Crystallization behavior of polypropylene with or without sodium benzoate as a nucleating agent

Abstract

The crystallization kinetics of polypropylene (PP) with or without sodium benzoate as a nucleating agent were investigated by means of DSC and polarized optical microscopy in isothermal and nonisothermal modes. A modified Avrami equation was applied to the kinetic analysis of isothermal crystallization. The addition of the nucleating agent up to its saturation concentration increased the crystallization temperature by 15 °C and shortened both the isothermal and nonisothermal crystallization half‐times. It was concluded that the sodium benzoate acted as a good nucleating agent for α‐form PP. By adding the nuclefier to PP, adequately controlled spherulites increased the mechanical properties including especially the Izod impact strength and shortened cycle time of PP. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1001–1016, 2001

Effect of the Molecular Structure of the Polymer and Nucleation on the Optical Properties of Polypropylene Homo- and Copolymers

“…After the quantitative analysis of these correlations an attempt is made to relate the determined parameters to the molecular structure of the polymer. Nucleation is very often used in polypropylene to increase stiffness and strength [23][24][25][26][27][28][29] , to improve productivity by increasing the temperature of crystallization [27][28][29][30] and to modify optical properties [17][18]31 . The efficiency of nucleation is usually estimated by DSC measurements, by changes in the peak temperature of crystallization (T cp ) 32 , which can be related to the thickness of the lamellae formed 33 .…”

Influence of nucleating agent on the crystallization kinetics and morphology of polypropylene

“…In the samples with NB, it is observed a decrease in Tc as the nucleating amount increases. This behavior indicates that the amount of NB used is above the ideal concentration to attain the highest nucleation rate and the excess of additive could be causing agglomeration, decreasing nuclei number and, by consequence, decreasing Tc [11] . Libster et al [12] showed that a good dispersion of NC in microemulsions causes super saturation since low amounts, indicating that higher amounts do not supply additional nuclei, that could explain the similar Tc values obtained for the different amounts of NC tested.…”

Processing and characterization of halloysite nanotubes filled polypropylene nanocomposites based on a masterbatch route: effect of halloysites treatment on structural and mechanical properties

“…On the basis of the recorded DSC thermograms, melting temperature (T m ), crystallization temperature (T c ), heat of fusion (!H m ) and relative degree of crystallinity (X c ) were determined. X c was calculated from the DSC crystallization curves with Equation (1): (1) where !H m is the specific melting heat or heat of fusion, calculated by integrating the area under the crystallization peak, "H°m is the theoretical specific melting heat of 100% crystalline isotactic PP, which is taken as 209 J/g [38], and w t is the weight fraction of nanotubes.…”