Antioxidants thermal stabilization

Additives. Compounds are often added to the polymer at the extruder or melt homogenizer. Common additives are antioxidants, thermal stabilizers, slip agents, antiblock agents, and uv stabilizers. 

Isonox . [Schenectady] Phenols antioxidant, thermal stabilizer for polymers and rubber systems. 

Key words polyaiylates polyesters antioxidants thermal stability polybutylene terephthalate. 

Additives are functional chemicals added to adhesives to ease the process and improve some properties. Many additives, like antioxidants, thermal stabilizers, UV stabilizers, polymer... 

Most of the resin systems used in commodity composites are slight modifications of the standard commercial mol ding grade material. Usually certain selected properties, such as purity or molecular weight range or distribution, are enhanced or carehiUy selected. In addition, special additives, such as flow controllers, thermal stabilizers, or antioxidants, are often added by the resin manufacturer prior to shipment. Many of the conventional or commodity-type resins used in thermoplastic composites are Hsted in Table 1 and the preparation of each of these is described. AH resins and blends described in the hterature are not Hsted, and the synthesis described is not the only procedure available, but is usually the most common commercial process. 

One key consideration in developing radiation curable adhesive systems is the thermal stability and volatility of any photoinitiators used. These chemicals are designed for liquid systems where these issues do not arise. Few of the commercial photoinitiators have adequate thermal stability at the highest hot melt temperatures (180-200°C) and many are too volatile. Reduced application temperatures and special antioxidant packages are often required. 

Fhgh reactivity and low thermal stability of many additives (especially antioxidants)... 

Chemical and thermal stabilizers both inactivate the byproducts of degradation processes, preventing them from causing further damage to the polymer. Their chemical structure and mobility in the part define their effectiveness in any given polymeric system. The most common type of chemical stabilizers are antioxidants. 

Why do the resins used in rotational molding processes typically contain a higher level of antioxidants and thermal stabilizers than the resins used to manufacture parts, by injection molding ... 

Mesitylene. One of the principal derivatives of mesitylene is the sterically hindered phenol of the structure shown in Figure 4. Its trade name is Ethanox 330 and it is produced by Albemade Corporation (formedy Ethyl Corporation) (31). Ethanox 330 is an important noncoloring antioxidant and thermal stabilizer for plastics, adhesives, rubber, and waxes (qv) (32,33) (see Antioxidants). The oral toxicity of Antioxidant 330 is extremely low (oral 1D. in rats > 15 g/kg) since its large size, Cc4H7 0, effectively eliminates absorption from the gastrointestinal tract. 

TG-DTA Characterisation of carbon black [149], flammability evaluation [64], polymer degradation studies [65], ageing studies [70-72], product control [77, 81], combustion performance [83], safety evaluation [83], antioxidation activity [68], pyrolysis of rubbers [82], thermal stability [67, 69, 76, 77], interfacial junctions in viscoelastic composites [78], weathering [72], vulcanisation [73], oxidative behaviour [79], materials evaluation [80], failure analyses [81],... 

It might be assumed that, as condensed-phase flame retardants function by modifying the normal thermal degradation processes of polymers, they would also function as thermal stabilizers and that thermal antioxidant stabilizers would show flame-retardant properties. However, these statements are rarely the case, and to understand why, it is necessary to compare the mechanistic aspects of flame retardance as discussed earlier with those of thermal degradation and thermal oxidation as well, briefly alluded earlier, and in the case of the latter, the Bolland and Gee mechanism,17 in Scheme 2.1. 

Cursory comparison of the character and behavior of flame retardants and thermal stabilizers including antioxidants yields the following ... 

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