scholarly journals Determining the Self-Limiting Electrospray Deposition Compositional Limits for Mechanically Tunable Polymer Composites

2021 ◽  
Author(s):  
Robert Green-Warren ◽  
Luc Bontoux ◽  
Noah McAllister ◽  
Dylan Kovacevich ◽  
Asaad Shaikh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Glassy Polymers ◽  
The Self ◽  
Charge Accumulation ◽  
Electrospray Deposition ◽  
Coating Technology ◽  
Nano Coating ◽  
Base Matrix ◽  
Curing Agents ◽  
Scanning Electron

Electrospray deposition (ESD) is a versatile micro/nano coating technology that utilizes the competition between surface charge of a droplet and its surface tension to create monodisperse generations of micro/nano droplets. ESD can deposit uniform thin films by including dilute solutes in these droplets. One mode of ESD, self-limiting electrospray deposition (SLED), has been shown to exist when glassy polymers are sprayed in a volatile solvent below the polymer glass transition temperature (Tg). This leads to charge accumulation on the coating surface that slows the growth of the film thickness. Since solutes can be easily blended in dilute ESD solutions, we investigate the SLED limits of self-limiting and non-self-limiting solute blends. As a motivating application, we focus on mechanical properties of the film. Specifically, we blend self-limiting polystyrene (PS) and SU-8 epoxy resin with different non-self-limiting mechanical modifiers, such as plasticizers and curing agents. To characterize the resulting morphologies and mechanical properties, we employ scanning electron microscopy and nanoindentation of as received and smoothed films. The results illustrate the formation of composited polymers that exhibit self-limiting ability by SLED, depending on the interaction between the two components. Further, mechanical properties could be effectively fine-tuned within these compositional ranges. This signifies the 3D coating capabilities through SLED can be implemented incorporating additional functionalities and properties beyond the base matrix.

Development of Poly(dimethylsiloxane)/BaTiO3 Nanocomposites as Dielectric Material

2012 ◽  
Vol 622-623 ◽  
pp. 897-900 ◽  
Author(s):  
Suryakanta Nayak ◽  
Tapan Kumar Chaki ◽  
Dipak Khastgir
Keyword(s):  
Mechanical Properties ◽  
Dielectric Constant ◽  
Electron Microscope ◽  
Barium Titanate ◽  
Dielectric Material ◽  
Volume Resistivity ◽  
Filler Concentration ◽  
Base Matrix ◽  
Batio3 Nanoparticles ◽  
Scanning Electron

Polymer-ceramic nanocomposites with controlled dielectric properties are prepared using poly(dimethylsiloxane) elastomer as base matrix and barium titanate as filler. Barium titanate (BaTiO3) used in this study is prepared by solid state reaction at high temperature. The effect of BaTiO3 nanoparticles on electrical and mechanical properties are extensively studied and found that dielectric constant of nanocomposites increases significantly with the increase in BaTiO3 concentration where as volume resistivity decreases continuously. Different mechanical properties are also studied for all the composites in order to find the effect of filler concentration. Morphology of the prepared BaTiO3 was studied by field emission scanning electron microscope (FESEM).

Effects of Recycled-Aluminum Additions on the Mechanical Properties of Sn-0.7Cu/Cu-Substrate Lead-Free Solder Joints

2013 ◽  
Vol 795 ◽  
pp. 446-450 ◽  
Author(s):  
Mohd Arif Anuar Mohd Salleh ◽  
Flora Somidin ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
N.Z. Noriman ◽  
Ramani Mayappan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Solder Joints ◽  
Lead Free ◽  
Lead Free Solder ◽  
Powder Metallurgy Technique ◽  
Cu Substrate ◽  
Base Matrix ◽  
Free Solder ◽  
Al Additions ◽  
Scanning Electron

Varying amount of recycled-Aluminum (0, 3.0, 3.5 and 4.0 wt.% re-Al) particulates produced from aluminium beverage cans were successfully reincorporated into Sn-0.7Cu base matrix solder material via powder metallurgy technique. This paper focuses on the mechanical properties aspect of the new solder when joint on Cu-substrate. The hardness of the composite solders sintered bulks was enhanced with the increasing re-Al additions. Moreover, the composite solders have shown enhancement of shear stress strength at the solder joints. Fracture surface of the failure samples were analyzed using scanning electron microscope (SEM) which have indicated all samples failed under ductile fracture mechanism. However, with the refining dimples formation shown on the fractograph, this report suggests the increasing re-Al reinforcement has optimized the solder joints ductility strength.

