Abstracts Book - IMRC 2018

• SE2-P014
STRUCTURE AND THERMO-MECHANICAL PROPERTIES
CORRELATION IN EXTRUDED FILMS OF HIGH PERFORMANCE
COPOLYESTER
Adriana Reyes Mayer 1,2 , Rosario Benavente Castro 3 , Manuela Calixto Rodriguez 2 , Manuel
Aguilar Franco 4 , Angel Romo Uribe 5 , Karina Santiago Santiago 2
1 Centro de Caracterización e Investigación en Materiales S.A. de C.V., CeCIM, Mexico.
2 Universidad Tecnológica Emiliano Zapata del Estado de Morelos, División Académica de
Mecánica Industrial, Mexico. 3 Instituto de Ciencia y Tecnología de Polímeros, Departamento de
Polímeros, Spain. 4 Universidad Nacional Autónoma de México, Laboratorio Central de
Microscopía IFUNAM, Mexico. 5 Polymer Nanocomposites Lab, Nanopolímeros, Mexico.
This investigation focused on the influence of thermal annealing on the
microstructure and thermo-mechanical properties of the thermotropic
copolyester based on 60 mol% (1,4)-hydroxybenzoic acid (B), 5 mol% (2,6)-
hydroxynaphthoic acid (N), 17.5 mol% terephthalic acid (T) and 17.5 mol%
biphenol (BP), named COTBP. The micro and nanostructure was investigated by
simultaneous wide- and small-angle X-ray scattering (WAXS, SAXS, respectively),
birefringence, scanning electron microscopy (SEM) and atomic force microscopy
(AFM). Extruded tapes 50 mm thick were annealed at 300 ºC under dry air
conditions. WAXS reavelaed fiber-like structure with crystalline order, whereas
SAXS patterns exhibited diamond-shaped diffuse scattering elongated along the
equatorial axis elucidating oriented nanovoids. Guinier analyses showed that
the radius of gyration Rg of nanovoids were ca. 17 nm along the extrusion
axis. Heat treatment produced a sharpening of the 002 meridional reflection
and the 110 equatorial reflection indicating an improvement of molecular
register and packing. The molecular alignment, as quantified by the order
parameter P 2 , increased as well as the degree of crystallinity c. On the other
hand, SAXS intensity along the equatorial axis decreased evidencing reduction
of Rg, i.e. lateral compression of the nanovoids and better molecular packing.
Birefrince evidenced a core and skin effect, with the core less oriented than the
skin. Thermal treatment homogenized the molecular orientation. The
morphology evolution was correlated with AFM measurements. Thermal
treatment also increased the thermal stability and the uniaxial tensile Young’s
modulus, E, along extrusion axis. Scanning electron microscopy, SEM, evidenced
an outer skin with an internal layered morphology which transformed into
sheet-like morphology with meandering fibrils. This investigation evidenced
thermally-induced microstructure reorganization correlating with improved
thermal and mechanical properties.