Test method glass transition temperature

Describe how we perform toughness testing on polymers with both the impact beam and the falling weight methods. Explain the different manners by which an amorphous polymer will fail above and below its glass transition temperature. 

ASTM E 1356-98, ASTM Book of Standards 2002. Standard Test Method for Assignment of the Glass Transition Temperature by Differential Scanning Calorimetry or Differential Thermal Analysis . ASTM International, Conshohocken, PA. 

These polymerization methods were carried out to produce small quantities of polymers for DSC and GPC analysis. These analyses were used to measure the efficiency of the polymerization and the glass transition temperature of the resulting polymers, as a screen for further development of selected materials. It was deemed at the time of the tests that a high glass transition temperature was... 

See also Methacrylate monomers polymerization data for, 16 279t Methacrylic ester polymers, 16 271-298. See also Methacrylate monomers Methacrylic esters analytical test methods and specifications for, 16 291-293 bulk polymerization of, 16 281-282 chemical properties of, 16 276-277 electrical properties of, 16 276 emulsion polymerization of, 16 285-288 glass transition temperature of, 16 273-274... 

It was also found that the tensile heat distortion temperatures of films containing only a few mole per cent of these units were considerably higher than those found for bisphenol A polycarbonate. X-ray diffraction studies made on the test samples used in the tensile heat distortion apparatus could not demonstrate an increase in crystallinity of the samples. Only a slight indication of increase of orientation was apparent. Glass transition temperatures measured by the refracto-metric method were considerably lower than the heat distortion temperatures. 

It is unfortunate that test methods for soft plastics and for rubbers, although very similar, are not identical, for example differences in tensile stress strain, tear and hardness methods. If they were aligned, much of debate about which method to use would be eliminated. For some properties, there is a distinct difference in approach. For example, glass transition temperature is frequently determined for plastics whilst various low temperature tests have been specifically developed for rubbers. 

D 3418 Test Methods Relating to Glass Transition Temperature... 

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. 

The influence of the cyclohexane ring on the glass transition temperature and sub-Tg transitions has been studied by dynamic mechanical methods [10,16,42]. These comparative studies have focused on the influence of the cyclohexyl substituent on observed thermal transitions. A systematic study of cycloalkyl substituents on alternating carbons of a polyethylene backbone was performed to study the influence of these substituents on the dynamic mechanical spectra of the polymers [42], These workers also prepared materials in which the cycloalkyl substituents were spaced away from the polymer backbone by successively longer methylene chains, testing the influence of ring proximity... 

Glass transition temperature, Tg, and storage modulus, E , were measured to explore how the pigment dispersion affects the material (i.e. cross-link density) and mechanical properties. Both Tg and E were determined from dynamic mechanical analysis method using a dynamic mechanical thermal analyzer (DMTA, TA Instruments RSA III) equipped with transient testing capability. A minimum of 3 to 4 specimens were analyzed from each sample. The estimated uncertainties of data are one-standard deviation. 

While TMA is one of the older and simpler forms of thermal analysis, its importance is in no way diminished by its age. Advances in DSC technology and the appearance of dynamic mechanical analysis (DMA) as a common analytical tool have decreased the use of it for measuring glass transitions, but nothing else allows the measurement of CTE as readily as TMA. In addition, the ability to run standardized material test methods at elevated temperatures easily makes TMA a reasonable alternative to larger mechanical testers. As the electronic, biomedical, and aerospace industries continue to push the operating limits of polymers and their composites, this information will become even more important. During the last 5 years a major renewed interest in dilatometry and volumetric expansion has been seen. Other thermomechanical techniques will also likely be developed or modernized as new problems arise. 

Elastomers are cross-linked macromolecules above the glass transition temperature. The cross-link density is the fundamental engineering quantity which, for instance, determines the modulus of elasticity. Usually, it is measured during vulcanization of well-defined rubber samples in a vulcameter by the moment necessary to perform a given torsional shear of the test sample. Swelling experiments can be performed alternatively, but are problematic for filled elastomers. Such measurements are based on the assumption that the measured quantity does not vary over the sample volume. Inhomogeneous cross-link densities can be determined from the surface hardness, but volumetric resolution is achieved by conventional methods only after cutting the sample. 

Indirect methods of miscibility determination (for example, the glass transition temperature from either thermal, dielectric, or mechanical tests NMR spectroscopic methods microscopy etc.). 

Borosilicate test tubes from commercial sources, Fiolax clear, Schott, were used in this study. The glass transition temperature was measured by the differential scanning calorimeter (DSC) (DSC2010, TA Instruments, USA) method [21]. The chemical composihon and the physical properties of the glass are shown in Table 1 [22]. The tubes having nominal thickness and outer diameter of 0.5 mm and 11.8 mm, respechvely, were cut in 100 mm long samples. The limited thickness of the tubes allows thermal equilibrium between the sample and the salt bath during the process. 

E 1356 (1998) Test method for glass transition temperatures by differential scanning calorimeter or differential thermal analysis... 

E 1640 (1999) Test method for assignment of the glass transition temperature by dynamic mechanical analysis E 1641 (1999) Test method for decomposition kinetics by thermogravimetry... 

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 assignment of the glass-transition temperatures hy differential scanning calorimetry or differential-thennal analysis Methods of test for determination of glass-transition temperature of electrical insulating materials... 

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. 

One method used to evaluate the upper working temperature of block copolymer systems is to measure the shear adhesion failure temperature (SAFT), a useful method to discover exactly what has been gained in the upper working temperature limits when resins are added to the styrene domain of polystyrene end-block systems to increase the effective glass transition temperature. Typically the test is set up as a standard shear test, either to the standard stainless steel panel or to polyester, with a 1 in. by 1 in. (25 mm by 25 mm) area and a load of 1 kg. The set-up is placed in an oven that can be accurately controlled so that the temperature is increased by 2.0°C (3.6°F) per minute, the temperature at which failure occurs being recorded as the SAFT. 

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