Key words: amorphous polylactide, carbon dioxide, foaming, nucleation
The features of the formation, development and stabilization of the structure of foamed amorphous D,L-polylactide during slow (quasi-isothermal) and fast (quasi-adiabatic) pressure relief of supercritical carbon dioxide used as a plasticizing/foaming agent have been investigated. The following regularities have been established: 1) the values of the foam expansion factor during quasi-adiabatic depressurization are significantly lower than in the quasi-isothermal regime due to significant dissi pation of the internal energy of the «polymer—foaming agent» system due to internal friction in the system; 2) an expansion-collapse effect is observed with quasi-isothermal foaming; 3) at an intermediate stage between nucleation and intensive development of foam, the growth of pore nuclei in the plasticized polymer has a self-similar character. The results obtained are significant for the selection of foaming modes that provide the required structural characteristics of the synthesized highly porous matrices intended for use in regenerative medicine and tissue engineering.
doi:10.34984/SCFTP.2021.16.2.012