scholarly journals Pyrolytic carbon resonators for micromechanical thermal analysis

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Long Quang Nguyen ◽  
Peter Emil Larsen ◽  
Tom Larsen ◽  
Sanjukta Bose Goswami ◽  
Luis Guillermo Villanueva ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Electrical Conductivity ◽  
Resonance Frequency ◽  
Quality Factor ◽  
Pyrolytic Carbon ◽  
Q Factor ◽  
Scanning Calorimetry ◽  
Quality Factor Q ◽  
Poly Caprolactone

Abstract Thermal analysis is essential for the characterization of polymers and drugs. However, the currently established methods require a large amount of sample. Here, we present pyrolytic carbon resonators as promising tools for micromechanical thermal analysis (MTA) of nanograms of polymers. Doubly clamped pre-stressed beams with a resonance frequency of 233 ± 4 kHz and a quality factor (Q factor) of 800 ± 200 were fabricated. Optimization of the electrical conductivity of the pyrolytic carbon allowed us to explore resistive heating for integrated temperature control. MTA was achieved by monitoring the resonance frequency and quality factor of the carbon resonators with and without a deposited sample as a function of temperature. To prove the potential of pyrolytic carbon resonators as thermal analysis tools, the glass transition temperature (Tg) of semicrystalline poly(L-lactic acid) (PLLA) and the melting temperature (Tm) of poly(caprolactone) (PCL) were determined. The results show that the Tg of PLLA and Tm of PCL are 61.0 ± 0.8 °C and 60.0 ± 1.0 °C, respectively, which are in excellent agreement with the values measured by differential scanning calorimetry (DSC).

scholarly journals Stability evaluation of tocopheryl acetate and ascorbyl tetraisopalmitate in isolation and incorporated in cosmetic formulations using thermal analysis

2010 ◽  
Vol 46 (1) ◽  
pp. 129-134 ◽  
Author(s):  
Mariana Mandelli de Almeida ◽  
Cibele Rosana Ribeiro de Castro Lima ◽  
Joyce Santos Quenca-Guillen ◽  
Elder Moscardini Filho ◽  
Lucildes Pita Mercuri ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Raw Materials ◽  
Skin Aging ◽  
Tocopheryl Acetate ◽  
Stability Evaluation ◽  
Scanning Calorimetry ◽  
Cosmetic Formulations ◽  
Cosmetic Formulation ◽  
Excellent Tool

In view of the increase in the number of cosmetic preparations containing antioxidant vitamins, chiefly, due to their action in preventing the process of skin aging, there is a need to develop pre-formulation studies and to validate analytical methods in order to obtain high quality products. Thus, the objective of this research was to evaluate and compare the thermal behavior of tocopheryl acetate and ascorbyl tetraisopalmitate as raw materials, and incorporated into a base cream. Thermogravimetry (TG / DTG) and differential scanning calorimetry (DSC) were used for this purpose. Both vitamins were found to be stable up to 250ºC. The base cream (placebo) and the sample (base cream containing the vitamins) presented different weight loss. Thermal analysis has shown itself to be an excellent tool for the characterization of these vitamins and can be used in routine analysis for quality control of this type of cosmetic formulation.

scholarly journals A Geometrical Study on the Roof Tile-Shaped Modes in AlN-Based Piezoelectric Microcantilevers as Viscosity–Density Sensors

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 658 ◽  
Author(s):  
Víctor Ruiz-Díez ◽  
Javier Toledo ◽  
Jorge Hernando-García ◽  
Abdallah Ababneh ◽  
Helmut Seidel ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Quality Factor ◽  
Q Factor ◽  
Liquid Media ◽  
Roof Tile ◽  
Aln Film ◽  
Monitoring Applications ◽  
Media Monitoring ◽  
Comprehensive Study

Cantilever resonators based on the roof tile-shaped modes have recently demonstrated their suitability for liquid media monitoring applications. The early studies have shown that certain combinations of dimensions and order of the mode can maximize the Q-factor, what might suggest a competition between two mechanisms of losses with different geometrical dependence. To provide more insight, a comprehensive study of the Q-factor and the resonant frequency of these modes in microcantilever resonators with lengths and widths between 250 and 3000 µm and thicknesses between 10 and 60 µm is presented. These modes can be efficiently excited by a thin piezoelectric AlN film and a properly designed top electrode layout. The electrical and optical characterization of the resonators are performed in liquid media and then their performance is evaluated in terms of quality factor and resonant frequency. A quality factor as high as 140 was measured in isopropanol for a 1000 × 900 × 10 µm3 cantilever oscillating in the 11th order roof tile-shaped mode at 4 MHz; density and viscosity resolutions of 10−6 g/mL and 10−4 mPa·s, respectively are estimated for a geometrically optimized cantilever resonating below 1 MHz.

