Thermal,mechanical and barrier properties of PLLA/PDBI blend films
Poly(lactic acid-co-glycolic acid butylenediyl ester)(PDBI)was synthesized by incorporating poly(butylene glycol itaconate)(PBI)into the main chains of poly(D-lactic acid)(PDLA),and then the PLLA/PDBI blend films were prepared by melt blending the as-synthesized PDBI with poly(L-lactic acid)(PLLA)at different mass ratios.The results indicated that the total crystallinity degree of the blend films presented an increasing trend at first and then de-creased with an increase in the mass ratio of PDBI to PLLA,and the most cubic composite crystals were formed at a PD-BI/PLLA mass ratio of 1/1.At such a mass ratio,the blend films obtained a total crystallinity degree of 9.12％with a melting point as high as 205 ℃,and their thermal properties were greatly improved.The elongation at break of the blend films exhibited an increasing trend at first and then decreased with an increase in the mass ratio of PDBI to PLLA,where-as their tensile strength and Young's modulus presented an opposite trend.The PDBI/PLLA blend film at a mass ratio of 1/1 presented a Young's modulus of 853.38 MPa and elongation at break of 285.07％.There was no change in the tensile strength;however,its elongation at break was 59 times as much as that of PLLA and 21 times as much as that of PDBI,indicating a change from a brittle fracture to the ductile one.The barrier performance of the blend films also showed an enhancement at first and then became weakened.At a PDBI/PLLA mass ratio of 1/1,the blend film exhibit-ed an O2 transmission amount of 309.4 cm3·m2/d and a maximum water contact angle of over 78 °,indicating good barri-erperformance and high hydrophobicity.
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