Nonisothermal crystallization kinetics of high‐density polyethylene/barium sulfate nanocomposites

The high‐density polyethylene (HDPE)/barium sulfate (BaSO₄) nanocomposites had been successfully prepared by melt‐blending. Nonisothermal melt‐crystallization kinetics of neat HDPE and HDPE/BaSO₄ nanocomposites was investigated with differential scanning calorimetry under different cooling rates. The nonisothermal crystallization behavior was analyzed by Ozawa, Avrami, and combined Ozawa–Avrami methods. It was found that the Ozawa method failed to describe the nonisothermal crystallization behavior of neat HDPE and HDPE/BaSO₄ nanocomposites. The modified Avrami method by Jeziorny was only valid for describing the middle stage of crystallization but was not able to describe the later stage of neat HDPE and HDPE/BaSO₄ nanocomposites crystallization. The value of Avrami exponent n for neat HDPE ranged from 3.3 to 5.7 and for HDPE/BaSO₄ nanocomposites ranged from 1.8 to 2.5. It is postulated that the values of n close to 3 are caused by spherulitic crystal growth with heterogeneous nucleation, whereas simultaneous occurrence of spherulitic and lamellar crystal growth with heterogeneous nucleation account for lower values of n. The combined Ozawa–Avrami method by Mo and coworkers (Polym. Eng. Sci., 37(3) , 568 (1997)) was able to satisfactorily describe the crystallization behavior of neat HDPE and HDPE/BaSO₄ nanocomposites. In addition, the activation energy of nonisothermal crystallization was determined using the Kissinger (J. Res. Natl. Bur. Stand., 57(4) , 217 (1956)) method, showing that the crystallization activation energy of HDPE/BaSO₄ nanocomposites was lower than that of neat HDPE. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Morphology and properties of nylon 6 and high density polyethylene blends in presence of nanoclay and PE‐g‐MA

In this study, we report the synergistic effect of nanoclay and maleic anhydride grafted polyethylene (PE‐g‐MA) on the morphology and properties of (80/20 w/w) nylon 6/high density polyethylene (HDPE) blend. Polymer blend nanocomposites containing nanoclay with and without compatibilizer (PE‐g‐MA) were prepared by melt mixing, and their morphologies and structures were examined with scanning electron microscopy (SEM) and wide angle X‐ray diffractometer (WAXD) study. The size of phase‐separated domains decreased considerably with increasing content of nanoclay and PE‐g‐MA. WAXD study and transmission electron microscopy (TEM) revealed the presence of exfoliated clay platelets in nylon 6 matrix, as well as, at the interface of the (80/20 w/w) nylon 6/HDPE blend–clay nanocomposites. Addition of PE‐g‐MA in the blend–clay nanocomposites enhanced the exfoliation of clays in nylon 6 matrix and especially at the interface. Thus, exfoliated clay platelets in nylon 6 matrix effectively restricted the coalescence of dispersed HDPE domains while PE‐g‐MA improved the adhesion between the phases at the interface. The use of compatibilizer and nanoclay in polymer blends may lead to a high performance material which combines the advantages of compatibilized polymer blends and the merits of polymer nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Gasoline permeation behavior and mechanical properties of polyamide 6/nanoclay,polyamide 6/PE‐g‐maleic anhydride blend,and polyamide 6/PE‐g‐maleic anhydride/clay nanocomposite

In this article, polyamide 6 (PA6)/clay nanocomposites, PA6/polyethylene grafted maleic anhydride (PE‐g‐MA) blends, and PA6/PE‐g‐MA/clay nanocomposites were prepared and their gasoline permeation behavior and some mechanical properties were investigated. In PA6/clay nanocomposites, cloisite 30B was used as nanoparticles, with weight percentages of 1, 3, and 5. The blends of PA6/PE‐g‐MA were prepared with PE‐g‐MA weight percents of 10, 20, and 30. All samples were prepared via melt mixing technique using a twin screw extruder. The results showed that the lowest gasoline permeation occurred when using 3 wt % of nanoclay in PA6/clay nanocomposites, and 10 wt % of PE‐g‐MA in PA6/PE‐g‐MA blends. Therefore, a sample of PA6/PE‐g‐MA/clay nanocomposite containing 3 wt % of nanoclay and 10 wt % of PE‐g‐MA was prepared and its gasoline permeation behavior was investigated. The results showed that the permeation amount of PA6/PE‐g‐MA/nanoclay was 0.41 g m^?2 day^?1, while this value was 0.46 g m^?2 day^?1 for both of PA6/3wt % clay nanocomposite and PA6/10 wt % PE‐g‐MA blend. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40150.     

