(Polymer polymerization rate detection) Pulse nuclear magnetic resonance analyzer

(Polymer polymerization rate detection) Pulse nuclear magnetic resonance analyzerbe based onLow field pulsed nuclear magnetic resonance technology is a powerful non-destructive analysis and testing tool. It has been widely used in fields including food, agriculture, materials, industrial quality testing and control, energy, medicine, etc. Pulse nuclear magnetic analyzer clones are found in industrial quality control and university research laboratories.

Low fieldPulse nuclear magnetic resonance analyzerEasy to operate, requiring only basic training to use the instrument, and suitable for industrial online applications. It has been widely used in various industrial and research institutions for routine quality control and process inspection.

Polymers have a wide range of applications, and their different physical and chemical properties make them suitable for different fields. Factories can design products with corresponding characteristics according to their needs. And how to optimize the conditions of polymerization reaction to achieve high efficiency and yieldPolymer products are a major concern for factories. Large molecule polymers are formed by repeating smaller simple molecules (monomers)It is very necessary to measure the change in polymerization rate or monomer to polymer conversion rate over time.

The speed of T2 relaxation can be used to evaluate the motion of molecules or segments, corresponding to the polymer polymerization processT2relaxation timeIt will decrease with the increase of molecular chain length, while the free monomerT2relaxation timeLonger, can be establishedT2The corresponding relationship between relaxation time and polymerization rate is studied to investigate the polymerization rate and conversion process.

(Polymer polymerization rate detection) Basic parameters of pulse nuclear magnetic resonance analyzer:

1. Magnetic field strength: 0.5 ± 0.05T
2. Probe coil: Ø 25mm;

Basic principle of low field pulsed nuclear magnetic resonance:

After the sample is placed in the magnet, the hydrogen nuclei in the sample will magnetize, forming a net magnetization parallel to the magnetic field. Applying a certain frequency of RF pulses to the sample will absorb RF energy, and after RF application, the evolution of nuclear spin state from excited state to equilibrium state can be observed. The energy isFID (free induction decay)Release in the form of attenuated signals.

FIDThe initial amplitude is proportional to the number of hydrogen nuclei in the sample.FIDThere are two main reasons for attenuation:

1Uneven magnetic field

2The interaction between hydrogen nuclei (spin)-Spin relaxation), influenced by time constantT2Control.

Can be achieved throughCPMGThe sequence eliminates the influence of magnetic field non-uniformity, which is composed of a series of pulses, each of which refocuses the signal attenuation caused by magnetic field non-uniformity. This signal consists of a series of refocused signals, known as "spin echo" signals, with each signal having a slightly smaller maximum amplitude than the previous one. The attenuation of echo amplitude is entirely attributed to spin spin relaxation.