Effect of nucleating agent on the nonisothermal crystallization kinetics of glass fiber‐ and mineral‐filled polyamide‐6 composites

Abstract

In this study, nonisothermal crystallization kinetics of glass fiber (GF) and clay-type mineral (MN)-reinforced polyamide-6 (PA6) composites prepared in a twin screw extruder were investigated by differential scanning calorimetry method in the presence and absence of an organic nucleating agent (NA). Kinetic parameters for the nonisothermal melt-crystallization process of samples were determined with several models namely Ozawa, Avrami, Jeziorny, and Liu-Mo. Crystallization rate parameters of the samples and nucleation activity of the fillers and additives were also calculated by the models suggested by Zhang and Dobreva and Gutzow, respectively. Crystallization activation energies of the samples were determined by the Kissinger model. It was found that the MN filler accelerates dramatically the crystallization rate of PA6 even without a NA. Small amount of NA also has a significant acceleration effect on the crystallization rate of PA6 composites. The rate acceleration effect of NA was found to be more pronounced in the composite sample reinforced with GF. Based on the kinetic study using of GF as major filler and small amount of clay-like MN in the PA6 composites could improve the mechanical properties and crystallization rate of injection-molded parts. V C 2012 Wiley Periodicals, Inc. J Appl Polym Sci 125: E268-E281, 2012

Thermal properties of glass fiber reinforced polyamide 6 composites throughout the direct long‐fiber reinforced thermoplastic process

“…The second decrease, which occurred after the second extruder, was possibly a result of the slight decrease occurring in the molecular weight and/or the incorporation of glass fibers at this stage of the process. Fibers when introduced to a polymer can act as heterogeneous nucleating agents during crystallization . If the fibers do act in such a way, they may have provided nucleation sites for crystal growth and decreased the time required for crystallization.…”

“…The two melting peaks (T m1 and T m2 , where T m1 < T m2 ) on the DSC heating curves (Fig. 7b) are associated with a difference in melting temperatures between the two phases present in the morphology (a and c) [4,24,25]. The aphase has polymer chains fully extended and oriented in an anti-parallel fashion while the c-phase has polymer chains twisted at an angle of approximately 608 to maintain complete satisfaction of hydrogen bonds.…”

Effect of wood flour as nucleating agent on the isothermal crystallization of poly(lactic acid)

“…[9,10] Thus, it is necessary to improve the crystallization rate of PLA. So far, numerous researchers have mainly focused on blending PLA with a nucleating agent [11][12][13][14][15] or other flexible polymers, [16][17][18][19][20] which are effective ways to enhance the crystallization rate of PLA.…”

Effects of process parameters on thermal properties of glass fiber reinforced polyamide 6 composites throughout the direct long‐fiber‐reinforced thermoplastics process

“…The further decrease of crystallization half‐time in the compressed plaque samples was possibly a result of the three factors that Fornes and Paul suggested and/or the incorporation of glass fibers in the second extruder. Fibers, when introduced to a polymer, can act as heterogeneous nucleating agents (NA) during crystallization . If the fibers did act in such a way, they may have provided nucleation sites for crystal growth and decreased the time required for crystallization.…”

“…Two melting peaks (T m1 and T m2 , where T m1 < T m2 ) were observed on the DSC heating curves (Fig. 8), which are associated with a difference in melting temperatures between the two phases present in the morphology (a and c) of PA6 [22][23][24]. Table 3 suggests that the change of extruder temperature or screw speed had little effect on the two melting peaks and degree of crystallinity.…”