Polypropylene—montmorillonite composites

Using clay derived from hydrated sihcates of aluminum combined with polymer materials would provide significant advantages in enhancing the physical properties compared to the use of polymers alone. The composites can be further improved, especially in melt processing, if they can be manufactured without the use of any organic solvent (Skaff et al., 2008). The Polypropylene—montmorillonite composites were... 

Stribeck N et al (2014) Studying nanostructure gradients in injection-molded polypropylene/ montmorillonite composites by microbeam small-angle X-ray scattering. Sci Tech Adv Mater 15(1) 015004... 

Electrical properties have been reported on numerous carbon fiber-reinforced polymers, including carbon nanoflber-modified thermotropic liquid crystalline polymers [53], low-density polyethylene [54], ethylene vinyl acetate [55], wire coating varnishes [56], polydimethyl siloxane polypyrrole composites [50], polyacrylonitrile [59], polycarbonate [58], polyacrylonitrile-polycarbonate composites [58], modified chrome polymers [59], lithium trifluoromethane sulfonamide-doped polystyrene-block copolymer [60], boron-containing polyvinyl alcohols [71], lanthanum tetrafluoride complexed ethylene oxide [151, 72, 73], polycarbonate-acrylonitrile diene [44], polyethylene deoxythiophe-nel, blends of polystyrene sulfonate, polyvinyl chloride and polyethylene oxide [43], poly-pyrrole [61], polypyrrole-polypropylene-montmorillonite composites [62], polydimethyl siloxane-polypyrrole composites [63], polyaniline [46], epoxy resin-polyaniline dodecyl benzene sulfonic acid blends [64], and polyaniline-polyamide 6 composites [49]. 

Qin H., Zhang S., Zhao C., Feng M., Yang M., Shu Z., Yang S., Thermal stability and flammability of polypropylene/montmorillonite composites . Polymer Degradation and Stability, 2004 85 807-813. 

Zhang, X., Yang, M., Zhao, Y, Zhang, S., Dong, X., Liu, X., Wang, D. and Xu, D. (2004), Polypropylene/montmorillonite composites and their application in hybrid fiber preparation by melt-spinning , J Appl Polym Sci, 92 (1), 552-558. 

Tables 4.28 and 4.29 show effect of a montmorillonite nanoclay employed as a masterbatch (PolyOne Nanoblend 1001) in polypropylene on polypropylene-based composite containing 50% (w/w) maple wood flour and on flexural strength and modulus of the WPC.

In the isothermal crystallization of polypropylene montmorillonite (PP-MMT) nanocomposites, it was found that the crystallinity of the composites decreased with increasing montmorillonite content, indicating the dispersion of MMT layers in the polypropylene matrices. The nanoparticles confined the polypropylene chains and hindered the polymer crystallization. The spherulites of the PP-MMT nanocomposites were greatly decreased in size as MMT was introduced. On the other hand, the crystallization rate increased dramatically with the increasing of MMT content. The interfacial free-energy per unit area perpendicular... 

Mixture surface plot of tensile modulus and of the polypropylene organically modified montmorillonite composites as a function of mixture components. (Reproduced from Mittal, V., /. Thermoplast. Compos. Mater., 21, 9, 2008a. With permission from Sage Publishers.)... 

Work by Lee et al. [14] provides a transition from discussions centered on polyethylene-montmorillonite nanocomposites to discussions focused on polypropylene-montmorillonite nanocomposites. An extruder was not employed to prepare the polymer nanocomposites. A Haake Banbury internal mixer prepared the polymer-montmorillonite concentrates (180°C, 10 min, and 50 r/min) and the final polymer composites. The montmorillonite in this study was Kunipia-F from Kunimine, Japan. Octadecylamine served as the organic modification for the montmorillonite. The polymer concentrates were prepared with polypropylene grafted with maleic anhydride (PP-g-MA Umex 1010 from Sanyo) and PE-g-MA (Umex 2000 from Sanyo). The PP-g-MA-organomont-morillonite concentrates demonstrated superior dispersion of the montmorillonite in relation to the PE-g-MA concentrates. Hence, most of the effort in preparing and characterization of the final polyethylene composites centered on the PP-g-MA-montmorillonite concentrates. The concentrations of montmorillonite in the concentrates were 12.5, 30,... 

