Effects of the ethylene–propylene–diene monomer microstructural parameters and interfacial compatibilizer upon the EPDM/montmorillonite nanocomposites microstructure: Rheology/permeability correlation

Attempts have been made to investigate the effects of ethylene–propylene–diene monomer (EPDM) rubber structural parameters on the developed microstructure, mechanical properties, rheology, and oxygen gas permeability of EPDM/organically modified montmorillonite (O‐MMT) nanocomposite samples prepared via melt mixing. Maleic anhydride grafted EPDM (EPDM‐g‐MAH) has been employed as an interfacial compatibilizer. The influence of the EPDM melt viscosity and chain linearity on the extent of exfoliation of the clay nanolayers has been evaluated through the calculation of the nanolayer aspect ratio (length/thickness) with the Halpin–Tsai model. The results are consistent with the X‐ray diffraction patterns of the samples. The flocculation of the clay nanolayers has been found to be more probable when O‐MMT is mixed with highly branched, low‐molecular‐weight EPDM. More exfoliation occurs when EPDM rubber with a high molecular weight but low branching is used. This has been confirmed by more nonlinear melt rheology behavior and broadening of the retardation time spectra. Maleated EPDM has been shown to be effective in enhancing the molecular intercalation of the clay nanolayers and the prevention of flocculation in both low‐molecular‐weight and high‐molecular‐weight EPDM matrices. Dynamic melt rheology measurements have revealed nonterminal behavior within the low‐frequency range by interfacially compatibilized molten samples with an EPDM‐g‐MAH/clay ratio of 3, regardless of the matrix molecular weight and chain linearity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effects of the compatibilizer structural parameters on microstructural formation in ethylene–propylene–diene monomer rubber/ethylene–propylene–diene monomer rubber‐g‐maleic anhydride/organoclay nanocomposites

Nanocomposite vulcanizates based on ethylene–propylene–diene monomer rubber (EPDM) and organically modified montmorillonite with improved mechanical and barrier properties were prepared via a melt‐mixing process in the presence of maleic anhydride grafted ethylene–propylene–diene monomer rubber (EPDM‐g‐MAH) as an interfacial compatibilizer. The effects of the EPDM Mooney viscosity as the matrix and also the compatibilizer molecular weight and its maleation degree on the developed microstructure were also studied. The annealing of the vulcanized nanocomposites based on a low‐Mooney‐viscosity EPDM matrix and low‐Mooney‐viscosity EPDM‐g‐MAH enhanced the flocculation of the dispersed clay platelets; this implied that the flocculated structure for the clay nanolayers was more thermodynamically preferred in these nanocomposites. This was verified by the decrease in the oxygen permeability of the nanocomposite vulcanizates with increasing annealing time. The tendency of the clay nanosilicate layers to flocculate within the matrix of EPDM was found to be influenced by the clay volume fraction, the maleation degree, and also, the Mooney viscosity of the compatibilizer. Interfacially compatibilized nanocomposites based on high‐molecular‐weight EPDM exhibited a more disordered dispersion of the clay nanolayers, with a broadened relaxation time spectra; this was attributed to the higher shearing subjected to the mix during the melt‐blending process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and evaluation of high‐performance ethylene–propylene–diene terpolymer/organoclay nanoscale composites

The main objective of this study was to synthesize and characterize the properties of ethylene–propylene–diene terpolymer (EPDM)/clay nanocomposites. Pristine clay, sodium montmorillonite (Na⁺–MMT), was intercalated with hexadecyl ammonium ion to form modified organoclay (16Me–MMT) and the effect of intercalation toward the change in interlayer spacing of the silicate layers was studied by X‐ray diffraction, which showed that the increase in interlayer spacing in Na⁺–MMT by 0.61 nm is attributed to the intercalation of hexadecyl ammonium ion within the clay layers. In the case of EPDM/16Me–MMT nanocomposites, the basal reflection peak was shifted toward a higher angle. However, gallery height remained more or less the same for different EPDM nanocomposites with organoclay content up to 8 wt %. The nanostructure of EPDM/clay composites was characterized by transmission electron microscopy, which established the coexistence of intercalated and exfoliated clay layers with an average layer thickness in the nanometer range within the EPDM matrix. The significant improvement in thermal stability and mechanical properties reflects the high‐performance nanocomposite formation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2429–2436, 2004     

