scholarly journals Enhanced Crystallinity and Antibacterial of PHBV Scaffolds Incorporated with Zinc Oxide

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Cijun Shuai ◽  
Chen Wang ◽  
Fangwei Qi ◽  
Shuping Peng ◽  
Wenjing Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Zinc Oxide ◽  
Zno Nanoparticles ◽  
Bone Repair ◽  
Porous Scaffold ◽  
Selective Laser Sintering ◽  
Polymer Chains ◽  
Relative Crystallinity ◽  
Cell Behaviors ◽  
Positive Results

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) has a great potential in bone repair, but unfortunately, the poor mechanical properties limit its further application. In this work, zinc oxide (ZnO) nanoparticles were incorporated into PHBV porous scaffold fabricated by selective laser sintering technique. It was because ZnO nanoparticles could provide nucleating sites for the orderly stacking of polymer chains, thereby enhancing the crystallinity of PHBV. It was well known that the mechanical properties of PHBV scaffold could be enhanced with the increase of crystallinity. More significantly, the released Zn2+ would combine negatively charged cell membranes of bacterial through electrostatic interaction and consequently destructed the protein structure and resulted in the death of bacterial, which was highly desired in reducing the risk of implant infection. Results indicated that the relative crystallinity of scaffold with 3 wt.% ZnO increased remarkably from 38% to 64% compared to pure PHBV scaffold, which effectively enhanced the compression strength and modulus by 56% and 51.5%, respectively. Moreover, the scaffold had a favorable antibacterial activity. Cell culture experiments proved that the scaffold could promote the cell behaviors. The positive results demonstrated the scaffold may serve as a potential replacement in bone repair.

FUNCTIONALIZED SBRs IN SILICA-REINFORCED TIRE TREAD COMPOUNDS: EVIDENCE FOR INTERACTIONS BETWEEN SILICA FILLER AND ZINC OXIDE

2016 ◽  
Vol 89 (4) ◽  
pp. 559-572 ◽  
Author(s):  
S. Maghami ◽  
W. K. Dierkes ◽  
J. W. M. Noordermeer
Keyword(s):  
Mechanical Properties ◽  
Zinc Oxide ◽  
Carbon Black ◽  
Rolling Resistance ◽  
Major Change ◽  
Polymer Chains ◽  
Silane Coupling Agents ◽  
Covalent Bonds ◽  
Oh Groups ◽  
Polar Functional Groups

ABSTRACT Unlike carbon black, silica is polar and naturally not compatible with nonpolar hydrocarbon elastomers. This lack of interaction or compatibility between the filler and the elastomer typically causes lower properties compared with carbon black–filled compounds. A common approach to deal with this problem is to use silane coupling agents in the system to link the silica and the polymer chains via covalent bonds. An alternative is the introduction of polar functional groups or chemically reactive groups into the elastomer chains, which can improve the compatibility of elastomers with fillers such as silica. In this article, the effect of three functionalized SBRs, one backbone modified with carboxylate moieties, one modified with dithiol groups, and one partially Si-coupled, on the dynamic and mechanical properties of a silica-reinforced tire tread compound will be discussed and compared with a reference compound that contains unmodified s-SBR as the main polymer. The results show the significant potential of two of these modified SBRs to reduce the rolling resistance of tire treads made thereof, while no major change in wet grip occurs. Zinc oxide is known as the best activator for sulfur vulcanization. Zn ions combine with accelerators to form an active complex that catalyzes the vulcanization process. However, in silica-filled compounds, ZnO may interfere with the silanization process because of its alkaline nature, and it may compete with the silanes in reacting with the acidic –OH groups on the surface of silica particles. When functionalized SBRs with higher polarity are used in silica compounds, ZnO may interact with these moieties as well. To investigate the effect of ZnO on the properties of the silica-reinforced tread compound, a series of compounds have been prepared, in which the addition of ZnO in a later stage was compared with conventional mixing. The dynamic and mechanical properties of the final compounds are discussed.

scholarly journals Analysis of Mechanical Properties and Permeability of Trabecular-Like Porous Scaffold by Additive Manufacturing

2021 ◽  
Vol 9 ◽  
Author(s):  
Long Chao ◽  
Chen Jiao ◽  
Huixin Liang ◽  
Deqiao Xie ◽  
Lida Shen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bone Repair ◽  
Bone Cells ◽  
Porous Scaffold ◽  
Bone Ingrowth ◽  
Voronoi Tessellation ◽  
Stress Shielding ◽  
Porous Scaffolds ◽  
Porous Structures ◽  
Element Analysis

