文中以高压CO2为发泡剂,通过固态间歇发泡法制备了聚对苯二甲酸乙二醇酯(PET)微孔发泡材料,研究了PET的结晶度对其发泡行为的影响.首先,利用PET的结晶特性在合适的条件下进行退火,制备出具有不同结晶度的原始样品.差示扫描量热分析数据表明,当退火温度为110℃,退火时间为10 min时,PET的结晶度从8.07％(无定形态)提高到16.00％(结晶态),且其结晶度随着退火时间的延长进一步提高.其次,采用快速升温法对PET片材进行物理发泡并结合CO2在PET基体内的扩散与PET结晶之间的关系对其发泡行为进行了研究.扫描电镜测试表明,随着PET原始样品结晶度的增加,其发泡材料的泡孔尺寸逐渐减小,泡孔密度逐渐增大;此外,对于同一样品,发泡温度越高,得到的泡孔尺寸越大.
Microcellular polyethylene terephthalate (PET) was prepared via solid-bath foaming with high-pressure CC2 as blowing agent,and the influence of the crystallinity of PET solid on the cell morphology of the resultant foams was also investigated.First,PET specimens with various crystallinities were prepared via annealing method,and characterized by differential scanning calorimetry (DSC).The results reveal that the degree of crystallinity of PET resin increases from 8％ for amorphous PET (APET) to 16％ for crystalline PET after annealing at 110 ℃ for 10 min.Further increasing the time would lead to much higher crystallinity.After that,the as-prepared PET solids were foamed by a sudden increase of foaming temperature.Furthermore,the foaming behaviors of PET resin could also be manipulated by adjusting the saturation concentration of CO2 in PET matrix.SEM images of the resulting microcellular PET foams indicate that,with increase of the crystallinity of original PET solid,the PET foams exhibit a decreasing tendency in the cell sizes and an increasing density in the foam density.In addition,the cell size of the foams intends to increase at elevated foaming temperatures.
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