Crystallization kinetics of polypropylene composites filled with nano calcium carbonate modified with maleic anhydride

The subject of this study was the crystallization behavior and thermal properties of polypropylene (PP)/maleic anhydride (MAH) modified nano calcium carbonate (nano‐CaCO₃) composites. In this study, 5 wt % nano‐CaCO₃ modified with different contents of MAH was filled into a PP matrix. X‐ray diffraction and differential scanning calorimetry were used to characterize the crystal morphology and crystallization kinetics of a series of composites. The results demonstrate that the nano‐CaCO₃ modified with MAH had an important effect on the thermal and morphological properties of the nanocomposites. The Avrami exponent of the pure PP was an integer, but those of the composites were not integers, but the crystallization rate constant decreased as the content of MAH in the nano‐CaCO₃ filler increased in isothermal crystallization. In nonisothermal crystallization, the kinetic parameter F(T) and the degree of crystallinity of pure PP were compared with those of the PP composites filled with nano‐CaCO₃. We suggest that heterogeneous nucleation existed in the PP composites and that the transformation and retention of the β‐form crystal into the α‐form crystal took place in the composite system and the β‐form crystal had a higher nucleation rate and growth process than the α‐form crystal in the PP composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of silicon dioxide on crystallization and melting behavior of polypropylene

The crystallization and melting behavior of isotactic polypropylene (iPP) and polypropylene copolymer (co‐PP) containing silicon dioxide (SiO₂) were investigated by differential scanning calorimeter (DSC). SiO₂ had a heterogenous nucleating effect on iPP, leading to a moderate increase in the crystallization temperature and a decrease in the half crystallization time. However, SiO₂ decreased the crystallization temperature and prolonged the half crystallization time of co‐PP. A modified Avrami theory was successfully used to well describe the early stages of nonisothermal crystallization of iPP, co‐PP, and their composites. SiO₂ exhibited high nucleation activity for iPP, but showed little nucleation activity for co‐PP and even restrained nucleation. The iPP/SiO₂ composite had higher activation energy of crystal growth than iPP, indicating the difficulty of crystal growth of the composite. The co‐PP/SiO₂ composite had lower activation energy than co‐PP, indicating the ease of crystal growth of the composite. Crystallization rates of iPP, co‐PP, and their composites depended on the nucleation. Because of its high rate of nucleation, the iPP/SiO₂ composite had higher crystallization rate than iPP. Because of its low rate of nucleation, the co‐PP/SiO₂ composite had lower crystallization rate than co‐PP. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1889–1898, 2006     

Poly(propylene)–poly(propylene)‐grafted maleic anhydride–organic montmorillonite (PP–PP‐g‐MAH–Org‐MMT) nanocomposites. II. Nonisothermal crystallization kinetics

The nonisothermal crystallization kinetics of poly(propylene) (PP), PP–organic‐montmorillonite (Org‐MMT) composite, and PP–PP‐grafted maleic anhydride (PP‐g‐MAH)–Org‐MMT nanocomposites were investigated by differential scanning calorimetry (DSC) at various cooling rates. Avrami analysis modified by Jeziorny and a method developed by Mo well‐described the nonisothermal crystallization process of these samples. The difference in the exponent n between PP and composite (either PP–Org‐MMT or PP–PP‐g‐MAH–Org‐MMT) indicated that nonisothermal kinetic crystallization corresponded to tridimensional growth with heterogeneous nucleation. The values of half‐time, Z_c; and F(T) showed that the crystallization rate increased with the increasing of cooling rates for PP and composites, but the crystallization rate of composites was faster than that of PP at a given cooling rate. The method developed by Ozawa can also be applied to describe the nonisothermal crystallization process of PP, but did not describe that of composites. Moreover, the method proposed by Kissinger was used to evaluate the activation energy of the mentioned samples. The results showed that the activation energy of PP–Org‐MMT was much greater than that of PP, but the activation energy of PP–PP‐g‐MAH–Org‐MMT was close to that of pure PP. Overall, the results indicate that the addition of Org‐MMT and PP‐g‐MAH may accelerate the overall nonisothermal crystallization process of PP. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3093–3099, 2003     

