Effect of carbon nanotubes content on crystallization kinetics and morphology of polypropylene
Effect of carbon nanotubes content on crystallization kinetics and morphology of polypropylene
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DOI：
10.1016/j.polymertesting.2008.10.001
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发表时间：
2009-02
期刊：
影响因子：
5.1
通讯作者：
M. Razavi‐Nouri;M. Ghorbanzadeh-Ahangari;A. Fereidoon;M. Jahanshahi
中科院分区：
文献类型：
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作者：
M. Razavi‐Nouri;M. Ghorbanzadeh-Ahangari;A. Fereidoon;M. Jahanshahi
在实验室混合器中，以聚丙烯（PP）和不同数量的单壁碳纳米管（SWNT）为原料，在0.25-2wt %范围内制备热塑性纳米复合材料。研究了SWNT含量对PP/SWNT纳米复合材料的热性能、力学性能和形貌的影响。用差示扫描量热法对PP和纳米复合材料的非等温结晶进行了研究，结果表明，在聚合物中加入SWNT不仅提高了PP的整体结晶速率，而且纳米复合材料的成核速率更高，晶粒尺寸分布也比PP更均匀。结果表明，在纳米复合材料中引入SWNT后，PP的球晶尺寸减小，成熟的球形晶体部分转变为未成熟的肾状或豆状晶体。采用等温球晶生长速率法研究了PP和纳米复合材料的结晶动力学，并根据Lauritzen-Hoffman理论计算了PP和纳米复合材料的成核常数Kg和端表面自由能σe。这两个参数的降低与纳米复合材料中PP的结晶速率高于原始聚合物的结晶速率一致。
Thermoplastic nanocomposites were prepared in a laboratory mixer using polypropylene (PP) and different amounts of single-walled carbon nanotubes (SWNT) in the range 0.25–2wt%. The effect of SWNT content on the thermal and mechanical properties and also morphology of the PP/SWNT nanocomposites were studied. The results obtained from nonisothermal crystallization of PP and the nanocomposites, which were carried out using the differential scanning calorimetry technique, showed that not only the overall rate of crystallization of PP increased when SWNT was added to the polymer but also the rate of nucleation was higher and the crystallite size distribution was more uniform for the nanocomposites than for PP. From the optical microscopy studies, it was found that the PP spherulites decreased in size when SWNT was introduced into the polymer and also the mature spherical shaped crystals of PP changed in part to the immature kidney- or bean-shaped crystal forms in the nanocomposites. In addition, the crystallization kinetics was also studied by using isothermal spherulitic growth rate, and the values of nucleation constant, Kg, and end surface free energy, σe, were calculated for PP and the nanocomposites according to Lauritzen–Hoffman theory. The reductions of these two parameters were in agreement with the fact that the rate of crystallization of PP in nanocomposites was higher than that of the pristine polymer.