Processing and Characterization of Thermoplastic Polyurethane Nanocomposite Thin Films

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Anandh Balakrishnan ◽  
Mrinal C. Saha
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Molecular Weight ◽  
Optical Microscopy ◽  
Carbon Nanofiber ◽  
Droplet Diameter ◽  
Thermoplastic Polyurethane ◽  
Scanning Calorimetry ◽  
Ultrasound Assisted ◽  
Set Up

In this article, we have set up protocols for fabricating thermoplastic polyurethane thin films of about 30 μm (neat polyurethane and carbon nanofiber (CNF) containing polyurethane) via ultrasound assisted atomization at 20 kHz. From processing to thin film peel off, we have set up procedures for fabricating our samples. Using optical microscopy, we have examined the manufacturing of these films from a droplet diameter perspective. Our optical microscopy results indicate that the final film microstructure was directly dependent on the physical properties of the neat/CNF reinforced solution. Mechanical testing of these films was then carefully carried out using a dynamic mechanical analyzer (DMA) unit utilizing a specialized thin film test clamp fixture. These test results were compared with control cast films fabricated from the same solutions. For the similar extensions, we observed a drastic increase in the softness of the atomized film. We surmise that the ultrasound assisted droplet generation concurrent with secondary atomization and evaporation could have resulted in reduction of the molecular weight of the polyurethane in our atomized samples relative to the neat ones. Differential scanning calorimetry (DSC) scans have been conducted to confirm the changes in molecular weight. Although results were inconclusive there is evidence of exotherms at 49C in our atomized samples suggested of changes to molecular weight distribution.

scholarly journals Dry Electrodes for Surface Electromyography Based on Architectured Titanium Thin Films

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2135 ◽  
Author(s):  
Marco S. Rodrigues ◽  
Patrique Fiedler ◽  
Nora Küchler ◽  
Rui P. Domingues ◽  
Cláudia Lopes ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Surface Electromyography ◽  
Silver Chloride ◽  
Thermoplastic Polyurethane ◽  
Skin Irritation ◽  
Normal Growth ◽  
Quality Parameters ◽  
Skin Impedance ◽  
Dry Electrodes

Electrodes of silver/silver chloride (Ag/AgCl) are dominant in clinical settings for surface electromyography (sEMG) recordings. These electrodes need a conductive electrolyte gel to ensure proper performance, which dries during long-term measurements inhibiting the immediate electrode’s reuse and is often linked to skin irritation episodes. To overcome these drawbacks, a new type of dry electrodes based on architectured titanium (Ti) thin films were proposed in this work. The architectured microstructures were zigzags, obtained with different sputtering incidence angles (α), which have been shown to directly influence the films’ porosity and electrical conductivity. The electrodes were prepared using thermoplastic polyurethane (TPU) and stainless-steel (SS) substrates, and their performance was tested in male volunteers (athletes) by recording electromyography (EMG) signals, preceded by electrode-skin impedance measurements. In general, the results showed that both SS and TPU dry electrodes can be used for sEMG recordings. While SS electrodes almost match the signal quality parameters of reference electrodes of Ag/AgCl, the performance of electrodes based on TPU functionalized with a Ti thin film still requires further improvements. Noteworthy was the clear increase of the signal to noise ratios when the thin films’ microstructure evolved from normal growth towards zigzag microstructures, meaning that further tailoring of the thin film microstructure is a possible route to achieve optimized performances. Finally, the developed dry electrodes are reusable and allow for multiple EMG recordings without being replaced.

Polydispersity Effects in Evaporation of Perfluoropolyether Thin Films

2001 ◽  
Author(s):  
Michael Stirniman ◽  
Jing Gui
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Molecular Weight ◽  
Weight Distribution ◽  
Evaporation Rate ◽  
Surface Interactions ◽  
Bulk Liquid ◽  
Vapor Pressures ◽  
Thin Film Evaporation ◽  
Film Evaporation

Abstract The evaporation rates of bulk liquid and thin films of an alcohol-derivatized perfluoropolyether have been studied experimentally and computationally. We find that the time dependence of the evaporation rate in both cases is dominated by the polydispersity, and can be described very well by a model that incorporates the molecular weight distribution, molecular-weight-dependent Arrhenius parameters of evaporation, and Raoult’s law of vapor pressures. Minor corrections to the model that account for surface interactions are necessary in the case of thin film evaporation.