EPDM/silicone blend layered silicate nanocomposite by solution intercalation method: Morphology and properties

Ethylene–propylene–diene terpolymer (EPDM)/silicone blend nanocomposites are prepared by solution method for the first time. EPDM and silicone rubber in their 50:50 (by weight) blend is intercalated within the silicate sheets of organically modified montmorillonite. Organic modification to the pristine sodium montmorillonite (Na‐MMT) surfaces is carried out by ion‐exchange reaction using hexadecyl ammonium chloride. The incorporation of such organic functional group makes Na‐MMT hydrophobic and expands the interlayer spacing between silicate sheets. The intercalated structure of EPDM/silicone blend nanocomposites is characterized by the X‐ray diffraction. Transmission electron microscopic characterization visualized the presence of both exfoliated and intercalated layered silicate in the polymer nanocomposites. The mechanical properties of the nanocomposites show a maximum improvement in tensile strength and elongation at break of 23 and 68%, respectively, compared with EPDM/silicone blend. The dielectric measurement demonstrates the increase in relative permittivity for the nanocomposite than the pure blend. The increase in the onset temperature of the thermal degradation of nanocomposites (∼52°C) corresponding to 1 wt% decomposition indicates the enhancement of thermal stability of (EPDM)/silicone blend due to interaction with silicates. POLYM. COMPOS., 35:1834–1841, 2014. © 2014 Society of Plastics Engineers     

Preparation and properties of ethylene–propylene–diene rubber/organomontmorillonite nanocomposites

Ethylene–propylene–diene rubber (EPDM)/organomontmorillonite (OMMT) nanocomposites were prepared with a maleic anhydride grafted EPDM oligomer as a compatibilizer via melt intercalation. X‐ray diffraction and transmission electron microscopy indicated that the silicate layers of OMMT were exfoliated and dispersed uniformly as a few monolayers in nanocomposites. The change in the crystallization behavior of the nanocomposites was examined. The nanocomposites exhibited great improvements in the tensile strength and tensile modulus. The incorporation of OMMT gave rise to a considerable reduction of tan δ and an increase in the storage modulus. Moreover, the solvent resistance of the nanocomposites increased remarkably. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 440–445, 2004     

Investigation on morphology and mechanical properties of polyamide 6/maleated ethylene‐propylene‐diene rubber/organoclay composites

Maleated ethylene‐propylene‐diene rubber (EPDM‐g‐MA) toughened polyamide 6 (PA6)/organoclay (OMMT) nanocomposites were prepared by melt blending. The role of OMMT in the morphology of the ternary composites and the relationship between the morphology and mechanical properties were investigated by varying the blending sequence. The PA6/EPDM‐g‐MA/OMMT (80/20/4) composites prepared by four different blending sequences presented distinct morphology and mechanical properties. The addition of OMMT could obviously decrease viscosity of the matrix and weaken the interfacial interactions between PA6 and EPDM‐g‐MA when blending EPDM‐g‐MA with a premixed PA6/OMMT nacocomposite, resulting in the increase of rubber particle size. The final mechanical properties are not only determined by the location of OMMT, but also by the interfacial adhesion between PA6 and EPDM‐g‐MA. Having maximum percentage of OMMT platelets in the PA6 matrix and keeping good interfacial adhesion between PA6 and EPDM‐g‐MA are beneficial to impact strength. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

Polyamide 6/maleated ethylene–propylene–diene rubber/organoclay composites with or without glycidyl methacrylate as a compatibilizer

