Effect of Green Plasticizer on the Performance of Microcrystalline Cellulose/Polylactic Acid Biocomposites

Abstract

In this study, we present the development of eco-friendly biocomposites composed of polylactic acid (PLA) and microcrystalline cellulose (MCC), using melt extrusion and compression molding processes. In all the studied samples, the PLA/MCC ratio was always 1:1, whereas the plasticizer triethyl citrate (TEC) was responsible for the improved dispersion of the MCC in PLA. Tensile tests proved that the developed biocomposites containing TEC show improved ductility and crystallinity, as confirmed by the X-ray diffraction (XRD) study. Furthermore, the water vapor and oxygen permeability of the biocomposites were found to decrease as the TEC content increases in the formulation. Nonetheless, migration analyses to a dry food simulant prove that the migration of TEC is slightly above the acceptable limits when biocomposites with 15 wt % TEC were used. Taking this into account, in combination with the ranking of all the developed biocomposites according to their performance through the technique for order of preference by similarity to ideal solution (TOPSIS) analysis, we concluded that the PLA/MCC samples with 10 wt % TEC can be considered the most suitable biocomposites for eco-friendly food packaging applications. These findings place the developed PLA/MCC biocomposites among the strong candidates for biobased food packaging materials able to be produced at a large scale following industrially applicable methods since they are cost-effective and have improved properties compared to the pure biopolymer.

Super Tough Polylactic Acid Plasticized with Epoxidized Soybean Oil Methyl Ester for Flexible Food Packaging

“…These results are in a good agreement with the migration test performed on PLA plasticized with several levulinic acid derivatives, which demonstrated that more polar plasticizers can migrate almost completely out of the PLA in pure water, water containing 10 vol % of ethanol, or 3 wt % of acetic acid . Triethyl citrate (TEC)-plasticized PLA showed similarly high migration into Tenax solid food simulants and the samples containing more than 10 wt % of TEC exceeded the migration limit . The results show that ESOME-plasticized PLA can be used directly for packaging of water and other hydrophilic liquids and foods like fruit juices.…”

“…51 Triethyl citrate (TEC)-plasticized PLA showed similarly high migration into Tenax solid food simulants and the samples containing more than 10 wt % of TEC exceeded the migration limit. 52 The results show that ESOMEplasticized PLA can be used directly for packaging of water and other hydrophilic liquids and foods like fruit juices. Alternatively, it could be aluminized or used in multilayer structures to prevent the migration into solid and lipophilic foods.…”

“…Initially small amounts of the ESOME plasticizer (5–10 wt %) significantly increased the chain mobility of PLA through which water molecules can diffuse faster, increasing the WVP. With higher ESOME content the phase separation is observed (Figure ) and it seems that ESOME droplets have a much higher water vapor barrier then PLA, increasing the tortuosity of the diffusion path. , In comparison to the semicrystalline PLA grades like 2003D (OP ∼25 (cm 3 mm)/(m 2 24 h) and WVP ∼ 114 (g mm)/(m 2 24 h)), the amorphous grade used in this study has similar barrier properties . Typically increased crystallinity decreases the permeability acting as a barrier, however.…”

Expanding Poly(lactic acid) (PLA) and Polyhydroxyalkanoates (PHAs) Applications: A Review on Modifications and Effects

“…Paul et al [ 168 ] reported the development of PLA/microcrystalline cellulose (MCC) bio composites via melt extrusion and compression molding. Triethylcitrate (TEC) was used as a plasticizer as well as to enhance the dispersion of the microcrystalline cellulose in the PLA matrix.…”

“…Results showed improvements in crystallinity and ductility. Results of the mechanical and migration properties suggested that PLA/MCC bio composites with 10 wt.% TEC is the most suitable combination for ecofriendly food packaging applications [ 168 ].…”