Dynamic Mechanical Analysis of Polymers and Rubbers

Abstract

Dynamic mechanical analysis (DMA) is the technique of applying a stress or strain to a sample and analyzing the response to obtain phase angle and deformation data. These data allow the calculation of the damping or tan δ; the storage, loss, and complex modulus; as well as complex viscosity and complex compliance. Two approaches are used: (i) forced frequency, where the signal is applied at a set frequency and (ii) free resonance, where the material is perturbed and allowed to exhibit free resonance decay. Most modern DMA instruments are of the forced resonance type. In both approaches, the technique is very sensitive to the motions of the polymer chains and it is a powerful tool for measuring transitions in polymers. It is estimated to be 100 times more sensitive to the glass transition than differential scanning calorimetry (DSC) and resolves other more localized transitions not detected in DSC. In addition, the technique allows the rapid scanning of a material's modulus and viscosity as a function of temperature or frequency. DMA may also be referred to as dynamic mechanical thermal analysis (DMTA), dynamic mechanical spectroscopy (DMS), or dynamic thermomechanical analysis (DTMA).

Hybrid Composite Membrane of Phosphorylated Chitosan/Poly (Vinyl Alcohol)/Silica as a Proton Exchange Membrane

“…Figure 5h-i shows that the T g peak value on tan δ curve (around 0.3) for NMPC/PVA-65 and NMPC/PVA-70 composite membranes experienced a decrease in the amorphous phase, corresponded to the decrease in amorphous percentage discussed in the XRD analysis (Section 3.2.1). According to the graphs, another peak might exist at temperatures below 35 • C, although the data did not include sufficiently low temperatures to fully capture this peak [52]. The storage modulus for all NMPC/PVA composite membranes is shown in Figure 5a-i, in which the trend was quite inconsistent.…”

“…Dynamic mechanical analysis (DMA) is a sensitive technique that yields information on bulk properties and thermal transitions, as well as other minor phase or structural changes of polymers [52]. The dynamic mechanical properties were demonstrated by the tan δ, storage modulus, and loss modulus.…”

“…The tan δ and loss modulus peaks were described as the glass transition temperature, where the tan δ peak occurred at a higher temperature than the loss modulus [53]. Tan δ is known as a good limit of the leather-like midpoint between the glassy and rubbery states, whereas the storage modulus is a limit of the recoverable stored strain energy, while the loss modulus is a limit of the energy consumed, which is lost as heat [52,54].…”

Nata de Cassava Type of Bacterial Cellulose Doped with Phosphoric Acid as a Proton Exchange Membrane

“…Tan δ is well-known for being a good limit of the leather-like midpoint between the glassy and rubbery states. The storage modulus limits the recoverable stored strain energy, and the loss modulus limits the energy consumed and lost as heat [ 34 , 35 ].…”

Avaliação in vitro dos efeitos da radiação ionizante em tecido ósseo bovino por espectroscopia ATR-FTIR e análise dinâmico-mecânica

“…A aplicação da carga tem por objetivo gerar uma deformação pré-determinada na amostra e estudar o comportamento da amostra ante a carga e a relaxação. A relação entre a força exercida para atingir tal deformação, o tempo de relaxação e as dimensões da amostra, permitem obter características biomecânicas como o módulo elástico e o amortecimento [8], [77]. …”