On the application of a single-crystal κ-diffractometer and a CCD area detector for studies of thin films

2013 ◽  
Vol 20 (4) ◽  
pp. 644-647 ◽  
Author(s):  
Henrik Hovde Sønsteby ◽  
Dmitry Chernyshov ◽  
Michael Getz ◽  
Ola Nilsen ◽  
Helmer Fjellvåg
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Crystal Orientation ◽  
Atomic Layer ◽  
Area Detector ◽  
Layer Deposition ◽  
Crucial Information ◽  
Key Features ◽  
Set Up

A multipurpose six-axis κ-diffractometer, together with the brilliance of the ESRF light source and a CCD area detector, has been explored for studying epitaxial relations and crystallinity in thin film systems. The geometrical flexibility of the six-axis goniometer allows measurement of a large volume in reciprocal space, providing an in-depth understanding of sample crystal relationships. By a set of examples of LaAlO3thin films deposited by the atomic layer deposition technique, the possibilities of the set-up are presented. A fast panoramic scan provides determination of the crystal orientation matrices, prior to more thorough inspection of single Bragg nodes. Such information, in addition to a broadening analysis of families of single reflections, is shown to correlate well with the crystallinity, crystallite size, strain and epitaxial relationships in the thin films. The proposed set-up offers fast and easy sample mounting and alignment, along with crucial information on key features of the thin film structures.

Initial Evolution of Cobalt Silicides in The Cobalt/Amorphous-Silicon Thin Film System

1991 ◽  
Vol 230 ◽  
Author(s):  
Hideo Miura ◽  
En Ma ◽  
Carl V. Thompson
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Amorphous Silicon ◽  
Amorphous Layer ◽  
X Ray Diffraction ◽  
Silicon Thin Film ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Initial Evolution ◽  
Cobalt Silicides

AbstractThe initial phase formation sequence for reactions in cobalt/ amorphous-silicon multi-layer thin films has been investigated using a combination of differential scanning calorimetry, thin film X-ray diffraction, and transmission electron microscopy. Multilayer thin films with various overall atomic concentration ratios and various bilayer thicknesses were used in this study. It was found that crystalline CoSi is always the first phase to nucleate in the interdiffused amorphous layer which preexisted at the as-deposited coba It/amorphous-si licon interface. The CoSi nucleates at temperatures as low as about 530 K, but does not grow until the next phase, which is Co2 Si when excess Co is available, starts to nucleate and grow. The activation energy of the CoSi nucleation was found to be 1.-6±0.1 eV.

Effect of Ultrasound and Strain Rate on Tensile Behavior of Neat Thermoplastic Polyurethane Thin Films

2010 ◽  
Author(s):  
Anandh Balakrishnan ◽  
Mrinal C. Saha
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Strain Rate ◽  
Mechanical Test ◽  
Thermoplastic Polyurethane ◽  
Optical Element ◽  
Mechanical Tests ◽  
Primary Objective ◽  
Scanning Calorimetry ◽  
Rate Dependent

Thermoplastic Polyurethane (TPU) thin films have many applications in engineering and biomedical fields. Examples include moisture sensors, load cells, optical element and biocompatible stens. The TPU is a block copolymer naturally phase segregates into thermodynamically incompatible hard- and soft-segments. The size of the segments and their spatial distribution can significantly affect the microstructure and mechanical properties of the TPU. In this paper, we propose to investigate the effect of ultrasound energy on mechanical properties of TPU thin films fabricated via a solution route utilizing Tetra Hydro Furan (THF) as a solvent. The times of sonication was fixed at 60 minutes whilst all films were fabricated at average thickness of 20+/-5 um. The primary objective of the study was to understand the influence of ultrasound and strain rates on the material microstructure and the resulting mechanical properties. Mechanical tests have been conducted at two different displacement rates, namely 5 and 10 mm/min. Our preliminary results indicate that ultrasound improves the strength of the neat TPU films. We also see that strain hardening is displacement or strain rate dependent. We attribute these results to changes in the hard (H) and soft (S) domain structure. To further understand these microstructural variations, we propose to conduct Differential Scanning Calorimetry (DSC). The data has been interpreted in conjunction with our mechanical test data.

scholarly journals Transformation and Mechanical Properties of TiNi Thin Films Sputter Deposited at Various Argon Pressures for Micromachine Actuators

1999 ◽  
Vol 11 (4) ◽  
pp. 258-262
Author(s):  
Seiji Shimizu ◽  
◽  
Katsutoshi Kuribayashi
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Mechanical Properties ◽  
Differential Scanning Calorimetry ◽  
Shape Memory Alloy ◽  
Room Temperature ◽  
Tensile Tests ◽  
Alloy Thin Film ◽  
Scanning Calorimetry ◽  
Sputter Deposited

