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Thermal strain recovery of anelastic monodomain liquid crystalline networks: Mechanically induced strains ratios
Author(s) -
Ren Wanting,
Kline Whitney M.,
McMullan Philip J.,
Griffin Anselm C.
Publication year - 2011
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201083972
Subject(s) - materials science , isotropy , curvature , strain (injury) , liquid crystal , polymer , composite material , thermal , thermodynamics , optics , geometry , physics , medicine , mathematics , optoelectronics
Abstract A series of smectic liquid crystalline network polymers was subjected to a large uniaxial stress at temperatures far below the clearing temperature. Their dimensional recovery is anelastic showing substantial retained strain. This process produced a temporally stable monodomain state. Upon heating this monodomain from room temperature, recovery of the original film dimensions occurs. The strain recovery (length) curves show a pronounced curvature as the temperature approaches the smectic–isotropic temperature. It is proposed that nanosegregation of netpoints in the smectic structure is responsible for the anelasticity and that the temperature dependence of the shape recovery is consistent with a balance between enthalpic and entropic forces with temperature. An interesting mechanically induced strains ratio (MISR) was observed on heating these pre‐stressed films. Loss of the monodomain structure near the isotropization temperature is postulated to rationalize the shape of the MISR curves.