Montmorillonite clay reinforcement

General discussions of the effect of reinforcing agents on the thermal properties of polymers include glass fiber-reinforced polyethylene terephthalate [28], multiwalled carbon nanotube-reinforced liquid crystalline polymer [29], polysesquioxane [30, 31], polynrethane [31], epoxy resins [32], polyethylene [33], montmorillonite clay-reinforced polypropylene [34], polyethylene [35], polylactic acid [36, 37], calcium carbonate-filled low-density polyethylene [38], and barium sulfate-filled polyethylene [39]. 

EFFECT OF MONTMORILLONITE CLAY REINFORCEMENT ON ELECTRICAL PROPERTIES OF POLYMERS... 

Nitrile Rubber. Vulcanized mbber sheets of NBR and montmorillonite clay intercalated with Hycar ATBN, a butadiene acrylonitrile copolymer have been synthesized (36). These mbber hybrids show enhanced reinforcement (up to four times as large) relative to both carbon black-reinforced and pure NBR. Additionally, these hybrids are more easily processed than carbon black-filled mbbers. 

Nylon-6. Nylon-6—clay nanometer composites using montmorillonite clay intercalated with 12-aminolauric acid have been produced (37,38). When mixed with S-caprolactam and polymerized at 100°C for 30 min, a nylon clay—hybrid (NCH) was produced. Transmission electron microscopy (tern) and x-ray diffraction of the NCH confirm both the intercalation and molecular level of mixing between the two phases. The benefits of such materials over ordinary nylon-6 or nonmolecularly mixed, clay-reinforced nylon-6 include increased heat distortion temperature, elastic modulus, tensile strength, and dynamic elastic modulus throughout the —150 to 250°C temperature range. 

Biobased epoxy nanocomposites can be reinforced with organo montmorillonite clay and carbon fibers obtained from poly(acryl-onitrile) (45). To get the organically modified clay into the glassy biobased epoxy networks, a sonication technique was used. In this way, clay nanoplatelets were obtained that were homogeneously dispersed and completely exfoliated in the matrix. 

Carbon black as a reinforcing additive has been employed in rubber manufacture for many years. One may argue that carbon black provides nanoparticle reinforcement for rubber. There are many reviews available on carbon black use in rubber.[46] We will focus on recent advancements in nanoparticle reinforcement. These advancements do not include carbon black. Most of the recent advancements in nanoparticle reinforcement in rubber have focused on montmorillonite clay.There are several reviews on rubber... 

Blends can also be reinforced with nanoscale inclusions, primarily for stiffening, as elongation to break usually suffers. However, that does not have to be the case. The identity of the phase containing the nanoparticle as well as its continuity in the blend are of prime importance to property development in the blend, as found for PP-EPDM blends reinforced with montmorillonite clay (Lee and Goettler 2004). 

Due to the brittleness of starch materials, plasticizers are commonly used. A frequently utilized low weight hydroxyl compoxmd is glycerol. Another effective plasticizer is water, although not the best because it evaporates easily. Still, starch-based materials readily absorb water and this may result in significant changes in the mechanical properties. Different routes have been explored in order to improve the mechanical properties and water resistance of starch materials. These are chemical modifications to the starch molecule, blends with polymers such as polycaprolactone [61], or reinforcement with different types of cellulose-based fillers, such as ramie crystaUites [62], and timicin whiskers [63], or montmorillonite clay particles [64]. 

Kaneko, M. L. Q. A. Romero, R. B. Do Carmo Goncalves, M., High Molar Mass Silicone Rubber Reinforced with Montmorillonite Clay Masterbatches Morphology and Mechanical Properties. Eur. Polym. J. 2010, 46, 881-890. 

Jimenez et al. also investigated blends of PCL reinforced by an organically-modified montmorillonite clay, with a view to using inert inorganic structures to enhance the properties of PCL for which Tg and T are low. With the montmorillonite having a layered structure, it was hoped to intercalate the polymer from solution with the clay [173]. 

