemical functional groups were strongly associated with changes of soil microbial community taxa and functional genes, which might be affected by the changes of soil characteristics.

Utilization of Surface-Modified Polymer and Glass Micro-Fibers as Reinforcement in Cement Composites

2018 ◽  
Vol 760 ◽  
pp. 225-230
Author(s):  
Jan Trejbal ◽  
Zdeněk Prošek ◽  
Josef Fládr ◽  
Pavel Tesárek
Keyword(s):  
Polymer Fibers ◽  
Cement Matrix ◽  
Interphase Interaction ◽  
Bending Tests ◽  
Chemical Surface ◽  
Modified Polymer ◽  
Four Point Bending ◽  
Macro Scale ◽  
Strong Adhesion ◽  
Surface Modified

The presented work focuses on plasma modifications of polymer and glass micro-fibers (having 32 and 14 μm in the diameter, respectively) used as randomly distributed and oriented reinforcement of concrete composites. Fiber surfaces were modified by means of the low-pressure coupled cold oxygen plasma in order to attain a strong adhesion with the cement matrix. From the perspective of micro scale, an impact of modifications on both the physical and the chemical surface changes of treated fibers was examined using: (i) a wettability measurements – an evaluation of an interphase interaction between demineralized water and fibers and (ii) the SEM microscopy – an assessment of a surface morphology. From the perspective of macro scale, the interaction between the two materials was examined by destructive four-point bending tests of the cement paste containing both the reference and treated fibers (specimens having dimensions equal to 40×40×160 mm, water to cement ration 0.4) were done. It was shown that the wettability of modified fibers was increased by approx. 10 % and 70 % in the case of glass and polymer fibers, respectively. The SEM morphology analysis revealed fine roughening of treated fibers, if compared to the reference ones. The mechanical testing pointed out on a toughness increase in the post-cracking response of loaded specimens.

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