# Poly(lactic acid)-Based Blends: A Comprehensive Review
## 8 Conclusions  
In this review, the positive aspects of using poly(lactic acid) blends with other fossil- and biobased polymers to improve a complex of physical-mechanical, diffusion-transport properties and biodegradation were studied. As a rule, most of polymer-polymer blends are considered thermodynamically incompatible. In case of polyesters such as poly(lactic acid), due to the presence of polar groups, blended polymers have a fairly strong intermolecular interaction by the mechanism of hydrogen bond formation. In turn, a high intermolecular interaction in PLA-other polymers blends induces an increase in miscibility of polymers and homogeneity of the materials structure, as well as an improvement of mechanical properties. In the numerous studies conducted, an effectiveness of the modification of PLA with various polymers to increase its elasticity, impact strength, heat resistance, rheological properties and biodegradation have been shown. The most promising modifiers for PLA are flexible-chain polymers, including poly(\(\varepsilon\)-caprolactone), poly(glycolic acid), poly(butylene adipate-co-terephthalate) and poly(ethylene-vinyl acetate). The blends PLA with poly(3-hydroxybutyrate) are also considered as the most promising for the creation of biocompatible and bioresorbable materials. The use of various oils, oligomers, and other liquid surfactants for PLA plasticization has a short-term effect associated with the intensive migration of these substances from the polymer matrix. According to a number of studies, PCL, PBAT, and EVA, when processed in the melt, can improve the processability \begin{table}
\begin{tabular}{c c c c c c c c c} \hline
**Polymer** & **Morphology** & **Tensile Strength,** & **Elongation** & **Elastic** & **Impact** & **Degree of** & **Degradation** & **Researchers** \\
**Systems** & **(SEM)** & **MPa** & **at Break, \%** & **MPa** & **kJ/m\({}^{2}\)** & **Crystallinity, \%** & **Degradation** & **Temperature, \({}^{*}\)C** & **Researchers** \\ \hline
80 PLA/20 PCL & & 68 \(\pm\) 2 & 20 \(\pm\) 2 & 2600 \(\pm\) 100 & 37 \(\pm\) 1 & 62.39/28.63 & 361.93 \(\pm\) 2.65 & [33] \\
80 PLA/20 PGA & & 130 & 22.6 & 3.9 & - & 39/35 & 354 & [50,119,120] \\
80 PLA/20 PBAAT & & 38.95 \(\pm\) 1.21 & 387.85 \(\pm\) 26.88 & 2250 & 4.85 \(\pm\) 0.27 & 39 & 422.9/378.7 & [121,122] \\
80 PLA/20 PBAAT & & 45 & 340 & 64 & 8.28 \(\pm\) 0.11 & 3.8 & 331 & [87,90] \\
75 PLA/25 PHB & & 16 \(\pm\) 3 & 7.1 \(\pm\) 1 & 1270 \(\pm\) 110 & 2.5 \(\pm\) 0.5 & 36 & 356/283 & [98,104] \\ \hline \end{tabular}
\end{table} 
Table 1: The main characteristics of blends based on PLA. and have a plasticizing effect on PLA. In addition to that, it has been proven that flexible chain polymers have a significant effect on the structural and dynamic properties of PLA, which are expressed in a change of crystallinity and crystallites size. Polyesters that are more susceptible to hydrolysis, such as PCL, PBAT, and PHA, can accelerate the biodegradation of PLA under nature and living conditions. PHA, first of all, PHB, are the most effective; however, these polymers cannot improve the physical and mechanical properties of PLA. In the near future, it is possible to predict the development of environmentally friendly multicomponent polymer blends based on PLA for a combination of high relative elongation, strength, and impact strength, on the one hand, and manufacturability during processing, on the other hand. Conceptualization, E.E.M. and A.A.O. ; methodology, L.I.V. ; software, M.V.P. ; validation, L.I.V., E.E.M. and A.A.O. ; formal analysis, A.A.O. ; investigation, L.I.V. ; resources, M.V.P. ; data curation, E.E.M. ; writing--original draft preparation, E.E.M. ; writing--review and editing, E.E.M. and A.A.O. ; visualization, M.V.P. ; supervision, A.A.O. ; project administration, E.E.M. ; funding acquisition, A.A.O. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable.