0000000000113708

AUTHOR

V. Città

showing 3 related works from this author

Characterization of blends of polypropylene with a semirigid liquid-crystal copolyester

1991

Abstract Blends with a liquid-crystal polymers (LCP) as one component show, in general, very interesting properties. Reduction of shear viscosity and improvement of mechanical properties are very remarkable. High melting temperatures and high costs of the LCP limit the use of these blends. A new class of thermotropic LCPs with flexible spaces, with relatively low melting temperatures, can overcome the first problem. In this work, rheological and mechanical properties of blends of polypropylene with low contents of this LCP are presented. Torque during extrusion and viscosity decrease with LCP content. Elastic modulus is remarkably increased when the LCP phase is oriented.

PolypropyleneMaterials sciencePolymers and PlasticsOrganic ChemistryGeneral Physics and AstronomyYoung's modulusThermotropic crystalchemistry.chemical_compoundViscositysymbols.namesakeRheologychemistryLiquid crystalMaterials ChemistrysymbolsPolymer blendComposite materialElastic modulusEuropean Polymer Journal
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Synthesis, properties and processability of a new class of semirigid liquid crystalline copolyesteramides

1995

Abstract A new family of semirigid main chain liquid crystalline polymers (LCPs), referred to as SBAN, characterized by fairly good processability and mechanical properties, and improved thermal resistance, have been synthesized by the melt polycondensation of sebacic acid (S), 4,4′-dihyhxybiphenyl (B), 4-aminobenzoic acid (A), and 2-hydroxy-6-naphthoic acid (N), in a wide range of compositions. The molar concentration of the A ahd N units, in these LCPs must be kept lower than ca 40 and 60%, respectively, in order to avoid the formation of homopolymeric blocks, which impair spinnability. The presence of A units grants the formation of hydrogen bonds between neighboring macromolecules, and …

chemistry.chemical_classificationMaterials scienceCondensation polymerMolar concentrationSebacic acidHydrogen bondPolymerCondensed Matter PhysicsPolyesterchemistry.chemical_compoundchemistryUltimate tensile strengthPolymer chemistryMacromolecule
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Melt spinning and mechanical properties of semirigid liquid-crystal copolyesters

1993

Melt-spinning and mechanical properties of fibers of a new class of semirigid thermotropic liquid-crystal polymers are presented. These copolyesters are synthesized from 4-4′-dihydroxybiphenyl (B), 4-hydroxybenzoic acid (H), and flexible units provided by aliphatic diacids. The flexible units depress the melting temperature without strongly depressing the mechanical properties. These liquid-crystal polymers can be easily spun at high draw ratios. Indeed, unlike rigid liquid-crystal polymers, relatively high draw ratios are needed to attain high mechanical strength. Tensile moduli of about 28 GPa and tensile strengths of about 350 MPa are obtained. © 1993 John Wiley & Sons, Inc.

chemistry.chemical_classificationMaterials sciencePolymers and PlasticsMelting temperaturePolymerCondensed Matter PhysicsThermotropic crystalchemistryLiquid crystalUltimate tensile strengthMechanical strengthMaterials ChemistryPhysical and Theoretical ChemistryComposite materialMelt spinningJournal of Polymer Science Part B: Polymer Physics
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