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Structure–property relationships for film‐forming copoly(amide imide)s
Author(s) -
Privalko Valery P.,
Mudrak Claudia V.,
Privalko Eleonora G.,
Usenko Andriy A.,
Pissis Policarpos
Publication year - 2003
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.336
Subject(s) - materials science , small angle x ray scattering , thermogravimetric analysis , diamine , dynamic mechanical analysis , imide , polymer chemistry , thermal stability , polyamide , dimethylacetamide , analytical chemistry (journal) , chemical engineering , scattering , composite material , polymer , organic chemistry , chemistry , optics , solvent , physics , engineering
Thin films of copoly(amide imide)s (coPAIs) from dichloro‐dianhydride of trimellitimide‐ N ‐acetic acid and mixtures of diphenylmethane diamine (DPA) and cardo 9,9′‐bis‐phenylfluorene diamine (CDA) cast from solutions in dimethylacetamide (DMAA) were characterized by wide‐angle and small‐angle X‐ray scattering (WAXS and SAXS), dynamic mechanical thermal analysis (DMTA) (temperature interval: 293–703 K, frequency range: 1–100 Hz), and thermogravimetric analysis (TGA) (nitrogen flux, temperature interval: 303–973 K). The mean interchain spacings (WAXS) smoothly increased with the CDA/DPA molar ratio from 0.55 nm for CDA/DPA = 0/1 up to 0.60 nm for CDA/DPA = 1/0. The smooth patterns of the SAXS curves for all coPAIs were explained by the smearing‐out of electron density differences between densely‐packed and loosely‐packed microregions of coPAIs due to the wide dispersion of their sizes. The step‐like patterns of the TGA traces in the temperature intervals below and above 600 K were associated with successive weight losses due to the evaporation of residual water and of DMAA, and to the thermal degradation of diamine and dianhydride chain fragments, respectively. As could be inferred from the TGA data, the loosely‐packed regions comprise about 25–35% of the total volume of studied coPAIs. The mechanical relaxations observed in all coPAIs at T β < T α′ < T α (DMA) were attributed to the onset of non‐cooperative segment motion in loosely‐packed regions, of cooperative segment motion in loosely‐packed regions, and of cooperative segment motion in densely‐packed regions, respectively. At constant frequency, the sub‐glass relaxations were roughly composition‐independent, while chain‐stiffening effect was assumed to be responsible for the smooth increase of T α′ and T α , as well as of the corresponding apparent activation energies with the CDA/DPA ratio. Copyright © 2003 John Wiley & Sons, Ltd.