By AZoM
Table of Contents
Introduction
Benefits of NMR
Calibration and Results
Recommended Instrument
Advantages of MQC-23
About Oxford Instruments Magnetic Resonance
Introduction
Polybutadiene or rubber is added during the polymerisation of styrene to increase the flexibility of polystyrene polymers. Monitoring closely the amount of added polybutadiene is essential to control the flexibility of the polystyrene polymer. Nuclear magnetic resonance (NMR) can offer a quick and efficient method for the regulation of polybutadiene content in Impact Polystyrene.
Benefits of NMR
NMR has a number of benefits over other techniques:
- It can be calibrated to cover a range from 0 to 100%.
- The measurement time is quick, around 32 seconds, enabling rapid sample throughput.
- The NMR technique is non-destructive and the analyzed polystyrene can still be used.
- NMR is insensitive to air voids between polystyrene granules.
- NMR is highly stable over the long-term and there is rarely need for adjusting the calibration parameters.
- NMR does not require the use of hazardous solvents.
- Both weighing and non-weighing methods are offered for this application.
Calibration and Results
For this case study, 12 samples of Impact Polystyrene were chosen for the measurement of polybutadiene content. Each sample was weighed into a tared 26-mm glass tube before measuring at room temperature in the MQC-23. Figure 1 shows the calibration generated from these samples. The graph shows the calibration of the NMR signal against a value of polybutadiene content obtained by a standard technique.
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Figure 1. Calibration of NMR data and given polybutadiene content. Green squares indicate outliers. Correlation: r =1, SD = 0.15.
Table 1 shows that the repeatability or accuracy of the NMR data is excellent.
Table 1. Repeatability of NMR measurement.
| Repeat number |
Polybutadiene Content (%) |
| 1 |
6.79 |
| 2 |
6.81 |
| 3 |
6.80 |
| 4 |
6.81 |
| 5 |
6.79 |
| 6 |
6.78 |
| 7 |
6.81 |
| 8 |
6.79 |
| 9 |
6.79 |
| 10 |
6.80 |
| AVERAGE |
6.80 |
| SD |
0.009 |
Recommended Instrument
The MQC-23 fitted with a 26-mm diameter or a 14-ml sample probe is a suitable instrument for this application. The Rubber in Impact Polystyrene package consists of the following:
- MQC-23 with a built in computer operating the latest version of Microsoft Windows with no need for a separate PC.
- Multiquant software including RI Calibration, RI Analysis, and the EasyCal ‘Rubber in Polystyrene’ application.
- 26-mm diameter glass tubes.
- Installation manual.
- ‘Rubber in Polystyrene’ method sheet.
Advantages of MQC-23
The advantages of MQC-23 are:
- High-signal sensitivity.
- Small benchtop footprint.
- Minimal maintenance.
- Recyclable sample tubes thus reducing consumable costs.
About Oxford Instruments Magnetic Resonance
Oxford Instruments Magnetic Resonance are committed to the development and manufacture of information-driven solutions for novel applications in life sciences, research and industrial process control. The company knowledge was founded in the field of Nuclear Magnetic Resonance (NMR) instrumentation, receiving high recognition for its innovation dating over forty years. Today Oxford Instruments Magnetic Resonance are focused on solving complex and often unique technology problems for the understanding of biomolecular structure and function across industrial, life science and drug discovery applications. In the industrial process area, the low field benchtop instruments offer fast, accurate and simple measurement solutions to routine Quality Control problems.
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This information has been sourced, reviewed and adapted from materials provided by Oxford Instruments Magnetic Resonance.
For more information on this source, please visit Oxford Instruments Magnetic Resonance.