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Determination of Melting Point of Paraffin by Open Capillary Method (CAT#: STEM-PPA-0062-YJL)

Introduction

Paraffin products are translucent soft waxes composed of a mixture of solid straight chain hydrocarbons. They are obtained from petroleum and are used for the manufacture of various products including cosmetics and electrical insulators. The quality of these products is controlled by testing their physical properties such as thermal behavior, viscosity and oil content. Due to the semi-solid nature of paraffin, their thermal behavior can be characterized by the technique known as Slip Melting Point. This technique is an important parameter for monitoring the purity and quality of paraffin samples.




Principle

Melting point is a characteristic property of solid crystalline substance. It is the temperature at which the solid phase changes to the liquid phase. This phenomenon occurs when the substance is heated.
In all major pharmacopoeias the open capillary method is described to determine the melting point (slip point) for fats, fatty acids, paraffin, and waxes. In a glass capillary tube open at both ends (1), 10 mm of sample is introduced (2), chilled to a given temperature and immersed into a water bath (3/4). The melting point with open capillary, also known as slip point or slip melting point, is the temperature at which the substance begins to rise in the capillary due to the effect of the increasing temperature and buoyancy.

Applications

Chemical industry; Cosmetic/pharmaceutical industry

Procedure

1. Prepare the substance.
2. Affix one of the capillaries to a thermometer.
3. Place the thermometer with an affixed capillary into a glass.
4. Increase the temperature.

Materials

• Sample Type: crystalline compounds