Influence of processing on structure of β‐nucleated poly(propylene) fibers

Abstract

Fibers colored with quinacridone pigment spun at low take-up velocities were obtained. The spun fibers, with a very high ␤-form content, were drawn at room temperature and at a temperature of 120°C at different draw ratios. They were then heat stabilized at different temperatures, ranging from 140 to 150°C for different time intervals. As a result of drawing, the transition from ␤ to mesophase, as well as that from ␤ to ␣, was observed. The ␤ to mesophase transition results from cold drawing at room temperature, while the ␤ to ␣ transition results from drawing at 120°C. In both cases, the significant decrease of ␤-form content occurs at the low draw ratio of 2. At higher draw ratios, the ␤-form content gradually decreases, and at a draw ratio of 7 the ␤-form disappears altogether. As a result of heat stabilization, the ␤ to ␣ transformation was observed. The first change of the ␤-form content was noticed at 140°C. For fibers stabilized at temperatures above 140°C, the decrease of the ␤-form content is more significant and increases with the increase of the stabilization temperature. At 150°C, a rapid drop of the ␤-form content occurs after only 3 min, and after a few more minutes the ␤-form disappears.

Study of the crystallization behaviors of isotactic polypropylene with sodium benzoate as a specific versatile nucleating agent

“…The transformation is not reversible and occurs in the temperature range of 130–150 °C 34. There have been many investigations into the transformation of trigonal into monoclinic modification in iPP 30, 35. Garbarczyk et al put forward that the essential factors for the occurrence of β → α transiton is heating temperature and heating time.…”

Nucleating agents based on graphene and graphene oxide for crystallization of the β-form of isotactic polypropylene

“…During the studies special attention was given to the quinacridone pigment considered as one of the most effective b-NA. By adding the quinacridone pigment injection mouldings [24], films [25,26] and fibres with high b-form content were obtained [27][28][29].…”

Deconvolution Analyses of Differential Scanning Calorimetry Profiles of β-Crystallized Polypropylenes with Synchronized X-ray Measurements

“…The most stable of these modifications is the α-form, which is obtainable by the conventional melt-crystallization process. In contrast, the β-form is the metastable modification, which often appears for quenching from melt − and crystallization with temperature gradation − or specific nucleation agents. − Some reports ,− indicate that the β-form transforms into the α-form during heating, annealing, or drawing through the melt-recrystallization process. Zhou et al .…”

“…In contrast, the β-form is the metastable modification, which often appears for quenching from melt [1][2][3] and crystallization with temperature gradation [4][5][6][7] or specific nucleation agents. [8][9][10][11][12][13][14][15] Some reports 7,[16][17][18][19][20] indicate that the β-form transforms into the R-form during heating, annealing, or drawing through the melt-recrystallization process. Zhou et al 18 discussed the possibility of this crystalline transition from the β-form to the R-form, based on the wide-angle X-ray diffraction (WAXD) change during the heating of the series of the samples prepared with different amounts of nucleation agent.…”