Morphologies and mechanical properties of pet films crystallized under high strain rates

Abstract

The morphologies of highly oriented PET films, crystallized in a longitudinal flow gradient, were examined using transmission electron microscopy, differential thermal analysis, thermomechanical analysis, birefringence measurements, and mechanical tensile tests. The morphology in the as‐drawn state of the samples consists of oriented single micellar blocks which are embedded in the amorphous matrix. Annealing above 180°C causes a morphological transformation into lamellalike crystals, which are formed by lateral crystallization, preferably at the sidefaces of the micellar blocks. An interpretation of the mechanical behavior is given in accordance with the morphological model.

Morphology in Oriented Semicrystalline Polymers

“…Dark-field TEM micrograph of an oriented fringed micellar morphology in PET. The white dots are the micellar crystals the crystals (white spots) are of the order of 10 nm [4]. A schematic sketch is also inserted.…”

“…In this case small dimensions and the high end surface free energy [26] can result in melting point depressions 6T, of more than 100 "C. At these high undercoolings 6T, melting of the oriented fringed micelles and recrystallization into a stacked lamellar type of morphology occur simultaneously and hence cannot be detected by common DSC measurements. Figure 14 shows PET having an oriented fringed micellar morphology before annealing and the transformed stacked lamellar morphology after annealing at 200 "C [4]. Since in general the oriented fringed micellar crystals are connected by an oriented amorphous matrix, the melting behaviour and consequently the morphological changes depend also on the constrains: annealing the sample with or without fixed ends.…”

Carbon nanotube/polyurethane films with high transparency, low sheet resistance and strong adhesion for antistatic application

“…Poly(ethylene terephthalate) (PET) lms are one of the commonly used packaging lms. Because of their high transparency, excellent mechanical properties, [1][2][3] gas barrier 4 and vapor barrier, 5 the PET lms have many packaging applications including food packaging lms, electronic products packaging lms, display device packaging lms, and so on. In recent years, PET packaging lms have been widely used in thin lm transistors, 6 solar cells, 7 and so on.…”

Rapid structural changes that take place during constrained annealing of biaxially stretched pet films

“…Substantial amount of "after the fact or off-line" studies were carried out in order to understand the structural changes that take place during the heat setting process of the uniaxially oriented PET fibers and films [4][5][6][7][8][9][10][11][12] and the biaxially oriented PET films [13][14][15][16][17][18].…”