Determining the compatibility between defoamers and polyurethane systems is a critical step that directly affects the final performance and quality of the product. Add a certain amount of defoamer to the polyurethane system and disperse it evenly by stirring or mixing. Then, observe whether the system exhibits layering, precipitation, or color changes. At the same time, the physical and chemical properties such as viscosity and pH value of the system can be measured to evaluate the effect of defoamers on the stability of the system. If the system remains stable without obvious layering, precipitation, or color changes, and there are no significant changes in physical and chemical properties, it can be preliminarily judged that the defoamer has good compatibility with the polyurethane system.

Apply polyurethane coating containing defoamers onto the substrate to form a coating film. Then, observe the surface condition of the coating, such as whether there are defects such as shrinkage holes and fish eyes. These defects are usually caused by incompatibility between defoamers and polyurethane systems. If the surface of the coating is flat and smooth, without defects such as shrinkage pores or fish eyes, it indicates good compatibility between the defoamer and the polyurethane system.

Add defoamers in the polyurethane production process and follow the normal production process. Observe whether there are abnormalities in the production process, such as difficult to eliminate foam, large changes in system viscosity, etc. If the foam is effectively controlled in the production process, and the system is stable without abnormal conditions, it can be considered that the defoamer has good compatibility with the polyurethane system.

Conduct performance tests on the produced polyurethane products, such as tensile strength, tear strength, wear resistance, etc. Meanwhile, observe whether the appearance and feel of the product meet the requirements. If the product performance is stable and meets the standard requirements, with good appearance and feel, it indicates that the defoamer has not had a negative impact on the performance of the polyurethane product and has good compatibility.

When choosing defoamers, it is important to understand their composition and properties. Different defoamer components may have different effects on polyurethane systems. Therefore, when selecting, the appropriate defoamer should be chosen based on the characteristics and requirements of the polyurethane system. The amount of defoamer also has a certain impact on compatibility. Excessive use of defoamers may cause abnormal conditions in the system or affect product performance. Therefore, the dosage should be strictly controlled during use and adjusted according to the actual situation. Environmental factors may also affect the compatibility between defoamers and polyurethane systems. Therefore, in the testing and practical application process, the impact of changes in environmental factors such as temperature and humidity on the stability of the system should be fully considered.

In summary, determining the compatibility between defoamers and polyurethane systems requires comprehensive consideration of multiple factors, and evaluation and verification through various means such as laboratory testing and practical application validation.