Dynamic rheological analysis importance

Measurement of viscoelastic and rheological properties of polymers are of increasing importance and recently developed instrumentation for measuring these properties discussed in Chapter 15 includes dynamic mechanical analysis, thermo-mechanical analysis... 

S.2.3.2. Dynamic Mechanical Analysis and Rheology The principles of DMA are equally applicable to liquids. In fact, dynamic mechanical methods are an important way to determine (to a first approximation) flow viscosity data for thermoplastics in the melt state, in lieu of using more expensive and... 

An important means of assessing the rheological behavior of polymer melts and concentrated solutions is the use of dynamic mechanical analysis. This consists in testing the mechanical response, or strain, of a polymeric material to a time-dependent stress, or, conversely, measuring the stresses generated by time-dependent strains. For simplicity, a... 

Thermogravimetric Analysis to study the thermal properties. Scanning Electron Microscope and Transmission Electron Microscopy to analyze the morphology of the materials, Atomic Force Microscopy to carry out a surface analysis and Dynamic Mechanical Analysis (DMA) to evaluate the mechanical properties, etc. Also, it is important for the study of such properties as rheology and X-ray diffraction. 

Dynamic mechanical techniques are important in the characterization of the rheological properties of polymers. In dynamic mechanical analysis, a small-amplitude oscillatory strain is applied to a sample, and the resulting dynamic stress is measured as a function of time. The dynamic mechanical technique allows the simultaneous measurement of both the elastic and the viscous components of the stress response. Typically, the temperature and deformation frequencies are changed in order to determine the mechanical relaxation spectrum of the system. The molecular basis of changes in the dynamic mechanical properties can be investigated using dynamic IR dichroism. 

Detailed analysis of the isothermal dynamic mechanical data obtained as a function of frequency on the Rheometrics apparatus lends strong support to the tentative conclusions outlined above. It is important to note that heterophase (21) polymer systems are now known to be thermo-rheologically complex (22,23,24,25), resulting in the inapplicability of traditional time-temperature superposition (26) to isothermal sets of viscoelastic data limitations on the time or frequency range of the data may lead to the appearance of successful superposition in some ranges of temperature (25), but the approximate shift factors (26) thus obtained show clearly the transfer viscoelastic response... 

Mechanical properties of biodegradable polyesters are important for applications such as materials for sutures and bioresorbable screws. The characterization of mechanical properties is carried out by means of tensile test, rheology, and dynamic mechanical temperature analysis. ... 

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