Content area
Full text
Abstract. PLA bio-blends with a predominantly biosourced PA10.10 in the composition range 10-50 wt% were prepared by melt blending in order to overcome the advanced brittleness of PLA. Due to the inherent immiscibility of the blends, 30 wt% of PA was needed to achieve a brittle-to-ductile transition and a co-continuous morphology was predicted at 58 wt% of PA. The initial enhancement of the PLA rheological behaviour through the environmentally friendly reactive extrusion process yielded a finer and more homogeneous microstructure and hence enhanced the mechanical properties of the bio-blends at much lower PA contents. The brittle-to-ductile transition could be achieved with only 10 wt% and co-continuity was observed already at 44 wt% of PA. Results indicate the significant potential of modifying PLA flow behaviour as a promising green manufacturing method toward expanding PLA-based bio-blends applications.
Keywords: biopolymers, rheology, material testing, mechanical properties
(ProQuest: ... denotes formulae omitted.)
1. Introduction
Poly (lactic acid) (PLA) is the front runner in the emerging bio-based and compostable plastic market. Initially, PLA has been viewed as a good alternative to commercial polymers for commodity applications (i.e. packaging). Unfortunately, its advanced brittleness at room temperature (RT) has been its major disadvantage for its implementation into high-value and durable applications (i.e. electronic or automotive).
Blending PLA with other engineering soft polymers represents an industrially relevant strategy for developing bio-based formulations with tailored performances [1]. Specifically, numerous works report the investigation of melt blending PLA with polyamides (PA) [2-7]. However, the inherent immiscibility of this binary polymer system results in rather poor mechanical properties. To overcome the aforementioned issue, Pai et al. [3] as well as Patel et al. [7] reported the first intents to compatibilize PLA/PA blends by adding titanium isopropoxide and a low molecular weight (Mw) epoxy resin, respectively. Unfortunately, a high PA content (>50 wt%) is needed to change the blend morphology from droplet-matrix to co-continuous in order to improve the mechanical properties [4, 6, 7]. Therefore, PLA/PA blends with a predominant PLA content still exhibit brittleness.
Polymer blends exhibiting a fine-tuned morphology with a significant reduced droplet size of the minor phase are promising due to their enhanced toughness in comparison to coarse sea-island morphologies [8]. Nuzzo et al. [6] reported the use of a third component (i.e....