超高分子量聚乙烯超临界CO2间歇发泡研究

Study on Supercritical CO2 Intermittent Foaming of UHMWPE

应用超临界CO2间歇发泡方法研究了温度、压力以及不同发泡工艺对超高分子量聚乙烯(UHMWPE)发泡的影响。结果表明:合适的饱和温度可以提高发泡倍率,减小泡孔尺寸,增加泡孔密度;发泡倍率和泡孔密度与饱和压力成正相关;对比不同工艺条件下的发泡结构与尺寸,得出正向发泡的泡孔尺寸小、泡孔密度高,而逆向发泡的泡孔尺寸大,但发泡倍率高。DSC结果表明:正向发泡的结晶度较高,发泡时异相成核数量增加,从而使泡孔尺寸减小、泡孔数量增加。比较正向和逆向发泡相同发泡倍率下的泡沫压缩性能,发现逆向发泡泡沫的弹性模量大于正向发泡泡沫。

The effects of temperature,pressure and different foaming processes on the foaming of UHMWPE were studied by using supercritical CO2 intermittent foaming method.The results show that:the suitable saturation temperature can increase foaming ratio,decrease cell size and increase cell density,and foaming ratio and cell density are positively correlated with saturation pressure.Comparing the foaming structure and size under different technological conditions,it is concluded that the forward foaming has smaller cell size and higher cell density,while the reverse foaming has larger cell size but higher foaming ratio.DSC results show that:the crystallinity of forward foaming is higher,and the number of heterogeneous nucleation increases during foaming,which resulted in the decrease of cell size and the increase of cell number.It is found that the modulus of elasticity of the reverse foam is larger than that of the positive foam compared to the foam compacting performance under the same foaming rate.