scholarly journals A Novel Probe-to-Probe Method for Measuring Thermal Conductivity of Individual Electrospun Nanofibers

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5220
Author(s):  
Nicholas Bonatt ◽  
John Carlin ◽  
Fangqi Chen ◽  
Yanpei Tian ◽  
Yi Zheng
Keyword(s):  
Thermal Properties ◽  
Mechanical Design ◽  
Electrospun Nanofibers ◽  
Probe Method ◽  
Polymer Nanofibers ◽  
Thermal Measurement ◽  
Thermal Boundary Conditions ◽  
Atomic Force ◽  
Polymer Nanofiber ◽  
Electrospinning Method

Polymer nanofibers have the ability to replace expensive materials, such as metals, ceramics and composites, in specific areas, such as heat exchangers, energy storage and biomedical applications. These properties have caused polymer nanofibers to be explored as solutions to a growing list of thermal management problems, driving an even greater need to better measure and understand the thermal properties of these nanofibers. This study intends to further the understanding of the thermal properties of polymer nanofibers through the use of a novel Probe-to-Probe measurement method. Polycaprolactone nanofibers fabricated using the electrospinning method can be easily collected and loaded into a traditional atomic force microscope through a mechanical design for thermal measurement. This Probe-to-Probe method demonstrates the ability to accurately measure the thermal boundary conditions about a polymer nanofiber with a heating prong temperature up to 400 ∘C and assists in characterizing its thermal properties.

Stereocomplex electrospun fibers from high molecular weight of poly(L-lactic acid) and poly(D-lactic acid)

2020 ◽  
Vol 40 (2) ◽  
pp. 136-142 ◽  
Author(s):  
Homa Maleki ◽  
Hossein Barani
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Thermal Properties ◽  
High Molecular Weight ◽  
Chemical Properties ◽  
Electrospun Fibers ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Atomic Force ◽  
Electrospinning Method

AbstractThe stereocomplex formation is a promising method to improve the properties of poly(lactide) (PLA)-based products due to the strong interaction of the side-by-side arrangement of the molecular chains. Recently, electrospinning method has been applied to prepare PLA stereocomplex, which is more convenient. The objective of the current study is to make stereocomplexed PLA nanofibers using electrospinning method and compare their properties and structures with pure poly(l-lactide) (PLLA) fibers. The stereocomplexed fibers were electrospun from a blend solution of high molecular weight PLLA and poly(d-lactide) (1:1 ratio). The morphology of the obtained electrospun fibers was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Differential scanning calorimetry was applied to study their thermal properties and crystallinity. Fourier transform infrared spectroscopy (FTIR) test was conducted on the samples to characterize their chemical properties. The SEM and AFM images indicated that smooth uniform fibers with a cylindrical structure were produced. Besides, the FTIR results and thermal properties confirmed that only stereocomplex crystallites formed in the resulting fibers via the electrospinning method.

Detection of accumulated continuously ethanol concentration by ZnO–SnO2 composite nanorods sensor

2021 ◽  
pp. 2150395
Author(s):  
Xiang-Bing Li ◽  
Da-Qian Mo ◽  
Xiao-Yan Niu ◽  
Qian-Qian Zhang ◽  
Shu-Yi Ma ◽  
...  
Keyword(s):  
Recovery Time ◽  
Ethanol Concentration ◽  
Physical Adsorption ◽  
X Ray Diffraction ◽  
Gas Sensitivity ◽  
X Ray ◽  
Atomic Force ◽  
Electrospinning Method ◽  
Response And Recovery ◽  
Composite Nanorods

ZnO–SnO2 composite nanorods with rough surfaces were synthesized via a coaxially nested needle electrospinning method. The morphology and nanostructure were characterized by scanning electron microscopy, atomic force microscope, EDS mapping, nitrogen physical adsorption, and X-ray diffraction. The synthesis mechanisms of ZnO–SnO2 nanorods were discussed, which combined the gas sensitivity advantages of different materials. ZnO–SnO2 nanorods sensor with good ethanol gas sensitivity achieved accurate measurement of continuous ethanol concentration. The sensor exhibited good selectivity to ethanol in the presence of formaldehyde, methanol, acetone, acetic acid, benzene, and xylene at 290[Formula: see text]C. The response and recovery time to 100 ppm ethanol were about 13 and 35 s, respectively. The energy band, barrier, charge transfer of ZnO–SnO2 composite material was discussed, and its optimization of gas sensitivity was analyzed in detail.

scholarly journals Ramesh Shrestha, Sheng Shen and Maarten P. de Boer *

Actuators ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 71 ◽  
Author(s):  
Ramesh Shrestha ◽  
Sheng Shen ◽  
Maarten P. de Boer
Keyword(s):  
Thermal Properties ◽  
Molecular Chain ◽  
Nanometer Scale ◽  
Mechanical And Thermal Properties ◽  
Polymer Nanofibers ◽  
Scale Size ◽  
Scale Test ◽  
High Degree ◽  
Micrometer Scale ◽  
Measurement Artifacts

Because they can achieve a high degree of molecular chain alignment in comparison with their bulk counterparts, the mechanical and thermal properties of polymer nanofibers are of great interest. However, due to their nanometer-scale size, it is difficult to manipulate, grip, and test these fibers. Here, we demonstrate simple repeatable methods to transfer as-drawn fibers to micrometer-scale test platforms where their properties can be directly measured. Issues encountered and methods to minimize measurement artifacts are also discussed.

scholarly journals Mechanical Properties of Electrospun, Blended Fibrinogen: PCL Nanofibers

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1843
Author(s):  
Jacquelyn M. Sharpe ◽  
Hyunsu Lee ◽  
Adam R. Hall ◽  
Keith Bonin ◽  
Martin Guthold
Keyword(s):  
Mechanical Properties ◽  
Strain Softening ◽  
Electrospun Nanofibers ◽  
High Energy ◽  
Optical Microscope ◽  
Ductile Material ◽  
Breaking Strain ◽  
Atomic Force ◽  
Microscope Technique ◽  
Afm Probe

Electrospun nanofibers manufactured from biocompatible materials are used in numerous bioengineering applications, such as tissue engineering, creating organoids or dressings, and drug delivery. In many of these applications, the morphological and mechanical properties of the single fiber affect their function. We used a combined atomic force microscope (AFM)/optical microscope technique to determine the mechanical properties of nanofibers that were electrospun from a 50:50 fibrinogen:PCL (poly-ε-caprolactone) blend. Both of these materials are widely available and biocompatible. Fibers were spun onto a striated substrate with 6 μm wide grooves, anchored with epoxy on the ridges and pulled with the AFM probe. The fibers showed significant strain softening, as the modulus decreased from an initial value of 1700 MPa (5–10% strain) to 110 MPa (>40% strain). Despite this extreme strain softening, these fibers were very extensible, with a breaking strain of 100%. The fibers exhibited high energy loss (up to 70%) and strains larger than 5% permanently deformed the fibers. These fibers displayed the stress–strain curves of a ductile material. We provide a comparison of the mechanical properties of these blended fibers with other electrospun and natural nanofibers. This work expands a growing library of mechanically characterized, electrospun materials for biomedical applications.

scholarly journals Emulsion-based systems for fabrication of electrospun nanofibers: food, pharmaceutical and biomedical applications

RSC Advances ◽  
2017 ◽  
Vol 7 (46) ◽  
pp. 28951-28964 ◽  
Author(s):  
Nooshin Nikmaram ◽  
Shahin Roohinejad ◽  
Sara Hashemi ◽  
Mohamed Koubaa ◽  
Francisco J. Barba ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Electrospun Nanofibers ◽  
Bioactive Materials ◽  
Electrospinning Method

Encapsulation of bioactive materials and drugs using the emulsion electrospinning method.

