Cracking in poly(trimethylene terephthalate) spherulites

Abstract

The crack behavior of poly(trimethylene terephthalate) spherulites was studied mainly by polarizing optical microscopy, along with scanning electron microscopy (SEM) and atomic force microscopy (AFM). In addition to the effects of temperature and constraining substrate, another important factor, film thickness, on the formation of crack was first put forward and investigated. The emergence of the first crack occurred at 120 C during cooling after crystallization at 190 C for the sample with a thickness of 31.0 lm. For the spherulites growing between glass sheets, it was interesting that the sample with a thickness of 26.0 lm exhibited the largest number of cracks measured per 200 lm of radius, whereas samples thicker than 100 lm or thinner than 1 lm did not induce the formation of crack. Also, spherulites growing between two polyimide and two Teflon sheets showed no crack. Glass sheets lubricated with silicon oil restrained the number of cracks but did not eliminate cracks. SEM revealed that the cracking was about 900 nm in width. In addition, the AFM results suggest that the cracks had a depth of at least 150 nm. V

Cracks in Polymer Spherulites: Phenomenological Mechanisms in Correlation with Ring Bands

“…Poly(trimethylene terephthalate) (PTT), being a much tougher polymer than PLLA or PHB, shows cracks only in more severe circumstances. Yao and Yang [ 44 ] studied cracking in poly(trimethylene terephthalate) (PTT) spherulites grown between two substrates, crystallized at T c = 190 °C and cooled to lower temperatures or ambient (120, 90, 40 °C). They reported that PTT spherulites grown between two polyimide and two Teflon sheets showed no cracks, but PTT film grown between two glass sheets lubricated with silicon oil displayed reduced number of cracks but did not totally eliminate cracks.…”

Differences Between Stereocomplex Spherulites Obtained in Equimolar and Non‐Equimolar Poly(L‐lactide)/Poly(D‐lactide) Blends

“…[25] The cracks are formed when samples are cooled from T c to low temperatures, and normally observed in polymers which can form relatively large spherulites. [26] Cracks within polyhydroxybutyrate, [27][28][29] poly(trimethylene terephthalate), [30] and PLLA [26] spherulites have already been observed. The formation of cracks can be affected by temperature, substrate, and film thickness.…”

Synthesis, thermal properties and crystalline morphology of poly(trimethylene terephthalate)/ZnO nanocomposites prepared by dual in situ polymerization

“…Except for pure PTT sample, obvious cracked spherulites morphologies were observed in all PTT/ZnO nanocomposite samples. Similar phenomenon in pure PTT had been discussed in our previous work . Cracked spherulites morphology in pure PTT was hugely influenced by crystallization process, sample thickness, crystallization substrate, and so on.…”

“…Similar phenomenon in pure PTT had been discussed in our previous work. [32] Cracked spherulites morphology in pure PTT was hugely influenced by crystallization process, sample thickness, crystallization substrate, and so on. For PTT/ZnO nanocomposite prepared by dual in situ polymerization, cracked spherulites morphologies were really complicated to discuss.…”