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Certification and Characterization of Photovoltaic Packaging
Published in Michelle Poliskie, Solar Module Packaging, 2016
Thermomechanical analysis (TMA) is a connecting rod dilatometer commonly used to measure polymer thermal expansion coefficients. Both the glass transition temperature and the coefficient of thermal expansion can be measured using TMA. During the experiment, the expansion probe is placed on the surface of the polymer with a nominal force (~1000 micronewtons [μΝ]) applied to the largest surface area (Figure 2.20). The polymer temperature is ramped in an inert atmosphere over the temperature range of interest. The increased temperature causes the polymer to expand, resulting in a vertical displacement of the probe. The coefficient of thermal expansion is calculated from the initial volume and the changes in displacement divided by the change in temperature, also known as the slope of the TMA curve (Figure 2.21). A discontinuity in the curve is present at the Tg of the polymer. The thermal expansion coefficient is measured on each side of the Tg.
The Use of Thermal Analysis in Polymer Characterization
Published in Nicholas P. Cheremisinoff, Elastomer Technology Handbook, 2020
Thermomechanical analysis (TMA) is a method for evaluating dimensional changes as a function of temperature, time, and environment. While DSC and TGA are concerned with the energetics of physical and chemical changes, TMA measures the dimensional effects associated with these changes. The samples are typically pieces of fabricated items rather than raw material. The sample is placed on a quartz stage which is surrounded by a furnace and a Dewar bottle for heating and cooling. A quartz expansion or penetration probe is brought to rest on the sample. As the sample expands or contracts, changes in the position of the probe are accurately monitored and translated as the dimensional change of the sample. Different loads may be applied to the sample.
Thermal analysis
Published in D. Campbell, R.A. Pethrick, J.R. White, Polymer Characterization, 2017
D. Campbell, R.A. Pethrick, J.R. White
Thermomechanical analysis (TMA) is the name given to a method capable of measuring the thermal expansion coefficient of materials in their most refined form, but which is sometimes used simply to determine the location of the glass transition temperature. Figure 12.9(a) shows the typical layout of the TMA apparatus.
One-pot synthesis of soluble wholly aromatic liquid crystalline copoly(ester amide)s with high thermal and dimensional stability
Published in Chemical Engineering Communications, 2020
Quang Vinh Nguyen, Jin Young Bae, Hoang Sinh Le
Fourier transform infrared (FTIR) spectrum of synthesized copoly(ester amide) was obtained by Nicolet 6700 spectrometer (Thermo Fisher Scientific Inc., USA) using KBr pellet method over infrared radiation ranging from 400 to 4000 cm−1. Proton nuclear magnetic resonance (1H-NMR) spectrum was recorded using a 500 Mhz Varian Unity Inova NB500 spectrometer (Varian Inc., USA), with deuterated dimethyl sulfoxide (DMSO-d6) as the NMR solvent. The molecular weight and polydispersity index (PDI) of the copolymers were measured by gel permeation chromatography (GPC) using a Waters Model 410 instrument with a refractive index detector (Shodex, RI-101) and a series of three Styragel columns (KF-803L, KF-802.5, and KF-802). Dimethylformamide (DMF) was used as GPC eluent at a flow rate of 1.0 mL min−1 and temperature of 40 °C. Differential scanning calorimetry (DSC) measurement was performed using DSC-Q20 (TA Instrument Inc., USA) with temperature ranging from 50 °C to 450 °C at a heating rate of 10 °C min−1 in nitrogen atmosphere. The weight loss behavior was evaluated in the temperature range from 50 °C to 600 °C at a heating rate of 10 °C min−1 in nitrogen atmosphere using a thermogravimetric analyzer (TGA) (TG209F3, Netzch, Germany). CTE values were determined using a thermomechanical analysis (TMA) apparatus (TMA Q400, TA Instruments Inc., USA) with temperature ranging from room temperature to 315 °C at a scanning rate of 2 °C min−1 and a frequency of 1 Hz. Wide-angle X-ray diffraction measurement was performed by D8 FOCUS X-ray diffractometer (Bruker AXS, Bruker Corp., Germany) under Ni-filtered CuKα radiation at room temperature. The rotation velocity of goniometry was 4° min−1. A polarized optical microscope (LV100POL, Nikon Corp. Japan) equipped with a Mettler Toledo FP-82 hot stage was utilized to observe the optical texture of synthesized copoly(ester amide)s.
Visualization of oil cells and preservation during drying of betel leaf (piper betel) using hot-stage microscopy
Published in Drying Technology, 2022
Viplav Hari Pise, Shivanand S. Shirkole, Bhaskar N. Thorat
Different thermal analyses measuring transition temperature like Differential scanning calorimetry (DSC), Thermomechanical Analysis (TMA), Dynamic mechanical analysis (DMA) and so on are commonly used to gather a wealth of information on the structural and physical properties of a wide range of materials. Microstructural changes are studied through various microscopic (SEM, TEM or AFM) images. However, each method has its merit, and demerit, for example, DSC, DMA, TMA do not provide insights into morphological changes. SEM, TEM, or AFM visualize the structures; however, real-time dynamic changes are challenging to obtain. Hot-stage microscopy (HSM) combines thermoanalytical techniques and optical microscopy, digital camera and image analysis of the changes during thermal experimentation. The evolution of HSM and the chronology of development and its applications in the pharmaceutical sector are well summarized by Arun Kumar et al.[21] HSM is also seen to be reported for synthesis and determination of mesomorphic properties of Liquid crystals,[22] crystal nucleation and growth of natural fats[23] and melt behavior of raw materials in ceramics.[24] HSM was used in the present study to observe and capture images of microstructural changes during dehydration. It provides a simultaneous study of dehydration, thermal analysis and structural changes at different temperatures and over the dehydration time. The pathway and the rate of mass transfer during dehydration, the effect of temperature on dehydration rate and microstructural changes, and the impact on retention of the oil glands during dehydration and rehydration can be documented. HSM allowed the monitoring of the still sample during the dehydration and rehydration. The work focuses on bringing out the microstructural changes and its impact on oil reserves/oil secretory cells (pearl glands) of betel leaf during the dehydration process. Also, it was desirable to study the effect of drying rate on the retention of phytochemicals (volatile oils). The HSM technique captured the cellular and other structural changes in dynamic mode, followed by a detailed analysis.