共混法制备开孔性聚丙烯泡沫材料的研究

发布时间：2018-04-04 12:32

  本文选题：聚丙烯　切入点：共混　出处：《华南理工大学》2011年硕士论文

【摘要】：开孔性发泡塑料是指塑料泡体中的泡孔不是封闭的,气泡间相互连通的一种泡沫塑料。独特的开孔结构能够使微粒和流体在泡沫内流动,通过精确控制开孔泡沫塑料的结构和泡孔的大小,就可以使通过材料粒子的大小得到控制,使不同粒径材料分离,实现特殊过滤用途。针对开孔性泡沫材料的这种独特作用,国内外学者开展了许多制备开孔性泡沫材料的研究,提出了一些泡沫塑料开孔成型的理论。聚丙烯(PP)具有物理和力学性能好、原料来源丰富和价格便宜等众多优点,利用聚丙烯来制备开孔性泡沫材料具有非常重要的现实意义。 本文以两相共混法制备开孔泡沫塑料理论为基础,探索一方面降低易破裂相强度,一方面提高泡孔壁支撑相熔体强度的发泡方法,以期制备得到开孔性良好、泡孔结构规整的开孔泡沫塑料。 本文首先采用PP/LLDPE共混体系进行发泡研究,确定大致工艺条件和配比;然后选用熔体强度较高的高熔体强度聚丙烯HMSPP代替普通PP制备得到共混原料,研究温度、原料配比等因素对共混体系发泡效果的影响;接着选用HMSPP/LLDPE:70/30体系作为考察对象,研究不同粒径成核剂、成核剂含量、发泡温度、发泡压力和剪切速率对共混体系发泡样品泡孔形貌和开孔效果的影响;最后,探索了几种提高共混体系发泡样品开孔率和完善泡孔结构的新方法。 研究结果表明:当采用PP/LLDPE共混体系作为开孔发泡研究对象,得到的发泡样品泡孔形貌不是很理想,所以采用HMSPP来代替普通PP进行共混发泡研究。我们发现HMSPP/LLDPE原料配比和发泡温度对共混体系的开孔发泡影响明显,当原料配比为70:30、发泡温度为130℃时样品发泡充分,泡孔形貌较规整,泡孔尺寸均匀。然后在此配比共混体系中,我们通过实验考察发现成核剂的加入使共混发泡体系的泡孔孔径更加均匀。当成核剂添加量为3%时,样品发泡效果较好,可以观察到明显的开孔结构。当体系添加5000目成核剂时的发泡效果不如添加2500目成核剂时好。通过开孔率测算发现,添加成核剂之后样品的开孔率和开孔泡孔占全部泡孔体积的比例明显提高。在开孔率改进新方法研究中,我们发现发现采用粉体LLDPE原料制备的共混体系发泡样品开孔率较采用粒料LLDPE时略有提高。而加入石蜡油后,共混体系发泡样品的泡孔孔径减小,泡孔表明变得更光滑,但是其开孔率较未加石蜡油的发泡样品有所下降。
[Abstract]:Open-cellular foam is a kind of foam in which the pores in the foam are not closed and the bubbles are connected with each other.By accurately controlling the structure and size of the porous plastics, the size of the particles through the material can be controlled and the materials of different particle sizes can be separated.Realize special filtering purpose.In view of this unique role of porous foam materials, many scholars at home and abroad have carried out research on the preparation of porous foam materials, and put forward some theory of porous molding of foam plastics.Polypropylene (PP) has many advantages, such as good physical and mechanical properties, abundant sources of raw materials and low price. It is of great practical significance to use polypropylene to prepare porous foam materials.In this paper, based on the theory of two-phase blending to prepare open-cell foamed plastics, the foaming method of reducing the strength of easily fracturing phase and increasing the melt strength of supporting phase of foaming wall is explored in order to obtain good pore opening property.A structured open-hole foam.In this paper, PP/LLDPE blend system was first used to study the foaming process, and then the high melt strength polypropylene (HMSPP) with high melt strength was used to prepare the blend material instead of ordinary PP, and the temperature was studied.The influence of the ratio of raw materials on the foaming effect of the blend system, and then select the HMSPP/LLDPE:70/30 system as the object of investigation, study the nucleating agent, nucleating agent content and foaming temperature of different particle size, the content of nucleating agent, the foaming temperature, and so on.The effects of foaming pressure and shear rate on the morphology and opening effect of foamed samples were investigated. Finally, several new methods to improve the porosity and improve the structure of foamed samples were explored.The results show that when the PP/LLDPE blend system is used as the research object of open-cell foaming, the foam morphology of the foamed sample is not ideal, so HMSPP is used to study the blending foaming of PP instead of the ordinary PP.It was found that the ratio of HMSPP/LLDPE raw materials and foaming temperature had an obvious effect on the open pore foaming of the blend system. When the ratio of raw materials was 70: 30 and the foaming temperature was 130 鈩，

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