Nanocomposites Materials

Yahiya kadaf Manea

Department of Chemistry

Aden University , Yemen

INTRODUCTION

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• Synthesis of Composite Materials for Chromatographic Column Separations. Conventional ion exchange resins although posses excellent ion exchange properties but suffers from two limitations, firstly they decompose at elevated temperatures and secondly do not withstand high ionizing radiations when used in atomic reactors. It is for these reasons scientists made efforts to synthesize inorganic ion exchangers that can cope with the above mentioned difficulties. One of the striking feature of inorganic ion exchangers is that they can be obtained in granular and fibrous form with cavities of desired size showing selectivity towards anions, cations or organic molecules. These materials also suffers from certain limitations. They undergo hydrolysis when used in aqueous systems and are obtained usually in powder form. In order to overcome these shortcomings encountered with organic and inorganic ion exchangers , attempts were made to develop organic –inorganic composite materials as ion exchangers. These composite materials exhibit properties entirely different from that of parent components. The composite materials are being investigated due to the following distinct properties:

• They show improved mechanical strength

• They have greater thermal and chemical stability

• Enhanced ion exchange capacity

• They can be synthesized in granular form suitable for column operations.

• They posses electrochemical properties as well as shows optical and magnetic behaviour. 

NANOCOMPOSITES• Nanocomposites, a high performance material exhibit unusual property

combinations and unique design possibilities. With an estimated annual growth rate of about 25% and fastest demand in engineering, plastics and elastomers, their potential is so striking that they are useful in several areas ranging from packaging to biomedical applications. In this unified overview the three types of matrix nanocomposites are presented underlining the need for these materials, their processing methods and some recent results on structure, properties and potential applications, perspectives including need for such materials in future space mission and other interesting applications together with market and safety aspects. Possible uses of natural materials such as clay based minerals, chrysotile and lignocellulosic fibres are highlighted. Being environmentally friendly, applications of nanocomposites offer new technology and business opportunities for several sectors of the aerospace, automotive, electronics and biotechnology industries.

CLASSIFICATION OF COMPOSITES

*Ref (1) Due to their large aspect ratios (i.e., size-to-volume ratios), sub micrometer size, and unique properties, nano sensors, nano probes, and other nano systems are revolutionizing the fields of chemical and biological analysis. Catalysis, separation, sorption, and fuel cells are other important fields for nanocomposite applications.

SOME APLLICATIONS OF NANOCOMPOSITEThe numbers of applications of nanocomposites have been growing at a rapid rate. The worldwide production is estimated to exceed 600,000 tonnes and is set to cover the following key areas in the next five to ten years: Drug delivery systems Anti-corrosion barrier coatings Lubricants and scratch free paint New fire retardant materials

UV Protection gels New scratch/abrasion resist materials

Superior strength fibers and filmsImprovements in mechanical property have results in major interest in nanocomposite in various automotive and general/industrial applications. These include potential for utilization as mirror housing on various vehicles types, door handles, engine covers and intake manifolds and timing belt covers. More general applications currently being considered include usage as impellers and blades for vacuum cleaners, power tool housings, mower hood and covers for portable electronic equipment such as mobile phones, pagers[1].

Fuel Tanks:The ability of nano clay incorporation to reduce solvent transmission through polymers such aspolyamides (Acrylamide ) has been demonstrated.

Films:The presence of filler incorporation at nano levels has also been shown to have significant effect on the transparency and haze characteristics of films. In comparison to conventionally filled polymers. With polyamide based composites, this effect has been shown to be due to modifications in the crystallization behavior brought about by the nano clay particles.Environmental protection:Water laden atmosphere have long been regarded as one of the most damaging environments, which polymeric materials can encounter. Thus ability to minimize the extent to which water is absorbed can be a major advantage.Available data indicate that significant reduction of water absorption in a polymer could be achieved by nano clay incorporation. Similar effect could also be achieved with polyamide-basednanocomposites.

OUTLOOKA nanocomposite is a composite material in which at least one of the dimensions of one of itsconstituents is at the nanometer size scale. The term usually also implies the combination of two (ormore) distinct materials, such as a ceramic and a polymer, rather than spontaneously phase-segregatedstructures. The challenge and interest in developing nanocomposites is to find ways to createmacroscopic components that benefit from the unique physical and mechanical properties of very smallobjects within them. Nanocomposites can be used in a variety of sensing schemes to enhance theperformance of sensing devices and open new horizons in their applications. Nanoparticles, nanowires,and nanotubes of various materials have already had an impact on the field of chemical sensors, rangingfrom gas sensors to glucose enzyme electrodes. Currently, nanocomposite-based protocols are beingexploited for detection of proteins, acid, toxic gases, etc. The property associated with nanowires andnanotubes which enable us to modify them with other elements such as polymers or a silica matriximparts high selectivity to these devices. Nanocomposite-based sensors are expected to have a majorimpact on clinical diagnosis, environmental monitoring, security surveillance, and ensuring the safety ofour food.