Difference Between Paraffin Wax and Microcrystalline Wax?

Petroleum wax and microcrystalline wax are colorless, odorless, solid saturated hydrocarbon mixtures distilled from crude oil. Their component molecules are larger in size, harder in overall hardness, and have higher melting points than vaseline.

1. Composition of paraffin wax and microcrystalline wax

Petroleum wax is mainly composed of long-chain normal and iso-alkanes, while microcrystalline wax contains many saturated hydrocarbons with long branched and cyclic chains in addition to normal and iso-alkanes. Therefore, microcrystalline wax has higher melting points, molecular weight, and viscosity after melting than petroleum wax, and has lower brittleness and is not easily broken.

Pure paraffin wax is white, odorless, and tasteless, while impure paraffin wax is yellow. Paraffin wax is insoluble in water, and its solubility in alcohols and ketones is very low. It is easily soluble in carbon tetrachloride, chloroform, ether, benzene, petroleum ether, carbon disulfide, various mineral oils, and most vegetable oils. The higher the melting point of paraffin wax, the smaller the solubility. Paraffin wax has stable chemical properties and is not easily acted upon by alkalis, inorganic acids, and halogens. Paraffin wax melts in heat and decomposes in high heat.

2. Differences between paraffin wax and microcrystalline wax

Microcrystalline wax and paraffin wax are both refined from petroleum, and the difference lies in the fact that paraffin wax comes from the fraction distilled from petroleum, while microcrystalline wax is separated from the residue left after petroleum distillation.

Microcrystalline wax used to be called earth wax because natural earth wax mines were once mined half a century ago. Unfortunately, this resource is now depleted. The reason why it is called "microcrystalline wax" is that its crystals are visibly smaller than those of paraffin wax under a microscope.

The crystal morphology of paraffin wax is generally large thin sheets, while microcrystalline wax is generally composed of finer needle-shaped or granular crystals. This makes their properties significantly different. Paraffin wax is brittle and easily breaks apart or even pulverizes when under stress, while microcrystalline wax has low hardness, good flexibility, and is easily deformed under stress and not easily broken.

Both are called wax, why is there such a big difference in their crystal morphology and properties? Ultimately, this is because their chemical composition and structure are different.

The main components of microcrystalline wax are higher molecular weight cyclic hydrocarbons and aromatic hydrocarbons with longer carbon chains, while paraffin wax mainly contains normal and iso-alkanes without branches.

Microcrystalline wax grades are divided according to their melting points, and the low melting point is the lowest temperature at which the wax sample can melt and drip under specified conditions. The first-class products have five grades including No. 70, No. 75, No. 80, No. 65, and No. 90, which can be selected according to temperature and other usage conditions.

Microcrystalline wax can also be used as a modifier for paraffin wax. Adding microcrystalline wax to paraffin wax can increase its plasticity, making it more suitable for making waterproof and moisture-proof paper and other materials.