Compositional Analysis of Rubber

The generic type of rubber, its composition (plasticizer/oil, polymer, carbon black, filler content) and the type of filler can be determined using different techniques.

Testing Services Offered

This Rubber Analysis service is offered from our European and Americas regional facilities.

Identification of type of rubber by FTIR

The generic type of rubber can be identified by FTIR or Pyrolysis-FTIR to find out whether the rubber material is a:

• Natural rubber (NR)
• Isoprene rubber (IR)
• Acrylonitrile butadiene rubber (NBR)
• Acrylic rubber (ACM)
• Chloropolyethylene (CM)
• Chloroprene rubber (CR)
• Fluorocarbon rubber (FKM)
• Polydimethylsiloxane (PDMS)
• Butyl rubber (IIR)
• Butadiene rubber (BR)
• Styrene butadiene rubber (SBR)
• Etc.

The infrared spectra of some rubbers are shown in Figure 1.

Figure 1. FTIR fingerprints of some rubbers

Compositional analysis of rubber by TGA

The composition of rubber can be determined by TGA in order to determine the level of the following constituents:

• Plasticizer
• Polymer
• Carbon black
• Filler

The TGA thermogram of a rubber sample is shown in Figure 2.

Figure 2. TGA thermogram of a rubber

TGA can be carried out in accordance with the following standards:

• ASTM D6370 Standard Test Method for Rubber-Compositional Analysis by Thermogravimetry (TGA)
• ASTM E1131 Standard Test Method for Compositional Analysis by Thermogravimetry

Identification of filler type and filler content by FTIR of Ash

The level of filler can be determined by an Ash test, and the remaining ash can be analysed by FTIR in order to identify the type of inorganic filler:

• Calcium carbonate (chalk, limestone)
• Silica
• Talc
• Barium sulphate
• Kaolin
• Etc.

Example of FTIR spectra of some inorganic fillers are shown in Figure 3.

Figure 3. FTIR fingerprints of some inorganic fillers