scholarly journals A Study on the Trimming Effects on the Quality Factor of Micro-Shell Resonators Vibrating in Wineglass Modes

Micromachines ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 695
Author(s):  
Lu ◽  
Xi ◽  
Xiao ◽  
Shi ◽  
Zhuo ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Quality Factor ◽  
Second Harmonic ◽  
Great Influence ◽  
Fem Simulation ◽  
Q Factor ◽  
Thermoelastic Damping ◽  
Frequency Trimming ◽  
Quality Factor Q ◽  
Anchor Loss

Frequency trimming based on mass and stiffness modification is an important post-fabrication process for micro-shell resonators (MSRs). However, the trimming effects on the quality factor are seldom studied, although they may have great influence on the performance of the resonator. This paper presents a study on the quality factor (Q-factor) variation of trimmed micro-shell resonators (MSR). Thermoelastic damping (QTED) and anchor loss (Qanchor) are found to be the dominant energy loss mechanisms resulting in the reduction of the overall Q-factor, according to finite element method (FEM). The effects of different trimming methods on QTED and Qanchor are studied here, respectively. It is found that trimming grooves ablated in the rim of the resonator can cause a ~1–10% reduction of QTED, and the length of trimming groove is positively related to the reduction of QTED. The reduction of QTED caused by the mass adding process is mainly related to the thermal expansion coefficient and density of the additive and contact area between the resonator and additive masses. Besides, the first and second harmonic errors caused by asymmetrical trimming can cause a 10–90% reduction of Qanchor. Finally, trimming experiments were conducted on different resonators and the results were compared with FEM simulation. The work presented in this paper could help to optimize the trimming process of MSRs.

scholarly journals Development of Pressure-Responsive PolyPropylene and Biochar-Based Materials

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 339 ◽  
Author(s):  
Amir Noori ◽  
Mattia Bartoli ◽  
Alberto Frache ◽  
Erik Piatti ◽  
Mauro Giorcelli ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Electrical Conductivity ◽  
Differential Scanning Calorimetry ◽  
Plastic Deformation ◽  
Electrical Properties ◽  
Tea Leaves ◽  
Scanning Calorimetry ◽  
A Value ◽  
Wide Range ◽  
Order Of Magnitude

In this research paper, we reported the synthesis of biochar-based composites using biochar derived from exhausted tea leaves and polypropylene. The resulting materials were deeply characterized investigating mechanical (dynamic mechanical thermal analysis), thermal (thermogravimetrical analysis and differential scanning calorimetry), morphological (field emission scanning microscopy) and electrical properties vs. temperature. Furthermore, electrical conductivity was studied for a wide range of pressures showing an irreversible plastic deformation. An increment of one order of magnitude in the conductivity was observed in the case of 40 wt% biochar loading, reaching a value of 0.2 S/m. The material produced exhibited the properties of an irreversible pressure sensor.

scholarly journals Manufacturing and Properties of Binary Blend from Bacterial Polyester Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and Poly(caprolactone) with Improved Toughness

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1118
Author(s):  
Juan Ivorra-Martinez ◽  
Isabel Verdu ◽  
Octavio Fenollar ◽  
Lourdes Sanchez-Nacher ◽  
Rafael Balart ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Impact Resistance ◽  
Precise Determination ◽  
Scanning Calorimetry ◽  
Binary Blend ◽  
Two Phases ◽  
Almost All ◽  
New Applications ◽  
Poly Caprolactone ◽  
Bacterial Polyesters

