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     

Rheology of poly(propylene)/clay nanocomposites

The linear and nonlinear shear rheological behaviors of poly(propylene) (PP)/clay (organophilic‐montmorillonite) nanocomposites (PP/org‐MMT) were investigated by an ARES rheometer. The materials were prepared by melt intercalation with maleic anhydride functionalized PP as a compatibilizer. The storage moduli (G′), loss moduli (G″), and dynamic viscosities of polymer/clay nanocomposites (PPCNs) increase monotonically with org‐MMT content. The presence of org‐MMT leads to pseudo‐solid‐like behaviors and slower relaxation behaviors of PPCN melts. For all samples, the dependence of G′ and G″ on ω shows nonterminal behaviors. At lower frequency, the steady shear viscosities of PPCNs increase with org‐MMT content. However, the PPCN melts show a greater shear thinning tendency than pure PP melt because of the preferential orientation of the MMT layers. Therefore, PPCNs have higher moduli but better processibility compared with pure PP.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2427–2434,2004     

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     

PP–PP‐g‐MAH–Org‐MMT nanocomposites. I. Intercalation behavior and microstructure

The melt‐direct intercalation method was employed to prepare poly(propylene) (PP)–maleic anhydride grafted poly(propylene) (PP‐g‐MAH)–organic‐montmorillonite (Org‐MMT) nanocomposites. X‐ray diffractometry (XRD) was used to investigate the intercalation effect, crystallite size, and crystal cell parameter in these composites. Two kinds of maleated PP, with graft efficiencies of 0.6 and 0.9 wt %, and two sorts of manufacturing processes were used to prepare nanocomposites and then to investigate their effects on intercalation behavior. The results showed that the intercalation effect was enhanced by increasing the content of PP‐g‐MAH, using maleated PP with higher graft efficiency, and adopting the mold process. The crystallite size of nanocomposites perpendicular to the crystalline plane, such as (040), (130), (111), and (041), reached the minimum value when the content of PP‐g‐MAH was 20 wt %. This result indicated that the crystallite size of PP in nanocomposites decreased by proper addition of PP‐g‐MAH. Maximum values in tensile strength (40.2 MPa) and impact strength (24.3 J/m) were achieved when the content of PP‐g‐MAH was 10 and 20%, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3225–3231, 2003     

Effect of polymer matrix/montmorillonite compatibility on morphology and melt rheology of polypropylene nanocomposites

In this study, Ca²⁺‐montmorillonite (Ca²⁺‐MMT) and organo‐montmorillonite (OMMT) were modified by three compatibilizers with different degrees of polarity [poly(ethylene glycol) (PEG), alkyl‐PEG, and polypropylene (PP)‐g‐PEG]. PP/MMT nanocomposites were prepared by melt blending and characterized using X‐ray diffraction and transmission electron microscopy. The results showed the degree of dispersion of OMMT in the PP/PP‐g‐PEG/OMMT (PMOM) nanocomposite was considerably higher than those in the PP/PEG/OMMT and PP/alkyl‐PEG/OMMT nanocomposites, which indicated that the dispersion was relative to the compatibility between modified OMMT and PP matrix. Linear viscoelasticity of PP/MMT nanocomposites in melt states was investigated by small amplitude dynamic rheology measurements. With the addition of the modified MMT, the shear viscosities and storage modulus of all the PP/MMT nanocomposites decreased. It can be attributed to the plasticization effect of PEG segments in the three modifiers. This rheological behavior was different from most surfactant modified MMT nanocomposites which typically showed an increase in dynamic modulus and viscosity relative to the polymer matrix. The unusual rheological observations were explained in terms of the compatibility between the polymer matrix and MMT. In addition, the mechanical properties of PP/MMT nanocomposites were improved. A simultaneous increase in the tensile strength and toughness was observed in PP/PMOM nanocomposites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

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     

Preparation of polypropylene/montmorillonite nanocomposites with an exfoliated structure by a designed route

Nanocomposites of polypropylene (PP) and montmorillonites (MMT) were prepared by solid‐phase grafting reactive organomontmorillonite (ROMT) and polar monomers onto powdered PP and melt‐blending granule PP with the master batches as PP/MMT grafting copolymers (PPMG). The structure and properties of the PP/MMT nanocomposites (PPMN) were investigated by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD) patterns, transmission electron microscopy (TEM), dynamic mechanical analysis, differential scanning calorimetry, and thermogravimetric analysis. GPC showed that the numerical molecular weight and polydispersity of the graft copolymers of PPMG were approximately 4793 and 2.197, respectively. FTIR confirmed the solid‐phase graft copolymerization. XRD and TEM indicated the formation of the exfoliated, layered silicates (tactoids). The mole ratio of compound alkylammoniums and the exothermic enthalpy from solid‐phase graft copolymerization played key roles in the formation of tactoids. The optimum mole ratio of organophilic alkylammonium to reactive alkylammonium was 3 : 1. The mechanical and thermal properties increased with the contents of PPMG, and a preferable state was achieved at approximately 8 phr PPMG (parts of reagent per 100 parts of PP) because of the plastification of the exfoliated silicates and the graft copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3889–3899, 2006     

Polypropylene/organically modified Sabah montmorillonite nanocomposites: Surface modification and nanocomposites characterization

The aim of the work is to extract, purify, and organically modify montmorillonite (MMT) of Lahad Datu, Sabah bentonite. The octadecylamine treated Sabah MMT (S‐OMMT) (2–8 wt%) was then melt blended with polypropylene (PP) and maleated polypropylene (PPgMAH) (10 wt%) via single screw nanomixer extruder followed by injection molding into test samples to examine the mechanical, thermal, and morphological properties of PP/S‐OMMT nanocomposites. Unmodified Sabah MMT (S‐MMT) and commercial grade MMT (Nanomer 1.30P) filled PP nanocomposites were also characterized for comparison purpose. X‐ray diffraction results showed that the interlayer spacing of S‐MMT increased after organic modification as Fourier transform infra‐red and elemental analysis evidenced the presence of octadecylamine. PP/S‐OMMT nanocomposites showed a better dispersion and strength compared to PP/Nanomer 1.30P nanocomposites due to its smaller MMT platelet size. differential scanning calorimetry and Thermogravimetry analysis revealed that the thermal stability and crystallinity of neat PP improved with the addition of all types of MMT. Dynamic mechanical analyzer showed that PP nanocomposites have higher storage modulus (E′) values than the neat PP over the whole temperature range. The new PP/S‐OMMT nanocomposites showed a comparable performance with PP/Nanomer 1.30P nanocomposites exhibiting promising future applications of S‐MMT in polymer/MMT nanocomposites. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Influence of organophilic clay and preparation methods on EVA/montmorillonite nanocomposites

Ethylene‐vinyl acetate copolymer (EVA)/montmorillonite MMT nanocomposites have been prepared by using different methods: one is from the organophilic montmorillonite (OMT) and the other is from the pristine MMT and reactive compatibilizer hexadecyl trimethyl ammonium bromide (C16). In this study, different kneaders were used (twin‐screw extruder and twin‐roll mill) to prepare nanocomposites. The nanocomposite structures are evidenced by the X‐ray diffraction (XRD) and high‐resolution electronic microscope (HREM). The thermal properties of the nanocomposites were investigated by thermogravimetric analysis (TGA). Moreover, the tensile tests were carried out with a Universal testing machine DCS‐5000. It is shown that different methods and organophilic montmorillonite have influence on EVA/MMT nanocomposites.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2416–2421, 2004     

Effective preparation and characterization of montmorillonite/poly(ε‐caprolactone)‐based polyurethane nanocomposites

In this study, montmorillonite (MMT)/poly(?‐caprolactone)‐based polyurethane cationomer (MMT/PCL‐PUC) nanocomposites were prepared and their mechanical properties, thermal stability, and biodegradability were investigated. PCL‐PUC has 3 mol % of quaternary ammonium groups in the main chain. The MMT was successfully exfoliated and well dispersed in the PCL‐PUC matrix for up to 7 wt % of MMT. The 3 mol % of quaternary ammonium groups facilitated exfoliation of MMT. The 1 wt % MMT/PCL‐PUC nanocomposites showed enhanced tensile properties relative to the pure PCL‐PU. As the MMT content increased in the MMT/PCL‐PUC nanocomposites, the degree of microphase separation of PCL‐PUC decreased because of the strong interactions between the PCL‐PUC chains and the exfoliated MMT layers. This resulted in an increase in the Young's modulus and a decrease in the elongation at break and maximum stress of the MMT/PCL‐PUC nanocomposites. Biodegradability of the MMT/PCL‐PUC nanocomposites was dramatically increased with increasing content of MMT, likely because of the less phase‐separated morphology of MMT/PCL‐PUC. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

聚丙烯／蒙脱土纳米复合材料的制备与性能

用烷基季铵盐对钠基蒙脱土进行有机化处理,使其成为有机蒙脱土。X射线衍射（XRD）表明有机阳离子已同钠离子发生离子交换作用,导致层间距扩大。用熔融插层法制备聚丙烯／蒙脱土纳米复合材料,测试了力学性能。通过XRD、DSC等手段研究了其结构与结晶行为,并与聚丙烯进行了对比。实验表明,通过熔融插层可使聚丙烯插层于蒙脱土片层之中,且所得聚合物的冲击强度有所提高。     

Preparation and characterization of polypropylene/clay nanocomposites with polypropylene‐graft‐maleic anhydride

Polypropylene (PP)/montmorillonite (MMT) nanocomposites were prepared by the esterification of propylene‐g‐maleic anhydride (MAPP) with MMT modified with α,ω‐hydroxyamines. The structural characterization confirmed the formation of ester linkages and the interaction between the silicate layers. In particular, X‐ray diffraction patterns of the modified clays and MAPP/MMT composites showed 001 basal spacing enlargement as great as 0.14–0.62 nm according to the type of α,ω‐hydroxyamine. Thermal characterization by thermogravimetric analysis for the composites revealed increased onset temperatures of thermal decomposition. The melting peak temperature decreased, and the crystallization peak temperature increased; this indicated that MMT retarded the crystallization of MAPP. Compounding PP with MAPP/MMT composites enhanced the tensile modulus and tensile strength of PP. However, the elongation at break decreased drastically even when the MMT content was as low as 0.4–2.0 wt %. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1229–1234, 2005     

Synthesis and properties of poly(methyl methacrylate)/clay nanocomposites using natural montmorillonite and synthetic Fe‐montmorillonite by emulsion polymerization

In this article, Fe‐montmorillonite (Fe‐MMT) was synthesized by hydrothermal method. For the first time, Fe‐MMT was modified by cetyltrimethyl ammonium bromide (CTAB), and poly(methyl methacrylate)(PMMA)/Fe‐MMT nanocomposites were synthesized by emulsion polymerization. Then poly(methyl methacrylate)(PMMA)/natural montmorillonite (Na‐MMT) and PMMA/Fe‐MMT nanocomposites were compared by Fourier transform infrared (FTIR) spectra, X‐ray diffraction (XRD) patterns, transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA). By XRD and TEM, it was found out that the morphology of PMMA/Fe‐MMT nanocomposites was different from that of the PMMA/Fe‐MMT nanocomposites when the content of two types of clay was same in the PMMA matrix. It was possible that the presence of iron may lead to some radical trapping, which enhances intragallery polymerization to be developed to improve layer dispersion in PMMA/Fe‐MMT systems. In TGA curves, the thermal stability and residue at 600°C of PMMA/Fe‐MMT nanocomposites were higher than those of PMMA/Na‐MMT nanocomposites. Those dissimilarities were probably caused by structural Fe ion in the lattice of Fe‐MMT. POLYM. COMPOS., 27:49–54, 2006. © 2005 Society of Plastics Engineers     

Surface modification of poly(propylene) by photoinitiators: Improvement of adhesion and wettability

