Thermoset 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. 

To balance some of the drawbacks produced by the rubber toughening of thermosets, inorganic fillers that increase modulus and yield stress can be added to generate hybrid composites. Inorganic fillers such as glass beads, alumina, or silica - with high values of modulus and strength - are frequently included in thermoset formulations. 

The combination with fibres has proved difficult however. Often there are issues with compatibility between bio-resins and fibres (both natural and synthetic), which cause defects in the composite structure and ultimately poorer physical properties. Castor-oil polyurethane was compared with phenolic resins when infused over sisal fibres however, the phenolic resins showed better structural performance when compared with the castor oil-based material [52]. This is not always the case, as some improvements have been made. Soybean oil thermoset polymers were used in a glass/flax hybrid composite resulting in improved mechanical performance [73], Thermoset resins were produced from triglyceride oils with a wide range of properties (tensile modulus 1-2 GPa, glass transition temperature Tg 70-120 °C) and glass- and hemp- fibre composites were manufactured [74,75]. 

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

K. Adekunle, S.-W.Cho, R. Ketzscher and M. Skrifvars, Mechanical properties of natural fiber hybrid composites based on renewable thermoset resins derived from soybean oil, for use in technical apphcations.. Appl. Polym. Sci. 124, 4530-4541 (2012). 

Recently, a series of thermoset organic-inorganic hybrid composites based on several types of octa-functional polyhedral oligomeric silsesquioxane (POSS) was... 

Current civil aircraft applications have concentrated on replacing the secondary stracture with fibrous composites where the reinforcement media have either been carbon, glass, Kevlar or hybrids of these. The matrix material, a thermosetting epoxy system, is either a 125 °C or 180 °C curing system with the latter becoming dominant... 

La Rosa, A.D., Cozzo, G., Latteri, A., Recca, A., Bjdrklund, A., Parrinello, E., Cicala, G., 2013. Life cycle assessment of a novel hybrid glass-hemp/thermoset composite. Journal of Cleaner Production 44, 69—76. 

Fiber reinforced thermosetting polymer composites have been used in the form of laminate, sandwich, grid stiffened, stitched, Z-pinned, three-dimensional (3-D) woven fabric, and hybrid structures. In addition to carrying the designed static/dynamic loads, most composite stmcmres experience some kind of low or high velocity impact incidents during their life cycle. A low velocity impact is not uncommon. For example, dropping a tool on to a composite stmcmre... 

In the last decade, considerable progress was observed in the field of PO/compatibil-izer (predominantly on the base of PO-g-MA)/organo-surface-modified clay nanocomposites. Polyethylene (PE), polypropylene (PP), and ethylene-propylene (EP) rubber are one of the most widely used POs as matrix polymers in the preparation of nanocomposites [3,4,6,30-52]. The PO silicate/silica (other clay minerals, metal oxides, carbon nanotubes, or other nanoparticles) nanocomposite and nanohybrid materials, prepared using intercalation/exfoliation of functionalized polymers in situ processing and reactive extrusion systems, have attracted the interest of many academic and industrial researchers because they frequently exhibit unexpected hybrid properties synergisti-cally derived from the two components [9,12,38-43]. One of most promising composite systems are nanocomposites based on organic polymers (thermoplastics and thermosets). 

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