Paraffin wax represents a petroleum-derived class of simple hydrocarbons, distinct from biological waxes as it comprises purely saturated alkanes rather than esters. Refined from crude oil via dewaxing of lubricating fractions, this versatile material dominates industrial wax applications due to its purity, consistency, and cost-effectiveness compared to natural esters like carnauba or beeswax.
Chemical Structure
Paraffin wax consists primarily of unbranched n-alkanes (CnH2n+2, n=20-40), with principal components n-docosane (C22H46) and n-octadecane (C28H58) comprising 80-90% of fully refined grades. Minor iso-paraffins (branched) and cycloalkanes with long side chains (2-10%) influence crystallinity; sp3-hybridized carbons form nonpolar chains with London dispersion forces dictating cohesion.
Physical Properties
Colorless to white, translucent solid (density 0.88-0.92 g/cm³, melting 46-68°C scaling with chain length, boiling ~350-600°C), paraffin wax exhibits low viscosity when molten (5-15 cP at 90°C) and insolubility in water/polar solvents but miscibility in hydrocarbons. Three crystal habits emerge: needle-like (macrocrystalline, slow cooling), plate-like (fully refined), or dendritic (branched impurities); oil content <0.5% defines "fully refined" grades.
Production Process
Dewaxing separates C20+ alkanes via chilling/centrifugation from lube oil stocks, followed by hydrotreating (removes aromatics/sulfur <5 ppm), sweating (fractionates by melting point), and percolation (decolorizes). Scale number (58-70°C melt range) grades performance; pharmaceutical USP grades achieve 99.9% hydrocarbons.
