Thicker Lamellae and Higher Crystallinity of Poly(lactic acid) via Applying Shear Flow and Pressure and Adding Poly(ethylene Glycol)

The Journal of Physical Chemistry. B
Jia-Feng RuZhong-Ming Li

Abstract

In this work, we explored the crystallization of poly(lactic acid) (PLA) blended with poly(ethylene glycol) (PEG) under two inevitable processing fields (i.e., flow and pressure) that coexist in almost all processing for the first time. Here, the PEG was incorporated into PLA as a molecular chain activity promoter to induce PLA crystallization. A homemade pressuring and shearing device was utilized to prepare samples and necessary characterization methods, such as differential scanning calorimetry, scanning electron microscopy, and synchrotron radiation, and were used to investigated the joint effects of PEG, pressure, and shear flow on the crystallization behaviors and morphologies of PLA/PEG samples. The results reveal that adding 3-5 wt % PEG into PLA can significantly increase the PLA crystallinity due to the efficient plasticization effect of PEG, while the PEG content reaches 10 wt %, the PLA crystallinity decreases drastically as the phase separation between PEG and PLA occurs. We also find that applying a higher pressure (∼100 MPa) can facilitate the formation of thicker lamellae with fewer defects as well as higher crystallinity under an equal degree of supercooling compared to normal pressure or a low pressure conditi...Continue Reading

References

Aug 6, 2002·Science·Richard A Gross, Bhanu Kalra
Feb 26, 2004·Angewandte Chemie·Stefan Mecking
Jan 10, 2006·Biomacromolecules·Long JiangJinwen Zhang
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Nov 17, 2012·ACS Applied Materials & Interfaces·Huan XuZhong-Ming Li
Mar 1, 2014·Advanced Materials·Guoming LiuDujin Wang

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