Biobased additive plasticizing Polylactic acid (PLA)

Abstract

SbstractPolylactic 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 (T g ), 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.

Crystallization of triethyl‐citrate‐plasticized poly(lactic acid) induced by chitin nanocrystals

“…The DSC curve of PLA showed T g , T cc , and T m at 62, 101, and 174 C, respectively, which are typical of semicrystalline polymers and similar to values reported in the literature. 9 Maiza et al 4 reported the same trend in their study of the plasticizing effect of TEC on the properties of PLA; they observed that T g decreased with an increase in the TEC content. This lowering of T g , T cc , and T m of PLA is attributed to the plasticizing effect of the plasticizer, that is, TEC.…”

“…4 Plasticizers promote the growth rate of crystallites 5 and act as processing aids 6 ; they also enhance the flexibility and ductility of polymer materials. 4 Plasticizers promote the growth rate of crystallites 5 and act as processing aids 6 ; they also enhance the flexibility and ductility of polymer materials.…”

Combined effect of a plasticizer and carvacrol and thymol on the mechanical, thermal, morphological properties of poly(lactic acid)

“…Because of its low molecular size, the plasticizer occupied the intermolecular spaces between the polymer chains. It reduced the energy for molecular motion and the formation of hydrogen bonding between the polymer chains and increased the free volume and molecular mobility . The addition of ATBC also affected T m and X c .…”

“…PLA was dried at 80 °C for 24 h in a vacuum oven before it was processed by melt blending . Materials with various formulations (Table ) were used to prepare the composites.…”

“…It is nontoxic and confirmed for use as an additive in food, personal care products, and medical plastic applications. They have good solubility in PLA because of polar interactions between the ester groups of PLA and the plasticizer . Acetyl tributyl citrate (ATBC) is a citrate ester plasticizer obtained from naturally occurring citric acid; it is accepted for contact with food products and has been demonstrated to effectively plasticize PLA …”