Jeyaraman Anandha kumar
Lecturer, Department of Textile Processing, G.R.G. Polytechnic College, Kuppepalayam,
Sarkar Samakulam , Coimbatore, India, Mail: anna_781@rediffmail.com
COMPOSITES
The word “composite” refers to the combination, on a macroscopic scale, of two or more
materials, different for composition, morphology and general physical properties. In many cases, and depending on the constituent properties, composites can be designed with a view to produce materials with properties tailored to fulfill specific chemical, physical or mechanical requirements. Most human tissues such as bones, tendons, skin, ligaments, teeth, etc., are composites, made up of single constituents whose amount, distribution, morphology and properties determine the final behavior of the resulting tissue or organ. Man-made composites can, to some extent, be used to make prostheses able to mimic these biological tissues, to match their mechanical behavior and to restore the mechanical functions of the damaged tissue.
Amongst the advantages of using cellulose in polymer composites, renewability, cheapness, high specific strength and modulus are the most important. Taking account of these properties, the present paper gives a widespread overview of the potential applications of cellulose-based composites in the medical field.
NATURAL GREEN COMPOSITES
The use of natural or synthetic materials to substitute or integrate body functions or organs, damaged by traumatic or pathologic events, to assist tissue healing or to correct abnormalities, dates far back to the beginning of medicine into ancient civilizations. Therapeutic innovations and the design and implementation of complex medical devices permit increased patient survival, significantly improve quality of life and contribute to increase life expectancy. The word “composite” refers to a heterogeneous combination, on a macroscopic scale, of two or more materials, differing in composition, morphology and usually physical properties, made to produce specific physical, chemical and mechanical characteristics. The combination of different
elements results in a material that maximizes specific properties. The advantage of composites is therefore that they show the best qualities of their constituents,and often exhibit some properties that the single constituents do not have. Moreover, composite materials allow a flexible design, since their structure and properties can be optimized and tailored to specific applications.[1].
Composite materials made from glass fibres or carbon fibres embedded into epoxy resins or unsaturated polyester typically exhibit excellent mechanical and thermal properties and are used in many applications, for instance in the aerospace and automotive fields. However, these materials are incinerated at the end of their life cycle, causing significant environmental issues [2]. Consequently, the increasing environmental awareness and ecological concerns have resulted in a renewed interest in natural-based and compostable materials, and therefore issues such as biodegradability and environmental safety are becoming important. Indeed, the concept of biocomposites made from cellulose-based feedstock appears to be an alternative route to
achieve ‘green’ polymer composites.
ADVANTAGES OF BIOCOMPOSITES
Natural fibres can be classified according to their origin: bast fibres (jute, flax, and hemp), leaf fibres (sisal and pineapple), seed fibres (cotton and coir), and other types which include wood and roots. Besides their abundance in nature, natural fibres have many advantages such as low weight, cheapness, renewability, and they exhibit good mechanical properties.Polymer composites reinforced by natural fibres have performances which are highly dependent on the chemical composition, structure, and physical and mechanical properties of the dispersed phase.[3,4].
Advantages and Disadvantages of Natural Fibres Products
Advantages of Natural Fibers Disadvantages of Natural Fibers
1. Environmental Aspects:
renewable resources
low energy requirements during production
carbon dioxide neutrality
disposal by composting
Lower strength, especially impact strength
2. Biological Aspects:
natural organic products
no dermal issue for their handling
do not pose a bio-hazard upon disposal Variable quality, influenced by weather
3. Production Aspects:
non-abrasive
great formability Poor moisture resistance which causes swelling of the fibres
4. Component Weight Issues:
lightweight (less than half the density of glass fibers) Restricted maximum processing temperature
5. Financial Aspects: Lower durability; Poor fire resistance
6. General Aspects:
safer crash behavior in tests (i.e., no splintering)
good thermal insulation and acoustic properties due to their hollow tubular structures
high specific strength
good sound insulation
price fluctuation by harvest results or agricultural politic Poor fibre/matrix adhesion
CONCLUSIONS
The use of composite materials for biomedical applications offers many new options and
possibilities for implants design. As a matter of fact, composite materials and components can be designed to obtain a wide range of mechanical and biological properties. The implant structure and its interactions with the surrounding tissues can be optimized by varying the constituents, the type and distribution of the reinforcing phase and adding coupling agents.Increasing environmental awareness and ecological concerns have renewed the interest in natural-based and compostable materials, and therefore issues such as biodegradability and environmental safety are becoming important. The concept of biocomposites made from cellulose-based feedstock appears to be an alternative route to achieve green polymer composites. From tissue engineering to biodevices, cellulose-based composites can be found in the most inspiring and challenging developments in the medical field.
