Dispersion Of Clay In Polymer Matrix Research Articles

Flame Retardant Nanocomposites of Polystyrene-Modified Sepiolite Clay

Flame retardancy is the property that is highly demanded when it comes to deal with plastics in different industries. In this research general purpose polystyrene (GPPS) and modified sepiolite clay are melt blended together to fabricate flame retardant nanocomposites. Structural analysis were performed with the help of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. Morphological analysis of the fabricated nanocomposites were carried out using scanning electron microscope (SEM). As a result of better clay dispersion in polymer matrix and intermolecular interactions, mechanical properties are also improved. The standard procedure (ASTM D4986-20) was followed for observing the flame retardancy of the fabricated nanocomposites. Tangible decrease is noted upto 48% in burning rate of the optimum sample which reflects improvement in flame retardancy.

Supercritical carbon dioxide-assisted process in synthesis of polymer/clay melt

Nanocomposites are currently being used in a number of fields, and new applications are continuously being developed including mechanical and biomaterial devices, as well as various in solar and fuel cells applications. Generally, the synthesis of polymer nanocomposites are done using solution chemistry, and this may raise serious concerns regarding air and water pollutions. Immediately, the ‘green’ method using supercritical carbon dioxide (scCO2) has grabbed the attention of researchers who are responsible to synthesize polymer composites by non-hazardous routes. Extrusion processes would benefit from the use of scCO2 since the rationale of the extrusion process is to formulate, provide texture and shape molten polymers by forcing them through a die. ScCO2 has been used in several studies as a medium of clay dispersion in polymer matrix by providing a solvent-free fabrication route for nanocomposites. Furthermore, it has more favorable interactions with polymers compared to other inert gases and has the ability to be dissolve in large quantities. It acts as a plasticizer, which modifies viscosity and interfacial properties of the polymer drastically. In this paper, experimental and theoretical studies of solubility and viscosity of several polymer melts in clay are discussed in detail. The assistance of scCO2 in clay dispersion and as a foaming agent has been reviewed extensively.

Synthesis and dynamic mechanical analysis of nanocomposite UV crosslinkable 100% solid acrylic pressure sensitive adhesives

A synthesis and characterization of nanocomposite solventless acrylic UV crosslinkable pressure sensitive adhesives is presented. Different prepolymers were synthesized using bulk polymerization procedure. The reaction mixture consisted of acrylic monomers (2-ethylhexyl acrylate, acrylic acid and t-butyl acrylate), azobisisobutyronitrile initiator, chain transfer agent n-dodecylmercaptan and unsaturated UV photoinitiator 4-acryloyloxybezophenone. Different formulations with different amounts of modified and unmodified montmorillonite (MMT) clays were tested and the prepolymer was characterized by viscosity measurements. UV crosslinking process was monitored using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Gel phase amount in crosslinked samples was determined by Soxhlet extraction. Clay dispersion in polymer matrix was investigated by X-ray diffraction analysis (XRD). Three basic adhesive properties, the tack, peel and shear strength were measured and the viscoelastic properties of crosslinked adhesive films were characterized using dynamic mechanical analysis (DMA). Results of the study showed high increase in prepolymer viscosity, when hydrophobic types of MMT clays were added in the reaction mixture. The addition of clay had a negative effect on UV crosslinking process. XRD analysis confirmed complete exfoliation and/or intercalation of modified clays in polymer matrix, depending on modifier amount and type. Results of adhesive properties testing showed a major influence of clay addition on adhesive properties, especially on shear strength. DMA analysis showed an increase in storage modulus (G′) and a decrease of tanδ values for adhesives synthesized with clay what also concurs with higher shear strength and implies an improved cohesion of adhesive.