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The first normal stress difference and viscosity in shear of liquid crystalline solutions of hydroxypropylcellulose: new experimental data and theory

1994-09Journal article Restricted access
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dc.contributor.authorFried, F.
dc.contributor.authorLeal, Catarina R.
dc.contributor.authorGodinho, M. H.
dc.contributor.authorMartins, A. F.
dc.date.accessioned2023-05-29T13:12:28Z
dc.date.available2023-05-29T13:12:28Z
dc.date.issued1994-09
dc.description.abstractThe constitutive equations for liquid crystalline polymers recently proposed by one of us [1] are applied here to interpret the behaviour of the shear viscosity η equation image and the first normal stress difference N1($ \dot \gamma $equation image) measured for liquid crystalline (LC) solutions of hydroxypropylcellulose in acetic acid. N1(equation image) is observed to change from positive to negative and again to positive, as the shear rate $ \dot \gamma $equation image increases, at lower concentrations, in the LC phase. The $ \dot \gamma $equation image-values at which N1 changes sign depend on the molecular mass (degree of polymerization) and on the concentration. η $ \dot \gamma $equation image shows a small Newtonian plateau at low shear rates and a strong shear-thinning at higher values of $ \dot \gamma $equation image. The rate of decrease of η $ \dot \gamma $equation image in this region shows an “hesitation” similar to one previously observed in LC solutions of poly-γ-benzyl-L-glutamate PBLG. All these observations can be rationalized within the frame-work of Martins' theory. The expressions for N1($ \dot \gamma $equation image) and η $ \dot \gamma $equation image derived from this theory fit very well (quantitatively) to the experimental data and some fundamental viscoelastic parameters of the system under study are thereby obtained for the first time.pt_PT
dc.description.versioninfo:eu-repo/semantics/publishedVersionpt_PT
dc.identifier.citationFRIED, F.; [et al] – The first normal stress difference and viscosity in shear of liquid crystalline solutions of hydroxypropylcellulose: new experimental data and theory. Polymers Advanced Technologies. eISSN 1099-1581. Vol. 5, N.º 9 (1994), pp. 596-599.pt_PT
dc.identifier.doi10.1002/pat.1994.220050922pt_PT
dc.identifier.eissn1099-1581
dc.identifier.urihttp://hdl.handle.net/10400.21/16160
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.publisherWiley Online Librarypt_PT
dc.relationPMCT/C/MPF/542/90 - JNICTpt_PT
dc.relationPMCT/C/CEN/662/90 - JNICTpt_PT
dc.relationFMRH/BM/964/93 - JNICTpt_PT
dc.subjectHydroxypropylcellulosept_PT
dc.subjectHPCpt_PT
dc.subjectLiquid crystal polymerpt_PT
dc.subjectRheologypt_PT
dc.subjectViscositypt_PT
dc.subjectFirst normal stress differencept_PT
dc.subjectSecond normal stress differencept_PT
dc.titleThe first normal stress difference and viscosity in shear of liquid crystalline solutions of hydroxypropylcellulose: new experimental data and theorypt_PT
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage599pt_PT
oaire.citation.issue9pt_PT
oaire.citation.startPage596pt_PT
oaire.citation.titlePolymers Advanced Technologiespt_PT
oaire.citation.volume5pt_PT
person.familyNameMarques Mendes Almeida da Rosa Leal
person.givenNameCatarina
person.identifierA-2814-2009
person.identifier.ciencia-idAF15-486E-BB15
person.identifier.orcid0000-0001-5871-4936
person.identifier.scopus-author-id7005379280
rcaap.rightsclosedAccesspt_PT
rcaap.typearticlept_PT
relation.isAuthorOfPublication4db8990d-5eb1-4515-ae7a-68873cf776a5
relation.isAuthorOfPublication.latestForDiscovery4db8990d-5eb1-4515-ae7a-68873cf776a5

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