21 essential testing and analysis technologies for modern textile testing

Ultraviolet absorption spectrum UV

Analysis principle: Absorb ultraviolet light energy, causing a transition of electron energy levels in molecules.

The representation method of the spectrum: the change of relative absorbed light energy with the wavelength of absorbed light.

Information provided: The position, intensity and shape of the absorption peak provide information about the different electronic structures in the molecule.

2. Fluorescence spectroscopy FS

Analysis principle: After being excited by electromagnetic radiation, it returns to the singlet ground state from the low singlet excited state and emits fluorescence.

Representation method of spectrum: the change of emitted fluorescence energy with the wavelength of light.

Information provided: Fluorescence efficiency and lifetime, providing information on the different electronic structures in the molecule.

3. Infrared absorption spectrometry IR

Analysis principle: Absorbing infrared light energy causes vibration and rotational energy level transitions of molecules with dipole moment changes.

The representation method of the spectrum: the relative transmitted light energy changes with the transmitted light frequency.

Information provided: position, intensity and shape of peaks, providing characteristic vibrational frequencies of functional groups or chemical bonds.

4. Raman spectroscopy Ram

Analysis principle: After absorbing light energy, it causes molecular vibrations with changes in polarizability, resulting in Raman scattering.

The representation method of the spectrum: the change of scattered light energy with Raman shift.

Information provided: position, intensity and shape of peaks, providing characteristic vibrational frequencies of functional groups or chemical bonds.

5. Nuclear Magnetic Resonance Spectroscopy NMR

Analysis principle: In an external magnetic field, the atomic nucleus with nuclear magnetic moment absorbs radio frequency energy and produces a transition in the nuclear spin energy level.

Representation method of the spectrum: the change of absorbed light energy with chemical shift.

Information provided: chemical shift, intensity, splitting number and coupling constant of the peak, providing information on the number of nuclei, chemical environment and geometric configuration.

6. Electron paramagnetic resonance spectroscopy ESR

Analysis principle: In an external magnetic field, unpaired electrons in molecules absorb radio frequency energy, causing electron spin energy level transitions.

The representation method of the spectrum: the absorbed light energy or differential energy changes with the magnetic field intensity.

Information provided: spectral line position, intensity, number of splits and hyperfine splitting constants, providing unpaired electron density, molecular bond properties and geometric configuration information.

7. Mass spectrometry MS

Analysis principle: Molecules are bombarded by electrons in a vacuum to form ions, which are separated by different m/e through electromagnetic fields.

Representation method of spectrum: express the relative kurtosis of ions as a function of m/e in the form of a bar graph.

Information provided: mass number and relative kurtosis of molecular ions and fragment ions, providing information on molecular weight, elemental composition and structure.

8. Gas Chromatography GC

Analysis principle: Each component in the sample is separated between the mobile phase and the stationary phase due to different distribution coefficients.

Representation method of spectrum: post-column effluent concentration changes with retention value.

Information provided: The retention value of the peak is related to the thermodynamic parameters of the component and is a qualitative basis; the peak area is related to the component content.

9. Inverse gas chromatography IGC

Analysis principle: The change in the retention value of the probe molecule depends on the interaction between it and the polymer sample as the stationary phase.

The representation method of the spectrum: the logarithmic value of the specific retention volume of the probe molecules changes with the reciprocal of the column temperature.

Information provided: The retention of probe molecules as a function of temperature provides the thermodynamic parameters of the polymer.

10. Fragmentation gas chromatography PGC

Analysis principle: Polymer materials crack instantly under certain conditions, and fragments with certain characteristics can be obtained.

Representation method of spectrum: post-column effluent concentration changes with retention value.

Information provided: fingerprints or characteristic fragment peaks of the spectrum, characterizing the chemical structure and geometric configuration of the polymer.

Gel Chromatography GPC

Analysis principle: When the sample passes through the gel column, it is separated according to the different hydrodynamic volumes of the molecules, and the large molecules flow out first.

Representation method of spectrum: post-column effluent concentration changes with retention value.

Information provided: Average molecular weight of the polymer and its distribution.

12. Thermogravimetry TG

Analysis principle: In a temperature-controlled environment, the sample weight changes with temperature or time.

