Plastics dynamical mechanical analysis

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... 

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. 

Car Carlowitz, B. Kunststoff-Tabellen. 4. Auflage, Carl Hanser Verlag, Munich, Vienna, 1995. 98Sep Sepe, M. Dynamical mechanical analysis for plastics engineering. Plastics Design Library, Norwich, 1998. 

S. Gill, Characterization of Composites by Dynamic Mechanical Analysis, Industrial R D, Apl. (1982). Passaglia and J. R. Knox, Viscoelastic Behavior and Time-Temperature Relationships, "Engineering Design for Plastics, E. Baer, ed.. Van Nostrand Reinhold (1964). 

Gelation of plasticized polymers can be conveniently observed by a dynamic mechanical analysis and microscopy (see more on this subject in Chapter 9). Aggregation and formation of clnsters in solntion can be followed by a dynamic light scattering experi-... 

By Dynamic Mechanical Analysis, formulation 100 phr PVC resin, 70 phr plasticizer, 2 ... 

The analyses of several polymers by dynamic mechanical analysis, DMA, are described in Sect. 4.5 in connection with the brief description of the DMA equipment. It was observed in such experiments that neither the viscosity nor the modulus are constant, as is assumed for the discussion of energy and entropy elasticity, outlined in Sects. 5.6.4 and 5.6.5, respectively. One finds a stress anomaly when the elastic limit of a material has been exceeded and plastic deformation occurs. Other deviations have the stress depend both on strain and rate of strain. Finally, a time anomaly exists whenever the stress/strain ratio depends only on time and not on the stress magnitude. 

Thermal analysis is well suited for characterizing and identifying plastics, as their properties are temperature dependent. It involves methods in which the substance is subjected to a controlled temperature program and the changes in the physical and chemical properties are measured as a function of temperature or time. The ambient atmosphere also influences the properties of plastic. Thermal analysis comprises traditional techniques differential scanning calorimetry (DSC), differential thermal analysis, thermogravimetric analysis, thermomechanical analysis, and more recent methods pressure differential scanning calorimetry, dynamic mechanical analysis, and differential photocalorimetry. 

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. 

Torsion pendulum n. A device for performing dynamic mechanical analysis in which a sample is deformed torsionally and allowed to oscillate in free vibration. Shah V (1998) Handbook of plastics testing technology. John Wiley and Sons, New York. 

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