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Kinetics and crystal structure of poly(lactic acid) crystallized nonisothermally: Effect of plasticizer and nucleating agent
Author(s) -
Xiao Hanwen,
Yang Li,
Ren Xiaomin,
Jiang Tao,
Yeh JenTaut
Publication year - 2010
Publication title -
polymer composites
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.577
H-Index - 82
eISSN - 1548-0569
pISSN - 0272-8397
DOI - 10.1002/pc.21004
Subject(s) - talc , materials science , avrami equation , crystallinity , crystallization , plasticizer , differential scanning calorimetry , kinetics , nucleation , composite material , reaction rate constant , atmospheric temperature range , polymer chemistry , chemical engineering , thermodynamics , organic chemistry , chemistry , crystallization of polymers , physics , quantum mechanics , engineering
The kinetics of neat poly(lactic acid) (PLA) and its composites with triphenyl phosphate (TPP) and/or talc crystallized nonisothermally at different cooling rates of 1, 2.5, 5, 7.5, and 10°C/min was analyzed by differential scanning calorimetry and described by Avrami equation and combined Avrami‐Ozawa equation. The results showed that talc acted as PLA nucleating agent accelerated crystallization rate by decreasing the crystallization half‐time t 1/2 or rate parameter F(T ), whereas TPP acted as PLA plasticizer decreased crystallization rate. For neat PLA and plasticized PLA, the average values of Avrami exponent n were almost close to each other, but added TPP decreased crystallization rate constant k . As for PLA composites with talc, the crystallization process was relatively complex, and was divided into three regimes. At a given cooling rate, the value of n 2 was almost larger than that that of n 1 or n 3 , whereas the value of k 2 was less than that of k 1 or k 3 . The effective activation energy Δ E x calculated from Friedman formula increased with the increase of relative crystallinity and TPP content, whereas decreased with the presence of talc. Wide angle X‐ray diffraction verified that all samples crystallized nonisothermally in cooling rate range of 1–10°C/min form α‐form. POLYM. COMPOS., 31:2057–2068, 2010. © 2010 Society of Plastics Engineers