{"id":1428,"date":"2010-01-03T15:23:01","date_gmt":"2010-01-03T20:23:01","guid":{"rendered":"https:\/\/www.ulprospector.com\/knowledge\/?p=1428"},"modified":"2018-02-09T14:01:03","modified_gmt":"2018-02-09T20:01:03","slug":"pe-material-performance-using-dma","status":"publish","type":"post","link":"https:\/\/ulprospector.ul.com\/1428\/pe-material-performance-using-dma\/","title":{"rendered":"Material Performance Using Dynamic Mechanical Analysis (DMA)"},"content":{"rendered":"

By Associated Polymer Labs, Inc.<\/p>\n

DMA is short for Dynamic Mechanical Thermal Analysis<\/a> (DMTA), which is another name for Dynamic Mechanical Rheological Testing (DMRT).<\/p>\n

Rheometers for mechanical rheometry are of two types:<\/p>\n

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  1. Linear displacement, RSA II Rheometrics Solids Analyzer<\/li>\n
  2. Rotational, SR5 Rheometrics Controlled Stress Rheometer<\/li>\n<\/ol>\n

    Rheology is the science that studies the deformation and flow of materials, whether in liquid, gel, melt, solid, or composite form, in terms or their elasticity and viscosity.<\/p>\n

    Elasticity is the ability of a material to store deformational energy, and can be viewed simply as the capacity of a material to regain its original shape after being deformed.<\/p>\n

    Viscosity is a measure of a material\u2019s resistance to flow and reflects the material\u2019s rate of dissipation of deformational energy through flow.<\/p>\n

    Materials respond to an applied force or displacement by exhibiting either elastic, Hookean, or viscous, Newtonian, behavior, or through a combination of these, called viscoelastic behavior, in which the response of the material is time and temperature dependent. Most polymeric materials are viscoelastic.<\/p>\n

    From these measurements, properties such as the elastic modulus E\u2019 or G\u2019, viscous modulus E” or G”, damping factor tangent d, and the glass transition temperature Tg are easily and precisely obtained. Furthermore, if the rheometer is sufficiently sensitive, normal stress differences can also be measured.<\/p>\n

    E is the symbol for the modulus measured in tension, compression, and bending. G is the modulus measured in shear. The relationship is E(t)=3G(t). Tangent d is the ratio of the viscous modulus to the elastic modulus; E”\/E\u2019 or G”\/G\u2019.<\/p>\n

    DMA is probably the most versatile thermal analysis method available, and no other single test method provides more information about a sample is a single test. Besides material properties, DMA provides a direct link between a material\u2019s chemical makeup and its mechanical behavior.<\/p>\n

    Materials can be characterized by DMA regardless of their kind, their physical state, or the form in which they are used. The material may be:<\/p>\n