China
Africa
Explore chapters and articles related to this topic
The Application of Microwave Energy for Fabrication of Polymer-Based Composite Materials
Published in Amit Bansal, Hitesh Vasudev, Advances in Microwave Processing for Engineering Materials, 2023
Manjeet Rani, Rajeev Kumar, Nishant Verma, Himanshu Pathak, Sunny Zafar
Dynamic mechanical analysis (DMA) is a versatile tool for determining the dynamic characteristics of materials. It can measure the properties of a range of materials, such as storage modulus (E′, G′), loss modulus (E″, G″), loss tangent (tan δ), glass transition temperature (Tg), and so on. The dependency of these properties on temperature can also be analyzed using DMA. The dynamic oscillating is applied to a specimen, and the material’s response to the cyclic force is analyzed. The curves were plotted to identify transition temperature based on noticeable changes in the curve. DMA result of a CFRPC is shown in Figure 9.5. The variation in the value of storage modulus (E′) is from 7 GPa to 30 GPa up to char temperature and reduced further. The viscoelastic material is given by loss modulus (E″). The value of E″ suddenly drops with an increase in temperature. A peak of storage modulus was found at the gelation point (240°C). The value of the degree of cure at this point was about 0.78. The value of loss tangent decreased first up to gelation point and, after attaining a small peak, decreased further.
Theoretical Aspects of Dynamic Mechanical Analysis
Published in Jose James, K.P. Pramoda, Sabu Thomas, Polymers and Multicomponent Polymeric Systems, 2019
Dynamic mechanical analysis (DMA) is a testing method used to study and characterize viscoelastic properties of polymers and soft materials. In this method, commonly a sinusoidal stress is applied, and the strain of the material is measured. The output determines the complex modulus and other temperature-related properties of the polymer. During the testing, temperature or the frequency of stress of the test sample are often varied, and variations in the complex modulus are measured. This approach can be used to find the glass transition temperature and examine molecular relaxation and particle–matrix interface characteristics. This work deals with the understanding of the theoretical aspects of DMA on polymer analysis, and the testing procedure and measurement of some DMA parameters are discussed.
Processing and Characterization of Modified Nanocellulose/Polyester Composites
Published in Tatjana Stevanovic, Chemistry of Lignocellulosics: Current Trends, 2018
Jelena Rusmirović, Milica Rančić, Aleksandar Marinković
Interactions between polymer chains and filler nanoparticles have influence on material crystallinity, phase formation, and dynamic mechanical properties of composite materials (Rusmirović et al. 2016). More information about composite material and filler-matrix interaction can be obtained applying dynamic mechanical tests that are especially sensitive to all kinds of transitions and relaxation processes of matrix over a wide range of temperature and frequency (Saha et al. 1999). Dynamic-mechanical analysis (DMA) is a sensitive technique, which measures the modulus (stiffness) and damping properties (energy dissipation) of materials as the materials are deformed under periodic stress (Saha et al. 1999). During a DMA testing, three parameters can be obtained: (1) storage modulus (G′), which is a measure of the maximum energy, stored in a material during one cycle of oscillation; (2) loss modulus (G′′), which is proportional to the amount of energy that has been dissipated as heat by the sample; and (3) mechanical damping term tanδ, which is the ratio of the G′′ to the G′ and is related to the degree of molecular mobility in the polymer material (Mandal and Alam 2012).
Mechanical and tribological performance evaluation of maleic anhydride grafted ethylene octene copolymer toughened acrylonitrile butadiene styrene/polyamide 6 composites strengthened with glass fibres
Published in The Journal of The Textile Institute, 2021
Shankare Gowda, Srinivas S, Santhosh G, Siddaramaiah Basavarajaiah
Dynamic mechanical analysis (DMA) is one of the imperative tools to study the viscoelastic properties of polymers and their composite analogues. The effect of glass fibre reinforcement on storage modulus and tan δ of MA-EOC/ABS/PA6/EG composites is displayed in Figures 13 and 14, respectively. The DMA studies support the inherent stiffness of material under dynamic loadings. As can be seen from Figure 13, the storage/stiffness modulus of MA-EOC/ABS/PA6/EG composites increases with EG content and decreases with temperature. Further, a maximum storage modulus of 1914 MPa was obtained with 15 wt% EG loadings, which is about 1.65 folds higher than pristine MA-EOC/ABS/PA6 blend. The observed increment is in accordance with earlier literatures (Gonzalez et al., 1999; Li et al., 2018). Besides, variation in tan δ, which is essentially the ratio of the loss modulus to the storage modulus shows a monotonic increase with EG content, especially at higher temperature regions, just above the glass transition temperature (Tg). The region in dynamic modulus–temperature curve, where inflection occurs and tan δ goes through a maximum is the glass transition temperature. The Tg values obtained from DMA thermograms is found to show a linear increase with EG content. Additionally, the tan δ peak of MA-EOC/ABS/PA6/EG composites are found to be red shifted towards higher temperature regions (with EG loadings). The observed shift tan δ peak reveals a strong interaction between glass fibre and MA-EOC/ABS/PA6 blend, which limits the segmental mobility of polyamide chains.