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Topics Covered
Introduction
Advantages of Nuclear Magnetic Resonance (NMR) over Other Techniques
Measurement of Mineral Oils in Crystal Polystyrene
Calibration and Mineral Oil Content
The MQC-23 NMR Instrument
Introduction
Mineral Oil is added to Crystal
Polystyrene to increase its flexibility.
This process requires a high degree of
regulation, as the addition of too much
mineral oil would dissolve the
polystyrene polymer. Nuclear Magnetic Resonance or NMR can provide
a rapid and effective means of
monitoring the mineral oil content in
crystal polystyrene.
Advantages of Nuclear Magnetic Resonance (NMR) over Other Techniques
- NMR has a number of advantages over other
techniques:
- It can be calibrated to cover a range from
0 to 100%.
- The measurement time is short (typically two
seconds), allowing rapid sample throughput.
- The NMR technique is non-destructive, so
polystyrene analysed is still usable.
- NMR is insensitive to air voids between
polystyrene granules.
- NMR is very stable over the long-term, so
calibrations will rarely require adjustment.
- NMR does not require the use of hazardous
solvents.
- Both weighing and non-weighing methods
are available for this application
Measurement of Mineral Oils in Crystal Polystyrene
Five samples of crystal polystyrene were
selected for the analysis of mineral oil
content. Each sample was weighed into a
tared 26mm glass tube and preconditioned
for an hour at 105ºC, before being placed in
an MQC-23 for analysis.
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Figure 1. The MQC-23 NMR instrument from Oxford Instruments.
Calibration and Mineral Oil Content
The graph in Figure 2 illustrates the
calibration of the NMR measurements against
mineral oil contents determined by an
alternative method for these samples.
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Figure 2. Calibration of NMR data and
reference values for oil content.
Correlation: r = 1; SD = 0.07.
The quality of the calibration exhibited in
Figure 1 is excellent, as indicated by the
correlation coefficient of 1 and the standard
deviation of 0.07.
The MQC-23 NMR Instrument
The MQC-23 NMR system is fitted with a 26mm diameter probe
is a suitable instrument for this application. The
Oil in Crystal Polystyrene package comprises:
- MQC-23 with a built-in computer operating
the latest version of Microsoft® Windows®
(no separate PC is required).
- MultiQuant software including RI Calibration,
RI Analysis, and the EasyCal ‘Oil in Crystal
Polystyrene’ application.
- 26mm glass tubes.
- Installation Manual.
- ‘Oil in Crystal Polystyrene’ method sheet.
In addition to this package you will also require:
- A dry heater and aluminium block with 26mm
holes for sample conditioning at 105ºC.
- A precision balance.
The instrument offers multiple advantages
over others on the market:
- High signal sensitivity.
- Small benchtop footprint.
- Low maintenance.
- Recyclable sample tubes, lowering consumable
costs.
- Minimal sample preparation.
Source: Oxford Instruments
For more information on this source, please visit Oxford Instruments Magnetic Resonance