scholarly journals Preparation and Mechanical Properties of Microcapsule-Based Self-Healing Cementitious Composites

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4866
Author(s):  
Shiping Jiang ◽  
Zhiyang Lin ◽  
Can Tang ◽  
Wenfeng Hao
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Composite Structures ◽  
Healing Time ◽  
The Self ◽  
Self Healing ◽  
Cementitious Composite ◽  
Healing System ◽  
Cement Based Materials ◽  
Curing Agents

Self-healing concrete designs can protect against deterioration and improve durability. However, there is no unified conclusion regarding the effective preparation and mechanical properties of self-healing concrete. In this paper, microcapsules are used in cement-based materials, the reasonable dosage of microcapsules is determined, and the self-healing performance of the microcapsule self-healing system under different curing agents is explored. The microcapsules and curing agent are shown to enhance the flexural and compressive strength of mortar specimens at relatively low contents. The optimal microcapsule content in terms of compressive strength is 1–3%. When the content of the microcapsule reaches 7%, the strength of the specimen decreases by approximately 30%. Sodium fluorosilicate is better-suited to the microcapsule self-healing cement-based system than the other two fluorosilicates, potassium fluorosilicate and magnesium, which have similarly poor healing performance as curing agents. Healing time also appears to significantly influence the microcapsule self-healing system; mortar specimens that healed for 28 days are significantly higher than those that healed for 7 days. This work may provide a valuable reference for the design and preparation of self-healing cementitious composite structures.

Electron Microscopic Observation of the Longitudinal Organization of Poly (p-Phenylene Terephthalamide) Fibers

1982 ◽  
Vol 40 ◽  
pp. 680-681
Author(s):  
Li Li-Sheng ◽  
L.F. Allard ◽  
W.C. Bigelow
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Microscopic Observation ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
Aromatic Polyamides ◽  
Radial Arrangement ◽  
Scanning Electron ◽  
Better Than

The aromatic polyamides form a class of fibers having mechanical properties which are much better than those of aliphatic polyamides. Currently, the accepted morphology of these fibers as proposed by M.G. Dobb, et al. is a radial arrangement of pleated sheets, with the plane of the pleats parallel to the axis of the fiber. We have recently obtained evidence which supports a different morphology of this type of fiber, using ultramicrotomy and ion-thinning techniques to prepare specimens for transmission and scanning electron microscopy.

scholarly journals Analysis of PLA Composite Filaments Reinforced with Lignin and Polymerised-Lignin-Treated NFC

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2174
Author(s):  
Diana Gregor-Svetec ◽  
Mirjam Leskovšek ◽  
Blaž Leskovar ◽  
Urška Stanković Elesini ◽  
Urška Vrabič-Brodnjak
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Tensile Strength ◽  
Glassy State ◽  
Nanofibrillated Cellulose ◽  
Dynamic Mechanical Properties ◽  
Initial Modulus ◽  
Surface Modified ◽  
Scanning Electron

Polylactic acid (PLA) is one of the most suitable materials for 3D printing. Blending with nanoparticles improves some of its properties, broadening its application possibilities. The article presents a study of composite PLA matrix filaments with added unmodified and lignin/polymerised lignin surface-modified nanofibrillated cellulose (NFC). The influence of untreated and surface-modified NFC on morphological, mechanical, technological, infrared spectroscopic, and dynamic mechanical properties was evaluated for different groups of samples. As determined by the stereo and scanning electron microscopy, the unmodified and surface-modified NFCs with lignin and polymerised lignin were present in the form of plate-shaped agglomerates. The addition of NFC slightly reduced the filaments’ tensile strength, stretchability, and ability to absorb energy, while in contrast, the initial modulus slightly improved. By adding NFC to the PLA matrix, the bending storage modulus (E’) decreased slightly at lower temperatures, especially in the PLA samples with 3 wt% and 5 wt% NFC. When NFC was modified with lignin and polymerised lignin, an increase in E’ was noticed, especially in the glassy state.

