PET/SiO_(2)复合材料的发泡温度窗口研究

Study on Foaming Temperature Window of PET/SiO_(2) Composites

为研究纳米二氧化硅(SiO_(2))对聚对苯二甲酸乙二酯(PET)复合材料发泡温度窗口的影响规律,制备了不同SiO_(2)含量的PET复合材料,并以二氧化碳为发泡剂,利用釜压发泡制备了PET/SiO_(2)复合发泡材料。然后,利用扫描电子显微镜研究了在不同温度下制备的PET/SiO_(2)复合发泡材料的泡孔结构,并统计和计算出泡孔尺寸、泡孔密度和膨胀倍率,再结合泡孔结构和膨胀倍率,界定出不同SiO_(2)含量的PET复合材料发泡温度的上下限,并得出发泡温度窗口,还研究了PET/SiO_(2)复合发泡材料的光反射率。结果发现,SiO_(2)对PET复合材料具有显著的气泡异相成核作用,随着SiO_(2)添加量的增加,泡孔尺寸减小、泡孔密度增大、膨胀倍率先增大后减小;发泡温度上限先升高后降低、下限升高,使得发泡温度窗口先变宽后变窄,这与SiO_(2)的气泡异相成核作用、对膨胀倍率的调节作用及对基体黏弹性的影响密切相关。随着SiO_(2)添加量的增加,PET复合发泡材料的光反射率逐渐增大,这归因于泡孔尺寸逐渐减小、泡孔密度逐渐增大更有利于光的反射。

In order to study the effect of nano-silica(SiO_(2))on the foaming temperature window of poly(ethylene terephthalate)(PET)composites,PET composites with various contents of SiO_(2) were prepared,and PET/SiO_(2) composite foams were prepared via batch foaming process with carbon dioxide as foaming agent.Then,the cell structure of PET/SiO_(2) composite foaming materials prepared at different temperatures was studied by scanning electron microscopy,and the cell size,cell density and expansion ratio were obtained.Combined with the cell structure and expansion ratio,the upper and lower limits of foaming temperature of PET composites with different SiO_(2) contents were defined,and the foaming temperature window was obtained.The light reflectivity of PET/SiO_(2) composite foam was also studied.The results show that SiO_(2) has prominent heterogeneous nucleation effect on PET/SiO_(2) composites.With the increase of SiO_(2) content,the cell size decreases,the cell density increases,and the expansion ratio increases first and then decreases.The upper foaming temperature limit first increases and then decreases,and the lower limit increases,leading to the foaming temperature window first broadens and then narrows.These phenomena are closely related with the effect of SiO_(2) on heterogeneous cell nucleation,expansion ratio and viscoelasticity of PET composites.With the increasing of SiO_(2) content,the reflectivity of PET composite foams gradually increases.This is attributed to the gradually decreases cell size and increases cell density being favorable for light reflection.