A review of the work found above with the preparation of polyethyl-ene-montmorillonite composites, polypropylene (polyethylene with pendant methyl groups)-montmorillonite composites, and polystyrene (polyethylene with pendant phenyl groups)-montmorillonite composites indicates that one can balance the hydrophilic-hydrophobic balance of polyethylene and polypropylene with polar functionality with the hydrophilic-hydrophobic balance of organomontmorillonite more effectively than with a similar strategy as regards polystyrene. 

Szkudlarek E, Piorkowska E, Boyer SAE, Haudin JM, Gadzinowska K. Nonisothermal shear-induced crystallization of polypropylene-based composite materials with montmorillonite. Eur Polym J 2013 49 2109-19. 

Kim K.-N., Kim H. and Lee J.-W., Effect of interlayer structure, matrix viscosity, and composition of a functionalized polymer on the phase structure of polypropylene-montmorillonite nanocomposites , Polym Eng Sci, 2001, 41, 1963-1969. 

There are two basic types of nanocomposites, in which particles are intercalated or exfoliated. In an intercalated composite the nanodispersed filler still consists of ordered structures of smaller individual particles, packed into intercalated structures. Exfoliated particles are those dispersed into practically individual units, randomly distributed in the composite. Layered silicates, such as montmorillonite clays or organoclays, can be used in nanocomposites. Because clays are hydrophilic and polyolefines are hydrophobic, it is not easy to make a nanocomposite based on polyethylene or polypropylene because of their natural incompatibility. 

Figure 20 shows TEM photographs of sodium-type montmorillonite, 2C18-Mt, and a composite prepared by kneading PT-Mt (one part 2C18-Mt to one part POLYTEL H) and polypropylene. The dispersion of the inorganic matter is on the order of microns, and the dispersibihty of the 2C18-Mt increased to the submicron order. Additional POLYTEL H was added so that silicate layers could be dispersed in the PP, which is a non-polar material, and a hybrid material was successfully created. 

Reddy and Das made a silica-supported zirconocene catalyst in situ, by subliming ZrCl4 onto a high surface area silica, then adding NaCp. This catalyst was combined with an organically modified montmorillonite (Cloisite 20A), mixed with additional MAO (Al/Zr = 500). Propylene polymerization was conducted in the gas phase, at 8 bar and 70°C. Despite the absence of an obvious mechanism for interaction between the catalyst with the clay, or the presence of a solvent to swell the clay, the composite material was claimed to contain delaminated clay on the basis of decreased basal peak intensity in the XRD. The polypropylenes showed low melting points (132°C-134°C) consistent with large amorphous fractions. 

The wide-angle x-ray diffraction patterns of the polypropylene nanocomposites with and without compatibilizer have been shown in Figure 10.11. The diffraction pattern of pure imidazolium-treated montmorillonite has also been plotted for comparison. The presence of basal peaks in all the composites containing different compatibilizers indicated that full exfoliation of the filler did not take place. Also, the increase in the basal plane spacing in the composites as compared to the modified filler or the composite without compatibilizer... 

Sumita M, Tsukumo Y, Miyasaka K et al (1983) Tensile yield stress of polypropylene composites filled with ultrafine particles. J Mater Sci 18 1758—1764 Thellen C, Orroth C, Froio D et al (2005) Influence of montmorillonite layered silicate on plasticized poly(l-lactide) blown films. Polymer 46 1716-11727 Uyama H, Kuwabara M, Tsujimoto T et al (2003) Green nanocomposites from renewable resources plant oil-clay hybrid materials. Chem Mater 15 2492-2494 Wang SF, Shen L, Zhang WD et al (2005a) Preparation and mechanical properties of chitosan/ carhon nanotuhes composites. Biomactomolecules 6 3067—3072... 

Pandis et al. [101] examined the morphology, microhardness, and electrical properties of melt-mixed or compression-molded composites based on conductive polypyrrole dispersed into a nonconductive polypropylene matrix either as a pure component or as a nanocomposite with sodium montmorillonite. The effects of the polypyrrole and montmorillonite content on the properties of the composites were studied, and the results are discussed in terms of microstructure. 

The improvement in the thermal performance of the polymers after the incorporation of filler was demonstrated in Figure 1.9 for poly(methyl methacrylate). Figure 1.14 further shows the thermal behavior of polypropylene nanocomposites containing different volume fractions of montmorillonite modified with dioctadecyldimethylammonium. Curve 1 represents the thermal degradation of pure polymer. Curve 2 represents the composite with 1 vol% clay. The thermal stability of the polymer was significantly enhanced. Further... 

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