Nonisothermal crystallization of poly(ethylene‐co‐glycidyl methacrylate)/clay nanocomposites

The nonisothermal crystallization of poly(ethylene‐co‐glycidyl methacrylate) (PEGMA) and PEGMA/clay were studied by differential scanning calorimeter, at various cooling rates. Avrami model modified by Jeziorny, Ozawa mode and Liu model could successfully describe the nonisothermal crystallization process. Augis–Bennett model, Kissinger model, Takhor model, and Ziabicki model were used to evaluate the activation energy of both samples. It was found that the activation energy of PEGMA/clay nanocomposite was higher than that of neat PEGMA. Experimental results also indicated that the addition of modified clay might retard the overall nonisothermal crystallization process of PEGMA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1335–1343, 2006     

Crystallization and thermal behavior of microcellular injection‐molded polyamide‐6 nanocomposites

This article presents the effects of nanoclay and supercritical nitrogen on the crystallization and thermal behavior of microcellular injection‐molded polyamide‐6 (PA6) nanocomposites with 5 and 7.5 wt% nanoclay. Differential scanning calorimetry (DSC), X‐ray diffractometry (XRD), and polarized optical microscopy (POM) were used to characterize the thermal behavior and crystalline structure. The isothermal and nonisothermal crystallization kinetics of neat resin and its corresponding nanocomposite samples were analyzed using the Avrami and Ozawa equations, respectively. The activation energies determined using the Arrhenius equation for isothermal crystallization and the Kissinger equation for nonisothermal crystallization were comparable. The specimen thickness had a significant influence on the nonisothermal crystallization especially at high scanning rates. Nanocomposites with an optimal amount of nanoclay possessed the highest crystallization rate and a higher level of nucleation activity. The nanoclay increased the magnitude of the activation energy but decreased the overall crystallinity. The dissolved SCF did not alter the crystalline structure significantly. In contrast with conventionally injection‐molded solid counterparts, microcellular neat resin parts and microcellular nanocomposite parts were found to have lower crystallinity in the core and higher crystallinity near the skin. POLYM. ENG. SCI., 46:904–918, 2006. © 2006 Society of Plastics Engineers     

Crystallization and melting properties of poly(butylene succinate) composites with titanium dioxide nanotubes or hydroxyapatite nanorods

Poly (butylene succinate) (PBS) nanocomposites with titanium dioxide nanotubes (TNTs) or hydroxyapatite nanorods (HAP) were prepared, and the effect of the nano‐inorganics on the nonisothermal crystallization and melting properties of PBS were studied in detail by differential scanning calorimeter. The nonisothermal crystallization kinetics of PBS and its nanocomposites were analyzed by the Avrami, Ozawa, and Mo methods. It is found that the presence of TNTs increases the crystallization temperature and rate of PBS composites, but decreases the crystallization activation energy and crystallinity. By comparison, the crystallization rate of the PBS composite is decreased with the addition of HAP. The melting, recrystallization, and remelting mechanism results in the formation of two melting endothermic peaks during the melting process of neat PBS and its nanocomposites. The model proposed by Mo could successfully describe the nonisothermal crystallization process of PBS and its nanocomposites. At a given crystallinity, the F(t) values decrease in the order of PBS/HAP, PBS, and PBS/TNTs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40335.     

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     

Synthesis of clay‐dispersed poly(styrene‐co‐methyl methacrylate) nanocomposite via miniemulsion atom transfer radical polymerization: A reverse approach

Poly(styrene‐co‐methyl methacrylate) nanocomposites were synthesized using reverse atom transfer radical polymerization (RATRP) in miniemulsion. Cetyltrimethylammonium bromide (CTAB) as a cationic surfactant applicable at higher temperatures was used for miniemulsion stabilization. Successful RATRP was carried out by using 4,4′‐dinonyl‐2,2′‐bipyridine (dNbPy) as ligand. Monodispersed droplets and particles with sizes in the range of 200 nm were revealed by dynamic light scattering (DLS). Conversion and molecular weight study was carried out using gravimetry and size exclusion chromatography (SEC) respectively. By adding clay content, a decrease in the conversion and molecular weight and an increase in the PDI value of the nanocomposites are observed. Thermal stability of the nanocomposites in comparison with the neat copolymer is revealed by thermogravimetric analysis (TGA). Increased T_g values by adding clay content was also obtained using differential scanning calorimetry (DSC). Scanning electron microscopy (SEM) images of the nanoconposite with 1 wt % of nanoclay loading, display monodispersed spherical particles with sizes in the range of ～ 200 nm. SEM findings are more compiled with dynamic light scattering (DLS) results. Well‐dispersed exfoliated clay layers in the polymer matrix of the nanocomposite with 1 wt % nanoclay loading is confirmed by transmission electron microscopy (TEM) images and X‐ray diffraction (XRD) data. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Crystallization kinetics of PE‐b‐isotactic PMMA diblock copolymer synthesized using SiMe2(Ind)2ZrMe2 and MAO cocatalyst

Polyethylene‐b‐poly(methyl methacrylate) (PE‐b‐PMMA) diblock copolymer has important interfacial applications. Hence, a PE‐b‐isotactic PMMA diblock copolymer was synthesized using SiMe₂(Ind)₂ZrMe₂ and MAO cocatalyst. The polymerization mechanism and the origin of PMMA isotacticity were duly explained. An appropriate nonisothermal Avrami‐Erofeev crystallization model was developed to compare the crystallization kinetics of the above copolymer with that of a PE homopolymer. For both polymers, the model well matched the entire differential scanning calorimeter crystallinity profile, notably for a single Avrami‐Erofeev index, and predicted cylindrical crystal growth. This model particularly overcomes the limitations of the published nonisothermal crystallization models, and provides interesting insight into PE crystallization. The PMMA block significantly decreased the heats of crystallization and fusion, % crystallinity, and the relative crystallization function; increased the nonisothermal crystallization rate constant; and introduced minimal dilution effect whereas the PE block formed a continuous or percolated phase. This study correlates catalyst structure, copolymer block tacticity, and PE nonisothermal crystallization and melting behavior. © 2012 American Institute of Chemical Engineers AIChE J, 59: 200–214, 2013     

Morphological,rheological and thermal studies in melt processed compatibilized PA6/ABS/clay nanocomposites

Multicomponent compatibilized blends of polyamide 6 (PA6) and styrene-butadiene-acrylonitrile (ABS) with co-continuous morphology are among commercial alloys with an interesting combination of properties. To further enhance the properties different amounts of nanoclay were incorporated into these blends through a one step melt mixing process. The effect of nanoclay addition on rheological, thermal stability, crystallization and morphological properties of the nanocomposites were investigated and compared with those of the neat blends. The nanoscale dispersion of the clay layers in the blends were confirmed through X-ray diffraction and transmission electron microscopy methods. Rheological investigation indicated an increased viscosity and melt elasticity for the nanocomposite systems. The viscosity of nanocomposites followed a shear thinning flow behavior and decreased with increasing shear rates. The changes in the rheological properties were accompanied by refinement of the co-continuous morphology. For thermal degradation under N₂ atmosphere, the onset and maximum of degradation temperatures for the nanocomposites were as high as the neat blends, while significant improvement in thermal stability (about 60 °C by 3 wt% clay addition) was observed in the air environment. In addition agglomerated clay particles did not significantly affect thermal stability of the polymer matrix. Non-isothermal crystallization results indicated that the clay layers had a retarding effect on the crystal growth rate and facilitated the formation of α crystalline form. In addition no nucleation effect was observed during the crystallization process due to incorporation of nanoclay into the blends.     

Bottle‐to‐bottle recycling of PET via nanostructure formation by melt intercalation in twin screw compounder: Improved thermal,barrier, and microbiological properties

Attempts have been made to modify the properties of the injection processing‐scraped PET (denoted as RPET) via intercalation with different levels of organically modified nanoclay (montmorillonite) by melt blending in a corotating twin screw compounder. The clay platelets dispersion state has been qualitatively correlated with the melt linear viscoelastic as well as tensile and barrier properties of the prepared nanocomposites. Oxygen permeation of the nanocomposite PET films showed significant reduction compared with the pristine PET polymer. All the PET/nanoclay composites exhibited no bacterial growth, with no potentiality to generate acetaldehyde, as measured by GC/Mass analyzer. X‐ray diffractometry and transmission electron microscopy performed on the scraped PET/organoclay nanocomposite samples showed increase in d₀₀₁ spacing of the clay layers and their dispersion throughout the PET matrix. Differential scanning calorimetry analysis showed higher crystallization temperature as well as crystallization enthalpy (ΔH_c) for the nanocomposite samples, compared with the unprocessed virgin PET. The RPET nanocomposite samples composed of 3 and 5% of nanoclay exhibited enhanced melt elastic modulus and pseudosolid‐like behavior at low shear frequencies measured by rheomechanical spectroscopy than the unfilled pristine‐scraped PET, indicating the formation of nanoscopic network structure by the clay platelets, which leads to the development of nanostructured resin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

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     

Epoxy/poly(ɛ‐caprolactone) nanocomposites: Effect of transformations of structure on crystallization

The influence of morphology of the epoxy/poly(?‐caprolactone) (PCL) system and corresponding nanocomposites with organophilized layered silicate on PCL crystallization was studied by differential scanning calorimetry, scanning, and transmission electron microscopy. The results obtained indicate a significant affecting of nonisothermal PCL crystallization by phase morphology brought about by the reaction‐induced phase separation (RIPS) influenced either by various nanoclay contents or the epoxy/PCL ratio. Dispersed morphology of PCL matrix with epoxy globules induces crystallization at higher temperatures. The inverse dispersed morphology of epoxy matrix with PCL inclusions causes crystallization at lower temperature. The co‐continuous morphology induces crystallization in both steps. Rate of the second crystallization step is substantially higher than that in the first step. No nucleation effect has been found in the nanocomposites with the added nanofiller. Multicomponent samples show retarded crystallization, i.e., lower crystallinities and lower overall crystallization rate compared with neat PCL. The results obtained suggest that it is primarily morphological/interfacial effects that play a decisive role in the crystallization behavior of PCL in the epoxy/PCL/clay system. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3197–3204, 2013     

PE/PE‐g‐MAH/Org‐MMT nanocomposites. II. Nonisothermal crystallization kinetics

The nonisothermal crystallization kinetics of high‐density polyethylene (HDPE) and polyethylene (PE)/PE‐grafted maleic anhydride (PE‐g‐MAH)/organic‐montmorillonite (Org‐MMT) nanocomposite were investigated by differential scanning calorimetry (DSC) at various cooling rates. Avrami analysis modified by Jeziorny, Ozawa analysis, and a method developed by Liu well described the nonisothermal crystallization process of these samples. The difference in the exponent n, m, and a between HDPE and the nanocomposite indicated that nucleation mechanism and dimension of spherulite growth of the nanocomposite were different from that of HDPE to some extent. The values of half‐time (t_1/2), K(T), and F(T) showed that the crystallization rate increased with the increase of cooling rates for HDPE and composite, but the crystallization rate of composite was faster than that of HDPE at a given cooling rate. Moreover, the method proposed by Kissinger was used to evaluate the activation energy of the mentioned samples. It was 223.7 kJ/mol for composite, which was much smaller than that for HDPE (304.6 kJ/mol). Overall, the results indicated that the addition of Org‐MMT and PE‐g‐MAH could accelerate the overall nonisothermal crystallization process of PE. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3054–3059, 2004     

Calorimetric and rheokinetic analyses merged to capture crystallization kinetics in polyamide/clay nanocomposites: Revisiting predictability of models

Crystallization kinetics of polymer/clay systems was the subject of numerous investigations, but still there are some ambiguities in understanding thermal behavior of such systems under isothermal and nonisothermal circumstances. In this work, isothermal rheokinetic and nonisothermal calorimetric analyses are combined to demonstrate crystallization kinetics of polyamide6/nanoclay (PA6/NC) nanocomposites. As the main outcome of this work, we detected different regimes of crystallization and compared them by both isothermal dynamic rheometry and nonisothermal differential scanning calorimetry (DSC), which has not been simultaneously addressed yet. A novel analysis, somehow different from the common ones, is used to convert the storage modulus data to crystallinity values leading to more reasonable Avrami parameters in isothermal crystallization. It was found based on isothermal rheokinetic studies that increase of NC content and shear rate are responsible for erratic behavior of Avrami exponent and crystallization rates. Optimistically, however, isothermal crystallization by rheometer was confirmed by DSC. Nonisothermal calorimetric evaluations suggested an accelerated crystallization of PA6 upon increasing NC content and cooling rate. The crystallization behavior was quantified applying Ozawa (r² between 0.070 and 0.975), and combinatorial Avrami–Ozawa (r² between 0.984 and 0.998) models, where the latter appeared more appropriate for demonstration of nonisothermal crystallization of PA6/NC nanocomposites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46364.     

Crystallization behavior of ultrahigh‐molecular‐weight polyethylene/polyhedral oligomeric silsesquioxane nanocomposites prepared by ethylene in situ polymerization

A [3‐t‐Bu‐2‐O? C₆H₃CH?N(C₆F₅)]₂TiCl₂ catalyst (bis(phenoxyimine)titanium dichloride complex – FI catalyst) was immobilized on disilanolisobutyl polyhedral oligomeric silsesquioxane (OH‐POSS) to prepare ultrahigh molecular‐weight polyethylene (UHMWPE)/polyhedral oligomeric silsesquioxane (POSS) nanocomposites during ethylene in situ polymerization. The dispersion state of POSS in the UHMWPE matrix was characterized by X‐ray diffraction measurements and transmission electron microscopy. It was shown that the OH‐POSS achieved uniformed dispersion in the UHMWPE matrix, although its polarity was unmatched. The isothermal and nonisothermal crystallization behavior of the nanocomposites was investigated by means of differential scanning calorimetry. The crystallization rate of the nanocomposites was enhanced because of the incorporation of POSS during the isothermal crystallization. POSS acted as a nucleus for the initial nucleation and the subsequent growth of the crystallites. For nonisothermal studies, POSS showed an increase in the crystallinity. The crystallization rate of the nanocomposites decreased because the presence of POSS hindered the crystal growth. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40847.     

Solid‐state polymerization of poly(ethylene terephthalate): Effect of organoclay concentration

Poly(ethylene terephthalate) (PET)/Cloisite 30B (C30B) nanocomposites of different organoclay concentrations were prepared using a water‐assisted extrusion process. The reduction of the molecular weight (M_w) of the PET matrix, caused by hydrolysis during water‐assisted extrusion, was compensated by subsequent solid‐state polymerization (SSP). Viscometry, titration, rheological, and dynamic scanning calorimetry measurements were used to analyze the samples from SSP. The weight‐average molecular weight (M_w) of PET increased significantly through SSP. PET nanocomposites exhibited solid‐like rheological behavior, and the complex viscosity at high frequencies was scaled with the M_w of PET. The Maron–Pierce model was used to evaluate the M_w of PET in the nanocomposites before and after SSP. It was found that the extent and the rate of the SSP reaction in nanocomposites were lower than those for the neat PETs, due to the barrier effect of clay platelets. Consequently, the SSP rate of PET increased with decreasing particle size for the neat PET and PET nanocomposites. The effect of the M_w of PET on the crystallization temperature, crystallinity, and the half‐time, t_½, of nonisothermal crystallization was also investigated. With increasing M_w of PET, t_½ increased, whereas T_c and X_c decreased. POLYM. ENG. SCI., 54:2925–2937, 2014. © 2014 Society of Plastics Engineers     

Nonisothermal crystallization kinetics of polyoxymethylene/montmorillonite nanocomposite

The nonisothermal crystallization kinetics of polyoxymethylene (POM), polyoxymethylene/Na–montmorillonite (POM/Na–MMT), and polyoxymethylene/organic–montmorillonite (POM/organ–MMT) nanocomposites were investigated by differential scanning calorimetry at various cooling rates. The Avrami analysis modified by Jeziorny and a method developed by Mo were employed to describe the nonisothermal crystallization process of POM/Na–MMT and POM/organ–MMT nanocomposites. The difference in the values of the exponent n between POM and POM/montmorillonite nanocomposites suggests that the nonisothermal crystallization of POM/Na–MMT and POM/organ–MMT nanocomposites corresponds to a tridimensional growth with heterogeneous nucleation. The values of half‐time and the parameter Z_c, which characterizes the kinetics of nonisothermal crystallization, show that the crystallization rate of either POM/Na–MMT or POM/organ–MMT nanocomposite is faster than that of virgin POM at a given cooling rate. The activation energies were evaluated by the Kissinger method and were 387.0, 330.3, and 328.6 kJ/mol for the nonisothermal crystallization of POM, POM/Na–MMT nanocomposite, and POM/organ–MMT nanocomposite, respectively. POM/montmorillonite nanocomposite can be as easily fabricated as the original polyoxymethylene, considering that the addition of montmorillonite, either Na–montmorillonite or organ–montmorillonite, may accelerate the overall nonisothermal crystallization process. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2281–2289, 2001     

Nonisothermal crystallization behaviors of poly(3‐hexylthiophene)/reduced graphene oxide nanocomposites

Poly(3‐hexylthiophene) (P3HT)/reduced graphene oxide (rGO) nanocomposites were prepared through in situ reduction of graphene oxide in the presence of P3HT. The nonisothermal crystallization behaviors of P3HT and P3HT/rGO nanocomposites were investigated by differential scanning calorimetry. The Avrami, Ozawa, and Mo models were used to analyze the nonisothermal kinetics. The addition of rGO remarkably increased the crystallization peak temperature and crystallinity of P3HT, but the crystallization half‐time revealed little variation. The crystallization activation energies were calculated by the Kissinger equation. The results suggested that rGO plays a twofold role in the nonisothermal crystallization of P3HT, that is, rGO promotes the crystallization of P3HT as nucleating agent, and meanwhile, it also restricts the motion of P3HT chains. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013