Synthesis and characterization of poly(butylene adipate-L-lactide-butylene terephthalate)

Poly(butylene adipate-L-lactide-butylene terephthalate) (PBLAT) was synthesized via a two-step method using terephthalic acid (PTA), adipic acid (AA), 1,4-butanediol (BDO), and L-lactide (L-LA) as polymerization monomers. The structure and properties of PBLAT affected by the content of L-LA were characterized by FTIR, 1 H-NMR, 13 C-NMR, GPC, XRD, DSC, and TG. The FTIR and NMR analyses confirmed that the structure of PBLAT conformed to the intended molecular design. GPC results showed that the number-average molecular weight ( \(\stackrel{-}{{M}_{n}}\) $\stackrel{-}{M_n}$ ) of PBLAT was between 13,026 and 23,246. The contact angle of all samples was less than 70°, demonstrating that the addition of L-LA enhanced the hydrophilicity of samples. DSC results showed that with an increase in L-LA content, the glass transition temperature (T_g) of PBLAT increased gradually, and the crystallinity initially increased before decreasing, which was consistent with the results of XRD. The highest 5% weight loss temperature of PBLAT was 343.0 °C, indicating that PBLAT has good thermal stability.