The effect of additives on the crystallization of poly (butylene terephthalate)

Abstract

The effect of glass fibers and some fire retardant additives on the kinetics and mechanism of crystallization of poly(butylene terephthalate) (PBT) has been investigated. Shorter half times of crystallization and higher optimum crystallization temperatures of the filled samples are attributed to the nucleating ability of the additives. Based on the percent crystallinity determined, the efficiency of the different quenching media studied can be arranged in the order: ice water > 25°C water ⩾ dry ice/ethanol > liquid nitrogen. The inefficient quenching of dry ice/ethanol arid liquid nitrogen media is attributed to their poor heat transfer. The Tg of these quenched samples is, however, independent of the percent crystallinity.

Polymer crystallization and precipitation‐induced wrapping of carbon nanofibers with PBT

“…Equal parts of the 0.1% CNF suspension and 2% PBT solution were then mixed at 150-160 C under continuous magnetic stirring for 1 h. The resulting mixture was slowly cooled down to [30][31][32][33][34][35][36][37][38][39][40] C, after which a few drops of the mixture were placed between glass slides and maintained at this temperature for 24 h. The formed crystals were analyzed under polarized light using a Nikon OPTIPHOT-POL2 optical microscope. To further understand the morphology, the crystallized CNF-PBT solution (prepared by mixing equal parts of 0.1% CNF suspension and 2% PBT solution in o-chlorophenol) was filtered and washed repeatedly with methanol, followed by overnight drying in vacuum oven at 50…”

“…40 The crystal sizes of PBT were observed to decrease because of the incorporation of glass fibers into the polymer solution. Park et al 41 have also studied the crystallization kinetics as well as nucleation effects of high loadings of glass fibers (30 wt %, 10 lm diameter, approximately 300 lm in length) in PBT dissolved in 10% TFA-CCl 4 (10% trifluoro acetic acid-carbon tetrachloride solution) and found that the filler particles led to an increase of the rate of crystallization.…”

Effect of Shearing on the Crystallization Behavior of Poly (Butylene Terephthalate) and PBT Nanocomposites

“…29 The observed crystallization behavior shows the effect of MWNTs on the crystallization kinetics of PBT under quiescent conditions, and the behavior is consistent with the reports in the literature. 3,6,8,9 In particular, the values shown in Table 1 confirm that the addition of MWNTs to the PBT produces an increase in the crystallization temperature T c . Similar results have been found by others as well.…”

“…MWNTs were purchased from Sunnano (China). As reported by the manufacturer, the diameter of the MWNTs was 10-30 nm, and the average bulk density was 1.5 g/cm 3 .…”

“…More compatible with industrial processes are melt-mixing techniques, where adequate shear forces are necessary to disperse the nanofiller within the polymer. Several studies have been reported in the literature which aim to quantify the crystallization kinetics in molten semi-crystalline polymers, including PP, 1,2 PBT, [3][4][5][6][7][8][9] PET, 10,11 Nylon 6, 12 i-PP, 13 and PTT. 14 The structure and properties of the nanocomposite can be further influenced by the large surface area of the MWNTs, which can act as nucleating agents influencing the crystallization process.…”