Development of polylactide bead foams with double crystal melting peaks
Development of polylactide bead foams with double crystal melting peaks
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DOI：
10.1016/j.polymer.2015.05.048
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发表时间：
2015-07-09
期刊：
影响因子：
4.6
通讯作者：
Park, Chul B.
中科院分区：
文献类型：
--
作者：
Nofar, Mohammadreza;Ameli, Aboutaleb;Park, Chul B.
在这项研究中，我们报告的聚乳酸（PLA）珠状泡沫的发展与双晶熔融峰结构。制备了具有3- 30倍膨胀比和平均泡孔尺寸范围为350 nm-15 μ m的PLA珠泡沫。我们发现，PLA的泡沫结构受到CO2饱和过程中产生的完美晶体（即具有高熔融温度的晶体）数量的显著影响。该结构还受到在发泡和冷却过程中形成的具有低熔融温度的晶体的影响。不同的CO2压力进一步影响结晶动力学的晶体与高熔融温度在饱和。在不同压力下，不同的结晶动力学也显著影响PLA泡沫的泡孔形态及其均匀性。在较高的饱和压力下，PLA中溶解的CO2含量的增加通过增加热力学不稳定性程度来促进泡孔成核速率。另一方面，在高压下，小尺寸的完美晶体被诱导为高熔点峰晶体。因此，这些晶体周围的异相泡孔成核得到进一步改善，这也导致产生更均匀的泡沫结构。此外，这项研究介绍了这种珠泡技术作为一种创新的新方法来生产纳米泡孔泡沫产品。(C)2015爱思唯尔有限公司版权所有。
In this study, we report the development of polylactide (PLA) bead foams with a double crystal melting peak structure. PLA bead foams with 3- to 30-fold expansion ratios and average cell sizes ranged from 350 nm to 15 mu m were prepared. We found that the PLA's foam structure was significantly affected by the amount of perfected crystals (that is, crystals with a high melting temperature) generated during CO2 saturation. The structure was also affected by crystals with a low melting temperature that formed during foaming and cooling. Various CO2 pressures further influenced the crystallization kinetics of the crystals with a high melting temperature during the saturation. At various pressures, different crystallization kinetics also significantly affected the PLA foam's cell morphology and its uniformity. At a high saturation pressure, the increased content of dissolved CO2 in the PLA promoted the cell nucleation rate through the increased degree of thermodynamic instability. On the other hand, at high pressures, small-sized perfect crystals were induced as high-melting peak crystals. Thus, the heterogeneous cell nucleation around these crystals was further improved, which also caused the generation of a more uniform foam structure. Moreover, this study introduces this bead foam technology as an innovative new way to produce nanocellular foam products. (C) 2015 Elsevier Ltd. All rights reserved.