Crystallization of poly(ethylene terephthalate) (PET) from the oriented mesomorphic form

Abstract

SYNOPSISYarns of different inherent viscosities, in the range 0.6-1.1 dL/g, spun in industrial plants, and drawn at room temperature to obtain mesomorphic samples, have been characterized. The evolution from the mesomorphic form toward the triclinic crystalline form has also been studied by combined differential scanning calorimetry ( DSC ) , dynamic mechanical analyses (DMA), and accurate wide angle X-ray diffraction experiments. The DMA analysis of the mesomorphic samples allows better resolution of the glass transition and crystallization phenomena, which are superimposed in the DSC scans. The degree of molecular orientation in the mesomorphic samples, and the temperature of crystallization from the mesomorphic form (SO-80°C) , are essentially independent of the polymer molar mass.

In situ WAXS/SAXS structural evolution study during uniaxial stretching of poly(ethylene therephthalate) nanocomposites in solid state: Poly(ethylene therephthalate)/montmorillonite nanocomposites

“…ARTICLE WWW.MATERIALSVIEWS.COM WILEYONLINELIBRARY.COM/APP J. APPL. A meridional reflection ð103Þ can be distinguished showing the appearance of periodical mesophase 37,38. SCI.…”

In situ WAXS/SAXS structural evolution study during uniaxial stretching of poly(ethylene terephthalate) nanocomposites in the solid state: Poly(ethylene terephthalate)/titanium dioxide and poly(ethylene terephthalate)/silica nanocomposites

“…In fact, the neck forms out of the sample center where the WAXS investigation was carried out [see Figure (c and h)]. As the strain of ln λ = 0.2 till sample brakeage, both PET/3D nanocomposites 2D WAXS patterns are characterized by two diffused spots at the equator, indicative of considerable polymer chains orientation into the stretching direction and a distinctive meridional reflection that is attributed to PM . This is connected to the neck propagation through the examined region of the sample [Figure (d and i)].…”

“…The mass fractions of the individual phases were taken as the ratio of the area for each phase to the total area of the equatorial profile. As the strain increases, the WAXS patterns can exhibit a pair of meridional mesomorphic reflection at about 2θ = 25.8°, indicating conformational regularity, and called PM . At this stage of deformation, the morphologies of the samples were considered to be composed of three phases: (i) amorphous, (ii) mesophase, and (iii) PM, mesophase with conformational periodicity perpendicular to the stretching direction.…”

Vibrational Spectra of Poly(ethylene terephthalate) Chains in the Mesomorphic Form

“…Many papers have been devoted to the mesomorphic form of PET, mainly to the transition toward the usual triclinic crystalline form, but also to the diffusion of organic vapors and to the possible influence of π–π interactions between the main‐chain phenylene groups on the mesomorphic order . Few papers have also reported infrared and Raman spectra of mesomorphic PET samples.…”