Morphology,thermal and mechanical properties of nylon 12/organoclay nanocomposites prepared by melt compounding

Nylon 12 (PA12) nanocomposites with different organoclay loadings were successfully prepared by melt compounding. X‐ray diffraction indicated the dominance of the exfoliated clay morphology throughout the matrix after mixing in a Brabender twin‐screw extruder, in accordance with transmission electron microscopy observations. Thermogravimetric analysis showed that the thermal stability of the PA12 matrix was improved by about 20 °C on incorporation of only 5 wt% clay. Tensile and nanoindentation tests indicated that the elastic modulus and the hardness steadily increased by about 52 % and 67 %, respectively, with a clay concentration up to 5 wt%, while improvements in tensile strength were limited. Impact strength decreased linearly by about 25 % as the clay loading increased (up to 5 wt%), indicating an embrittlement due to clay addition, as evidenced by SEM observation on the fracture surfaces. The embrittling effect may be due to the weak interfacial adhesion between the clay platelets and the polymer matrix. Copyright © 2004 Society of Chemical Industry     

Preparation and characterization of thermoplastic polyurethane/organoclay nanocomposites by melt intercalation technique: Effect of nanoclay on morphology,mechanical, thermal,and rheological properties

Nanocomposites based on thermoplastic polyurethane (TPU) and organically modified montmorillonite (OMMT) were prepared by melt blending. Organically modified nanoclay was added to the TPU matrix in order to study the influence of the organoclay on nanophase morphology and materials properties. The interaction between TPU matrix and nanofiller was studied by infrared spectroscopy. Morphological characterization of the nanocomposites was carried out using X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy techniques. The results showed that melt mixing is an effective process for dispersing OMMT throughout the TPU matrix. Nanocomposites exhibit higher mechanical and thermal properties than pristine TPU. All these properties showed an increasing trend with the increase in OMMT content. Thermogravimetric analysis revealed that incorporation of organoclay enhances the thermal stability of nanocomposites significantly. Differential scanning calorimetry was used to measure the melting point and the glass transition temperature (T_g) of soft segments, which was found to shift toward higher temperature with the inclusion of organoclays. From dynamic mechanical thermal analysis, it is seen that addition of OMMT strongly influenced the storage and loss modulus of the TPU matrix. Dynamic viscoelastic properties of the nanocomposites were explored using rubber process analyzer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Poly(ε-caprolactone)/clay nanocomposites prepared by melt intercalation: mechanical, thermal and rheological properties

(Nano)composites of poly(ε-caprolactone) (PCL) were prepared by melt blending the polymer with natural Na⁺ montmorillonite and montmorillonite modified by hydrogenated tallowalkyl (HTA)-based quaternary ammonium cations, such as dimethyl 2-ethylhexyl HTA ammonium and methyl bis(2-hydroxyethyl) HTA ammonium. Microcomposites or nanocomposites were prepared depending on whether neat or modified montmorillonites was used, as assessed by X-ray diffraction and transmission electron microscopy. Mechanical and thermal properties were studied as a function of the filler content by tensile testing, Izod impact testing, thermogravimetric analysis and differential scanning calorimetry. The rheological behaviour at 80 °C was also analysed in relation to the structure and content of the layered silicate. Effect of exfoliated silicates on the mechanical properties, thermal stability and flame resistance of PCL was considered. Stiffness and thermal stability improved with the filler loading until a content of 5 wt%. Further loading resulted in the levelling off and possibly in a decrease of these properties. A marked charring effect was observed upon exposure to a flame.     

Phase transformation and dielectric properties of polyvinylidene fluoride/organic-montmorillonite nanocomposites fabricated under elongational flow field

Compounding montmorillonite (MMT) with polymorphic polyvinylidene fluoride (PVDF) by melt intercalation method can induce the crystal phase transformation of PVDF, which is of great significance to obtain the electroactive PVDF. In this research, PVDF/Organic-Montmorillonite (OMMT) nanocomposites were prepared by a novel vane mixer, which was dominated by the elongational flow field in the whole plasticizing. The dispersion of OMMT, the crystal phase transformation of PVDF, and the resulting properties of nanocomposites were experimentally studied. The results of TEM and WAXD evidenced that homogeneous dispersion and desirable intercalation structure of OMMT were formed in the PVDF matrix under the effect of the elongational flow field. WAXD, FTIR, and DSC tests demonstrated that large amounts of β-phase of PVDF was formed due to the introduction of OMMT. The intercalation structure of OMMT and the crystal transformation of PVDF increased the dielectric constant and piezoelectric properties of nanocomposites, while the dielectric loss still maintained at a very low level. Finally, the effect of unique ''double-layer peeling'' mechanism of OMMT on the properties of nanocomposites was discussed.     

