Chem. J. Chinese Universities ›› 2018, Vol. 39 ›› Issue (9): 2089.doi: 10.7503/cjcu20180006

• Polymer Chemistry • Previous Articles     Next Articles

Improving Crystallization Behavior and Melt Strength of Poly(lactic acid) via Adding Talc and PLA-g-MAH

HAN Jiahui, HUANG Hanxiong*(), HUANG Yuxiao   

  1. Lab for Micro/Nano Molding and Polymer Rheology, Key Laboratory of Polymer Processing Engineering of the Ministry of Education, South China University of Technology, Guangzhou 510640, China
  • Received:2018-01-03 Online:2018-07-30 Published:2018-07-30
  • Contact: HUANG Hanxiong E-mail:mmhuang@scut.edu.cn
  • Supported by:
    † Supported by the Natural Science Foundation of Guangdong Province, China(No.2016A030308018).

Abstract:

Talc and PLA-g-maleic anhydride(PLA-g-MAH) were added to polylactide(PLA) to simultaneously improve its melt strength, crystallinity(Xc) and mechanical properties. Using a single-screw extruder with a chaotic mixing screw developed in our group, the PLA-g-MAH was prepared via reactive extrusion. Its grafting rate is measured to be 1%. Then, a series of PLA/talc(5%, 10% and 20%, mass fraction) and PLA/talc(20%, mass fraction)/PLA-g-MAH(5% and 10%, mass fraction) composites were prepared using the same extruder. The chaotic mixing in the extruder effectively improves the dispersion of the talc in the PLA matrix, and the talc of up to 20% almost does not agglomerate. Adding the PLA-g-MAH into the composites reduces the voids and the gaps around the talc on the cyrofractured surfaces and improves the interfacial adhesion between the PLA and talc. For the PLA/talc(20%) composite samples with 10% PLA-g-MAH, the α crystal content of the PLA is increased obviously and its Xc is increased to 31.6%. At 175 ℃, the melt strength for the PLA sample is relatively low(3.6 mN), and it is obviously enhanced(11.6 mN) for the composite sample with 20% talc. The explanation for this is as follows. The well dispersed talc has a reinforcing effect on the PLA melt and increases the crystallization behavior of PLA; moreover, the draw-down force can improve both effects of the orientation-induced PLA crystallization and the increased PLA crystallization behavior by the added talc. Compared with the PLA sample, the PLA/talc(20%)/PLA-g-MAH(5%) sample exhibits increments of 51.7% and 16.9% for the Young’s modulus and impact strength, respectively.

Key words: Poly(lactic acid), Talc, Maleic anhydride, Composite, Crystallization behavior, Melt strength

TrendMD: