DSC Differential Scanning Calorimeter for Measuring the Curing Degree of Adhesive

　1、 Definition of curing degree

Curing degree is an indicator that measures the degree to which a material transitions from a liquid or plastic state to a solid or hardened state. The specific definition and measurement methods of curing degree may vary in different fields, but usually involve changes in the physical or chemical properties of materials. Here are some common definitions of curing degree:

Chemical curing degree: In chemical reactions, especially in the curing process of polymers, curing degree refers to the percentage of chemical bonds formed between reactant molecules. This is usually measured by the progress of chemical reactions, for example, a fully reacted system has a 100% chemical curing degree.

Thermosetting degree: In thermosetting materials, the curing degree can be expressed as the curing stage reached by the material during the heating process. This is usually measured by thermal analysis techniques such as DSC (differential scanning calorimetry), which determine the change in heat of the material during heating.

　2、 Differential Scanning Calorimetry and Its Applications

The working principle of differential scanning calorimetry is to analyze the thermal properties of a sample by measuring the difference in heat flow between the sample and reference material under a controlled temperature program.

　　Working principle diagram of thermal flow DSC

Differential Scanning Calorimetry (DSC) is widely used in various fields such as plastics, rubber, coatings, adhesives, pharmaceuticals, petrochemicals, etc. It is mainly used for qualitative and quantitative analysis of polymer materials. Based on DSC curves, various thermodynamic and kinetic parameters can be determined, including melting point, glass transition temperature, crystallinity, melting heat, crystallization heat, purity, phase transition temperature, compatibility of different materials, specific heat capacity, reaction heat, transition heat, phase diagram, reaction rate, crystallization rate, crystallinity, and sample purity.

　3、 Experimental steps and analysis

1. Sample　

Adhesive material

　2. Testing instruments

The instrument used for measuring the curing degree of the adhesive in this test is DZ-DSC300C from Nanjing Dazhan InstrumentDifferential scanning calorimeterIt is a low-temperature differential scanning calorimeter with a temperature range of -40~600 ℃. It uses semiconductor refrigeration and has the advantages of fast cooling, high sensitivity, and supporting analysis software. It can collect test spectra in real time for data analysis.

　3. Testing method

The first stage is to raise the temperature from 25 ℃ to 270 ℃ at a rate of 10 ℃/min;

The second stage is to raise the temperature from 270 ℃ to 25 ℃ at a cooling rate of 20 ℃/min;

In the third stage, the temperature is raised from 25 ℃ to 270 ℃ at a rate of 10 ℃/min.

Introduce nitrogen gas at a flow rate of 50mL/min.

4. Test chart

　　Raw rubber test chart

　　Test spectrum of sample one

　　Test spectrum of sample three

5. Test data analysis

　　Calculation of curing rate:

Curing rate=(enthalpy value of original adhesive - enthalpy value after curing)/enthalpy value of original adhesive * 100%

　　6. Test reference standards

GB/T 32369-2015 Determination of curing degree of sealant