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Abstract

Different treatments of SnCl2 were utilized as a catalyst to synthesize poly (lactic acid) through direct polycondensation in solution. These treatments were in (i) a hydrous form (SnCl2.2H2O), (ii) an anhydrous form (SnCl2) and (iii) an impregnated form (SnCl2/g-Al2O3). The polycondensation was done at 138 0C and in nitrogen atmospheric with flow rate of 100 ml/min. L-lactic acid and a catalyst (1 wt. % of l-lactic acid) were mixed in solution of m-xylene and reacted in 500 ml flask. The maximum molecular weight (Mw) of obtained poly (lactic acid) was 104,392 Da after 72 hours with catalyst SnCl2/ ?-Al2O3. Grafting of obtained poly (lactic acid) chains into glycerol supported by hexametyl diisocyanate (HDMI) was successfully done. The grafted poly (lactic acid) had an average molecular weight three times higher than that of obtained poly (lactic acid). Infra-red spectra showed that the poly (lactic acid) can be produced using this synthesis technique and has molecular structure arranged mainly in amorphous phases. The maximum degree of crystallinity was found at 12.91% (DSC) or 14.56% (XRD) for obtained poly (lactic acid) with catalyst of SnCl2/ ?-Al2O3. These results showed that impregnation SnCl2 on ?-Al2O3 enhanced its performance to polymerize l-lactic acid and able to graft it into glycerol.