Browse Prior Art Database

Thermal Gravimetric Analyzer with Chemical Sensor

IP.com Disclosure Number: IPCOM000113648D
Original Publication Date: 1994-Sep-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 71K

Publishing Venue

IBM

Related People

Brand, JL: AUTHOR [+2]

Abstract

A method for increasing the utility of Thermal Gravimetric Analysis (TGA) is disclosed. TGA simply detects the weight loss of a sample as it is heated up. This invention describes how a chemical sensor can be added to a TGA to greatly increase the utility of the information obtained from a TGA analysis by helping to identify the different compounds released during the TGA.

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This is the abbreviated version, containing approximately 52% of the total text.

Thermal Gravimetric Analyzer with Chemical Sensor

      A method for increasing the utility of Thermal Gravimetric
Analysis (TGA) is disclosed.  TGA simply detects the weight loss of a
sample as it is heated up.  This invention describes how a chemical
sensor can be added to a TGA to greatly increase the utility of the
information obtained from a TGA analysis by helping to identify the
different compounds released during the TGA.

      TGA is commonly used to test materials.  A TGA test involves
placing a material on a sensitive balance.  The material is heated at
a constant rate.  The mass of the the material is plotted against
temperature.  TGA analysis tells at what temperature the material
outgasses or decomposes.  TGA does not give any chemical information.
Commonly a material, such as an adhesive, will outgas water and
monomer.  TGA does not identify what compounds left the material.

      A tin oxide semiconductor detector was added to the gas exhaust
of a commercial TGA.  Tin oxide detectors are commonly used as
chemical sensors.  The figure shows a graph of the result.  A small
amount of oil and water was added to a TGA pan.  Water evaporates
from the pan from 70 to 130ºC.  In a typical TGA analysis, any
material outgassing at those temperatures is attributed to water,
although that is not necessarily the case.  Superkool outgasses from
200 to 300ºC.  The TGA shows that 80% of the total mass left
at the lower temperature and 20% left at the higher temperature.
Because the chemical sensore is about 100 times more sensitive to
hydrocarbons than water, the analyst can say with confidence that the
initial mass loss is due to water and the second mass loss is due...