What are the methods for characterizing kaolin as fillers

01. Float and Sediment Method and Activation Index Method

Float and sink method is a relatively simple way to evaluate the modification effect of kaolin. The surface of unmodified kaolin is hydrophilic and oil repellent, and it will automatically move down in water. After modification, the surface characteristics of kaolin change, becoming hydrophilic and oil repellent. Due to the strong surface support force in water, it is forced to increase. If the modification effect is different, the floatation and sink conditions will also be different. This is an opportunity to evaluate the modification effect of kaolin.

The basic principle of the activation index method is similar to that of the float sink method, which refers to the percentage of kaolin floating on the river surface in the total quality of the kaolin sample. It is generally indicated by H, with a value of 0-1. The higher the H value, the better the modification effect.

02. Reasonable activation index method

The evaluation methods such as floating sedimentation method and activation index method can only reflect the horizontal lipophilic solubility of particles covered by modifiers, but can not reflect the level of organic molecular structure and organic chemistry fusion of kaolin particles.

The reasonable activation index value is obtained by measuring the activation index twice. The activation index H1 of modified kaolin was measured in the first time, and the detection sample was first cleaned with an organic solution (such as xylene) before measuring its activation index H2, H2/H1 in the second time × 100% is the reasonable activation index.

When the reasonable activation index value reaches above 70%, modified kaolin has a significant reinforcement effect on the polymer.

03. Surface wetting method

After modification, the surface of kaolin changes from hydrophilicity to hydrophobicity, and the interfacial tension also changes. The modification effect can be demonstrated by measuring the surface interfacial tension.

In general, the more the interfacial tension increases (from small to large), the better the modification effect. However, this type of method is one-sided and generally only reflects the hydrophobicity of the surface of kaolin particles and the level of being encapsulated by modifiers.

04. Infrared quantitative analysis

Infrared spectroscopy analysis was used to analyze the data of unmodified kaolin and modified kaolin. The modified kaolin had a digestion and absorption peak of the modifier on the infrared spectrum, indicating a difference in surface properties compared to before. Based on these differences, the surface modification effect of kaolin can be evaluated.

05. Adsorption force method

The size of the adsorption capacity of modified kaolin can also be determined by measuring the adsorption heat or using reverse gas chromatography analysis. The more adsorption heat is released and the larger the retention volume of vapor in the counter gas chromatograph column, the greater the adsorption capacity of kaolin and the better the modification effect.

06. Turbidity method

When the light source crosses the dispersed management system filled with kaolin, the incident angle will decrease, which can be used to change the compressive strength of the incident angle based on the thin and thick dispersed management system of the enterprise, i.e. turbidity τ To indicate.

The effect of surface modification of kaolin is demonstrated by measuring the turbidity change caused by the concentration change of kaolin powder using X-ray. The higher the turbidity, the better the dispersion of kaolin powder; The less foundation settlement, the better the modification effect.

07. Other methods

Immediate measurement of composite material properties is also one way. The reason for the surface modification of kaolin is due to its poor compatibility with composite materials as a filling material. Therefore, it is reasonable to conduct immediate measurements based on the characteristics of the composite material with kaolin added.

In addition to the above ways of expression, the modified effect of kaolin can also be expressed according to magnetic resonance, Differential thermal analysis and other ways. The basic principle of its clear modification effect is based on the transformation of characteristic curves caused by the composition of functional groups on the left and right surfaces of kaolin before and after modification, as well as the difference in bond energy.