Poly(D-lactic acid) as a rheological modifier of poly(L-lactic acid): Shear and biaxial extensional flow behavior
Poly(D-lactic acid) as a rheological modifier of poly(L-lactic acid): Shear and biaxial extensional flow behavior
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DOI：
10.1122/1.1687736
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发表时间：
2004-05
影响因子：
3.3
通讯作者：
H. Yamane;K. Sasai;M. Takano;Masaoki Takahashi
中科院分区：
文献类型：
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作者：
H. Yamane;K. Sasai;M. Takano;Masaoki Takahashi
研究了添加少量聚(D-乳酸)(PDLA)对聚(L-乳酸)(PLLA)熔体流变学的影响。添加到 PLLA 中的 PDLA 产生立体复合物，即使高于 PLLA 的 Tm，该立体复合物也不会熔化。由于组分聚合物的含量不平衡，立体络合物不会生长成大的微晶，而是充当PLLA链的交联点，导致长链支化的明显引入以及分子量的明显增加。分子结构的这种变化引起熔体流变学的变化，具体取决于PDLA的含量和分子量。添加低分子量的 PDLA 会显着影响 PLLA 熔体的剪切流变性，而高分子量的 PDLA 则不会产生如此显着的影响。然而，即使在 PDLA 含量非常低的情况下，添加具有高和低 Mw 的 PDLA 也会使 PLLA 熔体具有很强的应变硬化特性。
The effect of addition of a small amount of poly(D-lactic acid) (PDLA) on the melt rheology of poly(L-lactic acid) (PLLA) was investigated. PDLA added to PLLA produces a stereocomplex which stays unmelted even above Tm of PLLA. Because of the imbalanced contents of component polymers, the stereocomplex does not grow into a large crystallite but rather acts as a crosslinking point of PLLA chains resulting in the apparent introduction of the long chain branching as well as in the apparent increase in molecular weight. Such changes in the molecular structure give rise to the change in the melt rheology depending on the content and the molecular weight of PDLA. The addition of low Mw PDLA significantly affects the shear rheology of PLLA melts while high Mw PDLA does not give such a significant effect. However, the addition of PDLA with high and low Mw’s gives a strong strain hardening character to PLLA melt even at a very low PDLA content.