We studied the transformation and mechanical properties of Ti- 54.8-51.6 at % Ni shape memory alloy thin film actuators sputter-deposited at different argon pressures of 0.47-3.4 Pa. The higher the argon pressure, the lower the nickel composition. TiNi thin films were crystallized at 800C for 10min, aged at 400C for 6h, and analyzed by differential scanning calorimetry and tensile tests. All films showed 2-step transformation of martensite, R, and austenite phases. The maximum generative stress of 365MPa was obtained when the TiNi thin film actuator deposited at 2.0Pa was heated electrically to 30A/mm2 after deformation of 3.0% at room temperature.

Block Copolymer Thin Films Above and Below the Order-Disorder Transition Temperature

2000 ◽  
Vol 629 ◽  
Author(s):  
Ratchana Limary ◽  
Peter F. Green
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Molecular Weight ◽  
Transition Temperature ◽  
Block Copolymer ◽  
Film Thickness ◽  
Diblock Copolymer ◽  
Diblock Copolymers ◽  
Microphase Separation ◽  
Disorder Transition Temperature

ABSTRACTSymmetric diblock copolymers undergo a disorder to order transition below a microphase separation transition temperature. In this temperature range the structure is characterized by alternating lamellae of thickness L. In thin film geometries, the lamellae are oriented normal to the substrate if there is a preferential interaction between either of the block constituents and the substrate/copolymer or copolymer/vacuum interfaces. Depending on the relation between the film thickness and L, the topography of the film might comprise of holes, islands or spinodal-like structures. We show that in a polystyrene-b-poly(methyl methacrylate) diblock copolymer of molecular weight 20, 000 g/mol, above the microphase separation transition temperature, the topography of the film depends on the thickness. A heirarchy of bicontinuous patterns and holes is observed with increasing film thickness for films thinner than 35 nm.

Effect of solvent vapour annealing on polymer thin films and application in nonlinear optical fields

2014 ◽  
Vol 2 (41) ◽  
pp. 8662-8666 ◽  
Author(s):  
Shiwei Wang ◽  
Wanli Su ◽  
Yunhui Li ◽  
Rongwei Zhang ◽  
Xibin Wang ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Molecular Weight ◽  
Nonlinear Optical ◽  
Polymer Thin Films ◽  
Low Molecular Weight ◽  
Optical Fields ◽  
Polymer Thin Film ◽  
Solvent Vapour ◽  
Effect Of Solvent

Solvent vapour annealed (SVA) technique was successfully used in controlling the morphology of polymer thin film blending with low molecular weight chromophoric (LMWC) molecules.

scholarly journals The initial stages of explosion in nitroglycerine

1947 ◽  
Vol 191 (1025) ◽  
pp. 210-225 ◽  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Detonation Wave ◽  
Rotating Drum ◽  
Gaseous Mixtures ◽  
Sequence Of Events ◽  
Impact Initiation ◽  
Set Up

The sequence of events which occurs in a thin confined film of nitroglycerine, after an explosion is initiated by a condenser spark, has been examined by means of a rotating drum camera. It has been found that in a very thin film (< 0⋅01 mm. thick) the explosion begins as a gentle process which is propagated through the nitroglycerine film at 400 m./sec. After continuing for about 0⋅5 cm. this process is transformed suddenly to a more violent type of explosion which is propagated at 2000 m./sec. The explosion reproduces in miniature several of the well-known effects characteristic of the setting up of the detonation wave in gaseous mixtures. When explosion is initiated in the same manner in a thicker film, the 400 m./sec. type of propagation is not set up immediately but is preceded by a very much faster process (5000 m./sec.), which after propagating for a few millimetres is transformed into the normal 400 m./sec. process. Subsequent to this transformation the propagation continues exactly as in the very thin films. It is suggested that, under conditions of impact initiation, the propagation of the explosion through the film of nitroglycerine between the hammer and the anvil takes place in a manner closely similar to that which obtains after initiation by spark.

Studies on Water in the Hydration Chamber of a Modified Electron Microscope

1970 ◽  
Vol 28 ◽  
pp. 544-545
Author(s):  
R. C. Moretz ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electron Microscope ◽  
Steady State ◽  
Room Temperature ◽  
Small Mass ◽  
Equilibrium Pressure ◽  
Biological Objects ◽  
Mechanical Pump ◽  
Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

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