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Influence of mesophase–crystal transition on thermal and mechanical properties of stretched poly( L ‐lactide)
Author(s) -
Lv Ruihua,
Zou Shufen,
Na Bing,
Deng Huiyu,
Yu Zhiwei
Publication year - 2013
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.23525
Subject(s) - mesophase , materials science , annealing (glass) , lactide , crystallization , thermal stability , amorphous solid , glass transition , composite material , shrinkage , thermal , relaxation (psychology) , chemical engineering , crystallography , polymer , liquid crystal , thermodynamics , polymerization , chemistry , physics , optoelectronics , engineering , psychology , social psychology
The mesophase in the as‐stretched poly( L ‐lactide) (PLLA) exhibits low thermal stability and undergoes melting around T g . As a consequence, without constraints as‐stretched PLLA can recover to its original (unstretched) length while being held above T g . Upon constrained annealing at 70°C mesophase is transformed into highly oriented crystals, responsible for little free shrinkage and superior dimensional stability. At the same time, molecular orientation in the amorphous phase first decreases significantly due to thermodynamic relaxation, and then increases moderately with the advent of cold crystallization. It correlates well with the change of yield strength with respect to annealing time. POLYM. ENG. SCI., 53:2568–2572, 2013. © 2013 Society of Plastics Engineers