Effect of the mixing sequence on the morphology and properties of a polypropylene/polydimethylsiloxane/nano‐SiO2 ternary composite

Ternary composites of polypropylene (PP), polydimethylsiloxane (PDMS) elastomer, and nano‐SiO₂, prepared with three different mixing sequences, were studied for dispersion morphology and its effect on the crystallization of PP and the mechanical properties. The mixing sequence produced a significant effect on the dispersion morphology and, thereby, on the mechanical properties of the composites. A two‐step mixing sequence, in which nano‐SiO₂ was added in the second step to the PP/PDMS binary system, produced a significant encapsulation of nano‐SiO₂ by PDMS, and this, in turn, resulted in the poor modulus and impact strength of the composite. A one‐step mixing sequence of all three components produced a separated dispersion of PDMS and nano‐SiO₂ phases in the PP matrix with the occurrence of a fine band of nano‐SiO₂ particles at the boundaries of the PDMS domains and the presence of some nano‐SiO₂ filler particles inside the PDMS domains. This one‐step mixing sequence produced an improvement in the tensile modulus but a decrease in the impact strength with increasing nano‐SiO₂ content. In the third sequence of mixing, which involved a two‐step mixing sequence through the addition of PDMS in the second step to the previously prepared PP/nano‐SiO₂ binary system, the morphology of the dispersion showed separately dispersed PDMS and nano‐SiO₂ phases with a loose network of nano‐SiO₂ particles surrounding the PDMS domains. This latter series of ternary composites had the highest impact strength and exhibited high shear deformation under tensile and impact conditions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Nonisothermal crystallization kinetics of flame‐sprayed polyamide 1010/nano‐ZrO2 composite coatings

Polyamide1010 (PA1010) and its composite with nanometer‐sized zirconia (PA1010/nano‐ZrO₂) coatings were deposited using a flame spray process. The kinetics of nonisothermal crystallization of PA1010/nano‐ZrO₂ composite coatings was investigated by differential scanning calorimetry (DSC) at various cooling rates. Several different analysis methods were used to describe the process of nonisothermal crystallization. The results showed that the modified Avrami equation and Mo's treatment could describe the nonisothermal crystallization of the composite coatings very well. The nano‐ZrO₂ particles have a remarkable heterogeneous nucleation effect in the PA1010 matrix. The values of halftime and Z_c showed that the crystallization rate increased with increasing cooling rates for both PA1010 and PA1010/nano‐ZrO₂ composite coating, but the crystallization rate of PA1010/nano‐ZrO₂ composite coating was faster than that of PA1010 at given cooling rate. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Preparation of nano poly(phenylsilsesquioxane) spheres(nano‐PPSQ) and study of the thermal stability and crystallization behavior of PP/nano‐PPSQ composites

The preparation of nano poly(phenylsilsesquioxane) particles (nano‐PPSQ) and the influence of nano‐PPSQ on the thermal stability and crystallization of polypropylene (PP) were studied. The morphology and thermal stability of PP/nano‐PPSQ composites were characterized by scanning electron microscopy (SEM) and the thermogravimetric analysis (TGA). The SEM result showed that the particles were well dispersed in the PP matrix. The TGA results of the PP/nano‐PPSQ composites indicated that the incorporation of nano‐PPSQ can improve the thermal stability of PP. The crystallization behavior and kinetics of PP/nano‐PPSQ composite were studied by X‐ray diffraction (XRD) and differential scanning calorimetry (DSC). The XRD revealed that the addition of nano‐PPSQ influences the crystallinity and crystal size of PP. The Avrami, Ozawa, and combined Avrami/Ozawa (Mo method) equations were applied to describe the crystallization kinetics and estimate the kinetic parameters of mathematical models under the nonisothermal crystallization of PP and PP/nano‐PPSQ composites. The results show that nano‐PPSQ influences the crystallization temperature and rate. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Crystallization behavior of PA66/SiO2 organic‐inorganic hybrid material

