# Recent Approaches to the Plasticization of Poly(lactic Acid) (PLA) (A Review)
## 3 Compounding with Flexible Polymers (Blends)
At the same time, the glass transition temperature of the PLA phase is depressed, as the PLA-b-PC addition induces partial miscibility between PLA and PCL [54]. Figure 4 schematically shows the architecture of PLA blends with flexible polymers without/with the use of a compatibilizer. Since the flexible polymer content is usually no more than 30 wt%, the materials have a structure in the form of a PLA matrix with domains dispersed inside it (dispersed phase) of the flexible polymer. If present, the compatibilizer concentrates at the interface. The size and degree of dispersion of domains depend not  
only on the ratio of polymers but also on the technology for obtaining the materials and the presence of compatibilizer. The biodegradability of aliphatic polyesters is caused by the hydrolytic cleavage of chains at the ester bonds of aliphatic units under the action of water and microbial enzymes. It is important to note that PLA, unlike PCL, PBAT and PBSA, is subjected to rapid hydrolysis only at elevated temperatures, which limits the conditions for its composting [55]. The addition of easily hydrolyzable flexible polyesters will provide a higher rate of PLA hydrolysis. The possibility of regulating the diffusion and barrier properties by varying the ratio of PLA and PBAT in mixtures [41; 56], as well as the type and content of plasticizer [57], has been proven. Thus, it is possible to create materials with different rates of release of active additives by changing the diffusion parameters of a polymer matrix based on PLA/PBAT or PLA/PBSA in different ratios. Blending PLA with flexible polymers is a common plasticization method to produce commercial products. It is widely known that a large-scale biodegradable polymer material produced by Novamont S.p.A. (Novara, Italy) under the Mater-Bi brand and its recipe is constantly undergoing changes. The patent for Novamont S.p.A. (CA 2662105 from 2008) [58] describes a biodegradable multiphase composition containing a continuous phase of a hydrophobic polymer (poly(esters) or poly(amides)), a dispersed phase of starch in the form of nanoparticles with sizes less than 0.3 \(\upmu\)m and an additional dispersed phase of a hard and brittle polymer with an elastic modulus of more than 1000 MPa (PHA, PLA or poly(glycolic acid) (PGA)). The US patent 8747971 from 2014 by BASF describes the general composition of the material based on 25-60 wt% of starch, 40-75 wt% of synthetic aliphatic-aromatic copolyester of the commercial product Ecoflex from BASF (Ludwigshafen, Germany), 6-15 wt% of glycerol [59]. The following polymers and their blends were used in different years as synthetic aliphatic-aromatic copolyesters, which are the main carrier matrix of the material: PLA, PCL, PBA, PBAT, and others. For example, a material under the Ecovio brand by BASF consists of the compostable BASF polymer Ecoflex (61-67 wt%), PLA (Ecopla, by Cargill, Neuss, Germany) (7-13 wt%), and other additives. The invention ensures the production of thin films by blown extrusion with an elastic modulus of more than 300 MPa.