Títol:
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Crystalline structures and structural transitions of copolyamides derived from 1,4-diaminobutane and different ratios of glutaric and azelaic acids
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Autor/a:
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Olmo, Cristian; Casas Becerra, María Teresa; Martínez Guil, Juan Carlos; Franco García, María Lourdes; Puiggalí Bellalta, Jordi
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Altres autors:
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Universitat Politècnica de Catalunya. Departament d'Enginyeria Química; Universitat Politècnica de Catalunya. PSEP - Polimers Sintètics: Estructura i Propietats. Polimers Biodegradables. |
Abstract:
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Copolyamides derived from even 1,4-butanediamine and different mixtures of odd
dicarboxylic acids with a great difference in the number of methylene groups (i.e., glutaric and
azelaic acids with 3 and 7 groups, respectively) have been synthesized, characterized and structurally
studied. Calorimetric analyses revealed a complex behavior with multiple melting peaks associated
to lamellar reordering and the presence of defective crystals. Equilibrium melting temperatures were
evaluated and showed a eutectic behavior with composition. Copolymers were able to crystallize
even for samples with comonomer percentages close to 50%. Negative and ringed spherulites from
the melt state and small lath-like lamellar crystals from dilute solution crystallizations were attained.
Furthermore, calorimetric data pointed out the exclusion of the less abundant monomer from the
lattice of the predominant structure. All samples at room temperature showed a similar crystalline
structure (form I) defined by two predominant reflections at spacings close to 0.430 and 0.380 nm,
which has been related for even-odd nylons with a two-hydrogen bonded structure. Real time
synchrotron experiments showed that melt crystallized samples have two polymorphic transitions
on heating, which were practically reversible and consequently were also detected during cooling
from the melt state. Interestingly, a different behavior was detected among solution crystallized
samples and specifically the transition to the intermediate structure (form II) was not detected during
heating for samples enriched on the azelate component or more precisely when they were exclusively
crystallized in the form I. |
Matèries:
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-Àrees temàtiques de la UPC::Enginyeria dels materials -Àrees temàtiques de la UPC::Enginyeria química -Copolymers -Crystallization -Even-odd nylons -Copolyamides -Crystallization behavior -Crystalline structures -Thermal transitions -Hydrogen bonds -Copolímers -Cristal·lització |
Drets:
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Attribution 3.0 Spain
http://creativecommons.org/licenses/by/3.0/es/ |
Tipus de document:
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Article - Versió publicada Article |
Publicat per:
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Multidisciplinary Digital Publishing Institute (MDPI)
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