The poly 2‐hydroxy propylmethacrylate‐methyl methacrylate (PHPMA‐MMA)/SiO₂ composite, derived from 2‐hydroxy propylmethacrylate (HPMA), methyl methacrylate (MMA), and tetraethoxysilane (TEOS), was used to synthesize polyamide 66(PA66)/SiO₂ organic‐inorganic hybrid material. X‐ray diffraction (XRD) was used to investigate the lattice spacing change of the PA66/SiO₂ hybrid material. It was found that the addition of PHPMA‐MMA/SiO₂ composite nearly did not change the crystal form of PA66. The nonisothermal crystallization kinetics of PA66 and PA66/SiO₂ hybrid material was investigated by differential scanning calorimetry (DSC) with various cooling rates. At every given cooling rate, the start crystallization temperature of the PA66/SiO₂ hybrid material was higher than that of PA66, while the crystallization temperature range was narrower than that of PA66. Avrami analysis modified by the Jeziorny method, the Ozawa method, and a method developed by Liu were employed to describe the nonisothermal crystallization process of the samples. The results showed that the Jeziorny method and the Ozawa method were not suitable to describe the nonisothermal crystallization process of PA66/SiO₂ hybrid material; however, when the relative degree of crystallinity X (t) was less than 1 ? 1/e, ln [? ln (1 ? X (t))] was still linear to lnt. The Liu method was successful to describe the nonisothermal crystallization processes for both PA66 and the PA66/SiO₂ hybrid material. It was confirmed that the presence of PHPMA‐MMA/SiO₂ composite could increase the crystallization rate and had a hetero phase nucleation effect on the PA66 matrix. Moreover, the introduction of PHPMA‐MMA/SiO₂ could improve the crystallization active energy ?E calculated by the Kissinger equation, attributing to the strong interaction between the polyamide chains and the PHPMA‐MMA/SiO₂ composite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 810–817, 2006     

Effect of interfacial interaction on the crystallization and mechanical properties of PP/nano‐CaCO3 composites modified by compatibilizers

To investigate the effect of interfacial interaction on the crystallization and mechanical properties of polypropylene (PP)/nano‐CaCO₃ composites, three kinds of compatibilizers [PP grafted with maleic anhydride (PP‐g‐MA), ethylene–octene copolymer grafted with MA (POE‐g‐MA), and ethylene–vinyl acetate copolymer grafted with MA (EVA‐g‐MA)] with the same polar groups (MA) but different backbones were used as compatibilizers to obtain various interfacial interactions among nano‐CaCO₃, compatibilizer, and PP. The results indicated that compatibilizers encapsulated nano‐CaCO₃ particles, forming a core–shell structure, and two interfaces were obtained in the compatibilized composites: interface between PP and compatibilizer and interface between compatibilizer and nano‐CaCO₃ particles. The crystallization and mechanical properties of PP/nano‐CaCO₃ composites were dependent on the interfacial interactions of these two interfaces, especially the interfacial interaction between PP and compatibilizer. The good compatibility between PP chain in PP‐g‐MA and PP matrix improved the dispersion of nano‐CaCO₃ particles, favored the nucleation effect of nano‐CaCO₃, increased the tensile strength and modulus, but reduced the ductility and impact strength of composites. The partial compatibility between POE in POE‐g‐MA and PP matrix had little effect on crystallization and mechanical properties of PP/nano‐CaCO₃ composites. The poor compatibility between EVA in EVA‐g‐MA and PP matrix retarded the nucleation effect of nano‐CaCO₃, and reduced the tensile strength, modulus, and impact strength. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Crystallization and melting behavior of nano‐CaCO3/polypropylene composites modified by acrylic acid

Nano‐CaCO₃/polypropylene (PP) composites modified with polypropylene grafted with acrylic acid (PP‐g‐AA) or acrylic acid with and without dicumyl peroxide (DCP) were prepared by a twin‐screw extruder. The crystallization and melting behavior of PP in the composites were investigated by DSC. The experimental results showed that the crystallization temperature of PP in the composites increased with increasing nano‐CaCO₃ content. Addition of PP‐g‐AA further increased the crystallization temperatures of PP in the composites. It is suggested that PP‐g‐AA could improve the nucleation effect of nano‐CaCO₃. However, the improvement in the nucleation effect of nano‐CaCO₃ would be saturated when the PP‐g‐AA content of 5 phf (parts per hundred based on weight of filler) was used. The increase in the crystallization temperature of PP was observed by adding AA into the composites and the crystallization temperature of the composites increased with increasing AA content. It is suggested that the AA reacted with nano‐CaCO₃ and the formation of Ca(AA)₂ promoted the nucleation of PP. In the presence of DCP, the increment of the AA content had no significant influence on the crystallization temperature of PP in the composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2443–2453, 2004     

