Chinese university unveils breakthrough supercritical foaming tech for elastomers

Researchers at Qingdao University of Science and Technology (QUST) have developed a supercritical foaming technology for polymers and elastomers that experts have rated as reaching “an internationally leading level.” The breakthrough, announced on 1 June, stems from a project titled “key technologies and green industrial application of polymer autoclave supercritical foaming,” led by professor Zhang Zhenxiu. The research was conducted in collaboration with multiple industrial partners and targets sectors including new energy, advanced manufacturing, and energy-saving materials. Historically, core processes and high-end equipment for supercritical foaming have been dominated by foreign suppliers, constraining China’s domestic production capabilities. After nearly two decades of development, Zhang’s team created an integrated “process-equipment-material” platform covering the entire production chain. The new supercritical foaming method reportedly breaks through existing patent barriers in bead foaming technology by incorporating a high-pressure nitrogen recycling system with a recovery rate exceeding 90%. This enables the production of elastomer foams with “ultra-low” density, high dimensional accuracy, and uniform cell structures. On the equipment front, the team designed an automated supercritical foaming autoclave that improves sealing performance, temperature and pressure control, and operating efficiency. The equipment achieves a depressurisation rate six times higher than international benchmark levels while maintaining temperature control accuracy within ±1 degree Celsius. Material-wise, the project introduced modification techniques based on grafting, chain extension, and cross-linking technologies. These methods enhance control over foam cell morphology in elastomers and specialty rubbers, expanding processing windows for foaming operations. The project has yielded 38 granted invention patents, including four in Japan, and resulted in 51 published academic papers. Qingdao University confirmed that the technology has already been adopted commercially by several companies.