Relative modulus versus talc clay-reinforced agent content for nanocomposites based on a thermoplastic polyolefin or a triphenylene oxide matrix polypropylene plus ethylene-based elastomer showed that relative to a particular filler content, an appreciably higher modulus content was obtained for the montmorillonite reinforcing agent than for talc [156]. Doubling the modulus of the phenylene oxide requires about four times more talc than montmorillonite, with the talc-reinforced polymer having an improved surface finish. In the case of the talc-reinforced polymer, exfoliation is appreciably better than with clay reinforcement. The talc-reinforced polymer has automotive applications. 

The reinforcing properties of organically modified montmorillonite clay have been studied in several other polymers, including liquid crystalline polymers [45], and the suspension of montmorillonite in aqueous media containing polyelectrolytes [46]. 

Some important nanostructures include carbon nanotubes, montmorillonite type clays, and biomolecules such as proteins and DNA. Frequently, these nanomaterials self-assemble into highly ordered layers or structures arising from hydrogen bonding, dipolar forces, hydrophilic or hydrophobic interactions, etc. For maximum reinforcement, however, proper dispersal of these nanostructures has become a major research effort. The following sections will emphasize the structure and behavior of carbon nanotube and montmorillonite clay based nanocomposites. 

Polymer-based nanocomposites have been widely developed over the last two decades due to their highly specific mechanical properties compared to conventional polymer-based microcomposites [1], The reinforcement mechanism in nanocomposites may be attributed to the strong inter-particle and particle-matrix interactions due to the large specific surface area. Among this recent class of materials, the most intensive researches are focused on polymer-based nanocomposites reinforced with inorganic montmorillonite clay, and especially on their synthesis and characterization. However, their micromechanical modeling has been less investigated so far. 

A micromechanics-based model recently proposed by Anoukou et al. [7,8] was adopted in the present investigation to develop a pertinent model for describing the viscoelastic response of polyamide-6-based nanocomposite systems. Comparisons between the results from the micromechanical model and experimental data were considered for nanocomposites reinforced with modified and unmodified montmorillonite clay. Reasonable agreement between theoretical predictions and experimental data was noticed, the discrepancies being attributed to both uncertainties in the input data and a possible effect of reduced chain segment mobility in the vicinity of clay nanoplatelets. 

Varlot, K., Reynaud, E., Kloppfer, M.H., Vigier, G., and Varlet, J. (2001) Clay-reinforced polyamide preferential orientation of the montmorillonite sheets... 

The products produced by these researchers are organoclays and came to be developed commercially because of their distinctive absorptive, gel formation, lubrication, and rubber reinforcement characteristics [64 to 66]. The organic amine replacement of the montmorillonite clay cations significantly changed their absorptive characteristics. Of interest are the studies of Mortland et al. [67,68] in the 1980s on absorbing phenol and chlorophenol by organo-clays. 

Zhou, Y., Pervin, E, Rangari, V. K., and Jeelani, S. (2007). Influence of Montmorillonite Clay on the Thermal and Mechanical Properties of Conventional Carbon Fiber Reinforced Composites. Journal of Materials Processing Technology. 191 347-351. 

The absence of sepiolite and palygorskite from sediments and sedimentary rocks in other parts of the world is most likely due to a lack of attention on the part of researchers who have looked at clay mineral suites in the past. This can be explained in part by the similarity of the respective major low-angle peaks which can be confused with montmorillonite (12 8 sepiolite-one water layer montmorillonite) and illite (10.5 8 palygorskite-slightly "expanded" illite). A priori there is no reason why these minerals should be particular to French sedimentary rocks except that workers from this country have been particularly alert to their presence. This opinion is reinforced by the now-frequent reports of sepiolite and, to a lesser extent, palygorskite in sea sediments of the Atlantic shelf and ridge, Mediterranean, Red Sea and Pacific deep sea (see JOIDES reports—National Science Foundation Publications). 

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