Rheological, thermal and mechanical characterization of PBAT/PCL/Stearates blends

Jessé De Melo Silva,Laura Hecker De Carvalho,Fernanda Menezes De Sousa,Marcelo Augusto Gonçalves Bardi,Tatiara Gomes De Almeida

doi:10.33448/rsd-v11i3.26630

Jessé De Melo Silva, Laura Hecker De Carvalho + Show 3 more

Open Access

https://doi.org/10.33448/rsd-v11i3.26630

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Abstract

The slow degradation and the high environmental impact caused by inappropriate disposal of polymer products are the main factors prompting scientists to either substitute conventional polymers by biodegradable ones or to enhance biodegradation of short-lived polymer products, particularly those used in packaging. Polymer blends of conventional and biodegradable polymers is one of the alternative solutions found to improve mechanical properties and accelerate polymer degradation after disposal. This work investigates the effect of incorporating different metallic stearates (Zn and Mg) on the rheological, thermal and mechanical characteristics of 75PBAT/25PCL blends processed in an internal laboratory mixer. The results of torque rheometry suggest degradation during processing potentialized with the stearates incorporation, while that of DSC indicated that the crystallinity of the blends increased with the incorporation of additives. TG data showed a reduction in the thermal stability of the systems containing stearates. Incorporation of stearates resulted in strongly thermally degraded systems. Adding up to 0.25% of magnesium stearate to the blend 75PBAT/25PCL leads to a material that combines maintenance or improvement of properties combined with higher decomposition.

Highlights

Since the end of the 20th century, the search for polymeric materials that can replace polyolefins, maintain their mechanical properties as well as meeting market demands for competitiveness and economic viability, has been a challenge for science (Matta et al, 2018; Godavitarne et al, 2017)
The drop is more pronounced for blends containing magnesium, and in systems with a higher content of any of the stearates
The results show that, except for the blend containing 0.125% magnesium stearate, both torque and temperature of the 75PBAT/25PCL blend is higher than of those containing stearates

Summary

Introduction

Since the end of the 20th century, the search for polymeric materials that can replace polyolefins, maintain their mechanical properties as well as meeting market demands for competitiveness and economic viability, has been a challenge for science (Matta et al, 2018; Godavitarne et al, 2017). The interest in producing more sustainable products and the search for recyclable and/or less harmful materials to the environment after disposal has increased the use of biodegradable and compostable polymers significantly (Cesario et al, 2018). Consumers and governments started using these polymers as a potential alternative to reduce the volume of accumulated polymer in the short term in the environment, since these polymers besides being able to be recycled, can be composted and biodegraded in a relatively short time, without the products of its degradation affecting the soil negatively (Kijchavengkul et al, 2010; Avadi et al, 2011). (butylene-adipate-co-terephthalate) (PBAT) and poly (ε-caprolactone) (PCL) are biodegradable synthetic polymers, with different physical properties that, under ideal conditions of disposal, are relatively easy to decompose. PCL is a biodegradable aliphatic polyester with low melting point and high elasticity (Matta et al, 2014) often used as an additive in order to accelerate degradation of polymer composites and blends. According to Sousa et al (2018), PCL/PBAT blends are immiscible and show dispersed phase inversion at PCL content around 70% w/w

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