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Rheo-optical characterization of liquid crystalline acetoxypropylcellulose melt...
Teixeira, P. F.; Fernandes, Susete N.; Canejo, João; Godinho, Maria Helena; Covas, J. A.; Leal, Catarina Rosa; Hilliou, L.The rheological and structural characteristics of acetoxypropylcellulose (APC) nematic melt are studied at shear rates ranging from 10 s 1 to 1000 s 1 which are relevant to extrusion based processes. APC shows a monotonic shear thinning behavior over the range of shear rates tested. The negative extrudate-swell shows a minimum when a critical shear rate g_ c is reached. For shear rates smaller than g_ c, the fl...
When liquid crystalline cellulose flows and relaxes
Teixeira, P. F.; Fernandes, Susete N.; Canejo, João; Godinho, Maria Helena; Leal, Catarina Rosa; Hilliou, L.Cellulose-based liquid crystalline materials can generate stimuli-responsive fibbers and films [1,2]. Changes in orientational order, which can be affected by variation of temperature and UV irradiation as well as by the presence of solvent vapours, give rise to stresses, which result in strains and modifications in sample shape. The processing conditions of the liquid crystalline material are crucial for fibbe...
Influence of processing conditions on the morphological development and final m...
Filipe, Susana A.; Maia, J. M.; Leal, Catarina Rosa; Cidade, Maria TeresaThe main aim of this work is to study the influence of the application of different processing conditions on the morphological and mechanical properties of thermoplastic/ LCP blends, in which the viscosity ratios are inferior to unity and decrease with increasing temperature. The way the microstructure evolves along the extruder determines the final morphology and thus, the mechanical performance of the systems...
Evolution of the morphological and rheological properties along the extruder le...
Filipe, Susana A.; Cidade, Maria Teresa; Wilhelm, M.; Leal, Catarina Rosa; Maia, J. M.In a previous article, we reported on the evolution of the morphological and rheological properties along the length extruder for blends of a liquid-crystalline polymer (LCP), Rodrun LC3000, and polypropylene (PP). In this work, we extended this study to compatibilized PP/ Rodrun LC3000 blends, containing 10 wt % LCP and different compatibilizers, to determine the influence of the addition of a compatibilizer d...
A study of Rodrun LC3000/PP blends under different stationary and non-stationar...
Filipe, Susana A.; Maia, J. M.; Leal, Catarina Rosa; Cidade, Maria TeresaBlends containing liquid crystalline polymers and thermoplastics have been a topic of great interest for the scientific community due to their excellent performance and properties and thus, promising use in industrial applications. For that reason, from the eighties until today, these systems were widely studied and characterized in terms of their mechanical, morphological, and rheological properties under stat...
Influence of type of compatibilizer on the rheological and mechanical behaviour...
Filipe, Susana A.; Maia, J. M.; Duarte, Ana; Leal, Catarina Rosa; Cidade, Maria TeresaThe addition of small amounts of liquidcrystalline polymers to thermoplastics leads to the formation of in situ–reinforced materials, with improved processability and mechanical properties. Nevertheless, the lack of adhesion between the thermoplastic and the liquid-crystalline polymer often occurs, thus requiring the use of compatibilizers. In this case, the results of several previous works show that there is ...