Effect of melt processing conditions on mechanical properties of polyvinylchloride/organoclay nanocomposites

Abstract

Polyvinylchloride compositions have been prepared by the melt intercalation method using a single screw extruder. Different types of nanofiller based on natural sodium montmorillonite were tested. In particular, intercalating agents containing amine groups combined with co-intercalating agent (low or high molecular weight plasticiser) were examined to determine which is the most suitable not only for producing the largest basal spacing and subsequently the best exfoliation of clay tactoids in polymer matrix, but also for the highest beneficial influence on mechanical properties. In the case of improved exfoliation, the effect of compounding was investigated. Therefore, three values of screw speed were studied and some blends were compounded twice to study the retention time in a single screw extruder and the influence on orientation, dispersion and exfoliation of clay particles in the PVC matrix. Moreover, the effect of different types of plasticiser on mechanical properties was also studied. Bis(2-ethylhexyl) phthalate, Bis(2-ethylhexyl) adipate and Lankroflex epoxy plasticiser were tested. Dynamical thermo-mechanical properties were examined and the tensile properties of thin PVC sheets prepared by calendaring. Using X-ray diffraction and transmission electron microscopy, it was found that partially intercalated and disordered structures arose in polyvinylchloride composites containing sodium montmorillonite, while a fine dispersion of partial exfoliation of individual montmorillonite layers in polyvinylchloride matrix was observed when this clay was organically modified. Finally, the value of the tensile modulus for PVC nanocomposites containing as little as 5 wt-% montmorillonite was increased three times provided that the optimum melt processing conditions were used.     

Polystyrene–organoclay nanocomposites prepared by melt intercalation,in situ,and masterbatch methods

In this study, polystyrene (PS)/montmorillonite nanocomposites were prepared by melt intercalation, in situ polymerization, and masterbatch methods. In the masterbatch method, as the first step, a high clay content composite of PS–organoclay (masterbatch) was prepared by in situ polymerization, and then the prepared masterbatch was diluted to desired compositions with commercial PS in a twin‐screw extruder. The structure and mechanical properties of the nanocomposites were examined. X‐ray diffraction (XRD) analysis showed that the d‐spacing of the in situ formed nanocomposites increased from 32.9 Å for the organoclay powder to 36.3 and 36.8 Å respectively in nanocomposites containing 0.73 and 1.6 wt% organoclay, indicating intercalation. However, the d‐spacing of the other prepared materials remained nearly unchanged when compared with pure organoclay powder. Thus, at these low clay contents, in situ formed nanocomposites showed the best improvement in mechanical properties including tensile, impact strength, and Young's modulus. In situ polymerization method did not prove to be efficient at high clay loadings in terms of intercalation and mechanical properties. At high clay loadings, the effects of the three methods in promoting mechanical properties were not significantly different from each other. POLYM. COMPOS., 27:249–255, 2006. © 2006 Society of Plastics Engineers     

Mechanical and dynamic mechanical properties of nylon 66/montmorillonite nanocomposites fabricated by melt compounding

Nylon 66 nanocomposites were prepared by melt compounding of nylon 66 with organically modified montmorillonite (MMT). The organic MMT was pre‐modified with about 14 wt% of ammonium surfactant, much lower than the 35–46 wt% in most commercial organic MMT powders. Transmission electron microscope observation indicated that the MMT layers were well exfoliated in nylon 66 matrix. Dynamic mechanical analysis confirmed the constraint effect of exfoliated MMT layers on nylon 66 chains, which benefited the increased storage modulus, increased glass transition temperature and reduced magnitude of alpha relaxation peak. The effects of organic MMT loading levels on reinforcement and fracture behaviour of the nanocomposites were evaluated using tensile and three‐point bending tests. The addition of the organic MMT clearly increased Young's modulus and tensile strength but decreased ductility and fracture toughness of nylon 66. Copyright © 2004 Society of Chemical Industry     

Effect of SEBS on morphology, thermal, and mechanical properties of PP/organoclay nanocomposites

A simultaneously increase in stiffness and toughness is needed for improving polypropylene (PP) competitiveness in automotive industry. The aim of this paper is to investigate the effects of styrene-(ethylene-co-butylene)-styrene triblock copolymer (SEBS) on mechanical and thermal properties of PP, in the presence and the absence of nanoclay. The amount of SEBS in PP was ranged to obtain the matrix with the most favorable stiffness–toughness balance. For this purpose, SEBS domain size and distribution in PP/SEBS blends was determined by means of atomic force microscopy and correlated with mechanical properties. The influence of SEBS on the crystalline structure of PP in PP/organoclay nanocomposites was investigated by X-ray diffraction and differential scanning calorimetry, a synergistic effect of SEBS and nanoclay being pointed out. Moreover large improvement in the impact strength (almost 22 times) was obtained in the case of SEBS-containing nanocomposite in comparison with the composite without SEBS.     

