Properties of EMI grades compared to neat polymers

To enhance mechanical properties and decrease wear, glass fibres are added to polymers but they are abrasive and attack the opposing surface. According to the circumstances they can also increase the coefficient of friction. 

Carbon fibres are more satisfactory, simultaneously bringing a lower friction coefficient and lower wear. 

Silicon carbide is marketed as a surface enhancer (see Table 3.19). At levels of less than 10% it significantly improves the coefficient of friction and the wear resistance. 

General-purpose polymers, being thermal insulators, cannot dissipate heat generated by mechanical work or by electronic devices and so on. If the temperature rises, the mechanical properties of the polymer decrease and ageing speeds up. Eventually, the temperature can reach the melting point. 

To ease the dissipation of thermal flow, it is worthwhile to use dissipative additives such as ceramics, metal powders or carbon fibres that have a high thermal conductivity. 

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Table 3.17 Properties of EMI grades compared to neat polymers...

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