Silica reinforcement polyesters

Organic matrices are divided into thermosets and thermoplastics. The main thermoset matrices are polyesters, epoxies, phenolics, and polyimides, polyesters being the most widely used in commercial applications (3,4). Epoxy and polyimide resins are applied in advanced composites for structural aerospace applications (1,5). Thermoplastics Uke polyolefins, nylons, and polyesters are reinforced with short fibers (3). They are known as traditional polymeric matrices. Advanced thermoplastic polymeric matrices like poly(ether ketones) and polysulfones have a higher service temperature than the traditional ones (1,6). They have service properties similar to those of thermoset matrices and are reinforced with continuous fibers. Of course, composites reinforced with discontinuous fibers have weaker mechanical properties than those with continuous fibers. Elastomers are generally reinforced by the addition of carbon black or silica. Although they are reinforced polymers, traditionally they are studied separately due to their singular properties (see Chap. 3). 

Epoxy, polyester, phenolic and other resins are used as coatings and linings with or without reinforcement. Glass fiber, silica, carbon and many other materials can be used as filters or reinforcement to produce materials with specific properties of strength, flexibility, wear resistance and electrical conductivity. 

This technology was first commercially applied to polyurethane blend [121] and patented as Rimplast (for Reactive Injection Molding), but many polymers have since been blended with polysiloxane thanks to this method polyethylene [122], polypropylene [122,123], polyamide [124-130], polyesters [128,131-133], poly(phenylene ether) [134], fluorocarbons [135] and many more. Many of them include reinforcing fillers such as fumed silica. The silicone base involved can moreover contain reactive groups such as the epoxy group [136,137]. A typical silicone base useful for these blends was de-... 

Cementitious composites including FRP powder that was mainly composed of unsaturated-polyester resin, CaC03 (filler of FRP) and GF (reinforcement of FRP) were investigated. The grain size of FRP powder is similar to A3 silica sand. These suggest FRP powder to use as a substitute of A3 silica sand to extrudable composite. 

Unlike the polyurethanes and other previously discussed mortars, polyester cements are produced by a free radical chain copolymerization of a liquid unsaturated polyester and styrene. While most polyester composites are reinforced by fiber glass, polyester mortars are usually filled with silica, clay or alumina trihydrate (ATH). 

The reaction in rejection molding process (RIM), which has been used for large polyurethane moldings, may hlso be uAe d with filled polyesters (RRIM). Likewise, much hydraulic cement art may be adapted to polyester cement technology. Both of these cements have been reinforced with silica and asbestos. Actually, over 3 million tons of asbestos has been used annually, world wide, for the reinforcement of hydraulic cements to produce composite corrugated sheet and pipe. 

Fillers may be used at concentrations of 10% to 50%, targeted at some desired physical or chemical properties, but also frequently useful as cheape-ners. Wherever their major utility is to stiffen and strengthen, they will be termed "reinforcement," and in most cases have a fibrous structure. Useful fillers include limestone, quartz, silica, talcum, alumina and other minerals. Particle size and distribution are of highest importance. Low-cost fillers for thermosets (eliminating brittleness) include sawdust, paper or jute. The use of ground limestone (or precipitated Ca CO3) is mainly found in PVC and unsaturated polyester in the fields of construction and flooring. Currently,... 

A new area of development is to incorporate the filler permanently into the polymer matrix, by use of coupling reactions. This can increase impact strength and thermal properties of polyamides and modify the anisotropy of partially crystalline plastics, such as polyamides and polyesters. In polypropylene, bonding with kaolin can also improve scratch resistance, which is a useful benefit for automobile interior applications. Surface modification of fillers such as silica, mica, and wollastonite allows these to penetrate markets that were formerly the province of reinforcements such as carbon black and glass fibre. 

Thermosetting plactics are often reinforced by as much as 100 phr of various fillers, for example, wood flour, cotton flock asbestos and synthetic fibre used with phenolic thermosets, and silica flour, mica or talc with epoxies. Glass fibre reinforcement of polyester resins for structural, automotive, aerospace and marine applications is too well known to require comment. 

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