Polylactide (PLA) and acrylonitrile butadiene rubber (NBR) blends: The effect of ACN content on morphology, compatibility and mechanical properties

- Elasticity and complex viscosity of NBR increased with ACN content.
- Slopes of Cole-Cole and Han plots of PLA/NBR for lower ACN is higher.
- Interfacial tension between PLA and NBR increased with ACN content.
- Rubber particle size increased with ACN content.
- Impact strength and elongation properties of the blend significantly improved by adding 10 wt% NBR.

In this study, attempts have been put to prepare toughened polylactide (PLA) through melt blending with acrylonitrile butadiene rubber (NBR) via melt mixing process. The influences of acrylonitrile (ACN) content on the compatibility, microstructure, tensile properties and impact resistance have been investigated. A matrix-dispersed droplet morphology was noted for all blend samples, and the rubber particle size decreased with decreasing ACN content of NBR. This droplet size, impact strength and elongation all corresponded well to the interfacial interaction that was evidenced by surface tension analysis and melt rheology. It was noted that the interfacial tension decreased with decrease in ACN content, accordingly, the results from both Cole-Cole curves and Han plots indicated high homogeneity of the PLA blend with NBR containing lower ACN contents. On the other hand, all blends exhibited very similar glass transition temperatures and crystallinity. It is concluded that extent of thermodynamic compatibility of PLA and NBR determines the improvement of toughness. Incorporation of only 10 wt% NBR resulted in dramatic improvements of elongation at break and impact strength of PLA and largely retained the high tensile strength of neat PLA.

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