Crystallization kinetics of maleic anhydride-modified iPP studied by POM

Abstract

Melt nucleation and crystallization behavior of homo‐isotatic polypropylene (homo‐iPP), maleic anhydride (MAH)‐grafted‐iPP, and MAH‐modified iPP, produced from iPP and a small amount of MAH‐grafted‐iPP, was investigated by polarizing optical microscopy (POM), at Tc = 121–135oC. Nucleation processes at a given Tc were faster for modified PP as compared to neat iPP. The induction time for nucleation increased nonlinearly with increasing Tc and decreased for modified PP, probably as a result of promoted heterogeneous nucleation due to the presence of carbonyl groups of MAH‐grafted‐PP. The average spherulite sizes were decreased by modification, and the growth rate was enhanced in maleated PP and modified PP. The induction time approach was applied to the results obtained by POM to compare the tendency for heterogeneous nucleation of neat and MAH‐modified PP. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3107–3118, 2000

Crystallization of Polypropylene: Application of Differential Scanning Calorimetry Part Ii. Crystal Forms and Nucleation

“…The morphology of iPP crystallized from the melt has been studied extensively over the past few decades using PLM [45][46][47], transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) [48]. From investigation carried out by polarizing microscopy, dynamically and isothermally, on the analysis of nucleation morphology of iPP, a lot of information concerning the induction period, nucleation density, growth-rate of the spherulites, and distribution of the dimension of the spherulites can be obtained (Fig.…”

“…Results showed that iPP could crystallize in a wide range of spherulite dimensions (from 10-50 μm to 280-370 μm) depending on the temperature of crystallization and crystallization conditions as well as the presence of nucleating agents [45][46][47][50][51][52]. The presence of maleic grafted PP (PP-g-MA) used as a modifier for PP split films leads to alteration of the crystallization kinetics, although a spherulitic morphology similar to neat PP was developed [45].…”

Advances in Polypropylene Based Materials

“…Isotactic PP has been studied extensively for its polymorphic characteristics and crystallization behavior since 1960s [9] and the results of these studies are reported in many monographic [see, for instance summarized Ref. 10 and 11] and journal publications [12][13][14][15][16][17][18][19]. Its crystalline morphology influences greatly the overall polymer properties (rheological, physical and mechanical) and the properties of the final products made of PP.…”

“…The melting temperature of the β-form lamellae is near 152 to 164 o C, while the melting of the α-form lamellae occurs above 164 o C. Moreover, the α-form lamellae can still grow in the temperature range from 152 to 164 o C. iPP can crystallize in a wide range of spherulite dimensions (from 10-50 μm to 280-370 μm) depending on the temperature of crystallization and crystallization conditions as well as the presence of nucleating agents [35][36][37]. The presence of maleic grafted PP (PP-g-MA), most often used as an adhesion modifier for PP composite applications, leads to alteration of the crystallization kinetics, without any significant changes in polymer spherulitic morphology ( Figure 2) [16]. Selective nucleating agents are sometimes added to PP, before or during processing, to induce appearance of a certain polymorphic modification, to enhance the crystallization, to obtain more uniform morphology and to alter its mechanical properties or transparency.…”

Crystallization of Polypropylene: Application of Differential Scanning Calorimetry Part I. Isothermal and Non-Isothermal Crystallization

“…So, different methods of chemical modification of PPs are developed to improve compatibility with and the adhesion to the reinforcing fibers. The grafting of different monomers, such as acrylic and methacrylic acids, acrylamide, ethylene glycol methacrylate as well as maleic anhydride (MAH), offers improved adhesion to numerous filler and decreased critical tension, introducing polar functional groups into the polymer backbone without affecting the basic properties of the polymer [21][22][23].…”