Chinese university develops 'supercritical foaming technology' for elastomers

Qingdao, China – Researchers at the Qingdao University of Science and Technology (QUST) have developed a 'supercritical foaming technology' for polymers and elastomers that has been assessed by a panel of experts as reaching “an internationally leading level.”

The research, titled "key technologies and green industrial application of polymer autoclave supercritical foaming", was evaluated by a research team led by professor Zhang Zhenxiu, QUST announced 1 June.

According to QUST, the project was developed jointly with several industrial partners and addresses long-standing challenges in supercritical foaming, a technology used in sectors including new energy, advanced manufacturing and energy-saving materials.

The university said core processes and high-end equipment for supercritical foaming have historically been dominated by ‘foreign suppliers,’ limiting China’s domestic production capabilities.

After nearly 20 years of research, Zhang's team developed what the university described as an integrated "process-equipment-material" platform covering the full production chain.

On the processing side, the researchers developed a supercritical foaming method that, according to the university, breaks through existing patent barriers in bead foaming technology.

The process incorporates a high-pressure nitrogen recycling system with a recovery rate of more than 90%.

The team said the technology enables production of elastomer foams with "ultra-low density", high dimensional accuracy and uniform cell structures.

In equipment development, the researchers designed an automated supercritical foaming autoclave intended to address issues including sealing performance, temperature and pressure control, and operating efficiency.

According to QUST, the equipment achieves a depressurisation rate ‘six times higher than international benchmark levels,’ while maintaining temperature control accuracy within -1 and +1 degree Celsius.

The project also involved the development of material-modification techniques based on grafting, chain extension and cross-linking technologies.

These were designed to improve control over foam cell morphology in elastomers and speciality rubbers and to expand processing windows for foaming operations.

QUST said the project has generated 38 granted invention patents, including four patents in Japan, and resulted in the publication of 51 academic papers.

The university added that the technology has already been adopted commercially by several companies.