Polyamide 6 (PA6)/maleated ethylene–propylene–diene rubber (EPDM‐g‐MA)/organoclay (OMMT) composites were melt‐compounded through two blending sequences. Glycidyl methacrylate (GMA) was used as a compatibilizer for the ternary composites. The composite prepared through via the premixing of PA6 with OMMT and then further melt blending with EPDM‐g‐MA exhibited higher impact strength than the composite prepared through the simultaneous blending of all the components. However, satisfactorily balanced mechanical properties could be achieved by the addition of GMA through a one‐step blending sequence. The addition of GMA improved the compatibility between PA6 and EPDM‐g‐MA, and this was due to the reactions between PA6, EPDM‐g‐MA, and GMA, as proved by Fourier transform infrared analysis and solubility (Molau) testing. In addition, OMMT acted as a compatibilizer for PA6/EPDM‐g‐MA blends at low contents, but it weakened the interfacial interactions between PA6 and EPDM‐g‐MA at high contents. Both OMMT and GMA retarded the crystallization of PA6. The complex viscosity, storage modulus, and loss modulus of the composites were obviously affected by the addition of OMMT and GMA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Compatibilizing effect of ethylene–propylene–diene grafted maleic anhydride terpolymer on the blend of polyamide 66 and thermal liquid crystalline polymer

Polyamide 66–thermal liquid crystalline polymer (PA66/TLCP) composites containing 10 wt% TLCP was compatibilized by ethylene–propylene–diene‐grafted maleic anhydride terpolymer (MAH‐g‐EPDM). The blending was performed on a twin‐screw extrusion, followed by an injection molding. The rheological, dynamic mechanical analysis (DMA), thermal, mechanical properties, as well as the morphology and FTIR spectra, of the blends were investigated and discussed. Rheological, DMA, and FTIR spectra results showed that MAH‐g‐EPDM is an effective compatibilizer for PA66/TLCP blends. The mechanical test indicated that the tensile strength, tensile elongation, and the bending strength of the blends were improved with the increase of the content of MAH‐g‐EPDM, which implied that the blends probably have a great frictional shear force, resulting from strong adhesion at the interface between the matrix and the dispersion phase; while the bending modulus was weakened with the increase of MAH‐g‐EPDM content, which is attributed to the development of the crystalline phase of PA66 hampered by adding MAH‐g‐EPDM. POLYM. COMPOS., 27:608–613, 2006. © 2006 Society of Plastics Engineers     

Novel preparation and properties of EPDM/montmorillonite nanocomposites

This article reports on a novel route to develop ethylene–propylene–diene rubber (EPDM)/montmorillonite nanocomposites Modification of the MMT was carried out with maleic anhydride (MA), which acts as the intercalation agent for MMT and the vulcanizing agent for EPDM matrix, as well as the compatibilizer for the EPDM and MMT phases. The effect of MA‐modified MMT in nanocomposites was investigated by focusing on three major aspects: structural analysis, thermal properties, and material properties. The d‐spacings of both the MA modified MMT and exfoliated nanocomposites were investigated by X‐ray diffraction (XRD), and the morphology of these nanocomposites was examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Dynamic mechanical analysis confirms the constraint effect of exfoliated MMT layers on EPDM chains, which benefited the increased storage modulus, increased glass transition temperature. Thermogravimetric analysis indicates that there is some enhancement in degradation behavior between the nanocomposites and EPDM matrix. The nanocomposites exhibit great improvement in tensile strength and modulus, as well as elongation‐at‐break. The effects of MA addition on the formation of nano‐metric reinforcement and on the mechanical properties of nanocomposites are discussed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2578–2585, 2006     

Effect of montmorillonite on properties of styrene–butadiene–styrene copolymer modified bitumen