Nonisothermal crystallization behavior and crystals morphology of poly(trimethylene terephthalate)/nano‐calcium carbonate composites

Nonisothermal crystallization behavior and crystal morphology of poly(trimethylene terephthalate) (PTT) composites filled with modified nano‐calcium carbonate (CaCO₃) had been investigated by using differential scanning calorimetry and polarized optical microscopy. The modified Avrami equation and Ozawa theory were used to investigate the nonisothermal crystallization, respectively. The particles of nano‐CaCO₃, acting as a nucleation agent in composites, accelerated the crystallization rate by decreasing the half‐time of crystallization or increasing the parameters of Z_c and K(T). Moreover, the nano‐composite with 2 wt% nano‐CaCO₃ exhibited the highest crystallization rate. The Avrami and the Ozawa exponents, n and m of the nano‐composites, were higher than those of neat PTT, suggesting more complicated interaction between molecular chains and the nanoparticles that cause the changes of the nucleation mode and the crystal growth dimension. The effective activation energy calculated from the Friedman formula was reduced as nano‐CaCO₃ content increased, suggesting that the nano‐CaCO₃ made the molecular chains of PTT easier to crystallize during the nonisothermal crystallization process. The optical micrographs showed that much smaller or less perfect crystals were formed in composites because of the presence of the nano‐CaCO₃ particles. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Morphology and properties of PET/PA‐6/SiO2 ternary composites

A kind of hydrophilic nano‐SiO₂ was applied to poly(ethylene terephthalate)/polyamide‐6 (PA‐6) blends. Melt‐blended composites were prepared at various component ratios and different nano‐SiO₂ levels. Mechanical, morphological, dynamic mechanical, and thermal tests were carried out to characterize the properties, morphology, and compatibilization of the composites. Increased impact strength, tensile strength, and modulus were observed by adding nano‐SiO₂ particles in the blends. The nano‐SiO₂ particles were found to be preferentially dispersed in PA‐6, resulting in an increase of glass transition temperature and crystallization of PA‐6. The mechanism of morphology and properties changes was discussed based on the selective dispersion of nano‐SiO₂ particles in the blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2288–2296, 2007     

Coincorporation of nano‐silica and nano‐calcium carbonate in polypropylene

In this study, various polypropylene (PP) nanocomposites were prepared by melt blending method. The effects of different spherical nanofillers, such as 50 nm CaCO₃ and 20 nm SiO₂, on the linear viscoelastic property, crystallization behavior, morphology and mechanical property of the resulting PP nanocomposites were examined. Rheological study indicated that coincorporation of nano‐SiO₂ and nano‐CaCO₃ favored the uniform dispersion of nanoparticles in the PP matrix. Differential scanning calorimeter (DSC) and polarizing optical microscopy (POM) studies revealed that the coincorporation of SiO₂ and CaCO₃ nanoparticles could effectively improve PP crystallizability, which gave rise to a lower supercooling temperature (ΔT), a shorter crystallization half‐life (t_1/2) and a smaller spherulite size in comparison with those nanocomposites incorporating only one type of CaCO₃ or SiO₂ nanoparticles. The mechanical analysis results also showed that addition of two types of nanoparticles into PP matrix gave rise to enhanced performance than the nanocomposites containing CaCO₃ or SiO₂ individually. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effective method for dispersing SiO2 nanoparticles into polyethylene

