EXPRESS: Raman Spectroscopy for Monitoring Polymerization, Quality Control, and Additive Distribution in Styrene–Divinylbenzene Based Proppants

Raman spectroscopy was applied to monitor polymerization, verify quality control, and analyze additive distribution in styrene–divinylbenzene (Sty–DVB) based proppants. The method relies on C=C vibrational markers to follow monomer consumption, crosslinking, and additive incorporation. Quality control included quantifying vinyl, cis, and trans C=C in polybutadiene (PB) modifiers and the ethyl-vinyl benzene (EVB) content in DVB crosslinkers. EVB content by Raman showed excellent agreement with independent carbon-13 nuclear magnetic resonance (¹³C-NMR) measurements. Styrene copolymerization with DVB was tracked in real time using a fiber-optic Raman probe in a temperature-controlled microreactor. DVB accelerates styrene consumption due to its higher reactivity and radical stabilization. PB additives do not affect overall polymerization kinetics. In terms of additives, Raman calibration confirms that PB double bonds remain largely unreacted, consistent with limited copolymerization and phase separation. Polyphenylene oxide (PPO) slows down Sty polymerization while Raman mapping demonstrates its homogeneous dispersion within the matrix, validating its incorporation and expected impact on material properties. Overall, Raman spectroscopy provides a direct, non-invasive, and scalable approach to monitor polymerization and verify additive distribution, establishing it as a practical tool for process optimization in Sty–DVB proppant formulations.