Polyhydroxyalkanoates (PHAs) represent a promising group of bacterial polyesters for new applications. Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) is a very promising bacterial polyester with potential uses in the packaging industry; nevertheless, as with many (almost all) bacterial polyesters, PHBH undergoes secondary crystallization (aging) which leads to an embrittlement. To overcome or minimize this, in the present work a flexible petroleum-derived polyester, namely poly(ε-caprolactone), was used to obtain PHBH/PCL blends with different compositions (from 0 to 40 PCL wt %) using extrusion followed by injection moulding. The thermal analysis of the binary blends was studied by means of differential scanning calorimetry (DSC) and thermogravimetry (TGA). Both TGA and DSC revealed immiscibility between PHBH and PCL. Mechanical dynamic thermal analysis (DMTA) allowed a precise determination of the glass transition temperatures (Tg) as a function of the blend composition. By means of field emission scanning electron microscopy (FESEM), an internal structure formed by two phases was observed, with a PHBH-rich matrix phase and a finely dispersed PCL-rich phase. These results confirmed the immiscibility between these two biopolymers. However, the mechanical properties obtained through tensile and Charpy tests, indicated that the addition of PCL to PHBH considerably improved toughness. PHBH/PCL blends containing 40 PCL wt % offered an impact resistance double that of neat PHBH. PCL addition also contributed to a decrease in brittleness and an improvement in toughness and some other ductile properties. As expected, an increase in ductile properties resulted in a decrease in some mechanical resistant properties, e.g., the modulus and the strength (in tensile and flexural conditions) decreased with increasing wt % PCL in PHBH/PCL blends.

scholarly journals Preparation of Multicomponent Biocomposites and Characterization of Their Physicochemical and Mechanical Properties

2020 ◽  
Vol 4 (1) ◽  
pp. 18
Author(s):  
Yuriy A. Anisimov ◽  
Duncan E. Cree ◽  
Lee D. Wilson
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Physicochemical Properties ◽  
In Situ Polymerization ◽  
Structural Parameters ◽  
Dye Adsorption ◽  
Mechanical Analysis ◽  
Scanning Calorimetry ◽  
Swelling Properties

This work focused on a mutual comparison and characterization of the physicochemical properties of three-component polymer composites. Binary polyaniline–chitosan (PANI–CHT) composites were synthesized by in situ polymerization of PANI onto CHT. Ternary composites were prepared by blending with a third component, polyvinyl alcohol (PVA). Composites with variable PANI:CHT (25:75, 50:50 and 75:25) weight ratios were prepared whilst fixing the composition of PVA. The structure and physicochemical properties of the composites were evaluated using thermal analysis (thermogravimetric analysis (TGA), differential scanning calorimetry (DSC)) and spectroscopic methods (infrared (IR), nuclear magnetic resonance (NMR)). The equilibrium and dynamic adsorption properties of composites were evaluated by solvent swelling in water, water vapour adsorption and dye adsorption isotherms. The electrical conductivity was estimated using current–voltage curves. The mechanical properties of the samples were evaluated using dynamic mechanical analysis (DMA) and correlated with the structural parameters of the composites. The adsorption and swelling properties paralleled the change in the electrical and mechanical properties of the materials. In most cases, samples with higher content of chitosan exhibit higher adsorption and mechanical properties, and lower conductivity. Acid-doped samples showed much higher adsorption, swelling, and electrical conductivity than their undoped analogues.

Performance Investigate and Analysis of 96 × 10 Gbps DWDM System Using Suitable Rating from Optical Amplifiers

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Chakresh Kumar ◽  
Ghanendra Kumar
Keyword(s):  
Quality Factor ◽  
Fiber Length ◽  
Optical Amplifiers ◽  
The Other ◽  
Superior Performance ◽  
Q Factor ◽  
Probability Of Error ◽  
Raman Amplifier ◽  
Quality Factor Q ◽  
Dwdm System

AbstractThe objective of current work is to design and analyzed 96×10 Gbps DWDM system taking EDFA, SOA, and RAMAN amplifier as an inline amplifiers up to a fiber length of 300 km. The performance of EDFA, SOA, and RAMAN amplifier is measured on the basis of power received, Q-factor, probability of error and BER for various values of fiber distance. In this paper it has been proved that for 96 channels DWDM system at 10 Gbps bit rate, EDFA reveals superior performance as far as the amount of power received is concerned. The value of quality factor (Q-factor) for RAMAN amplifier is almost identical to that of the Q-factor for EDFA and is higher than the Q-factor for SOA till a fiber length of roughly 80 km thereafter SOA reveals somewhat better Q-factor than EDFA and RAMAN amplifier. As far as BER is concerned EDFA and RAMAN amplifier show roughly identical and somewhat lower BER than SOA till a fiber length of roughly 80 km, afterwards SOA reveal somewhat lesser BER till the fiber length of 210 km. In relation to the probability of error P(E), It is analyzed that P(E) remains more or less same for the entire set of optical amplifiers(OAs) but beyond the fiber length of 240 km EDFA shows somewhat lower P(E) than the other two OAs. At the end the Eye diagrams for the three OAs are also figure out.

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