Synthesis and Use of Glycerol Based Hyperbranched Biopolyesters as Impact Modifiers for Poly (Butylene Succinate) Matrix
Glycerol sources of different purity and succinic acid were employed for the synthesis of hyperbranched polyesters. Biobased polymers termed poly (glycerol succinate) (PGS) were obtained by polycondensation. The aim of this research was to determine the influence of impurities of glycerol source on the chemical and mechanical properties of PGS. It was found that the presence of free fatty acid residues in glycerol source is increasing the glass transition temperature of polyesters and decreasing their cross-linking density due to the incorporation of fatty acid residues to PGS structure. By these reasons, only high purity glycerol (>98% glycerol content) based PGS could effectively improve impact properties of poly (butylene succinate) (PBS) showing a 3-fold increment on impact strength while tensile strength was reduced to half original value of virgin PBS. These results show that efficient biobased impact modifiers for bioplastics can be obtained using biodiesel derived glycerol purified to high extent.