Nucleating agent-containing P(LLA-mb-BSA) multi-block copolymers with balanced mechanical properties
In order to obtain high performance bioplastics and thermoplastic elastomers, P(LLA-mb-BSA) multi-block copolymers containing 30 wt % and 70 wt % soft segment (PLBSA30 and PLBSA70 for short) were synthesized via chain extension and coupling of poly(L-lactic acid) (PLLA) and poly(butylene succinate -co- adipate) (PBSA) prepolymers in the presence of 1% nucleating agent (NA). They were characterized with proton nuclear magnetic resonance ( 1 H NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), polarizing optical microscopy (POM), thermal gravimetric analysis (TGA), transmission electron microscope (TEM), and tensile and impact test. The relatively high molecular weights of ( M n 8200 g/mol and 3100 g/mol for PLLA and PBSA, respectively) the polyester sequences are helpful to improve the PLLA crystallization and the flexibility of the PBSA soft segment. Nucleation effect further accelerates the crystallization of PLLA segment. The synergistic effect of these factors results in good balance between stiffness and toughness. PLBSA30s containing 1% zinc citrate (ZnCC) or talc behave as ultra-tough bioplastics with ultrahigh impact strength over 50 kJ/m 2 and excellent tensile properties. PLBSA70 containing 1% ZnCC possesses elongation at break of 600% and retains high modulus (56 MPa) and strength (16 MPa) and therefore behaves as an excellent thermoplastic elastomer. The excellent and balanced properties would extend the end applications of these PLLA-based materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44777.
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