scholarly journals Effects of Various Types of Expandable Graphite and Blackcurrant Pomace on the Properties of Viscoelastic Polyurethane Foams

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1801
Author(s):  
Rafał Oliwa ◽  
Joanna Ryszkowska ◽  
Mariusz Oleksy ◽  
Monika Auguścik-Królikowska ◽  
Małgorzata Gzik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Structure ◽  
Oxygen Index ◽  
Polyurethane Foams ◽  
Expandable Graphite ◽  
Ftir Analysis ◽  
Limiting Oxygen Index ◽  
Peak Heat Release Rate ◽  
Physical And Chemical ◽  
Scanning Electron

We investigated the effect of the type and amount of expandable graphite (EG) and blackcurrant pomace (BCP) on the flammability, thermal stability, mechanical properties, physical, and chemical structure of viscoelastic polyurethane foams (VEF). For this purpose, the polyurethane foams containing EG, BCP, and EG with BCP were obtained. The content of EG varied in the range of 3–15 per hundred polyols (php), while the BCP content was 30 php. Based on the obtained results, it was found that the additional introduction of BCPs into EG-containing composites allows for an additive effect in improving the functional properties of viscoelastic polyurethane foams. As a result, the composite containing 30 php of BCP and 15 php of EG with the largest particle size and expanded volume shows the largest change in the studied parameters (hardness (H) = 2.65 kPa (+16.2%), limiting oxygen index (LOI) = 26% (+44.4%), and peak heat release rate (pHRR) = 15.5 kW/m2 (−87.4%)). In addition, this composite was characterized by the highest char yield (m600 = 17.9% (+44.1%)). In turn, the change in mechanical properties is related to a change in the physical and chemical structure of the foams as indicated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis.

scholarly journals Corrosion Behavior and Mechanical Properties of a Nanocomposite Superhydrophobic Coating

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 652
Author(s):  
Divine Sebastian ◽  
Chun-Wei Yao ◽  
Lutfun Nipa ◽  
Ian Lian ◽  
Gary Twu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Nanocomposite Coating ◽  
Superhydrophobic Coating ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Images ◽  
Scanning Electron

In this work, a mechanically durable anticorrosion superhydrophobic coating is developed using a nanocomposite coating solution composed of silica nanoparticles and epoxy resin. The nanocomposite coating developed was tested for its superhydrophobic behavior using goniometry; surface morphology using scanning electron microscopy and atomic force microscopy; elemental composition using energy dispersive X-ray spectroscopy; corrosion resistance using atomic force microscopy; and potentiodynamic polarization measurements. The nanocomposite coating possesses hierarchical micro/nanostructures, according to the scanning electron microscopy images, and the presence of such structures was further confirmed by the atomic force microscopy images. The developed nanocomposite coating was found to be highly superhydrophobic as well as corrosion resistant, according to the results from static contact angle measurement and potentiodynamic polarization measurement, respectively. The abrasion resistance and mechanical durability of the nanocomposite coating were studied by abrasion tests, and the mechanical properties such as reduced modulus and Berkovich hardness were evaluated with the aid of nanoindentation tests.

scholarly journals Modification of Mechanical Properties of High-Strength Titanium Alloys VT23 and VT23M Due to Impact-Oscillatory Loading

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 80 ◽  
Author(s):  
Mykola Chausov ◽  
Janette Brezinová ◽  
Andrii Pylypenko ◽  
Pavlo Maruschak ◽  
Liudmyla Titova ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloys ◽  
High Strength ◽  
The Self ◽  
Self Organization ◽  
Two Phase ◽  
Rolled Metal ◽  
Technological Method ◽  
Equilibrium Processes ◽  
Production Conditions

A simple technological method is proposed and tested experimentally, which allows for the improvement of mechanical properties in sheet two-phase high-strength titanium alloys VT23 and VT23M on the finished product (rolled metal), due to impact-oscillatory loading. Under impact-oscillatory loading and dynamic non-equilibrium processes (DNP) are realized in titanium alloys, leading to the self-organization of the structure. As a result, the mechanical properties of titanium alloys vary significantly with subsequent loading after the realization of DNP. In this study, the test modes are found, which can be used in the production conditions.

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