Different benzophenone‐type photoinitiators were photografted onto poly(propylene) (PP). The polymer surfaces were analyzed by means of contact angle measurements, UV spectroscopy, and FTIR‐ATR. The modified samples showed a better wettability and higher surface energies, increasing from 26 mN/m for pure PP to 36 mN/m for the modified samples. The UV spectrum of the modified PP films showed two absorption bands that could be related to the grafted initiator. The effect of irradiation time and photoinitiator concentration was investigated. Different acrylates were grafted efficiently onto the modified polymer surfaces. FTIR‐ATR and contact angle measurements confirmed the presence of the grafted chains. The surface energy of the grafted surfaces of samples increased to 70 mN/m, depending on the type of acrylate used. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2341–2350, 2004     

Effect of clay on the morphology of blends of poly(propylene) and polyamide 6/clay nanocomposites

PP/NPA6 blends composed of poly(propylene) (PP) and polyamide 6/clay nanocomposites (NPA6) were prepared by twin‐screw extrusion and melt‐drawn into ribbons by a ribbon extrusion process. The influence of clay on the morphology of PP/NPA6 ribbons was investigated by means of field‐emission scanning electron microscopy and optical microscopy. The results show that at low clay content (3, 5 wt%), NPA6 exhibited continuous lamellar structure in PP as pristine PA6 did in a PP/PA6 blend, but at a higher clay content (10 wt%) only ellipsoids or elongated ellipsoids were observed. In order to explain the morphological difference, two factors, ie the compatibilization effect and melt rheology, have been taken into consideration. It has been found that both factors, and probably mainly the variation in melt rheology, were responsible for the morphological difference in the PP/NPA6 blends with different clay contents under the extensional flow field. Copyright © 2004 Society of Chemical Industry     

Investigation Into Poly(propylene)/Montmorillonite/Calcium Carbonate Nanocomposites

Summary: A novel method was used to prepare poly(propylene)/montmorillonite/calcium carbonate nanocomposites by melt‐mixing, using pristine montmorillonite (MMT), hexadecyltrimethylammonium bromide (C16), calcium carbonate (CaCO₃) and a matrix in a twin‐screw extruder. Two different sizes of calcium carbonate were used (nanosized CaCO₃ and micron‐sized CaCO₃, the average sizes being 60 nm and 12 μm respectively). The nanocomposite structure was evidenced using X‐ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution electronic microscopy (HREM). Tensile tests and Izod notch impact tests suggested that the incorporation of nanosized CaCO₃ into PP/montmorillonite nanocomposites increased the mechanical properties of the composites, but the improvement in the micro‐sized CaCO₃‐filled PP/montmorillonite nanocomposites was found to be minimal. The thermal stability and flammability properties were characterized by thermogravimetric analysis (TGA) and a cone calorimeter respectively.

     

Poly(etherimide)/montmorillonite nanocomposites prepared by melt intercalation

A novel aromatic amine organo‐modifier synthesized in our previous work was used to treat montmorillonite (MMT) and the organo‐modified MMT was used to prepare poly(etherimide) (PEI)/MMT nanocomposites by a melt intercalation method. MMT treated by this amine exhibited large layer‐to‐layer spacing and a high ion‐exchange ratio (>95%). The nanocomposites were characterized with X‐ray diffraction (XRD), transmission electron microscopy (TEM), dynamic mechanical analysis, a universal tester, thermogravimetric analysis, and by differential scanning calorimetry. The results of XRD and TEM showed that the nanocomposites formed exfoliated structures even when the MMT content was 10 wt %. When the MMT content was below 3 wt %, the PEI/MMT nanocomposites were strengthened and toughened at the same time. The nanocomposites also showed marked decreases in coefficient of thermal expansion and solvent uptake. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1857–1863, 2003     

Preparation and characterization of maleic anhydride‐g‐polypropylene/diamine‐modified clay nanocomposites

