Editing Thermogravimetric analysis (section)

==Thermogravimetric analyzer==

Thermogravimetric analysis (TGA) is conducted on an instrument referred to as a thermogravimetric analyzer. A thermogravimetric analyzer continuously measures mass while the temperature of a sample is changed over time. Mass, temperature, and time are considered base measurements in thermogravimetric analysis while many additional measures may be derived from these three base measurements.

A typical thermogravimetric analyzer consists of a precision balance with a sample pan located inside a furnace with a programmable control temperature.  The temperature is generally increased at constant rate (or for some applications the temperature is controlled for a constant mass loss) to incur a thermal reaction.  The thermal reaction may occur under a variety of atmospheres including: [[air|ambient air]], [[vacuum]], inert gas, oxidizing/reducing gases, corrosive gases, carburizing gases, vapors of liquids or "self-generated atmosphere"; as well as a variety of [[pressure]]s including: a high vacuum, high pressure, constant pressure, or a controlled pressure.

The thermogravimetric data collected from a thermal reaction is compiled into a plot of mass or percentage of initial mass on the y axis versus either temperature or time on the x-axis.  This plot, which is often [[Smoothing|smoothed]], is referred to as a TGA [[curve]].  The first [[derivative]] of the TGA curve (the DTG curve) may be plotted to determine [[inflection points]] useful for in-depth interpretations as well as [[differential thermal analysis]].

A TGA can be used for materials characterization through analysis of characteristic decomposition patterns.   It is an especially useful technique for the study of [[polymer]]ic materials, including [[thermoplastics]], [[thermosets]], [[elastomers]], [[composite material|composites]], [[plastic film]]s, [[fibers]], [[coatings]],  [[paints]], and [[fuels]].

===Types of TGA===

There are three types of thermogravimetry:

*Isothermal or static thermogravimetry: In this technique, the sample weight is recorded as a function of time at a constant temperature.
*Quasistatic thermogravimetry: In this technique,  the sample temperature is raised in sequential steps separated by isothermal intervals, during which the sample mass reaches stability before the start of the next temperature ramp. 
*Dynamic thermogravimetry: In this technique, the sample is heated in an environment whose temperature is changed in a linear manner.