热塑弹性体超临界流体间歇发泡过程中的基本问题

Fundamental Issues for Batch Foaming of Thermoplastic Elastomers with Supercritical Fluids

超临界流体间歇发泡的体系黏弹性易于调节、加工参数易于控制、加工装备便于设计和实现,是热塑弹性体物理发泡领域中最受关注的技术路线.本文首先综述了热塑弹性体物理发泡相关文献、研发历程和应用现状;阐明间歇发泡技术的相关概念、技术特点以及热塑弹性体与超临界流体的相互作用,重点讨论热塑弹性体间歇发泡的“高弹态发泡”特征以及处于高弹态状态下的泡孔成核、泡孔生长、泡孔结构定型、泡沫收缩机制及其调控策略.其次,综述了热塑弹性体发泡薄膜的制备方法、热塑弹性体发泡珠粒水蒸气成型过程、珠粒界面黏结强度和分子链界面扩散机制.此外,还从分子链化学结构、泡孔结构、材料宏观结构等角度总结了热塑弹性体发泡材料弹性性能,揭示热塑弹性体发泡材料的结构—弹性性能关系.最后对热塑弹性体超临界流体间歇发泡技术进行了展望.

The viscoelasticity of a supercritical fluid batch foaming system is easily controllable,and its processing parameters and equipment are also readily adjustable,making it the most favored technical pathway in the physical foaming of thermoplastic elastomers.This review introduces the literature,research and development history,as well as the current application status of thermoplastic elastomer foams.Firstly,the review clarifies the basic concepts,technical characteristics,and interaction between thermoplastic elastomer and supercritical fluid.It also discusses the characteristics of“high-elastic foaming”during batch foaming of thermoplastic elastomer,as well as the mechanisms of cell nucleation,growth,and structure shaping,along with regulatory strategies for foam shrinkage in high-elastic state.Secondly,this review examines the preparation methodology for preparing foamed films made from thermoplastic elastomers,the steam-chest molding process applied to thermoplastic elastomer foamed beads,and the strength of the interface between the beads,as well as the mechanism of inter-bead bonding.Additionally,the elastic properties of foam materials made of thermoplastic elastomers based on the chemical structure of molecular chains,cellular structure,and material macrostructure are summarized.Furthermore,the relationship between the structure and elastic properties of thermoplastic elastomer foams is investigated.Finally,the development for the batch foaming of thermoplastic elastomers with supercritical fluids is prospected.