研究目的
Investigating the effect of shock wave at atomic and molecular level on poly (methyl methacrylate) (PMMA) under laser driven shock compression and static compression.
研究成果
Comparative studies of PMMA with dynamic and static compression have shown that all vibrational modes exhibit pressure-induced broadening and blue shifting. The pressure-induced peak shifts vary linearly with pressure. The study provides insights into the mode Grüneisen parameters and bond anharmonicities, which are slightly higher than earlier reported data using static pressure. The shock velocity and pressure measured are in good agreement with hydrodynamic simulations.
研究不足
The maximum pressures in dynamic compression are limited due to damage threshold limit of the confining glass. The study is focused on pressures up to ~1.9 GPa in dynamic and ~16 GPa in static compression.
1：Experimental Design and Method Selection:
The study utilized time-resolved Raman spectroscopy to investigate the changes in molecular vibrations of PMMA under laser driven shock compression and static compression. A layered target configuration was used to enhance the shock pressure.
2：Sample Selection and Data Sources:
PMMA sheets of specific thickness were used. The samples were characterized using FT Raman, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC).
3：List of Experimental Equipment and Materials:
A nanosecond Q-switched Nd: YAG laser system, DAC for static compression, and a 0.5-m Raman spectrometer with gated intensified charge coupled device camera as a detector were used.
4：5-m Raman spectrometer with gated intensified charge coupled device camera as a detector were used.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The experiments were performed on confined geometry target assembly by pump and probe technique. The shock pressure inside PMMA was varied by changing the laser energy on the aluminium foil.
5：Data Analysis Methods:
The vibrational modes were measured as a function of dynamic shock and static compression. The Grüneisen parameters and bond anharmonicities in PMMA were determined using compression behaviour of Raman modes.
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