Irtracer 100 infrared spectrometer

The synthetic product was characterized by the potassium bromide (KBr) tabletting method using an IRTRacer-100 infrared spectrometer (Shimadzu Corporation, Kyoto, Japan). A small amount of sample was mixed well with KBr in a mortar and ground thoroughly, and the ground powder was pressed into a complete and transparent sheet using a tablet press. The scanning wavelength range was from 500 to 4000 cm⁻¹, the resolution ratio was 4 cm⁻¹, and the sample scanning times were 32.
To further characterize the molecular structure of LDMS, its NMR hydrogen spectrum was measured using an Avance NEO 400 MHz NMR spectrometer (Bruker, Berlin, Germany). The signal was collected by dissolving 3 mg of sample in heavy water and cycling 16 times.
The thermal stability of LDMS was measured using a thermal analyzer (TGA550, Mettler Toledo Co. Shanghai, China) in a N₂ environment. The experimental temperature range was 50.0 to 800.0 °C, and the heating rate was 10.0 °C/min.
The relative molecular mass distribution of the filtrate reducer samples LDMS and Driscal was determined by gel chromatography using a Waters 1515 GPC type gel chromatograph (Waters Corporation, Milford, MA, USA). The mobile phase of the test was 0.1 mol/L aqueous sodium nitrate solution, and the standard was polyethylene glycol (PEG).

Differential scanning calorimetry (DSC) measurements were taken with a PE Diamond instrument. About 10 mg powder was placed at the heating rate of 5~20 °C/min under a flow of N₂ (20 mL/min).
Fourier transform infrared spectroscopy (FTIR) spectra were recorded on the IRTracer 100 infrared spectrometer of Shimadzu company (Kyoto, Japan) in Japan. The KBr pressing method was used in the testing process. The spectra were collected over the 4000~400 cm⁻¹ wavenumber range at room temperature.
Thermogravimetric analysis (TGA) was conducted on PI before and after curing on the STA499F3 thermal analyzer, and the powder (about 3~10 mg) was heated from 25 °C to 800 °C at a heating rate of 20 °C/min in a N₂ environment.
Scanning electron microscope (SEM) of SU3500 of Hitachi High-tech Corporation (Hitachinaka, Japan) was used to observe the micro-morphology of PI resins before and after curing in vacuum mode, and the voltage was 10 kV.