关键词: 差示扫描量热法, 熔点, 石蜡, 偏倚

Abstract: The melting point of paraffin wax was determined by means of differential scanning calorimetry (DSC) method, simulating the measuring process of melting point of paraffin wax(cooling curve method). The effects of starting and stopping temperatures, nitrogen purge gas flow rate, temperature rising and falling rate, sample mass, constant temperature time, sample preparation method, and temperature rising and falling times on the measurement results were studied,the suitable conditions for determining the melting point of paraffin wax by DSC method were determined, and the bias between DSC method and standard method (GB/T 2539-2008) was investigated. The results showed that the heating rate and cooling rate was 10 ℃/min and 5 ℃/min respectively when the melting point of paraffin wax was determined by DSC method, and the melting time should not exceed 1 h when the melting point was 20-30 ℃ above the predicted melting point. By testing 14 kinds of paraffin wax samples with 6 kinds of DSC instruments, the deviation between DSC and standard method was calculated to be -1.14 ℃. DSC method is a simple, rapid and repeatable method for determining the melting point of paraffin wax,and can be used as a control analysis method to quickly and accurately determine the melting point of paraffin wax.

Key words: differential scanning calorimetry method, melting point, paraffin wax, deviation