Rheology and crystallization of long-chain branched poly(l-lactide)s with controlled branch length
Rheology and crystallization of long-chain branched poly(l-lactide)s with controlled branch length
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DOI：
10.1021/ie300524j
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发表时间：
2012-08
影响因子：
4.2
通讯作者：
Liangyan Wang;X. Jing;Haibo Cheng;Xiuli Hu;Lixin Yang;Yubin Huang
中科院分区：
文献类型：
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作者：
Liangyan Wang;X. Jing;Haibo Cheng;Xiuli Hu;Lixin Yang;Yubin Huang
通过丙交酯的开环聚合和聚乳酸预聚物末端羟基与HDI的NCO基团的偶联反应，合成了一系列分支长度可控的长支链聚乳酸（LCB-PLA）。考察了反应条件对LCB-PLA合成的影响，并通过1H NMR和SEC-MALLS对产物的结构进行了表征。通过调节预聚物的聚合度和组成，得到了不同分支密度和分支点间分子量的LCB-PLA。研究了大分子链支化对聚乳酸流变性能和结晶性能的影响。LCB结构有助于提高零剪切粘度，复数粘度，储能模量，熔体强度和拉伸流动下的应变硬化。热行为表明，该分支结构具有较好的热稳定性。
A series of long-chain branched poly(l-lactide)s (LCB-PLAs) with controlled branch length were prepared by a simple and efficient method through a combination of ring-opening polymerization (ROP) of l-lactide and a coupling reaction between the terminal OH groups of the PLA prepolymers and the NCO groups of HDI. The influences of reaction conditions on the synthesis of the LCB-PLAs were investigated, and the structures of the resultant LCB-PLAs were characterized by 1H NMR spectroscopy and SEC-MALLS. By adjusting the degree of polymerization and the composition of the prepolymers, LCB-PLAs with different branch densities and molecular weights between branch points were obtained. The effect of macromolecular chain branching on the rheology and crystallization of PLA was also investigated. The LCB structure contributed to the enhancement of the zero-shear viscosity, complex viscosity, storage modulus, melt strength, and strain hardening under elongational flow. Thermal behavior indicated that the branch str...