**6.11. Bronsted acidity**

constant relative humidity, was reduced. The result of micro-tensile test of nanocomposite film showed that Young modulus improved up to 500% at 5 wt.% of montmorillonite [42].

Important properties of fiber-forming polymers may be improved using montmorillonite as a filler [43]. In general, clay mineral (nm) showed flame–retardant effects as assessed by a reduction in the peak heat release rate for various thermoplastic polymers including polystyrene, polyamide-6, polypropylene, polyamide-12, poly(methyl methacrylate), polyethylene,

Montmorillonite-nylon-6 (nm) composite was produced through melt bending or compounding technique followed by injection molding using percent loading of organo-montmorillonite (nm) composites ranging 0–5 wt.% content. The desired properties of tensile and flexural properties were indicated optimum at 5 wt.% loading. Other improvement observed includes storage modulus, stiffness, and heat distortion temperature, and the reduction in water

Nanometer-sized particles of montmorillonite may be introduced in polymers/fibers, resulting in an increased resistance to electricity, chemicals, heat and flaming, and enhanced ability

Montmorillonite may be incorporated in fiber-forming polymer through electrospinning/melt spinning. Electrospinning is the technique successfully used for the production of a variety of

The properties of polymer nanofiber produced through electrospinning are influenced by melt viscosity, surface tension, dielectric permeability, electric field strength, solvent proper-

Interest in using the clay was observed to obtain the flame-retardant properties in cotton fiber [44]. The two types of local clay samples study to evaluate the flame-retardant effects on

Aqueous water dispersion was applied to bleached cotton fabric. The finished fabric was assessed using vertical flame-retardant test BS EN ISO 6940 2004. Flame retardancy was improved as indicated by the ease of ignition and the char length of burnt cotton fabric.

The growing variety of montmorillonite utilization is perhaps indicated by the use of bentonite in the study to form a part of deep geological repository for spent nuclear fuel. Pure homo ionic Ca-montmorillonite may be considered bentonite-similar system to obtain information on natural bentonite behavior. Water-saturated structure and porosity of Ca-montmorillonite were studied using X-ray diffraction, small angle X-ray scattering, nuclear magnetic resonance, transmission electron microscopy, and ion exclusion. The obtained results indicate

ties to evaporate, polymer molecular weight, and concentration.

**6.9. Flame-retardant finishing of cotton fiber**

**6.10. Geological repository for spent nuclear fuel**

multiple porosity for the bentonite structure [45].

**6.8. Effects in fiber-forming polymer**

16 Current Topics in the Utilization of Clay in Industrial and Medical Applications

and ethylene vinyl acetate (EVA).

absorption relative to virgin nylon-6.

to block UV light.

polymer nanofibers.

bleached cotton fabric.

Synthetic mica-montmorillonite (SMM) shows Bronsted acidity. SMM studied, for Bronsted acidity, was based on


The evaluation of SMM for adsorption energies using ammonia and pyridine showed the acid strength. The composition of SMM platelets influences the acidity [46]. Interesting results were obtained in the study explaining the Bronsted acidity in relation to the platelet structure.

The strongest acidity was demonstrated by SMM structure where octahedral [AlO]+ was replaced adjacent to tetrahedral [Si-(OH)-Al] moieties in the tetrahedral layer.

Bronsted and Lewis acid catalytic sites in montmorillonite provided the useful applications [47]. The exchangeability of interlayer cations, through ion exchange, helps in altering the acidic nature. Modified montmorillonite types known as montmorillonite-K-10 (produced by the calcinations of montmorillonite) were found as efficient catalysts. Cation exchange produces more effective montmorillonite types including Fe<sup>+</sup> montmorillonite and clayfen.

Sodium montmorillonite (NaMMT) is indicated to accelerate the curing of urea-formaldehyde resin. In acid-curing conditions, urea-formaldehyde resin was used as adhesive for plywood and wood particleboard. Cross-linking of urea-formaldehyde in the presence of NaMMT produces plywood with improved water resistance. An accelerating effect on urea-formaldehyde curing was observed in differential scanning calorimetry results. Dry internal bond strength of wood particleboard increases with small additions of NaMMT [48].

Organic reagents synthesized using montmorillonite types (cation substituted) used as catalyst include α- aryl β-hydroxycyclic amines, silanols, and methyl cinamates, and the production of multi-substituted imidazopyridines, imidazopyrazines, and imidazopyrimidines.
