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Effect of molecular weight and crystallinity on poly(lactic acid) mechanical properties
Author(s) -
Perego Gabriele,
Cella Gian Domenico,
Bastioli Catia
Publication year - 1996
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19960103)59:1<37::aid-app6>3.0.co;2-n
Subject(s) - crystallinity , materials science , tacticity , izod impact strength test , crystallization , flexural strength , lactic acid , flexural modulus , composite material , amorphous solid , lactide , modulus , young's modulus , polymer , chemical engineering , ultimate tensile strength , copolymer , polymerization , crystallography , chemistry , genetics , biology , bacteria , engineering
Several samples of poly(lactic acid) with different molecular weights and tacticity have been prepared, and some PLLA injection moulded specimens have been annealed to promote their crystallization. From the characterization data, poly( L ‐lactide) showed more interesting mechanical properties than poly( D, L ‐lactide), and its behavior significantly improves with crystallization. In fact, annealed specimens possess higher values of tensional and flexural modulus of elasticity, Izod impact strength, and heat resistance. The plateau region of flexural strength as a function of molecular weights appears around M v = 35,000 for PDLLA and amorphous PLLA and at higher molecular weight, around M v = 55,000, for crystalline PLLA. The study of temperature effect shows that at 56°C only crystalline PLLA still exhibits useful mechanical properties. © 1996 John Wiley & Sons, Inc.