Dynamic Mechanical Analysis, plasticizer

Compliance, elastic n. Symbol S. An elastic constant, which is the ratio of a strain or strain component to a stress or stress component. For a perfectly elastic material it is the reciprocal of the elastic modulus. For a viscoelastic material the modulus and compliance are not reciprocally related due to their different time dependencies. Sepe MP (1998) Dynamic mechanical analysis. Plastics Design Library, Norwich, New York. 

Dynamic mechanical analyzer n. An instrument that can test in an oscillating-flexural mode over a range of temperature and frequency to provide estimates of the real , i.e., in-phase, and imaginary , i.e., out-of-phase parts of the complex modulus. The real part is the elastic component, the imaginary part is the loss component. The square root of the sum of their squares is the complex modulus. With polymers, the components and the modulus are usually dependent on both temperature and frequency. ASTM D 4065 spells out the standard practice for reporting dynamic mechanical properties of plastics. An example of a DMA thermogram of different Perkin-Elmer Inc., manufactures the Diamond DMA instrument. Polymer films is shown. Sepe MP (1998) Dynamic mechanical analysis. Plastics Design Library, Norwich, New York. 

Dynamic mechanical analysis. Plastics Design Library, Norwich, New York. 

Dynamic mechanical analysis. Plastics Design Library, Norwich Pittance JC (ed) (1990) Engineering plastics and composites. SAM International, Materials Park). 

Tangent Modulus The slope of the curve at any point on a static stress-strain graph (dcr/ds) expressed in pascals per unit of strain. This slope is the tangent modulus in whatever mode of stress the curve has arisen from - tension compression, or shear. [Since strain is dimensionless, the unit given for modulus is normally just stress (Pa).] (Sepe MP (1998) Dynamic mechanical analysis. Plastics Design Library, Norwich). 

The volatile content of the treated paper is important because moisture acts as a temporary plasticizer to promote resin flow during early stages of pressing (9). Dynamic mechanical analysis of the treated paper is a very useful means to study the initial flow stages of a resin and the cure time required to complete cross-linking (10). 

In dynamic mechanical analysis of plastics, the material is subjected to a sinusoidal variation of stress and the strain is recorded so that 1, 2 and S can be determined. The classical variation of these parameters is illustrated in Fig. 2.55. 

The epoxy resin formed by tetraglycidyl 4,4 -diamino diphenyl methane and 4,4 -diamino diphenyl sulfone was characterized by dynamic mechanical analysis. Epoxy specimens were exposed to varying dose levels of ionizing radiation (0.5 MeV electrons) up to 10,000 Hrads to assess their endurance in long-term space applications. Ionizing radiation has a limited effect on the mechanical properties of the epoxy. The most notable difference was a decrease of approximately 40°C in Tg after an absorbed dose of 10,000 Mrads. Sorption/desorption studies revealed that plasticization by degradation products was responsible for a portion of the decrease in Tg. 

The complex sorption behavior of the water in amine-epoxy thermosets is discussed and related to depression of the mechanical properties. The hypothesized sorption modes and the corresponding mechanisms of plasticization are discussed on the basis of experimental vapor and liquid sorption tests, differential scanning calorimetry (DSC), thermomechanical analysis (TMA) and dynamic mechanical analysis. In particular, two different types of epoxy materials have been chosen low-performance systems of diglycidyl ether of bisphenol-A (DGEBA) cured with linear amines, and high-performance formulations based on aromatic amine-cured tetraglycidyldiamino diphenylmethane (TGDDM) which are commonly used as matrices for carbon fiber composites. 

Sepe, Michael P., Dynamic mechanical analysis for plastics engineering, pp. 6-16 (1998)... 

Reaction of kenaf with succinic anhydride were done in xylene at 120°C and WPGs up to 80% were achieved [32]. Dynamic mechanical analysis was done on acetone-extracted esterified fibers in the WPG range of 30-80. The data showed that there was a reduced transition temperature from about 170°C down to about 135°C and that there was no change in this first transition temperature as the WPG increases. The data showed that complete modification of that melting species had taken place at a WPG of m35. This thermal behavior is similar to reported trends observed for water-plasticized lignin in wood. 

Elastomeric systems are quite commonly monitored by thermal techniques. Mohler [5] has discussed how DSC is used to characterize the quality of blends of elastomers. Changes in polymer Tg can point to miscible phases that might otherwise require a microscopic techmque to establish. The cold crystallization of a polymer in a blend can also be examined using the relaxation enthalpy of the sample. Vacuum TG can look at plasticizer content separate from polymer degradation. Dynamic mechanical analysis (DMA) is always a powerful technique with elastomers. Dimensional stability, storage modulus, loss modulus and loss factor are all important for this class of materials and are... 

Figure 10.27 illustrates the process whereby we can evaluate the recyclabihty of plastic waste. After initial crushing, injection-molded samples are analyzed simultaneously by different physico-chemical characterization techniques, such as dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) or RSR. These transformation/analysis cycles can repeat up to eight times, and we observe the evolution of the different characteristics at each stage. 

M. P. Sepe, Dynamic Mechanical Analysis for Plastics Engineering, Plastics Design Library/ William Andrew, New York, 1998. 

Plastics - Thermomechanical analysis (TMA) - Determination of linear thermal expansion coefficient and glass transition temperature Plastics - Thermomechanical analysis (TMA) - Determination of softening temperature Plastics - Determination of dynamic mechanical properties -General principles Plastics - Dynamic mechanical analysis - Determination of glass transition temperature Plastics - Dynamic mechanical analysis - Calibration... 

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