Human bone cells live in a complex environment, and the biomimetic design of porous structures attached to implants is in high demand. Porous structures based on Voronoi tessellation with biomimetic potential are gradually used in bone repair scaffolds. In this study, the mechanical properties and permeability of trabecular-like porous scaffolds with different porosity levels and average apertures were analyzed. The mechanical properties of bone-implant scaffolds were evaluated using finite element analysis and a mechanical compression experiment, and the permeability was studied by computational fluid dynamics. Finally, the attachment of cells was observed by confocal fluorescence microscope. The results show that the performance of porous structures can be controlled by the initial design of the microstructure and tissue morphology. A good structural design can accurately match the performance of the natural bone. The study of mechanical properties and permeability of the porous structure can help address several problems, including stress shielding and bone ingrowth in existing biomimetic bone structures, and will also promotes cell adhesion, migration, and eventual new bone attachment.

scholarly journals Advancement in Microstructural, Optical, and Mechanical Properties of PVA (Mowiol 10-98) Doped by ZnO Nanoparticles

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
N. B. Rithin Kumar ◽  
Vincent Crasta ◽  
B. M. Praveen
Keyword(s):  
Mechanical Properties ◽  
Zinc Oxide ◽  
Zno Nanoparticles ◽  
Main Chain ◽  
Average Particle Size ◽  
Testing Machine ◽  
Average Particle ◽  
Zno Nanoparticle ◽  
X Ray ◽  
Xrd Studies

The current paper explores the preparation of PVA nanocomposites by doping with zinc oxide (ZnO) nanoparticles using the method of coagulation and solvent casting technique. The dopant zinc oxide nanoparticle is prepared by simple precipitation method and is confirmed by the X-ray diffraction (XRD) studies. The XRD studies explore that the average particle size of the synthesized nanoparticles is 55 nm and show that the crystallinity factor of PVA nanocomposites is influenced by the interaction occurring between the PVA main chain and the ZnO nanoparticle. The FTIR spectroscopy suggests that the formulation of complexes occurring between the dopants and the PVA main chain is due to inter or intra molecular hydrogen bonding. UV-vis spectra explore the dramatic decrease in the optical energy gap of nanoparticles doped polymer composites and the variations of Urbach energy (Eu) related to crystallinity for various dopant concentrations. The mechanical properties of the PVA nanocomposites were explored using universal testing machine (UTM) that reflects that, for x=15% doping concentration, there is an increase in the tensile strength, stiffness, and Young’s modulus, whereas, for x=7.5% concentration, the percentage total elongation at fracture is found to be the maximum. The morphological behavior and homogenous nanoparticle distribution in the composites were examined by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDAX).

scholarly journals EFFECTS OF IMPREGNATION WITH STYRENE AND NANO-ZINC OXIDE ON FIRE-RETARDING, PHYSICAL, AND MECHANICAL PROPERTIES OF POPLAR WOOD

CERNE ◽  
2016 ◽  
Vol 22 (4) ◽  
pp. 465-474 ◽  
Author(s):  
Siroos Habibzade ◽  
Hamid R. Taghiyari ◽  
Asghar Omidvar ◽  
Hamid R. Roudi
Keyword(s):  
Mechanical Properties ◽  
Zinc Oxide ◽  
Zno Nanoparticles ◽  
Ignition Time ◽  
Physical And Mechanical Properties ◽  
Dry Weight ◽  
Poplar Wood ◽  
Nano Zinc Oxide ◽  
Wood Polymer ◽  
Nano Zinc

ABSTRACT Nanoparticles have been vastly applied in wood polymer composites (WPCs) in the recent years to improve some of the drawbacks of solid wood species. In the present study, the effects of ZnO nanoparticles on fire retarding, physical, and mechanical properties of polymerized poplar wood were investigated. Poplar specimens were impregnated with styrene monomer, containing four different contents of nano-zinc oxide (ZnO) (0, 0.5, 1 and 1.5%, based on the dry weight of monomer). Results of the scanning electron microscopy (SEM) showed homogeneous dispersion of ZnO nanoparticles in the WPC matrix. Nano-zinc oxide improved physical properties such as dimensional stability and water absorption. Moreover, mechanical properties increased in comparison to the control specimens. The impregnation process also significantly improved some of the fire-retarding properties, including the ignition time; however, the flammability nature of styrene aggravated some others, such as carbonized area. It was concluded that, although most of the properties were improved, the final application of WPC should be taken in to consideration before making decision on whether or not to impregnate populus wood with styrene.