Clay/styrene–butadiene–styrene (SBS) modified bitumen composites were prepared by melt blending with different contents of sodium montmorillonite (Na‐MMT) and organophilic montmorillonite (OMMT). The structures of clay/SBS modified bitumen composites were characterized by XRD. The XRD results showed that Na‐MMT/SBS modified bitumen composites may form an intercalated structure, whereas the OMMT/SBS modified bitumen composites may form an exfoliated structure. Effects of MMT on physical properties, dynamic rheological behaviors, and aging properties of SBS modified bitumen were investigated. The addition of Na‐MMT and OMMT increases both the softening point and viscosity of SBS modified bitumens and the clay/SBS modified bitumens exhibited higher complex modulus, lower phase angle. The high‐temperature storage stability can also be improved by clay with a proper amount added. Furthermore, clay/SBS modified bitumen composites showed better resistance to aging than SBS modified bitumen, which was ascribed to barrier of the intercalated or exfoliated structure to oxygen, reducing efficiently the oxidation of bitumen, and the degradation of SBS. POLYM. ENG. SCI., 47:1289–1295, 2007. © 2007 Society of Plastics Engineers     

Influence of the type of quaternary ammonium salt used in the organic treatment of montmorillonite on the properties of poly(styrene‐co‐butyl acrylate)/layered silicate nanocomposites prepared by in situ miniemulsion polymerization

Hybrid latices of poly(styrene‐co‐butyl acrylate) were synthesized via in situ miniemulsion polymerization in the presence of 3 and 6 wt % organically modified montmorillonite (OMMT). Three different ammonium salts: cetyl trimethyl ammonium chloride (CTAC), alkyl dimethyl benzyl ammonium chloride (Dodigen), and distearyl dimethyl ammonium chloride (Praepagen), were investigated as organic modifiers. Increased affinity for organic liquids was observed after organic modification of the MMT. Stable hybrid latices were obtained even though miniemulsion stability was disturbed to some extent by the presence of the OMMTs during the synthesis. Highly intercalated and exfoliated polymer‐MMT nanocomposites films were produced with good MMT dispersion throughout the polymeric matrix. Materials containing MMT modified with the 16 carbons alkyl chain salt (CTAC) resulted in the largest increments of storage modulus, indicating that single chain quaternary salts provide higher increments on mechanical properties. Films presenting exfoliated structure resulted in the largest increments in the onset temperature of decomposition. For the range of OMMT loading studied, the nanocomposite structure influenced more significantly the thermal stability properties of the hybrid material than did the OMMT loading. The film containing 3 wt % MMT modified with the two 18 carbons alkyl chains salt (Praepagen) provided the highest increment of onset temperature of decomposition. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Investigation of crystallization behavior in dynamically vulcanized EPDM–nylon copolymer blends

A thermoplastic vulcanizate (TPV) of a ethylene–propylene–diene terpolymer (EPDM) and nylon copolymer (PA) was prepared by dynamic vulcanization. Maleic anhydride (MAH)–grafted EPDM (EPDM–g–MAH), MAH‐grafted EPR (EPR–g–MAH), and chlorinated polyethylene (CPE) were used as compatibilizers. The effect of dynamic vulcanization and compatibilizer on the crystallization behavior of PA was investigated. Differential scanning calorimeter measurement results showed no pronounced shift in the crystallization temperature for PA in EPDM–PA TPV compared to that for PA in the neat state, whereas the crystallization temperature increased after adding compatibilizer. The decrease in the crystallinity of TPVs was a result of the crystallization occurring in confined spaces between rubber particles. The equilibrium melting temperature (Tm⁰) of the PA copolymer was measured and was determined to be 157°C. The isothermal crystallization kinetics of PA in the neat and TPV states also was investigated. The crystallization rate was highest in the compatibilized TPV and lowest in the neat PA, whereas it was intermediate in the uncompatibilized TPV unvulcanized blends. Compared with unvulcanized EPDM–PA blends, the dynamic vulcanization process seemed to cause an obvious increase in the crystallization rate of the PA copolymer, especially when a suitable compatibilizer was used. This occurred because the dynamic vulcanization introduced fine crosslinked rubber particles that could act as heterogeneous nucleating centers. In addition, the use of a suitable compatibilizer permitted the formation of finely dispersed vulcanized rubber particles and therefore increased the density of the nucleating centers. The complex morphology of the blends was investigated by atomic force microscopy to evaluate the effect of compatibilizer on the size of the dispersed rubber particles. Compared with the morphology of TPVs with the same dosage of EPDM–g–MAH compatibilizer, the morphology of TPVs using EPR–g–MAH as compatibilizer showed much smaller dispersed rubber particles, which may have contributed to the higher crystallization rate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 824–829, 2003     

