Thermoplastic Hybrid Composites

In Secs. 13.2-13.3 the principles of toughening of thermosets by rubber particles, and the role of morphologies, interfacial adhesion, composition, and structural parameters on the toughening effect are analyzed. Section 13.4 is devoted to the use of initially miscible thermoplastics for toughening purposes. The effect of core-shell rubber particles is discussed in Sec. 13.5 and, in Sec. 13.6, miscellaneous ways of toughening thermosets (liquid crystals, hybrid composites, etc.), are analyzed. 

Traditional composite panels are made from veneers and from mat-formed eomposites bonded by adhesive. More recently wood has also been combined (eompression moulded or extruded) with synthetic polymers, e.g. thermoplastic polymers, to make wood-polymer composites (WPC). WPC products have been growing very rapidly in the recent years, especially in the deeking market, where Woleott (2004) observed that their market share has grown from 2% in 1997 to 14% in 2003. Further, much research work has explored the use of fibre-reinforced polymers (FRP) to enhance the structural performance of engineered wood eomposites, ealled FRP-wood hybrid composites (Dagher et ai, 1998 Shi, 2002). 

J. He, Y. Wang, and H. Zhang. In situ hybrid composites of thermoplastic poly(ether ether ketone), poly(ether sulfone) and polycarbonate. Compos. Sci. Tech., 60 1919-1930, 2000. 

A hybrid composite [121,122] can contain more than one type of reinforcement and/or more than one type of matrix, with the objective of improving or lowering the cost of the basic composite [123]. The second reinforcement may be a fiber (continuous or chopped), particles or whiskers. The fiber reinforcement can be in the same laminae and interspersed using any textile process such as weaving, or in different laminae, interspersing plies to obtain the desired mechanical/ physical properties. A sandwich composite is a special case which has an interlayer of a material such as A1 foil or a honeycomb. The matrix may be different for each type of reinforcement, or added to infiltrate the reinforced matrix (e.g. a thermoplastic resin such as PSU) to confer controlled viscosity in the matrix, or an elastomer (e.g. CTBN) for increased toughness. 

These widely cited papers contribute to dimming the boundary between the polymer blend and polymer composite. Blends of thermofiopic LCPs with thermoplastic polymers are processed and molded by conventional techniques such as extrusion, injection molding, and spinning with related equipment. However, the resultant products have the characteristic reinforced structure and mechanical behaviors of fiber-reinforced plastics or composites. It is common where technical terms of LCP blends and in situ composites have the same meaning. LCP blends almost refer to blends with thermofiopic LCPs as the minor portion so that in sim composites and newly invented in situ hybrid composites are the main content of this chapter on polymer blends. 

A reinforced structure of thermoplastics, named as the in situ hybrid composite, consists of three components in principle macroscopic fibers such as glass fiber, carbon fiber, or aramid fiber microscopic LCP fibrils and a matrix resin [157]. Macroscopic fibers are in their fibrous form before the fabrication of the reinforced composite, while LCP fibrils are generated in situ during the melt processing of the ternary composite. 

The work carried out by Kalaprasad and Thomas [34] shows different chemical surface modifications such as alkali, acetic anhydride, stearic acid, permanganate, maleic anhydride, silane, and peroxides improving the interfacial adhesion and compatibility between the fiber and matrix. A polyethylene thermoplastic matrix with sisal and glass hybrid composites was developed. The results showed that in all treatments, tensile strength increased about 10-30% and peroxide treatment showed maximum tensile strength and Young s modulus [34]. 

Keywords Hybrid composites, glass fiber, vegetable fibers, thermoplastic, thermoset... 

A wide variety of research work is being conducted worldwide with sometimes conflicting ideas. Focus usually lies on physical, especially water absorption and degradation, and mechanical properties of hybrid composites. The research on electrical, thermal, acoustic and dynamic mechanical properties of hybrid vegetable/glass thermoplastic composites, however, is more restrict. 

H. Anuar, S.H. Ahmad, R. Rasid, and N.S. Nik Daud, Tensile md impact properties of thermoplastic natural rubber reinforced short glass fiber and empty fruit bunch hybrid composites. Polym. Plast. Technol. Eng. 45, 1059-1063 (2006). 

Mountasir, A., Hoffmann, G., Cherif, C., Kunadt, A., Fischer, W.J., 2011. Mechanical characterization of hybrid yam thermoplastic composites from multi-layer woven fabrics with function integration. J. Thermoplast. Compos. Mater. 25 (6), 729-746. 

The macroscopic inorganic fibers worsen the processability of the composites, increasing abrasion on the processing equipment surface. A solution to this problem may be the addition of LC Polymer to ease the processability due to the very low melt viscosity of LC Polymer. Moreover, they also provide reinforcement effect at a microscale. These types of composite, in which thermoplastics are reinforced by both organic and inorganic fibers, are called "in-situ hybrid" composites. The fillers, whiskers and fibers are used as inorganic reinforcements for this type of composite. 

H. Anuar, W.N. Wan Busu, S.H. Ahmad, R. Rasid. Reinforced thermoplastic Natural Rubber hybrid composites with Hibiscus Cannabinus, L and short glass fiber—part 1 processing parameters and tensile properties. /. Compos. Mater., 42, 1075-1087,2008. 

DESIGN OF THERMOPLASTIC MATRIX HYBRID COMPOSITE GAS CYLINDERS FOR DOMESTIC APPLICATIONS... 

This paper proposes to examine the influence of different processing parameters upon the resulting microstructure of a carbon black/carbon fiber hybrid filled thermoplastic composites. 

Thermoplastics can also lead to composites and hybrids including other conventional materials - such as paper, cardboard, metals and glass - to integrate several functionalities thanks to the exceptional combination of properties for example, multilayers of polyethylene (a water barrier) and PVA (an oil barrier), shatterproofing of glass containers. .. 

HTPC (Hybrid ThermoPlastic Composite) bumper beams made by Plastic Omnium are used by General Motors on the Pontiac Montana, Chevrolet Venture and Oldsmobile Silhouette. Continuous woven fibres are overmoulded with a long or short fibre reinforced polypropylene to save weight (6 kg), enhance impact resistance (20-40%) and integrate numerous functions such as reinforcement ribs. The process is fully automated. 

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