scholarly journals Characterization and in vitro assessment of three-dimensional extrusion Mg-Sr codoped SiO2-complexed porous microhydroxyapatite whisker scaffolds for biomedical engineering

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Chengyong Li ◽  
Tingting Yan ◽  
Zhenkai Lou ◽  
Zhimin Jiang ◽  
Zhi Shi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Proliferation ◽  
Pore Size ◽  
Osteogenic Differentiation ◽  
Bone Repair ◽  
Porous Scaffold ◽  
Porous Scaffolds ◽  
Sprague Dawley ◽  
Active Elements

Abstract Background Large bone defects have always been a great challenge for orthopedic surgeons. The use of a good bone substitute obtained by bone tissue engineering (BTE) may be an effective treatment method. Artificial hydroxyapatite, a commonly used bone defect filler, is the main inorganic component of bones. Because of its high brittleness, fragility, and lack of osteogenic active elements, its application is limited. Therefore, its fragility should be reduced, its osteogenic activity should be improved, and a more suitable scaffold should be constructed. Methods In this study, a microhydroxyapatite whisker (mHAw) was developed, which was doped with the essential trace active elements Mg2+ and Sr2+ through a low-temperature sintering technique. After being formulated into a slurry, a bionic porous scaffold was manufactured by extrusion molding and freeze drying, and then SiO2 was used to improve the mechanical properties of the scaffold. The hydrophilicity, pore size, surface morphology, surface roughness, mechanical properties, and release rate of the osteogenic elements of the prepared scaffold were detected and analyzed. In in vitro experiments, Sprague–Dawley (SD) rat bone marrow mesenchymal stem cells (rBMSCs) were cultured on the scaffold to evaluate cytotoxicity, cell proliferation, spreading, and osteogenic differentiation. Results Four types of scaffolds were obtained: mHAw-SiO2 (SHA), Mg-doped mHAw-SiO2 (SMHA), Sr-doped mHAw-SiO2 (SSHA), and Mg-Sr codoped mHAw-SiO2 (SMSHA). SHA was the most hydrophilic (WCA 5°), while SMHA was the least (WCA 8°); SMHA had the smallest pore size (247.40 ± 23.66 μm), while SSHA had the largest (286.20 ± 19.04 μm); SHA had the smallest Young's modulus (122.43 ± 28.79 MPa), while SSHA had the largest (188.44 ± 47.89 MPa); and SHA had the smallest compressive strength (1.72 ± 0.29 MPa), while SMHA had the largest (2.47 ± 0.25 MPa). The osteogenic active elements Si, Mg, and Sr were evenly distributed and could be sustainably released from the scaffolds. None of the scaffolds had cytotoxicity. SMSHA had the highest supporting cell proliferation and spreading rate, and its ability to promote osteogenic differentiation of rBMSCs was also the strongest. Conclusions These composite porous scaffolds not only have acceptable physical and chemical properties suitable for BTE but also have higher osteogenic bioactivity and can possibly serve as potential bone repair materials.

Studies on structural, optical and mechanical properties of MWCNTs and ZnO nanoparticles doped PVA nanocomposites

2015 ◽  
Vol 4 (5) ◽  
Author(s):  
Rithin Kumar N.B. ◽  
Vincent Crasta ◽  
B.M. Praveen ◽  
Mohan Kumar
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Zinc Oxide ◽  
Polyvinyl Alcohol ◽  
Zno Nanoparticles ◽  
Precipitation Method ◽  
Solvent Casting ◽  
Casting Method ◽  
Multiwalled Carbon ◽  
Optical And Mechanical Properties

AbstractThis paper presents a novel class of multiwalled carbon nanotubes (MWCNTs) and zinc oxide (ZnO) doped polyvinyl alcohol (PVA) nanocomposites prepared using coagulation and solvent casting method. The dopant, ZnO nanoparticles, was prepared using precipitation method, and another dopant, MWCNTs, was treated with H

scholarly journals New Manufacturing Process of Composites Reinforced with ZnO Nanoparticles Recycled from Alkaline Batteries

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1619
Author(s):  
Isaac Lorero ◽  
Mónica Campo ◽  
Gilberto Del Rosario ◽  
Félix Antonio López ◽  
Silvia González Prolongo
Keyword(s):  
Mechanical Properties ◽  
Zinc Oxide ◽  
Glass Transition ◽  
Transition Temperature ◽  
Zno Nanoparticles ◽  
Epoxy Matrix ◽  
Alkaline Batteries ◽  
Manufacturing Method ◽  
Experimental Parameters ◽  
Zno Particles