Photodegradation of some low‐density polyethylene–montmorillonite nanocomposites containing an oligomeric compatibilizer

The photo‐oxidation behavior at the exposed surfaces of maleated low‐density polyethylene [LDPE poly(ethylene‐co‐butylacrylate‐co‐maleic anhydride) (PEBAMA)] and montmorillonite (MMT) composites was studied using attenuated total reflection Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), transmission electron microscopy (TEM), and mechanical testing. Two different MMT clays were used with the maleated polyethylene, an unmodified clay, MMT, and an organically modified montmorillonite (OMMT) clay which was significantly exfoliated in the composite. The morphologies of sample films were examined by XRD and TEM. The results were explained in terms of the effect of the compatibilizing agent PEBAMA on the clay dispersion. It was found that the OMMT particles were exfoliated in the polymer matrix in the presence of the PEBAMA, whereas the MMT clay particles were agglomerated in this matrix. Both mechanical and spectroscopic analyses showed that the rates of photo oxidative degradation of the LDPE‐PEBAMA–OMMT were higher than those for LDPE and LDPE‐PEBAMA–MMT. The acceleration of the photo‐oxidative degradation for LDPE‐PEBAMA–OMMT is attributed to the effects of the compatibilizer and the organic modifier in the composite. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40788.     

Effects of EPDM‐g‐MAH compatibilizer and internal mixer processing parameters on the properties of NR/EPDM blends: An analysis using response surface methodology

This study evaluates the effects of ethylene‐propylene‐diene‐monomer grafted maleic anhydride (EPDM‐g‐MAH) and internal mixer melt compounding processing parameters on the properties of natural rubber/ethylene‐propylene‐diene rubber (NR/EPDM) blends. Using Response Surface Methodology (RSM) of 2⁵ two‐level fractional factorial, we studied the effects of NR/EPDM ratio, mixing temperature, Banbury rotor speed, mixing period, and EPDM‐g‐MAH contents in NR/EPDM blends. The study found that the presence of EPDM‐g‐MAH in NR/EPDM blends had a predominant role as a compatibilizing agent, which affected the processability and properties of the final material. We also determined the model fitting with constant determination, R² of 99.60% for tensile strength (TS) response with a suggested combination of mixing process input parameters. The reproducibility of the proposed mixing strategy was then confirmed through model validation with a minor deviation at +2.303% and higher desirability of 0.960. This study is essential in providing a process design reference for NR/EPDM blends preparation by melt‐blending and the role of a compatibilizer from the systematic Design of Experiment (DOE) approach. The experimental findings were further supported with swelling and cross‐link density measurements, differential scanning calorimetry analysis, and observation of fracture morphology using a scanning electron microscope. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42199.     

Synergetic toughness and morphology of poly(propylene)/nylon 11/maleated ethylene‐propylene diene copolymer blends

Polypropylene (PP)/nylon 11/maleated ethylene‐propylene‐diene rubber (EPDM‐g‐MAH) ternary polymer blends were prepared via melt blending in a corotating twin‐screw extruder. The effect of nylon 11 and EPDM‐g‐MAH on the phase morphology and mechanical properties was investigated. Scanning electron microscopy observation revealed that there was apparent phase separation for PP/EPDM‐g‐MAH binary blends at the level of 10 wt % maleated elastomer. For the PP/nylon 11/EPDM‐g‐MAH ternary blends, the dispersed phase morphology of the maleated elastomer was hardly affected by the addition of nylon 11, whereas the reduced dispersed phase domains of nylon 11 were observed with the increasing maleated elastomer loading. Furthermore, a core‐shell structure, in which nylon 11 as a rigid core was surrounded by a soft EPDM‐g‐MAH shell, was formed in the case of 10 wt % nylon 11 and higher EPDM‐g‐MAH concentration. In general, the results of mechanical property measurement showed that the ternary blends exhibited inferior tensile strength in comparison with the PP matrix, but superior toughness. Especially low‐temperature impact strength was obtained. The toughening mechanism was discussed with reference to the phase morphology. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Solid‐state graft polymerization of styrene in spherical polypropylene particles in the presence of montmorillonite

