Issue 2, 2017, Issue in Progress

Effect of uniaxial pre-stretching on the microstructure and mechanical properties of poly[(ethylene oxide)-block-(amide-12)]-toughened poly(lactic acid) blend

Abstract

Highly oriented poly(lactic acid) (PLA)/20 wt% poly[(ethylene oxide)-block-(amide-12)] (PEBA) blends were prepared via uniaxial pre-stretching technology at 60 °C and 25 °C to improve the mechanical properties of PLA. For the pre-stretching process at 60 °C, the tensile strength and modulus of the pre-stretched PLA/PEBA blend dramatically increased with the increasing pre-stretching ratio (PSR), whereas the elongation at break for all the pre-stretched specimens was much higher than that of the neat PLA, suggesting that PEBA had an excellent toughening effect for PLA under uniaxial pre-stretching. The integrated morphological and structural analyses based on scanning electron microscopy (SEM) and wide-angle X-ray diffraction (WAXD) indicated that the amorphous PLA phase started to develop orientation, mesophase, and even defective α crystal as parts of the key structure from the strengthening and stiffening effect by pre-stretching. Compared to the pre-stretching process at 60 °C, the strengthening and stiffening effect was abated for the blend pre-stretched at 25 °C. Moreover, the elongation at break significantly decreased with the increasing PSR, indicating that the pre-stretched blend in the hot pre-stretching process (60 °C) had more outstanding toughness than that in the cold pre-stretching process (25 °C). The possible reason for this is that the crack and pore defects formed during the pre-stretching process at 25 °C severely restricted the improvement of the mechanical properties of the blend. The thermal behavior of the pre-stretched blend tested by differential scanning calorimetry (DSC) showed that on increasing the PSR, glass transition temperature increased, cold-crystallization temperature decreased, and the degree of crystallinity increased, which further demonstrated the formation of the orientation or crystallization by pre-stretching.

Graphical abstract: Effect of uniaxial pre-stretching on the microstructure and mechanical properties of poly[(ethylene oxide)-block-(amide-12)]-toughened poly(lactic acid) blend

Supplementary files

Article information

Article type
Paper
Submitted
25 Oct 2016
Accepted
28 Nov 2016
First published
03 Jan 2017
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2017,7, 712-719

Effect of uniaxial pre-stretching on the microstructure and mechanical properties of poly[(ethylene oxide)-block-(amide-12)]-toughened poly(lactic acid) blend

Y. Chen, L. Han, Z. Li, J. Kong, D. Wu, Z. Cao and L. Dong, RSC Adv., 2017, 7, 712 DOI: 10.1039/C6RA25729A

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