Polypropylene (PP)/montmorillonite (MMT) nanocomposites were prepared by compounding maleic anhydride‐g‐polypropylene (MAPP) with MMT modified with α,ω‐diaminododecane. Structural characterization confirmed the formation of characteristic amide linkages and the intercalation of MAPP between the silicate layers. In particular, X‐ray diffraction patterns of the modified clay and MAPP/MMT composites showed 001 basal spacing enlargement as much as 1.49 nm. Thermogravimetric analysis revealed that the thermal decomposition of the composite took place at a slightly higher temperature than that of MAPP. The heat of fusion of the MAPP phase decreased, indicating that the crystallization of MAPP was suppressed by the clay layers. PP/MAPP/MMT composites showed a 20–35% higher tensile modulus and tensile strength compared to those corresponding to PP/MAPP. However, the elongation at break decreased drastically, even when the content of MMT was as low as 1.25–5 wt %. The relatively short chain length and loop structure of MAPP bound to the clay layers made the penetration of MAPP molecules into the PP homopolymer phase implausible and is thought to be responsible for the decreased elongation at break. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 307–311, 2005     

Effect of clay modification on the morphological,mechanical, and thermal properties of polyamide 6/polypropylene/montmorillonite nanocomposites

Polyamide 6/polypropylene (PA6/PP = 70/30 parts) blends containing 4 phr (parts per hundred resin) of organophilic montmorillonite (OMMT) were prepared by melt compounding. The sodium montmorillonite (Na‐MMT) was modified using three different types of alkyl ammonium salts, namely dodecylamine, 12‐aminolauric acid, and stearylamine. The effect of clay modification on the morphological and mechanical properties of PA6/PP nanocomposites was investigated using x‐ray diffraction (XRD), transmission electron microscopy (TEM), tensile, flexural, and impact tests. The thermal properties of PA6/PP nanocomposites were characterized using thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and heat distortion temperature (HDT). XRD and TEM results indicated the formation of exfoliated structure for the PA6/PP nanocomposites prepared using stearylamine modified montmorillonite. On the other hand, a mixture of intercalated and exfoliated structures was found for the PA6/PP nanocomposites prepared using 12‐aminolauric acid and dodecylamine modified montmorillonite. Incorporation of OMMT increased the stiffness but decreased the ductility and toughness of PA6/PP blend. The PA6/PP nanocomposite containing stearylamine modified montmorillonite showed the highest tensile, flexural, and thermal properties among all nanocomposites. This could be attributed to better exfoliated structure in the PA6/PP nanocomposite containing stearylamine modified montmorillonite. The storage modulus and HDT of PA6/PP blend were increased significantly with the incorporation of both Na‐MMT and OMMT. The highest value in both storage modulus and HDT was found in the PA6/PP nanocomposite containing stearylamine modified montmorillonite due to its better exfoliated structure. POLYM. COMPOS., 31:1156–1167, 2010. © 2009 Society of Plastics Engineers     

Biodegradable polyester layered silicate nanocomposites based on poly(ϵ‐caprolactone)

Nanocomposites based on biodegradable poly(?‐caprolactone) (PCL) and layered silicates (montmorillonite, MMT) were prepared either by melt interaction with PCL or by in situ ring‐opening polymerization of ?‐caprolactone as promoted by the so‐called coordination‐insertion mechanism. Both non‐modified clays (Na⁺ ‐MMT) and silicates modified by various alkylammonium cations were studied. Mechanical and thermal properties were examined by tensile testing and thermogravimetric analysis. Even at a filler content as low as 3 wt% of inorganic layered silicate, the PCL‐layered silicate nanocomposites exhibited improved mechanical properties (higher Young's modulus) and increased thermal stability as well as enhanced flame retardant characteristics as a result of a charring effect. It was shown that the formation of PCL‐based nanocomposites depended not only on the nature of the ammonium cation and related functionality but also on the selected synthetic route, melt intercalation vs. in situ intercalative polymerization. Interestingly enough, when the intercalative polymerization of ?‐caprolactone was carried out in the presence of MMT organo‐modified with ammonium cations bearing hydroxyl functions, nanocomposites with much improved mechanical properties were recovered. Those hybrid polyester layered silicate nanocomposites were characterized by a covalent bonding between the polyester chains and the clay organo‐surface as a result of the polymerization mechanism, which was actually initiated from the surface hydroxyl functions adequately activated by selected tin (II) or tin (IV) catalysts.