Study on Petroleum Derived Waxes and Their Uses |
Thesematerials represent a significant fraction of petroleum. They are refined byvacuum distillation. Paraffin waxes are mixtures of saturated n- andisoalkanes, naphthenes, and alkyl- and naphthene-substituted aromaticcompounds. The degree of branching has an important influence on theproperties. Millions of tons of paraffin waxes are produced annually. They areused in foods (such as chewing gum and cheese wrapping), in candles andcosmetics, as non-stick and waterproofing coatings and in polishes. Paraffin wax refers to a white orcolorless soft solid that is used as a lubricant and for other applications. Itis derived from petroleum and consists of a mixtureof hydrocarbon molecules containing between twenty and forty carbonatoms. It is solid at room temperature and begins to melt aboveapproximately 37 °C (99 °F); its boiling point is >370deg C. In chemistry, paraffin is used synonymously with "alkane", indicating hydrocarbons with the general formula CnH2n+2. The name is derived from Latin parum ("barely")+ affinis, meaning"lacking affinity" or "lacking reactivity"indicating paraffin's unreactive nature. Paraffin wax ismostly found as a white, odorless, tasteless, waxy solid, with a typicalmelting point between about 46 and 68 °C (115 and 154 °F), andhaving a density of around 900 kg/m3. It is insoluble inwater, but soluble in ether, benzene, and certain esters.Paraffin is unaffected by most commonchemical reagents but burns readily. Thehydrocarbon C31H64 is a typical component ofparaffin wax. Paraffinwax is an excellent electrical insulator, with anelectrical resistivity of between 1013 and 1017 ohmmetre. This is better than nearly all other materials except some plastics(notably Teflon). It is an effective neutron moderator and wasused in James Chadwick's 1932 experiments to identify the neutron. Paraffinwax is an excellent material to store heat, having a specific heatcapacity of 2.14–2.9 J g−1 K−1 (joule per gram kelvin)and a heat of fusion of 200–220 J g−1. This property is exploited inmodified drywall for home building material: a certain type (with theright melting point) of wax is infused in the drywall during manufactureso that, when installed, it melts during the day, absorbing heat, andsolidifies again at night, releasing the heat. Paraffin wax phase changecooling coupled with retractable radiators was used to cool the electronics ofthe Lunar Rover. Wax expands considerably when it melts andthis allows its use in wax thermostatic element thermostats forindustrial, domestic and, particularly, automobile purposes.