Polyamides reinforcement with mineral

More than 60% of polyamides are reinforced with glass fibres (in more than 80% of reinforced grades) or mineral fillers (more than 10%). 

The selected scenario comprises the conceptual design of a polymerization process for the production of Polyamide-6 (PA6) from caprolactam [99, 104]. PA6 is a thermoplastic polymer with a world production capacity of more than 4 million tons per year (as of 2006). The most frequent use of PA6 is the production of fibers, which are used in home textiles, bath clothing and for carpet production. In addition, PA6 is used as an engineering construction material if high abrasion resistance, firmness, and solvent stability are required. Glass-fiber reinforced and mineral material-filled PA6 is a preferred construction material if a combination of rigidity, elasticity and refractory quality characteristics are required. 

Polyamide resins and compounds are used in a wide range of applications, which reflects the very broad range of grades currently available. Products are sold either as unreinforced resin or in compound form with mineral or glass fibre reinforcements. 

Crystalline polymers show the greatest interaction with minerals. In amorphous polymers, minerals merely increase stiffness, with little or no reinforcing effect. Polypropylene, high density polyethylene, thermoplastic polyester and polyamides are crystalline polymers. Low density polyethylene, polystyrene and polycarbonate are amorphous. 

Nylon family These are polyamides resulting fi-om the condensation reaction of an amine funetion and an acid function. As a family, they are tough and hard. They are resistant to many liquids and have low coefficients of thermal expansion. They ean be reinforced with glass fibers, carbon, and minerals. Applications include molded parts for electrieal power transmission, molded parts for a wide range of automotive functions, pulleys, bearings and items which need good abrasion resistance and toughness. 

Glass beads act as a mineral filler with an aspect ratio of 1. Table 3.6 displays results for glass bead reinforced polyamide. The effect ratio is the performance of the reinforced polymer divided by the performance of the neat polymer. 

It is well accepted that the good properties of the isotactic polypropylene as an engineering polymer matrix in thermoplastic composite materials and engineering blends are seriously affected by the inability of this polymer to develop an adequate level of interfacial interaction with polar components such as mineral fillers (calcium carbonate) and reinforcements (talc, mica, wollastonite), synthetic reinforcements (glass fibers, carbon fibers, and nanotubes), or engineering polymers such as polyamide, aliphatic polyesters, and so on. 

Mechanical stren fth tensile, flexural, impact and compressive strength Mechanical properties such as tensile and flexural strength are mainly affected by reinforcements but the addition of these materials (especially glass fiber) may also create a more brittle compound (as with reinforced polyamides), and an elastomeric modifier may often be added to counter this tendency. Elastomeric additives are also widely used to improve impact strength, especially at subzero temperatures. Mineral fillers can improve compressive strength. 

Figure. 5.100. A glass fiber reinforced polyamide with elastomer was cryoultrathin sectioned with an older diamond knife, due to the presence of the glass fibers, and images of the sections unstained (A) and stained with RUO4 vapor (B) showed the dark dispersed phase of the elastomer in the latter and the irregularly shaped mineral particles in the former. The broken glass fibers are the larger structures in the image. At higher magnification (C), the dark dispersed phase is more clearly resolved as fairly round particles about 0.2/tm in diameter. (From Wood [186] used with permission of the American Chemical Society Rubber Division.)...

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