Biobased additive plasticizing Polylactic acid (PLA)

Mounira Maiza,Guilhem Quintard,Mohamed Tahar Benaniba,Valerie Massardier-Nageotte

doi:10.1590/0104-1428.1986

Abstract

Polylactic acid (PLA) is an attractive candidate for replacing petrochemical polymers because it is from renewable resources. In this study, a specific PLA 2002D was melt-mixed with two plasticizers: triethyl citrate (TEC) and acetyl tributyl citrate (ATBC). The plasticized PLA with various concentrations were analyzed by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), melt flow index (MFI), thermogravimetric analysis (TGA), X-ray diffraction (XRD), UV-Visible spectroscopy and plasticizer migration test. Differential scanning calorimetry demonstrated that the addition of TEC and ATBC resulted in a decrease in glass transition temperature (Tg), and the reduction was the largest with the plasticizer having the lowest molecular weight (TEC). Plasticizing effect was also shown by decrease in the dynamic storage modulus and viscosity of plasticized mixtures compared to the treated PLA. The TGA results indicated that ATBC and TEC promoted a decrease in thermal stability of the PLA. The X-ray diffraction showed that the PLA have not polymorphic crystalline transition. Analysis by UV-Visible spectroscopy showed that the two plasticizers: ATBC and TEC have no effect on the color change of the films. The weight loss plasticizer with heating time and at 100°C is lesser than at 135 °C. Migration of TEC and ATBC results in cracks and changed color of material. We have concluded that the higher molecular weight of citrate in the studied exhibited a greater plasticizing effect to the PLA.

Highlights

Biobased polyesters have attracted much attention due to citrate esters[11,12,13,14,15], oligomeric lactic acid[16] and triacetine[14,16].their biodegradability and biocompatibility which offer clear There are several important considerations when choosing advantages for both customers and environment
At 30% of triethyl citrate (TEC) and acetyl tributyl citrate (ATBC), the glass transition of Polylactic acid (PLA) decreases from 62.23 °C to 17.49 °C and to 26.91 °C, respectively. These values of glass transition temperature (Tg) obtained by Dynamic mechanical analysis (DMA) have the same tendency of the results found by the Differential scanning calorimetry (DSC), where Tg is decreased by the addition of plasticizer
The thermal properties of plasticized PLA shows that TEC and ATBC are effective in lowering the glass transition temperature (Tg), the melting temperature (Tm) and the cold crystallization temperature (Tcc) of the PLA

Summary

Introduction

Biobased polyesters have attracted much attention due to citrate esters[11,12,13,14,15], oligomeric lactic acid[16] and triacetine[14,16]. Their biodegradability and biocompatibility which offer clear There are several important considerations when choosing advantages for both customers and environment. In recent a plasticizer for PLA for biomedical applications It should years, Polylactic acid (PLA) is one of the most promising be a nontoxic substance miscible with the polymer, candidates as partial alternative of petrochemical polymers creating a homogeneous blend. From petroleum resources, which are rarely used alone by which have been proved as effective plasticizers for PLA, themselves, and needs to improve some properties by an citrate esters are used as plasticizers with a variety of inclusion of additives[2]

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Conclusion