Sulfur Crosslinking Bond Length Analysis in Vulcanized Rubber
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Solution Overview
Problem
Current methods for analyzing the length of sulfur crosslinking bonds in vulcanized rubber are limited, as they can only accurately measure mono- and poly-sulfur linkages, and struggle with insoluble samples due to the need for uniform mixing with a solvent, which is toxic and time-consuming.
Innovation Solution
A method using NMR spectra with an external standard, where separate 13C NMR spectra of the standard substance and vulcanized rubber are obtained, and FID amplification values are used to calculate the length of sulfur crosslinking bonds through specific equations, allowing for accurate analysis without the need for solvent mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the solvent method is used to analyze sulfur crosslinking bonds, then the types of crosslinking bonds can be distinguished, but the measurement time is long and toxic solvents must be used
Solution Approach 1:
The patent extracts and analyzes only the specific signal regions corresponding to sulfur crosslinking bonds from the NMR spectrum, rather than requiring complete solvent extraction and analysis of all components. This selective extraction of relevant spectral information enables rapid identification of mono-, di-, and poly-sulfur linkages without the time-consuming solvent method procedures.
2Measurement precision
If internal standard is added to the sample for quantitative analysis, then accurate quantification can be performed, but uniform mixing is difficult for insoluble samples like vulcanized rubber
Solution Approach 1:
The patent segments the quantitative analysis process into two independent parts: (1) obtaining the NMR spectrum of the vulcanized rubber sample, and (2) separately obtaining the NMR spectrum of the internal standard substance. By analyzing the integrated intensities of specific signals from these separate measurements, the method achieves accurate quantification without requiring physical mixing of the insoluble rubber sample with the standard, thus avoiding the uniform mixing problem.
3Measurement precision
If NMR is used to analyze sulfur crosslinking bonds, then mono-sulfur and poly-sulfur linkages can be identified, but the average sulfur length cannot be analyzed due to insignificant chemical shift differences
Solution Approach 1:
The patent applies preliminary deconvolution processing to the NMR signal regions corresponding to sulfur crosslinking bonds before quantification. By mathematically resolving the overlapping signals into distinct components representing mono-, di-, and poly-sulfur linkages, the method extracts detailed compositional information that enables calculation of average sulfur length, thereby recovering information that would otherwise be lost due to signal overlap and insignificant chemical shift differences.
Data Source
AI summary
The present invention relates to a method for analyzing the length of sulfur crosslinking bonds in a vulcanized rubber using NMR spectrum. In some embodiments, the method comprises obtaining, independently, a carbon-13 nuclear magnetic resonance (13C NMR) spectrum of a standard substance, wherein the standard substance containing carbon atoms, and a 13C NMR spectrum of the vulcanized rubber, wherein the 13C NMR spectrum of the standard substance and the 13C NMR spectrum of the vulcanized rubber are obtained under the same conditions; obtaining, independently, free induction decay (FID) amplification values of characteristic peaks in the 13C NMR spectrum of the standard substance, and FID amplification values of characteristic peaks in the 13C NMR spectrum of the vulcanized rubber; and measuring the length of sulfur crosslinking bonds in the vulcanized rubber.