Summary
Two compounds were analyzed and a formula reconstructed from the results.
This approximated formula was compared to the original compound. The techniques
required for reconstruction of the compound include chemical identification of
the components, quantitative and semi-quantitative analysis and a thorough
understanding of the application and processing requirements of the product.
Stress-strain properties were used as a final guideline. The accuracy of the
analysis can be shown as follows:
1. Quantitative determination of polymer, carbon black, filler and
extractables content was most accurate and readily determined. In the
two compounds analyzed agreement was within 5% on the major components.
2. Qualitative determination of the polymer is again accurate and fairly
easily determined by I.R. Specific polymer grades are, however, difficult
to determine and are most often approximated based on knowledge of the
compounds’ use.
3. Determination of the carbon black type is being investigated but in
general the application of the compound and its physical properties
is still used to determine the type of black.
4. Filler ash analysis is very accurate qualitatively and semi-quantitatively.
Knowledge of rubber compounding is useful in determining some levels.
5. Extract analysis allows accurate determination of antidegradants and
some plasticizers. Because of the purity of some of the chemicals,
changes which occur in vulcanization and difficulty of separation of
the large number of possible ingredients in the extract, this analysis
is often the riiost difficult.
Interpretation of the results with respect to measured stress-strain
properties and known application of the compounds allowed a close approximation
of the original formula to be made. These techniques can be used to analyse
for one component or an entire compound as was done here. For identification
of single components controls should be run. In the case of identification of
the complete compound, the final control is an actual factory trial.
To obtain a full-text copy of this paper, please email Tom Knowles or visit Rubber Division, ACS at www.rubber.org
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