Fibre-reinforced polymer composites chemical properties

The performance of natural fibre reinforced polymer composites depends on several factors, including fibre chemical composition, cell dimensions, microfibrillar angle, defects, structure, physical and mechanical properties, and the interaction of a fibre with the polymeric matrix [28]. The knowledge about the characteristics of the fibre is essential in order to expand the effective use of lignocellulosic materials for polyethylene composites and to improve their performance. 

Joseph K, Thomas S, Pavithran C (1996) Effect of chemical treatment on the tensile properties of short sisal fibre-reinforced polyethylene composites. Polymer 37 5139-5149... 

Hepworth DG, Hobson RN, Bruce DM, Farrent JW (2000) The use of unretted hemp fibre in composite manufacture. Compos A 31 1279-1283 Idicula M, Boudenne A, Umadevi L, Ibos L, Candau Y, Thomas S (2006) Thermophysical properties of natural fibre reinforced polyester composites. Compos Sci Technol 66 2719-2725 Ioffe R, Andersons J, Wallstrom L (2003) Strength and adhesimt characteristics of elementary flax fibers with different surface treatments. Compos A 34 603-612 John MJ, Anandjiwala RD (2008) Recent developments in chemical modification and characterization of natural fiber-reinforced composites. Polym Compos 29 187-207 John MJ, Anandjiwala RD, Thomas S (2009) Hybrid cranposites. In Thomas S, Pothan LA (eds) Natural fiber reinforced polymer composites macro to nanoscale. Old City, Philadelphia, pp 315-328... 

Fibre-reinforced polymer (FRP) composites are composed of fibres and matrices, which are bonded through the interface to ensure that the composite system as a whole gives satisfactory performance. Part 1 deals with FRP composite matrix materials which provide the foundation for composite materials. Chapter 2 reviews the chemistry of phenolic resins together with their mechanical and thermal properties. Chapter 3 discusses polyester thermoset resins as matrix materials. An overview of the chemistry of vinylester resins, together with their mechanical and chemical properties, as well as their use as a matrix material in the construction industry, is provided in Chapter 4. The final chapter in Part 1 begins with a review of the epoxy resins commonly available on the market, and then focuses on the principal characteristics of epoxy resin composite systems and their practical applications. 

Scanning transmission X-ray microscopy has been used most extensively for polymer research, e.g. for bulk characterisation of polymeric materials with chemical sensitivity at a spatial resolution of 50 nm [739], STXM has also been used for the analysis (morphology, size distributions, spatial distributions and quantitative chemical compositions) of copolymer polyol-reinforcing particles in polyurethane [740], Pitkethly [741] has reviewed the role of microscopy in the evaluation of fibre/matrix interfacial properties and micromechanical characteristics of fibre-reinforced plastic composites. 

Noorunnisa Khanam R, Abdul Khalil H.P.S., Jawaid M., Ramachandra Reddy G., Surya Narayana C., Venkata Naidu S. 2010 SisallCarbon Fibre Reinforced Hybrid Composites Tensile, Flexural and Chemical Resistance Properties. J Polym Environ 18 727-733. 

Kalaprasad, G. Francis, Bejoy Thomas, Selvin Kumar, C. Radhesh Pavithran, C. Groeninckx, G. Thomas, Sabu, Effect of fibre length and chemical modifications on the tensile properties of intimately mixed short sisal/glass hybrid fibre reinforced low density polyethylene composites. Polymer Intenuitional, 53(11), 1624—1638 (2004). 

Van de Velde K, Kiekens P (2001) Thermoplastic polymers overview of several properties and their consequences in flax fibre reinforced composites. Polym Test 20(8) 885-893 Van de Weyenberg I, Ivens J, De Coster A, Kino B, Baetens E, Verpoest I (2003) Influence of processing and chemical treatment of flax fibers on their composites. Compos Sci Technol 63 (9) 1241-1246... 

Nekkaa S, Guessoum M, Chebira F, Haddaoui N (2008) Effect of fibre content and chemical treatment on the thermal properties of Spartium junceum fiber-reinforced polypropylene composites. Int J Polym Mater 57 771-784... 

Pineapple leaf fibre (PALF), which is rich in cellulose, relatively inexpensive and abundantly available has the potential for polymer-reinforced composite. PALF at present is a waste product of pineapple cultivation. Hence, without any additional cost input, pineapple fibres can be obtained for industrial purposes. Among various natural fibres, PALFs exhibit excellent mechanical properties. These fibres are multicellular and lignocellulosic. They are extracted from the leaves of the plant Ananus cosomus belonging to the Bromeliaceae family by retting. The main chemical constituents of pineapple fibres are cellulose (70-82%), lignin (5-12%) and ash (1.1%). The superior mechanical properties of PALFs are associated with their high cellulose content. 

The chapter demonstrates that in spite of the incompatibility between hydrophilic natural fibres and hydrophobic polymeric matrices, the properties of natural fibre composites can be enhanced through chemical modifications. The chemical treatments have therefore played a key role in the increased applications of natural fibre composites in the automotive sector. Recent work has also shown that if some of the drawbacks of natural fibres can be adequately addressed, these materials can easily replace glass fibres in many applications. The chapter has also shown that there have been attempts to use natural fibre composites in structural applications, an area which has been hitherto the reserve of synthetic fibres like glass and aramid. The use of polymer nanocomposites in applications of natural fibre-reinforced composites, though at infancy, may provide means to address these efficiencies. Evidence-based life-cycle assessment of natural fibre-reinforced composites is required to build confidence in the green composites applications in automotive sector. 

Polyimide characterised by thermal and thermal-oxidative stability at elevated temperatures, chemical resistance and good mechanical properties is relatively new in the family of polymer foams [3]. In some cases, depending on the nses, additional reinforcement can be inclnded. Examples are fibre reinforced foams and syntactic foams which are composites containing hollow glass, ceramic or plastic micro-spheres dispersed throughout the polymer matrix. 

The ultimate strength of a composite of fibre and polymer is basically dependent upon the stress-strain relationship of its components. Any fibre whose strength and modulus of elasticity is greater than a polymer is capable of theoretically providing reinforcement to that polymer. Practically, however, the difference in properties has to be considerable to obtain efficient reinforcement and the effectiveness of the reinforcement is dependent upon the degree of adhesion which can be achieved. Other factors which also influence the properties of a composite are relative volumes of reinforcement and matrix, their physical and chemical properties, the temperature resistance and, of very considerable importance, the fibre length which is being used. 

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