Using Demercurated Lighting Phosphor and MSWI Scrubber Residues to Prepare High Performance Plastic Concrete

2009 ◽  
Vol 610-613 ◽  
pp. 55-60
Author(s):  
Wu Jang Huang ◽  
Wei Chu ◽  
Ling Hui Hsieh ◽  
Jian Guo Chen
Keyword(s):  
Thermal Properties ◽  
Epoxy Resin ◽  
Solid Waste ◽  
High Performance ◽  
Waste Incineration ◽  
Type I ◽  
Phosphor Powder ◽  
Force Microscopy ◽  
Atomic Force ◽  
Plastic Concrete

This study aimed to prepare a high performance plastic concrete made of epoxy resin and Portland type-I cement mixed with at least one inorganic solid waste of demercurated lighting phosphor powder or municipal solid waste incineration scrubber residue. The ratio between liquid epoxy resin and cement was 1:2; the scrubber residue and demercurated phosphor powder were added as modifiers for cement component in order to improve the strength and thermal properties of synthesized plastic concrete. The results indicate that, the addition of scrubber residue causes a decrease in both strength and thermal properties; whereas, the demercurated phosphor powder can replace 100% of the contents of cement without any significantly change in either strength or thermal properties. Atomic force microscopy and Raman spectroscopy were used to characterize the chemical structure of cured concrete and the results indicate that the surface softness increases with an increase in the mixed percentage of epoxy resin.

scholarly journals Micro and nanocomposites of polybutadienebased polyurethane liners with mineral fillers and nanoclay: thermal and mechanical properties

2017 ◽  
Vol 15 (1) ◽  
pp. 46-52 ◽  
Author(s):  
Pablo Ross ◽  
Germán Escobar ◽  
Guillermo Sevilla ◽  
Javier Quagliano
Keyword(s):  
Thermal Properties ◽  
Polymer Chains ◽  
Toluene Diisocyanate ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Elongation At Break ◽  
Force Microscopy ◽  
Atomic Force ◽  
Mineral Fillers

AbstractMicro and nanocomposites of hydroxyl terminated polybutadiene (HTPB)-based polyurethanes (NPU) were obtained using five mineral fillers and Cloisite 20A nanoclay, respectively. Samples were prepared by the reaction of HTPB polyol and toluene diisocyanate (TDI), and the chain was further extended with glyceryl monoricinoleate to produce the final elastomeric polyurethanes. Mechanical and thermal properties were studied, showing that mineral fillers (20%w/w) significantly increased tensile strength, in particular nanoclay (at 5% w/w). When nanoclay-polymer dispersion was modified with a silane and hydantoin-bond promoter, elongation at break was significantly increased with respect to NPU with C20A. Thermal properties measured by differential scanning calorimetry (DSC) were not significantly affected in any case. The molecular structure of prepared micro and nanocomposites was confirmed by Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. Interaction of fillers with polymer chains is discussed, considering the role of silanes in compatibilization of hydrophilic mineral fillers and hydrophobic polymer. The functionalization of nanoclay with HMDS silane was confirmed using FTIR. Microstructure of NPU with C20A nanoclay was confirmed by Atomic Force Microscopy (AFM).

scholarly journals Nanostructured Fibers Containing Natural or Synthetic Bioactive Compounds in Wound Dressing Applications

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2407 ◽  
Author(s):  
Alexa-Maria Croitoru ◽  
Denisa Ficai ◽  
Anton Ficai ◽  
Natalia Mihailescu ◽  
Ecaterina Andronescu ◽  
...  
Keyword(s):  
Wound Healing ◽  
Healing Process ◽  
Electrospun Nanofibers ◽  
Natural Compounds ◽  
Electrospinning Process ◽  
Wound Dressings ◽  
Wound Healing Process ◽  
Skin Substitutes ◽  
Bioactive Constituents ◽  
Electrospinning Method

The interest in wound healing characteristics of bioactive constituents and therapeutic agents, especially natural compounds, is increasing because of their therapeutic properties, cost-effectiveness, and few adverse effects. Lately, nanocarriers as a drug delivery system have been actively investigated and applied in medical and therapeutic applications. In recent decades, researchers have investigated the incorporation of natural or synthetic substances into novel bioactive electrospun nanofibrous architectures produced by the electrospinning method for skin substitutes. Therefore, the development of nanotechnology in the area of dressings that could provide higher performance and a synergistic effect for wound healing is needed. Natural compounds with antimicrobial, antibacterial, and anti-inflammatory activity in combination with nanostructured fibers represent a future approach due to the increased wound healing process and regeneration of the lost tissue. This paper presents different approaches in producing electrospun nanofibers, highlighting the electrospinning process used in fabricating innovative wound dressings that are able to release natural and/or synthetic substances in a controlled way, thus enhancing the healing process.

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