Solid-State Drawing of Commercial Poly(Lactic Acid) (PLA) Based Filaments

Julian Walker,Mariana Melaj,Celina Bernal,Ezequiel Pérez,Rocio Giménez

doi:10.3389/fmats.2019.00280

Julian Walker, Mariana Melaj + Show 3 more

Open Access

https://doi.org/10.3389/fmats.2019.00280

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Abstract

In the present work, solid-state drawing of commercial PLA-based extruded filaments was investigated. Two different filaments were used: one based on neat PLA and the other based on PLA filled with copper particles. The effect of the processing parameters such as the drawing temperature and the draw ratio on the material morphology and thermal and mechanical behavior was analyzed. A specially designed device which simulates the solid-stated drawing stage frequently used for fibers manufacturing was applied. The drawing effects were evidenced by the results of the degree of crystallinity and tensile parameters, as well as by SEM analysis and topographical observations of the surfaces of the filaments. From these results, it was concluded that the draw ratio is more important than the drawing temperature as a determining factor of the tensile performance of the PLA-based filaments investigated. However, the drawing temperature plays a key role to establish the critical draw ratio to obtain stable solid-state drawing.

Highlights

The production of high-modulus and high-strength polymeric fibers has been the subject of many investigations for a long time focusing on different types of polymers such as polyethylene terephthalate (PET) (Rudolf et al, 2012), polyethylene (PE) (D’Amato et al, 2012) or aramid resins (Mai et al, 2015), among others.Melt spinning is one of the most widely used processes for fibers production at industrial level (Walczak, 2002)
The filaments were drawn at fixed temperatures up to different draw ratios to obtain the processing window to warrant that significantly long segments can be drawn in a stable condition
The undrawn filament and the filament drawn at 100◦C and draw ratio (DR) = 3.5 displayed the cold crystallization peak due to the lower level of ordering induced by drawing at higher temperatures without significant restriction to molecular relaxation, leading to cold crystallization during heating in Differential Scanning Calorimetry (DSC) (Gupta et al, 2007)

Summary

Introduction

The production of high-modulus and high-strength polymeric fibers has been the subject of many investigations for a long time focusing on different types of polymers such as polyethylene terephthalate (PET) (Rudolf et al, 2012), polyethylene (PE) (D’Amato et al, 2012) or aramid resins (Mai et al, 2015), among others.Melt spinning is one of the most widely used processes for fibers production at industrial level (Walczak, 2002). Samples drawn at a higher draw ratio (DR = 5.5), on the other hand, presented a different tensile behavior exhibiting much more significant strain hardening as a result of the higher degree of chain orientation induced by solid-state drawing at this DR (Lin et al, 2019).

Results

Conclusion