Nanocomposites Materials of PLA Reinforced with Nanoclays Using a Masterbatch Technology: A Study of the Mechanical Performance and Its Sustainability

Abstract

Packaging consumes around 40% of the total plastic production. One of the most important fields with high requirements is food packaging. Food packaging products have been commonly produced with petrol polymers, but due to environmental concerns, the market is being moved to biopolymers. Poly (lactic acid) (PLA) is the most promising biopolymer, as it is bio-based and biodegradable, and it is well established in the market. Nonetheless, its barrier properties need to be enhanced to be competitive with other polymers such as polyethylene terephthalate (PET). Nanoclays improve the barrier properties of polymeric materials if correct dispersion and exfoliation are obtained. Thus, it marks a milestone to obtain an appropriate dispersion. A predispersed methodology is proposed as a compounding process to improve the dispersion of these composites instead of common melt procedures. Afterwards, the effect of the polarity of the matrix was analyzing using polar and surface modified nanoclays with contents ranging from 2 to 8% w/w. The results showed the suitability of the predispersed and concentrated compound, technically named masterbatch, to obtain intercalated structures and the higher dispersion of polar nanoclays. Finally, the mechanical performance and sustainability of the prepared materials were simulated in a food tray, showing the best assessment of these materials and their lower fingerprint.

Nanoclay Effect into the Biodegradation and Processability of Poly(lactic acid) Nanocomposites for Food Packaging

“…However, the reduction has not the same trend in the case of 4% w / w reinforced nanocomposite, as the barrier properties against vapors were slightly improved from the 2 to the 4 w / w % reinforcement content. The results could be related to the higher agglomeration and lower intercalation effect in this nanocomposite, as it has been observed in previous work [ 20 ]. It is difficult to obtain an adequate intercalation of nanoclays by melt mixing methodologies.…”

“…Additionally, the huge differences in the polarity of the matrix and the reinforcement limit its dispersion. The differences in the intercalation were observed previously in another work [ 20 ]. The improvement in the barrier properties is still far from other plastics used for packagings such as polyethylene (PE), which has a poor affinity for water which enhances that property, or polyethylenetherephtalate (PET) [ 51 , 52 , 53 ].…”

“…The composites materials were produced as published in previous work [ 20 ]. In summary, a masterbatch methodology was used to facilitate the production and dispersion of the nanoclays by melt mixing.…”

“…Therefore, the fabrication of composite systems based on the structure of polyesters with hydrolytic susceptibility and reinforced with nanodispersed systems to induce barrier character is one of the potential ways to develop useful materials to be used as packaging. PLA is the most often used biodegradable polymer matrix [15][16][17][18][19][20][21], also including its copolymers [22,23], reinforced with nanostructured particles. In this sense, the nanoparticles that have demonstrated the best behavior against the diffusion of gases through the polymer are layered silicates and their organomodifications, due to their capacity to be exfoliated to promote intercalation between the polymer chains.…”

Development and Characterization of Pectin Films with Salicornia ramosissima: Biodegradation in Soil and Seawater

“…In recent decades, a considerable number of packaging films have been developed using biopolymers, such as proteins, and polysaccharides. More recently, the combination of clays, nanostructures, and other innovative materials has been studied for novel packaging applications [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. In addition to biopolymers, plant-derived bioactive compounds—such as essential oils, minerals, carotenoids, vitamins, and polyphenols, among others—have been used to modify the films’ antioxidant, antimicrobial, and physicomechanical properties [ 10 , 11 , 12 , 13 , 14 , 15 ].…”