Representation method of the spectrum: the change curve of the weight fraction of the sample with temperature or time.

Information provided: The steep drop of the curve is the weight loss area of the sample, and the plateau area is the thermal stability area of the sample.

13. Thermogravimetric analysis DTA

Analysis principle: The sample and the reference material are in the same temperature-controlled environment. Due to the difference in thermal conductivity between the two, a temperature difference occurs, and the temperature changes with the ambient temperature or time are recorded.

Representation method of spectrum: temperature difference curve with ambient temperature or time.

raise� Information: Provides information on the thermal transition temperature of the polymer and various thermal effects.

14. Differential scanning calorimetry DSC

Analysis principle: The sample and the reference material are in the same temperature-controlled environment. When the temperature difference is maintained at zero, the change in energy required with the ambient temperature or time is recorded.

Representation method of the spectrum: the change curve of heat or its change rate with ambient temperature or time.

Information provided: Provides information on the thermal transition temperature of polymers and various thermal effects.

15. Static thermal-mechanical analysis TMA

Analysis principle: The deformation of the sample under the action of constant force changes with temperature or time.

Representation method of spectrum: sample deformation value changes curve with temperature or time.

Information provided: Thermal transition temperatures and mechanical states.

16. Dynamic thermal-mechanical analysis DMA

Analysis principle: The deformation of the sample under the action of periodically changing external forces changes with temperature.

Representation method of spectrum: Modulus or tgδ changes with temperature curve.

Information provided: Thermal transition temperature modulus and tgδ.

17. Transmission electron microscopy TEM

Analysis principle: When the high-energy electron beam penetrates the sample, scattering, absorption, interference and diffraction occur, causing contrast to form on the phase plane and display an image.

Spectrum representation methods: mass-thickness contrast image, bright field diffraction contrast image, dark field diffraction contrast image, lattice fringe image, and molecular image.

Information provided: crystal morphology, molecular weight distribution, micropore size distribution, multiphase structure, lattice and defects, etc.

18. Scanning electron microscopy SEM

Analysis principle: Use electronic technology to detect the secondary electrons, backscattered electrons, absorbed electrons, X-rays, etc. produced when high-energy electron beams interact with samples and amplify the images.

Representation methods of spectra: backscattering image, secondary electron image, absorption current image, line distribution and surface distribution of elements, etc.

Information provided: fracture morphology, surface microstructure, microstructure inside the film, micro-area element analysis and quantitative element analysis, etc.

19. Atomic absorption AAS

Principle: The sample to be tested is atomized through an atomizer, and the atoms to be measured absorb the light of the hollow cathode lamp of the element to be measured, so that the energy detected by the detector becomes lower, and the absorbance is obtained. Absorbance is proportional to the concentration of the element to be measured.

20. Inductively coupled high-frequency plasma ICP

Principle: The high temperature generated by argon plasma is used to completely decompose the sample to form atoms and ions in the excited state. Since the atoms and ions in the excited state are unstable, the outer electrons will transition from the excited state to a lower energy level, thus emitting characteristic spectrum line. After the light is split by a grating, a detector is used to detect the intensity of a specific wavelength. The intensity of the light is proportional to the concentration of the element to be measured.

21.X-ray diffraction XRD

Principle: X-rays are optical radiation generated by the transition of electrons in the inner layer of atoms under the bombardment of high-speed moving electrons. There are mainly two types of continuous X-rays and characteristic X-rays. Crystals can be used as X-ray gratings. The coherent scattering produced by these large numbers of atoms or ions/molecules will cause light interference, thereby affecting the intensity of the scattered X-rays to increase or decrease. Due to the superposition of scattered waves from a large number of atoms, they interfere with each other and produce a high-intensity beam called X-ray diffraction line.

To satisfy the diffraction conditions, Bragg’s formula can be applied: 2dsinθ=λ

Apply X-rays of known wavelength to measure the θ angle to calculate the interplanar spacing d, which is used for X-ray structural analysis; the other is to use a crystal with known d to measure the θ angle to calculate the characteristic X-ray Wavelength, and then the elements contained in the sample can be found from existing data.