What is driving the price gap between PSU, PPSU, and PES resins in China?

What is driving the price gap between PSU, PPSU, and PES resins in China?
The polysulfone family shows a clear price hierarchy in the Chinese market: PSU averages around 85,000-91,000 yuan/ton, PES around 74,500-105,000 yuan/ton, and PPSU the highest at 115,000-165,000 yuan/ton. This spread reflects both structural differences and supply dynamics. PPSU commands the premium due to superior heat resistance, impact strength, and more complex polymerization requiring biphenyl units, which raise production costs. PES sits between PSU and PPSU in performance but benefits from better processability. Domestic capacity expansion is underway—Shandong Haoran has 6,500 tons/year, Kingfa 6,000 tons—but high-end grades, especially PPSU from Solvay, still command prices above 350,000 yuan/ton. Import substitution is progressing but slowly, keeping the price ladder steep.