The most important of the nylon resins are ZYTEL® lubricatedversions 101L and 101F. These are 66 nylons made by thepolymerization of hexamethylenediamine and adipic acid,each of which contain six carbon atoms. They possess anoutstanding balance of properties – combining strength,moderate stiffness, high service temperature and a high levelof toughness. They are particularly resistant to repeatedimpact, have low coefficients of friction and excellent resistanceto abrasion. They resist fuels, lubricants and mostchemicals, but are attacked by phenols, strong acids andoxidizing agents.The 66 nylons are easily injection moulded. The general purposemoulding resins readily fill thin section moulds due tolow melt viscosity. These crystalline polymers set up rapidly,especially the nucleated and lubricated ZYTEL® 135F.The combination of easy fill and fast set up allows very fastmoulding cycles.Nylons absorb moisture from the air and 66 nylon equilibratesat about 2,8% water at 50% RH and at about 8,5% at 100%RH. This plasticizes the nylon, lowering its strength andstiffness but increasing its toughness and elongation.Moisture absorption increases dimensions of 66 nylons by0,6% at 50% RH and about 2,6% at 100% RH. The processis reversible, that is, the strength and stiffness increase anddimensions decrease as moisture content decreases. Absorptionand desorption are slow processes. For example, it takesabout 125 days for a 1,5 mm thick dry specimen to reachequilibrium moisture content when exposed to 50% relativehumidity.Nylon resins are not considered primary electrical insulatorsbut their high temperature properties, their toughness andabrasion resistance, and their chemical resistance, combinedwith electrical properties adequate for most power frequenciesand voltages, have made them the choice for a widevariety of electrical applications.Toughened DuPont nylon resinsDuPont has developed a series of toughened nylon resins