In this work, cetyltrimethyl ammonium bromide and methacryloyloxyethyhrimethyl ammonium chloride were used to prepare organophilic montmorillonite (O‐MMT). Then, polypropylene (PP)–clay nanocomposites were prepared by the in situ grafting polymerization of styrene (St)‐containing O‐MMT onto PP with tert‐butyl perbenzoate as an initiator in the solid state. Fourier transform infrared spectroscopy, gel permeation chromatography, transmission electron microscopy, and X‐ray diffraction were applied to study the structure of the layered silicate and modified PP. The surfaces of the composites and, thus, the distribution of the clay in the PP matrix were characterized by scanning electron microscopy. The rheology and mechanical properties were studied and are discussed. According to the characterization results, OMMT and St were already grafted onto the PP main chain. Also, the intercalated structure of montmorillonite could be stabilized, and a stable exfoliated structure could be attained. Namely, intercalated PP/OMMT nanocomposites were obtained. The rheological results clearly show that these PP/OMMT nanocomposites had long‐chain‐branched structures. The peroxide modification of PP had minor effects on the tensile and bending strengths of the modified PP; however, this modification resulted in a significant reduction in the impact strength. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of EPDM‐g‐MAH on the morphology and properties of PA6/EPDM/HDPE ternary blends

The formation of core‐shell morphology within the dispersed phase was studied for composite droplet polymer‐blend systems comprising a polyamide‐6 matrix, ethylene‐propylene‐diene terpolymer (EPDM) shell and high density polyethylene (HDPE) core. In this article, the effect of EPDM with different molecular weights on the morphology and properties of the blends were studied. To improve the compatibility of the ternary blends, EPDM was modified by grafting with maleic anhydride (EPDM‐g‐MAH). It was found that core‐shell morphology with EPDM‐g‐MAH as shell and HDPE as core and separated dispersion morphology of EPDM‐g‐MAH and HDPE phase were obtained separately in PA6 matrix with different molecular weights of EPDM‐g‐MAH in the blends. DSC measurement indicated that there may be some co‐crystals in the blends due to the formation of core‐shell structure. Mechanical tests showed that PA6/EPDM‐g‐MAH/HDPE ternary blends with the core‐shell morphology exhibited a remarkable rise in the elongation at break. With more perfect core‐shell composite droplets and co‐crystals, the impact strength of the ternary blends could be greatly increased to 51.38 kJ m^?2, almost 10 times higher than that of pure PA6 (5.50 kJ m^?2). POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Exfoliation targeted toughness enhancement in polypropylene‐blend‐ montmorillonite nanocomposites

BACKGROUND: Both exfoliated and toughened polypropylene‐blend‐montmorillonite (PP/MMT) nanocomposites were prepared by melt extrusion in a twin‐screw extruder. Special attention was paid to the enhancement of clay exfoliation and toughness properties of PP by the introduction of a rubber in the form of compatibilizer toughener: ethylene propylene diene‐based rubber grafted with maleic anhydride (EPDM‐g‐MA). RESULTS: The resultant nanocomposites were characterized using X‐ray diffraction, atomic force microscopy, scanning electron microscopy, thermogravimetric analysis, dynamic mechanical analysis and Izod impact testing methods. It was found that the desired exfoliated nanocomposite structure could be achieved for all compatibilizer to organoclay ratios as well as clay loadings. Moreover, a mechanism involving a decreased size of rubber domains surrounded with nanolayers as well as exfoliation of the nanolayers in the PP matrix was found to be responsible for a dramatic increase in impact resistance of the nanocomposites. CONCLUSION: Improved thermal and dynamic mechanical properties of the resultant nanocomposites promise to open the way for highly toughened super PPs via nanocomposite assemblies even with very low degrees of loading. Copyright © 2008 Society of Chemical Industry     

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