The nonisothermal crystallization behavior and kinetics of polytetrafluoroethylene (PTFE) and PTFE/solid glass microsphere (SGM) composites were investigated with differential scanning calorimetry at various cooling rates (?'s). Three methods, namely, the Jeziorny, Ozawa and Mo methods, were used to describe the nonisothermal crystallization process. The results show that the peak temperature, crystallinity (X_c), and crystallization half‐time were strongly dependent on the content of SGMs and ?. The SGMs in the PTFE/SGM composites exhibited a higher nucleation activity. The nonisothermal crystallization kinetics of PTFE and the PTFE/SGM composites was analyzed successfully with the Jeziorny and Mo methods; however, the Ozawa equation was invalid for the nonisothermal crystallization process. The crystallization activation energy determined with the Kissinger equation was remarkably lower when a small amount of SGMs (5%) was added and then gradually increased and finally became slightly lower than that of pure PTFE as the content of SGMs increased up to 25% in the composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Novel intercalated nanocomposites of polypropylene/organic‐rectorite/polyethylene‐octene elastomer: Rheology,crystallization kinetics,and thermal properties

The melt blending method was applied to prepare ternary composites of polypropylene (PP)/organic‐rectorite (OREC)/polyethylene‐octene elastomer (POE) at constant content of 2 phr (parts per hundred PP) of OREC and 5, 10, 15 phr of POE (named PRE25, PRE210, and PRE215, separately) via twin‐screw extruder. At the same time the binary composites of OREC/PP at 2 phr loading of OREC, named PR2 were prepared in order to investigate effects of OREC and POE on rheology and crystallization properties of composites. The rheology was characterized on capillary rheometer, nonisothermal crystallization kinetics on differential scanning calorimetry (DSC), and thermal stability properties on thermogravimetric analysis (TG). It is found that melting PR2 and PRE systems conform to the law of Non‐Newton and shear‐thinning behavior is observed for both systems. The apparent viscosity of the melt decreases with the increase of POE loadings. The crystallization halftime (t_1/2) of PRE is shorter, the rate constant Zc larger, which indicates OREC and POE has the heterogeneous nucleation effect and the crystallization rate of PP was increased. The enthalpy of PRE is lower than that of PR2 and pure PP at the same conditions, which shows that the relative crystallinity of PRE composites are reduced. TG curves show that the ternary systems have higher thermal stability in contrast with pure PP. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1915–1921, 2005     

PP/PP-g-NH2/纳米SiO2复合材料的非等温结晶

采用示差扫描量热法（DSC）研究了聚丙烯/氨基化聚丙烯/纳米二氧化硅（PP/PP-g-NH₂/SiO₂）复合材料的非等温结晶行为。利用Caze法对结晶动力学进行了分析,Avrami指数n表明纳米SiO₂和PP-g-NH₂的加入改变了PP的结晶成核和生长机理;运用Dobreva法研究了纳米粒子的成核活性,结果表明纳米SiO₂成核活性差,增容剂PP-g-NH₂明显增强其成核活性;采用Friedman法分析了复合材料的结晶有效能垒,研究表明加入纳米SiO₂使PP的结晶有效能垒降低,添加PP-g-NH₂则进一步降低复合体系的结晶有效能垒;当纳米粒子含量为3%时,添加5% PP-g-NH₂能有效提高纳米粒子成核活性,降低复合材料结晶有效能垒。     

Nonisothermal Crystallization Modeling and Simulation for Polypropylene/Nano CaSO4 Composites with Variations in Nanosizes and Wt.% of Loading

Avrami and Ozawa's combined analysis was employed to study the nonisothermal crystallization kinetics of Polypropylene (PP): CaSO₄ (of 12 and 22 nm) composites using a Differential Scanning Calorimeter (DSC). The parameters, such as Avrami's exponent (n) and growth rate constant (Z_t), that characterized the system of different nanosize composites and virgin PP, were determined. The relative degree of crystallinity as a function of temperature for PP/nano CaSO₄ composites at the same cooling rate and the Sigmoidal shape of curves indicate a strong interaction between PP molecules and the nanolayer, which leads to greater nucleation with a reduction in nanosizes. The theoretical combination of kinetic equations was found to be suitable to describe the physical phenomena of real system. The values of parameters n, Z_t and predicted time t for crystallization at a single cooling rate were obtained from the mathematical model.     

