Lyotropic liquid crystalline cellulose derivatives in blends and molecular composites

J. M G Cowie, V. Arrighi, J. Cameron, I. McEwan, I. McEwen

Research output: Contribution to journalArticle

Abstract

Solutions of cellulose tricarbanilate (CTC) in methyl acrylate (MA) and methyl methacrylate (MMA) were prepared. The MA and MMA monomers were subsequently polymerised to produce a series of molecular composites, in which the amount of CTC and the degree of substitution (DS) of the tricarbanilate groups were varied. The CTC solutions were studied using polarised microscopy and indicated isotropic behaviour in solutions with a CTC concentration of less than 33 wt%. Solutions of 33-45 wt% CTC were found to have a nematic texture and a chiral nematic texture was detected on sheafing of 45 wt% solutions. The mechanical properties and morphologies of the composites were investigated using dynamic mechanical thermal analysis (DMTA), tensile testing and scanning electron microscopy. Tensile testing measurements illustrated the reinforcing behaviour of the CTC on the composite, with the initial modulus increasing by up to 250% at 45 wt% CTC. Scanning electron microscope (SEM) micrographs for composites with <45 wt% CTC revealed a one-phase system. DMTA measurements indicated the existence of a double Tg at DS of the tricarbanilate of less than 3, with a single Tg for composites containing cellulose with degrees of carbanilate substitution equal to 3. The 45 wt% CTC composite showed a broad relaxation process at 350 K and another relaxation at higher temperature (490 K) corresponding to the glass transition of the CTC itself. This result, which is indicative of phase separation, is consistent with the SEM micrographs showing distinctive layered structures within the film. © 2001 Elsevier Science Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)9657-9663
Number of pages7
JournalPolymer
Volume42
Issue number24
Publication statusPublished - 28 Aug 2001

Keywords

  • Cellulose tricarbanilate
  • Methyl acrylate
  • Molecular composite

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