Premium
(Co)polymers of L ‐lactide, 2. Mechanical properties
Author(s) -
Grijpma Dirk W.,
Pennings Albert J.
Publication year - 1994
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1994.021950516
Subject(s) - comonomer , ultimate tensile strength , izod impact strength test , lactide , copolymer , polymer , brittleness , polymer chemistry , materials science , polymerization , flexural strength , composite material , chemical engineering , chemistry , engineering
The effect of copolymerization of L ‐lactide with several lactones and cyclic carbonates and the processing variables in compression moulding of poly( L ‐lactide) homopolymers on the mechanical properties was investigated. Sharp maxima in the impact strength versus comonomer composition and heat of fusion were obtained, reflecting the important role of the presence of a crystalline fraction in the material. Crystalline domains increase the interconnectivity of a physical polylactide network and decrease the molecular weight between these physical crosslinks. The brittle strength concomitantly increases, and as the yield stress remains more or less constant, an increase in impact strength is observed. Very high crystalline as‐polymerized poly( L ‐lactide) prepared with less active catalysts on the other hand has an extremely low entanglement density and therefore a low brittle tensile strength.