Nonisothermal crystallization behavior of highly exfoliated polypropylene/clay nanocomposites prepared by in situ polymerization

Polypropylene/clay nanocomposites (PPCNs) were prepared via an in situ polymerization method with a Ziegler–Natta/clay compound catalyst in which the MgCl₂/TiCl₄ catalyst was embedded in the clay galleries. The wide‐angle X‐ray diffraction and transmission electron microscopy results showed that the clay particles were highly exfoliated in the polypropylene (PP) matrix. The nonisothermal crystallization kinetics of these PPCNs were investigated by differential scanning calorimetry at various cooling rates. The nucleation activity were calculated by Dobreva's method to demonstrate that the highly dispersed silicate layers acted as effective nucleating agents. The Avrami, Jeziorny, Ozawa, and Mo methods were used to describe the nonisothermal crystallization behavior of the PP and PPCNs. Various parameters of nonisothermal crystallization, such as the crystallization half‐time, crystallization rate constant, and the kinetic parameter F(t), reflected that the highly exfoliated silicate layers significantly accelerated the crystallization process because of its outstanding nucleation effect. The activation energy values of the PP and PPCNs determined by the Kissinger method increased with the addition of the nanosilicate layers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

NONISOTHERMAL CRYSTALLIZATION KINETICS AND MECHANICAL PROPERTIES OF PP/NANO-SiO2 COMPOSITES

The nonisothermal crystallization kinetics of polypropylene (PP)/nano-SiO₂ composites was studied by means of differential scanning calorimetry (DSC). The modified Avrami theories by Jeziorny, Ozawa, and Mo were used to analyze the data of DSC. The results showed that both the Jeziorny and Mo methods could describe this system very well, but the Ozawa analysis failed. The activation energy was evaluated by the Kissinger method. It was found that the crystallization activation energy of PP was higher than that of PP/nano-SiO₂ composites. The determined results of mechanical properties showed that the addition of nano-SiO₂ increased the mechanical properties of the PP. Micrographs of Polarized optical micrograph (POM) further demonstrated that nano-SiO₂ could toughen the PP.     

Interfacial effects in polypropylene–silica nanocomposites

Grafted inorganic nanoparticles can greatly improve the mechanical performance of polymers. To examine the effects of the interfacial characteristics generated by the grafting polymer bonded to nanoparticle surfaces, we chemically grafted nano‐silica with different polymers and then melt‐mixed it with polypropylene (PP). We extracted the homopolymers produced during the graft polymerization from the grafted products before the composites were manufactured to get rid of the side effects of the nongrafting polymers. We tailored the interfacial interaction between the grafted nano‐SiO₂ and PP matrix by changing the amount of the grafting polymers on the nanoparticles, that is, the grafting percentage. Mechanical tests indicated that all the composites incorporated with grafted nano‐SiO₂ particles possessed much higher impact strength than untreated SiO₂/PP composites and neat PP. The greatest contribution of the particles was made at a low grafting percentage. Tensile measurements showed that the treated nanoparticles could provide PP with stiffening, strengthening, and toughening effects at a rather low filler content (typically 0.8 vol %) because of the enhanced interfacial adhesion resulting from molecular entanglement and interdiffusion between the grating polymers on the nanoparticles and matrix macromolecules. The presence of grafting polymers on the nanoparticles provided the composites with a tailorable interphase. The tensile performance of the composites was sensitive to the nature of the grafting polymers. Basically, a hard interface was beneficial to stress transfer, whereas a soft one hindered the development of cavities in the matrix. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1771–1781, 2004     

Nonisothermal crystallization behavior of glass‐bead‐filled polypropylene

The effects of the glass‐bead content and size on the nonisothermal crystallization behavior of polypropylene (PP)/glass‐bead blends were studied with differential scanning calorimetry. The degree of crystallinity decreased with the addition of glass bead, and the crystallization temperature of the blends was marginally higher than that of pure PP at various cooling rates. Furthermore, the half‐time for crystallization decreased with an increase in the glass‐bead content or particle size, implying the nucleating role of the glass beads. The nonisothermal crystallization data were analyzed with the methods of Avrami, Ozawa, and Mo. The validity of various kinetic models for the nonisothermal crystallization process of PP/glass‐bead blends was examined. The approach developed by Mo successfully described the nonisothermal crystallization behavior of PP and PP/glass‐bead blends. Finally, the activation energy for the nonisothermal crystallization of pure PP and PP/glass‐bead blends based on the Kissinger method was evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2026–2033, 2006