This work involved the development of a synthetic method to produce a novel bio-based triblock
copolymer (PLA-NR-PLA) that consisted of poly(lactic acid) and natural rubber. The 1
H NMR analysis
showed the presence of new ester linkages that resulted from a reaction between the carboxyl endgroups
of the PLA prepolymer and the hydroxyl end-groups of the HTNR, together with the characteristics
of the PLA endblock and the HTNR midblock. The Mn of PLA-NR-PLA as determined from the GPC
agreed with that from the calculation. The DSC and TGA results also substantiated the formation of a
block copolymer. PLA-NR-PLA acted as a toughening agent for PLA and as a compatibilizer in the PLA/NR
blend. The PLA-NR-PLA was as good as a toughening agent as NR although the PLA-NR-PLA had a much
lower molecular weight than the NR. The compatibilization effect was more dominant in the blend
containing 10% rubber than in the blend that contained >10% rubber. The compatibilization effect was
also observed in the morphology of the blend as a reduction in the rubber particle diameter. PLA-NR-PLA
not only increased the impact strength of the blends, but also increased the elongation at break.