Transparent copolyester/organoclay nanocomposites prepared by in situ intercalation polymerization: Synthesis,characterization, and properties

In this study, amorphous poly(ethylene terephthalate‐co‐1,3/1,4‐cyclohexylenedimethylene terephthalate) (PETG)/organoclay nanocomposites was synthesized by the in situ intercalation polymerization of terephthalic acid, ethylene glycol, 1,3/1,4‐cyclohexanedimethanol, and organoclay. The organoclay was obtained by modifying sodium montmorillonite (clay) with hexadecyl triphenylphosphonium bromide. The thermal, mechanical, optical, and gas barrier properties of these PETG nanocomposites with various organoclay contents (0–3 wt%) were discussed. The differential scanning calorimetry and X‐ray analyses revealed that all of the nanocomposites were amorphous. X‐ray diffraction and transmission electron micrographs showed that the organoclay was well dispersed in the polymer matrix, although some parts of the agglomerated layers remained on the scale of several hundreds of nanometers. The thermal stability and the mechanical property of the nanocomposites increased with organoclay content. The optical transmittances of nanocomposites that contained 0.5, 1, and 3 wt% of organoclay were 86.8%, 84.4%, and 77.4%, respectively. The oxygen transmission rate of the nanocomposite that contained 3 wt% of organoclay was about 50% of the PETG base polymer. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Morphology and mechanical properties of polypropylene/organoclay nanocomposites

Polypropylene (PP) nanocomposites were prepared by melt intercalation in an intermeshing corotating twin‐screw extruder. The effect of molecular weight of PP‐MA (maleic anhydride‐ modified polypropylene) on clay dispersion and mechanical properties of nanocomposites was investigated. After injection molding, the tensile properties and impact strength were measured. The best overall mechanical properties were found for composites containing PP‐MA having the highest molecular weight. The basal spacing of clay in the composites was measured by X‐ray diffraction (XRD). Nanoscale morphology of the samples was observed by transmission electron microscopy (TEM). The crystallization kinetics was measured by differential scanning calorimetry (DSC) and optical microscopy at a fixed crystallization temperature. Increasing the clay content in PP‐ MA330k/clay, a well‐dispersed two‐component system, caused the impact strength to decrease while the crystallization kinetics and the spherulite size remained almost the same. On the other hand, PP/PP‐MA330k/clay, an intercalated three‐component system containing some dispersed clay as well as the clay tactoids, showed a much smaller size of spherulites and a slight increase in impact strength with increasing the clay content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1562–1570, 2002     

熔体插层制备硅橡胶/蒙脱土纳米复合材料的性能研究

通过熔体插层成功制备了硅橡胶／蒙脱土纳米复合材料，通过XRD和SEM分析可知，在所选择的两步工艺务件下。蒙脱土被硅橡胶分子链插层剥离。获得剥离型的纳米复合材料。同时，测试了其力学性能和耐热性能。所得到的复合物的性能较纯硅橡胶有很大的提高，且与气相法白炭黑填充体系的性能相当。并且研究了硅烷偶联剂对填料-硅橡胶之间的增强作用。     

Preparation of high-impact polystyrene nanocomposites with organoclay by melt intercalation and characterization by low-field nuclear magnetic resonance

Recycled high-impact polystyrene nanocomposites with organoclay were prepared. Clay of the smectite group (montmorillonite) with two types of intercalated compounds was used (Viscogel S4 and Viscogel S7). The polymer nanocomposites were prepared by melt intercalation, applying two shear intensities in a twin screw extruder. The nanostructured materials obtained were characterized by NMR relaxometry, X-ray diffraction, thermogravimetric analysis, melt flow index and mechanical analyses. The results showed that the nanostructured materials presented a mixed intercalated/exfoliated morphology. The organophilic clay, Viscogel S7, generated polymer nanocomposites with better dispersion and distribution (at low concentrations) than those produced with the Viscogel S4. The shear rate was effective for dispersion of the nanoparticles. The materials processed at 600 rpm showed better dispersion than those processed at 450 rpm. The characterization techniques chosen were effective. They were complementary and permitted comparison among the polymer nanocomposites. The use of low-field NMR relaxometry allowed measurement of the spin–lattice relaxation time of hydrogen (T₁H), which provided more precise information on the mobility of the materials, thus complementing and explaining the results obtained by X-ray diffraction.     

