Mechanical tests glass-transition temperature

ASTM E 1640-99, ASTM Book of Standards 2002. Standard Test Method for Assignment of the Glass Transition Temperature by Dynamic Mechanical Analysis . ASTM International, Conshohocken, PA. 

Ta = glass transition temperature determined in a dynamic mechanical test, K... 

Blends of PCL with PVC were shown to exhibit only one glass-transition temperature (Tg), which for blends quenched from the melt could be represented as a function of composition by the Gordon-Taylor Tg equation. By similar criterion, the PCL blends with NC were shown to be compatible for the composition range 0-50% NC by weight. With higher concentrations of NC, both thermal and mechanical testing indicated that multiple amorphous phases were present, even though the films were clear. 

In order to select materials that will maintain acceptable mechanical characteristics and dimensional stability one must be aware of both the normal and extreme thermal operating environments to which a product will be subjected. TS plastics have specific thermal conditions when compared to TPs that have various factors to consider which influence the product s performance and processing capabilities. TPs properties and processes are influenced by their thermal characteristics such as melt temperature (Tm), glass-transition temperature (Tg), dimensional stability, thermal conductivity, specific heat, thermal diffusivity, heat capacity, coefficient of thermal expansion, and decomposition (Td) Table 1.2 also provides some of these data on different plastics. There is a maximum temperature or, to be more precise, a maximum time-to-temperature relationship for all materials preceding loss of performance or decomposition. Data presented for different plastics in Figure 1.5 show 50% retention of mechanical and physical properties obtainable at room temperature, with plastics exposure and testing at elevated temperatures. 

Dynamic mechanical testing was conducted in uniaxial extension with an Imass Corp. Dynastat Mark II instrument. Specimens were typically 35 mm in length and 12 mm wide. The measurements were made over a frequency range of from 0.01 to 100 s" at various temperatures down through the glass transition temperature of the sample. 

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. 

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