The difference between supercritical foaming and chemical foaming

Date:2024-07-16

When it comes to supercritical foaming, many people may find it difficult to understand what kind of process it is, and they may need to understand what the supercritical state is. In fact, from another perspective, it is also called physical foaming. Although the process flow of chemical foaming is not completely the same, there are some similarities between the two. The essential difference between the two lies in the different foaming agents.

 

1、 The essential difference between the two

 

Physical foaming: Supercritical fluids such as carbon dioxide and nitrogen are treated with high temperature and high pressure to act as foaming agents. The process of supercritical fluids turning into gases at room temperature and pressure is a physical change.
 
超临界发泡和化学发泡的区别
 
Chemical foaming: Chemical foaming agents such as azodicarbonamide and sodium bicarbonate. Taking azodicarbonamide (also known as AC foaming agent) as an example, it produces nitrogen, carbon monoxide, carbon dioxide, and ammonia during thermal decomposition, which is a chemical change.
 
超临界发泡和化学发泡的区别

 

2、 Advantages, disadvantages, and process comparison of the two

 

Supercritical foaming
  • Supercritical foaming is used to prepare pure foam materials with food safety grade and good compatibility with the skin.
    Compared with chemical foaming, supercritical foaming has a finer cell structure and more stable performance.
    Supercritical foamed foam has greater impact strength, better thermal stability, toughness, good sound insulation performance, and lower thermal conductivity and thermal conductivity.
    Long saturation time can affect production efficiency, and rapid heating or rapid pressure relief require high energy and equipment safety requirements.
 

超临界发泡和化学发泡的区别

Supercritical sheet foaming process, Suzhou Shensai
 
Chemical foaming (taking azodicarbonamide as an example):
  • The maximum gas generation, relatively uniform pores, superior performance, and wide range of applications.
    The decomposition temperature can be adjusted without affecting the curing and molding speed, and the process is very mature.
    AC foaming agent is a yellow crystal, and decomposition can easily produce a large number of by-products, such as particle size not being fine enough, which can lead to the production of many by-products, resulting in a taste and color deviation in the product.

超临界发泡和化学发泡的区别

Chemical foaming process of EVA sheet
 

3、 The development trend of foaming technology

 

Supercritical foaming is an emerging process. In the past, traditional chemical foaming was difficult to achieve lightweight and low-density properties for some materials. However, the development of supercritical foaming technology can enable more materials to achieve lightweight and low-density properties while also having the advantages of environmental protection and cleanliness, which is in line with the current carbon neutrality development strategy.

 


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