Organic Chemicals – In-Depth

Polymers and Plastics are discussed on their own page here.  Other organic chemicals will be discussed on this page.

Thermogravimetry or TGA:

  • Weight of each component of liquid organic chemical mixtures provided different decomposition or evaporation temperature ranges
  • Confirmation of a particular organic chemical compound based on its decomposition or oxidation temperature
  • Weight of volatile or adsorbed organic solvents in various solid materials

Differential Scanning Calorimetry or DSC:

  • Specific heat measurement
  • Thermally induced reaction generating heat output
  • Detection of polymorphism
  • Measure the heat and temperature of crystallization upon cooling and subsequent melting temperature and latent heat upon heating
  • Measure the heat of vaporization
  • Detection of impurities or secondary components by distinct melting temperatures, crystallization temperatures, or by thermally stimulated reaction with the primary ingredient
  • Oxidation temperature and energies
  • Detect isomorphic organic components by reactions at or above the melting temperature
  • Producing a phase diagram for a physical system

Thermomechanical Analysis or TMA or Dilatometry:

  • Thermal expansion properties, coefficient of thermal expansion (CTE) of polymers and elastomers
  • Determination of phase change temperatures in polymers such as due to glass transition temperature and crystallization
  • Measure the softening temperature of a polymer

FTIR or Infrared Spectroscopy:

  • Identification of bonding groups
  • Identify organic chemical
  • Detect changes in a chemical due to degradation
  • Identify organic contaminants or additives

Contaminated Ethyl Acetate samples from the top and bottom of a large storage vesselContaminated Ethyl Acetate samples from the top and bottom of a large storage vessel. FTIR identified the organic contaminant.

GC-MS or Gas Chromatography – Mass Spectroscopy:

  • Separates and allows the identification of many organic chemicals which may be components of a complex substance
  • Measures and identifies organic contaminants in a substance
  • Identifies volatile organic chemicals using Headspace Solid-Phase Micro-Extraction

Wavelength Dispersive XRF:

  • Quantitatively determine the composition for carbon, nitrogen, and elements sodium and heavier
  • Detect very low concentration heavy elements down to about ten ppm
  • Determine if bromine is present and if so, provides alert that further analysis for restricted brominated organic compounds is required
  • Detect and measure contaminants in an organic substance provided they have distinctive elements in them, such as wear particles in oil or a chlorocarbon in a hydrocarbon

Optical Microscopy:

  • Examine liquid drop or layer for particulates
  • Examine precipitates from drying or cooling liquid
  • Examine residues of evaporated liquid

SEM/EDX:

  • Examine filtered precipitates from drying or cooling liquid and determine the elemental composition
  • Examine residues of evaporated liquid and determine the elemental composition

X-ray Photoelectron Spectroscopy or XPS or ESCA:

  • Examine filtered precipitates from organic liquids, determining the elemental composition and chemistry of the particle surfaces
  • Examine residues of evaporated liquids and determine the elemental composition and chemical phases in the residues

Contact Angle Measurements:

  • Measures the wettability of a surface with a given liquid. Either or both the surface and the liquid may be an organic substance. The surface might be a polymer.
  • Measure the surface energy or surface tension. The polar and the dispersive surface tension can be measured by using several different liquids on the surface.
  • Dynamic surface tension effects can be measured as the liquid changes the properties of the surface

Density Measurements:

  • Measure the density of the organic substance
  • The density may indicate a contaminant or an additive