Rheology Mechanical Analysis

Rheology and mechanical analysis are usually familiar techniques, yet the exact tools and the far-reaching capabilities may not be so familiar. Rheology is the study of how materials flow and deform, or when testing solids it is called dynamic mechanical thermal analysis (DMTA). 

During rheometer and dynamic mechanical analyses instruments impose a deformation on a material and measure the material s response that gives a wealth of very important information about structure and performance of the basic polymer. As an example stress rheometers are used for testing melts in various temperature ranges. Strain controlled rheology is the ultimate in materials characterization with the ability to handle anything from light fluids to solid bars, films, and fibers. 

With dynamic testing, the processed plastic s elastic modulus (relating to energy storage) and loss modulus (relative measure of a damping ability) are determined. Steady testing provides information about creep and recovery, viscosity, rate dependence, etc. 

Understanding and properly applying the following information to product design equations is very important. A material having this property is considered to combine the features of a so-called perfect elastic solid and a perfect fluid. It represents the combination of elastic and viscous behavior of plastics that is a phenomenon of time-dependent, in addition to elastic deformation (or recovery) in response to load. 

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Traditionally, rheology was a subject concerned principally with mechanical properties. The principal instrument used for mechanical analysis of complex... 

An appropriate cure cycle was established based on the results obtained from the thermal analysis and cure rheology studies of the resin and cured BCB bar and dogbone shaped samples were fabricated for testing. Bar shaped specimens had the dimensions of 3.5 x 0.5 X 0.125 and were used to stake compact tension specimens for fracture toughness studies and for dynamic mechanical analysis of a torsion bar. Dogbone shaped specimens for tensile tests had a gauge area of 1 x 0.15 and were approximately 0.040 thick. 

Dynamic mechanical analysis methods are frequently used to investigate polymerization and curing processes in reactive systems. These methods allow us to obtain both relative and absolute rheological characteristics of a material. Measurements can be made in both the fluid and solid states without affecting the inherent structure of the polymerizing system. 

A very important part of emulsion study is the availability of methodologies to study emulsions. In the past ten years, both dielectric methods (1) and rheological methods (2) have been exploited to study formation mechanisms and the stability of emulsions formed from many different types of oils. Standard techniques, including NMR, chemical analysis techniques, microscopy, interfacial pressure, and interfacial tension, are also being applied to emulsions. These techniques have largely confirmed findings noted in the dielectric and rheological mechanisms. 

The science of adhesion is truly multi-disciplinary, demanding a consideration of concepts from such topics as surface chemistry, polymer chemistry, rheology, stress analysis and fracture mechanics. It is, nevertheless, important for the technologist to possess a qualitatively correct overall picture of the various factors influencing adhesion and controlling joint performance in order to make rational judgements concerning the selection and use of adhesives. 

PA-1010 (75)/PP (5-25)/ PP-g-AA (5 % AA) (0-20) Internal mixer at 205 °C/SEM/rheology/ mechanical properties/selective solvent extraction/ESCA nitrogen analysis Zhang and Yin 1997... 

Rheology, Dynamic Mechanical Analysis, and Dielectric Analysis. 

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... 

Dynamic mechanical analysis provides putative information on the viscoelastic and rheological properties (modulus and damping) of materials. Viscoelasticity is the characteristic behavior of most materials in which a combination of elastic properties (stress proportional to strain rate) is observed. Dynamic mechanical analysis simultaneously measures the elastic properties (modulus) and viscous properties (damping) of materials. 

Some of the viscoelastic and rheological properties of polymers that can be measured by dynamic mechanical analysis are [90-92]... 

Khoshravan and Bathias [13] used dynamic mechanical analysis to measure rheological and viscoelastic properties of glass fiber-reinforced polyether ether ketone. 

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