Thermomechanical analysis test

ASTM E 1545-00, ASTM Book of Standards 2002. Standard Test Method for Assignment of the Glass Transition Temperature by Thermomechanical Analysis . ASTM International, Conshohocken, PA. 

Dynamic properties are more relevant than the more usual quasi-static stress-strain tests for any application where the dynamic response is important. For example, the dynamic modulus at low strain may not undergo the same proportionate change as the quasi-static tensile modulus. Dynamic properties are not measured as frequently as they should be simply because of high apparatus costs. However, the introduction of dynamic thermomechanical analysis (DMTA) has greatly widened the availability of dynamic property measurement. 

B. Cassel and B. Twombly, Materials Characterization by Thermomechanical Analysis (A. T. Rega and C. M. Neag, eds.), ASTM STP 1136 (Philadelphia American Society for Testing and Materials, 1991), 108-119. 

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. 

ASTM E831, 2003. Standard test method for linear thermal expansion of solid materials by thermomechanical analysis. 

Thermomechanical Analysis (TMA). Thermomechanical analysis (TMA) measures shape stability of a material at elevated temperatures by physically penetrating it with a metal rod. A schematic diagram of TMA equipment is shown in Fig. 2.23. In TMA, the test specimen s temperature is raised at a constant rate, the sample is placed inside the measuring device, and a rod with a specified weight is placed on top of it. To allow for measurements at low temperatures, the sample, oven, and rod can be cooled with liquid nitrogen. 

CHARACTERIZATION. Melting points were determined on an E. I. DuPont Series 99 Thermal Analyzer at 20°C/min. Inherent viscosities of polyamic acid solutions were obtained at a concentration of 0.5% (w/w) in DMAc at 35°C. Glass transition temperatures (T ) of the fully cured polymer films were measured by thermomechanical analysis (TMA) on a DuPont 943 Analyzer in air at 5°C/min. Films fully-cured at 300°C were tested for solubility at 3-5% (w/w) solids concentration in DMAc,N,N-dimethylformamide (DMF), and chloroform (CHCl-j). Solubilities at room temperature were noted after periods of 3 hours, 1 day and 5 days. Refractive indices of 1 mil thick films were obtained at ambient temperature by the Becke line method (11) using a polarizing microscope and standard immersion liquids obtained from R. P. Cargille Labs. 

Earnest, C.M. Assignment of glass transition temperatures using thermomechanical analysis. In Assignment of the Glass Transitions Seyler, R.J., Ed. American Society for Testing and Materials Philadelphia, U.S.A., 1994 ASTM STP 1249, 75-87. 

Thermomechanical analysis methods are used in geometries more commonly associated with traditional mechanical testing to increase sensitivity or to mimic other tests. The most common of these are the flexural and penetration modes. Flexure studies involve loading a thin beam, often a splinter of material, with a constant load of lOOmN or more and heating until... 

Thermomechanical analysis heating rate 2.5°C/min ASTM method D696. ASTM method D648-56 264 psi (1.8 MPa) test. 

Specific techniques require the recording of other parameters, for example the load on the sample in thermomechanical analysis. Calorimetric methods, too, require attention to the exact details of each experiment. In the following chapters the principles and practice of thermal analysis and of calorimetry will be described and illustrated with some of the many examples of its use in industry, academic research and testing. 

C. M. Earnest, Assignment of Glass Transition Temperatures Using Thermomechanical Analysis , in R. J. Seyler (ed.). Assignment of the Glass Transition, ASTM STP 1249, American Society for Testing and Materials, Philadelphia, 1994, pp. 75-87. 

E 1782 (1998) Vapour pressure by DSC/DTA E 1824 (1996) Standard Test Method for Assignment of a Glass Transition Temperature using Thermomechanical Analysis under Tension... 

Standard Test Method for Distortion Temperature in Three-Point Bending by Thermomechanical Analysis... 

Thermomechanical-analysis (TMA) testing is used to measure a material s expansion coefficient above and below the glass-transition temperature or Tg. Thermomechanical analysis continuously monitors the expansion of a probe on a sample as a function of temperature. The standard test method for TMA is ASTM D3386, Coefficient of Linear Thermal Expansion of Electrical Insulating Materials.In addition to the glass-transition temperature or Tg, the expansion coefficients above and below Tg are reported. 

The applied part of this study relied on a standard peel test in which closely set vertical and horizontal cut lines had been incised on the specimen surface, and on a dynamic thermomechanical analysis of finish flexibility at constant temperature [32,33,46]. 

Preferably, thermomechanical analysis (TMA) is used to determine the linear thermal expansion coefficient of polymers according to ISO 11359. TMA uses a constant applied load (0.1 g to 5 g) and cylindrical or rectangular specimens with plane-parallel surfaces. The test is conducted with a low heating rate. An average or a differential coefficient of thermal expansion can be obtained, according to Eq. 3.5 and Eq. 3.6. 

Figure 2. Thermomechanical analysis of tensile test on paper inmpregnated with different types of low molecular weight lignins displacement as a function temperature. Standard is the displacement obtained with non-impregnated paper used as a control.

The three resins above were tested by thermomechanical analysis (TMA) on a Met-tler 40 apparatus. Triplicate samples of beech wood alone, and of two beech wood plys each 0.6 mm thick bonded with each resin system were tested. Sample dimensions were 21 mm x 6 mm x 1.2 mm. The samples were tested in non-isothermal mode from 40°C to 220°C at heating rates of 10°C/min, 20°C/min and 40°C/min with a Mettler 40 TMA apparatus in three-point bending on a span of 18 mm. A continuous force cycling between 0.1 N and 0.5 N and back to 0.1 N was applied on the specimens with each force cycle duration being 12 s. The classical mechanics relation between force and deflection E = [L /(4bh )][AF/(Af)] (where L is the sample length, AF the force variation applied and A/ the resulting deflection, b the width and h the thickness of the sample) allows calculation of the modulus of elasticity E for each case tested and to follow its rise as functions of both temperature and time. The deflections A/ obtained and the values of E obtained from them proved to be constant and reproducible. 

The resins were tested dynamically by thermomechanical analysis (TMA) on a Met-tler 40 apparatus. Triplicate samples of beech wood alone, and of two beech wood... 

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