A new manufacturing method of thermosetting resins reinforced with dense particles is developed in the present work. A rotary mold is used, avoiding the natural sedimentation of particles through applying centrifuge forces. A deep study of the sedimentation phenomenon is carried out in order to evaluate the main experimental parameters which influence the manufacturing of composite. The used reinforcement is zinc oxide (ZnO) obtained by a new recycling method from spent alkaline batteries. In order to compare the benefits, commercial ZnO nanoparticles are also analyzed. Recycled ZnO particles enhance the interaction of the epoxy matrix due to their inner moisture, allowing the manufacture of composites with relatively high ceramic content. Moreover, an increment in the glass transition temperature of the epoxy matrix and in the mechanical properties, such as its stiffness and hardness, is achieved.

Syntheses and Evaluation of Copolymer 6-Aminohexanoic Acid and 4R-Hydroxy-L-Proline for Bone Repair

2012 ◽  
Vol 562-564 ◽  
pp. 506-511
Author(s):  
Jia Chun Jiang ◽  
Zhi Tong Zhao ◽  
Guo Yu Lv ◽  
Yong Gang Yan ◽  
Deng Xue Wu
Keyword(s):  
Mechanical Properties ◽  
Weight Loss ◽  
Bone Repair ◽  
Bone Growth ◽  
Polymer Chains ◽  
Condensation Polymerization ◽  
Natural Bone ◽  
Infrared Spectrometer ◽  
Melt Condensation ◽  
Synthetic Copolymer

A novel synthetic copolymer (PAA) for bone repair was prepared by melt condensation polymerization with 6-aminohexanoic acid (He) and 4R-hydroxy-L-proline (Hyp). The structure and thermal property were characterized by infrared spectrometer (IR), nuclear magnetic resonance (H1NMR) and differential scanning calorimeter (DSC). The results indicated that the PAA had amide linkages in their polymer chains. The Tg of PAA was 57.56°C and significantly higher than that of nylon6, 50.46°C. Meanwhile, the intrinsic viscosity and mechanical properties were investigated at different He/Hyp ratios. It revealed that appropriate introduction of Hyp group could control the degree of polycondensation and adjusted mechanical properties of PAA obviously close to natural bone. The prepared polymers had about 2.12~18.21 % weight loss after 8-week soaking in PBS, showed degradable properties which was essentials to new bone growth. The copolymer of He and Hyp with ratios of 90/10 had 6.57 % weight loss and maintained the yield compressive strengths with about 67.51 MPa after 8 weeks, which exhibited a compatible mechanical properties and degradation speed for bone repair.

Broad studies of graphene and low-density polyethylene composites

2018 ◽  
Vol 51 (6) ◽  
pp. 527-561 ◽  
Author(s):  
Maziyar Sabet ◽  
Hassan Soleimani
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Thermal Stability ◽  
High Specific Surface Area ◽  
Polymer Chains ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Lattice Order ◽  
Relative Crystallinity ◽  
Local Lattice

Graphene (Gr) distribution in low-density polyethylene (LDPE) considerably increased thermal stability, thermal conductivity, mechanical properties, and flexural properties of LDPE/Gr composites. Addition of Grs to LDPE postponed the time for making the polymer brittle. High specific surface area and superior properties of Gr improved thermal stability, conductivity, storage modulus, and mechanical properties of composites. The electrical conductivity of LDPE/Grs composites upgraded owing to the thermal stability of Grs in LDPE matrix. In terms of rheology, the addition of Grs augmented viscosity of the LDPE matrix. Addition of Grs to LDPE nucleates crystallization by reducing the activation energy along with rising crystallization onset temperature. Adding Gr facilitated decreasing aggregation, expanded crystallinity, improved the local lattice order of LDPE/Grs, and advanced Grs contact with LDPE. Thus, on a macroscopic scale, Gr constrains mobility of polymer chains, causing a growth in stiffness and strength of the composite. The distribution of Grs in LDPE at micron size scale was verified by atomic force microscopy and other microscopic testers. With further Grs inclusions to LDPE, the activation energy reduced, Grs proceeded as nucleating agents throughout the crystallization of composites, and increased the enhancement of relative crystallinity of LDPE/Gr compounds. The percolation phenomenon of LDPE/Gr composite occurred about 0.5 wt% of Gr loading. Due to further addition of Gr to LDPE, the impermeability of oxygen through the conduit raised somehow the LDPE/Gr sample with 0.5 wt% Gr content, generated a sharp improvement, and dropped fuel permeation with about 37% in comparison with pure LDPE.

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