Effect of organoclay on the morphology,mechanical, thermal,and rheological properties of organophilic montmorillonite nanoclay based thermoplastic polyurethane nanocomposites prepared by melt blending

Polymer nanocomposites based on the thermoplastic polyurethane (TPU) and organically modified montmorillonite (OMMT) was prepared by melt intercalation technique using a laboratory internal batch mixer followed by compression molding. Varying amount of organically modified nanoclays (1, 3, 5, 7, and 9 wt%) was added to the TPU matrix to examine the influence of organoclay on nanophase morphology and structure–property relationships. The interaction between TPU matrix and nanofiller was studied by infrared spectroscopy. The morphology of nanocomposites was studied by X‐ray diffraction, transmission electron microscopy, and atomic force microscopy that shows melt mixing by a batch mixer is an effective method for dispersing OMMT throughout the TPU matrix. Thermogravimetric analysis revealed that incorporation of organoclay enhances the thermal stability of the nanocomposites significantly. Differential scanning calorimetry was employed to measure the melting point and glass transition temperature (T_g) of soft segments. The reinforcing effect of the organoclay was determined by dynamic mechanical analysis and physico–mechanical testing. The effects of nanoclay concentration and processing parameters on the dynamic viscoelastic properties of the nanocomposites were studied by a rubber process analyzer using frequency sweep. A significant increase in the viscosity and storage modulus of the nanocomposites was found with the increasing clay content. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Unsaturated polyester/montmorillonite nanocomposites with improved mechanical and thermal properties fabricated by in situ polymerization

Although organically modified montmorillonite (OMMT) has been incorporated into unsaturated polyester (UP) resin to enhance properties, the aggregation often leads to defects which directly affect the properties of nanocomposites. In this work, OMMT slurry modified by a new allyl surfactant with carbon–carbon double bond, hexadecyl allyl dimethyl ammonium chloride (C₁₆‐DMAAC), was employed to prepare nanocomposites by in situ polymerization. The results illustrated that the existence of OMMT slurry helped monomers enter the OMMT galleries, leading to well‐dispersed OMMT in the UP matrix. The mechanical properties and thermal properties of OMMT nanocomposites were improved. With OMMT loading of 5 wt %, the tensile strength and flexural strength can be improved by 22% and 38%, respectively. Meanwhile, the onset thermal decomposition temperature (T_–10) value was ameliorated from 310.6 °C to 330.6 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45251.     

Morphology,thermal, and mechanical properties of polyamide 66/clay nanocomposites with epoxy‐modified organoclay

A new kind of organophilic clay, cotreated by methyl tallow bis‐2‐hydroxyethyl quaternary ammonium and epoxy resin into sodium montmorillonite (to form a strong interaction with polyamide 66 matrix), was prepared and used in preparing PA66/clay nanocomposites (PA66CN) via melt‐compounding method. Three different types of organic clays, CL30B–E00, CL30B–E12, and CL30B–E23, were used to study the effect of epoxy resin in PA66CN. The morphological, mechanical, and thermal properties have been studied using X‐ray diffraction, transmission electron microscopy (TEM), mechanical, and thermal analysis, respectively. TEM analysis of the nanocomposites shows that most of the silicate layers were exfoliated to individual layers and to some thin stacks containing a few layers. PA66CX–E00 and PA66CX–E12 had nearly exfoliated structures in agreement with the SAXS results, while PA66CX–E23 shows a coexistence of intercalated and exfoliated structures. The storage modulus of PA66 nanocomposites was higher than that of the neat PA66 in the whole range of tested temperature. On the other hand, the magnitude of the loss tangent peak in α‐ or β‐transition region decreased gradually with the increase in the clay loading. Multiple melting behavior in PA66 was also observed. Thermal stability more or less decreased with an increasing inorganic content. Young's modulus and tensile strength were enhanced by introducing organoclay. Among the three types of nanocomposites prepared, PA66CX–E12 showed the highest improvement in properties, while PA66CX–E23 showed properties inferior to that of PA66CX–E00 without epoxy resin. In conclusion, an optimum amount of epoxy resin is required to form the strong interaction with the amide group of PA66. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1711–1722, 2006     

Preparation and properties of epoxy nanocomposites. Part 2: The effect of dispersion and intercalation/exfoliation of organoclay on mechanical properties

The effect of the dispersion and intercalation/exfoliation of organoclay on the mechanical properties of epoxy nanocomposites was studied. The epoxy resin was EPON828 and the hardener was Jeffamine D‐230. The organoclay Cloisite 30B was used. Nanocomposites were prepared by different mixing devices that can generate different shear forces, such as a mechanical stirrer, a microfluidizer, and a homogenizer. The results indicate that the modulus increases almost linearly with the clay loading and also is improved with the quality of microdispersion, although the latter plays a less important role. On the other hand, only good dispersion can improve the strength, while poor dispersion results in loss of strength. The strength levels off above 4 wt% organoclay loading. It can be concluded that finer and more uniform dispersion increases the clay surface area available for interaction with the matrix and reduces stress concentration in the large aggregates that initiate the failure under stress. It is also observed that the presence of C30B does not significantly affect the glass transition (T_g) of the epoxy systems regardless of the level of clay dispersion and clay loading. Dynamic mechanic analysis (DMA) shows the positive effect of dispersion and intercalation/exfoliation on the storage modulus of epoxy nanocomposites (ENCs). POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Ternary nanocomposites: Curing,morphology, and mechanical properties of epoxy/thermoplastic/organoclay systems

The influence of two organically modified montmorillonites on the curing, morphology and mechanical properties of epoxy/poly(vinyl acetate)/organoclay ternary nanocomposites was studied. The organoclays and poly(vinyl acetate) (PVAc) provoked contrary effects on the epoxy curing reaction. Ternary nanocomposites developed different morphologies depending on the PVAc content, that were similar to those observed in the epoxy/PVAc binary blends. The organoclays were only located in the epoxy phase independently of the morphology. All nanocomposites showed intercalated structures with similar clay interlayer distances. Both PVAc and organoclays lowered the T_g of the epoxy phase, the presence of clays did not influence the T_g of the PVAc phase. The addition of the organoclays to the epoxy improved stiffness but lowered ductility while the adition of PVAc improved toughness although reduced stiffness of epoxy thermoset. Ternary nanocomposites exhibited optimal properties that combine the favourable effects of the clay and the thermoplastic. POLYM. COMPOS., 37:2184–2195, 2016. © 2015 Society of Plastics Engineers     

Morphology development,melt linear viscoelastic properties and crystallinity of polylactide/polyethylene/organoclay blend nanocomposites

Polylactide/polyethylene blends (PLA/PE) and their nanocomposites were prepared via the melt blending process. The effects of organoclay, compatibilizer (PE‐g‐MA), and PE content on morphology, linear viscoelastic properties of the melt and cold crystallization of the samples have been studied. The Palierne model is applied to predict the rheological behavior of unfilled blends. It implies that there is a quantitative agreement between model and experimental data for low PE content blend. From WAXD and the rheological behavior, it is shown that organoclay exhibits a higher extent of intercalation and dispersion in PLA/PE/organoclay nanocomposite than in PLA/organoclay nanocomposite. The DSC results present that the addition of compatibilizer into blend nanocomposite increases cold crystallization temperature of PLA by about 3°C. This can be explained by the role of compatibilizer in transfer of a part of organoclay from PLA matrix to droplets resulting in increase of PLA chain mobility and, therefore, slightly greater cold crystallization temperature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41300.     

Effects of organoclay Soxhlet extraction on mechanical properties, flammability properties and organoclay dispersion of polypropylene nanocomposites

The organic treatment on a layered silicate used in nanocomposite synthesis is the interface between the hydrophilic layered silicate (clay) and hydrophobic polymer in the case of polypropylene. However, the typical synthesis of an organoclay can result in excess organic treatment which can hinder mechanical and flammability benefits. This excess organic treatment may result in plasticization of the polymer matrix, possibly removing some of the mechanical and flammability property benefits provided by the nanocomposite. In this paper, the effects of using Soxhlet Extraction on the Organoclays after synthesis was investigated. Soxhlet extraction times on organoclays were found to have an effect on the mechanical and flammability properties of the resulting polypropylene nanocomposite. The removal of excess organic treatment by Soxhlet extraction resulted in improvements in flex modulus, improved clay dispersion, delayed time to ignition, and lowered heat release rate during burning.