There are many types of plasticizers, and each has its own advantages. How to choose a plasticizer correctly? In fact, there are certain principles in choosing plasticizers.
First of all, it must have good compatibility with PVC resin. When the plasticizer and resin are mixed with each other, the compatibility between the two is good, the plasticizing efficiency is high, the plasticizer does not segregate, does not ooze, the product has good flexibility and long service life. Compatibility refers to the mutual affinity when two or more substances are mixed, that is, molecular-level miscibility. Good compatibility can form a homogeneous mixed system. According to the general rule, the closer the polarity, the easier it is to dissolve each other. Therefore, the closer the solubility parameter of the plasticizer is to the solubility parameter of the resin, the better the compatibility between the two. The dielectric constant is a function of molecular polarity, and it is greatly affected by the dipole moment and hydrogen bonds. The dielectric constant can be used as a parameter to judge the compatibility of plasticizers. The solubility parameter of polyethylene is 9.5-10.013]. The constant is 3.2-3.6F/m, the solubility parameter of the plasticizer is generally 8.4- 11.4, and the dielectric constant is 4-SF/m. At this time, the compatibility is ideal.
Secondly, it has low mobility and high plasticizing efficiency. Infrared spectroscopy was used to study the migration rate of PVC film plasticizer. The results show that the migration of PVC plasticizers is time-sensitive. In the initial stage of migration, the migration rate is faster, and the migration concentration is linear with the square root of the migration time. Then the migration rate gradually slows down and finally tends to balance. Temperature has a great influence on the migration rate of plasticizers. As the temperature increases, the migration rate accelerates, and its migration coefficient is proportional to the absolute temperature of the thermodynamics. If you start from the perspective of reducing or eliminating the exudation of small molecular plasticizers , Chlorination and chlorination in-situ grafting reactions were used to modify dioctyl phthalate (DOP), which effectively inhibited the migration of small molecule plasticizers.
Finally, good cold resistance, good electrical insulation; resistance to water, oil and solvent extraction; low volatility; good thermal stability of the plasticizer itself; flame retardant is required in some occasions; the plasticizer itself must be colorless and non- Smelly, some require non-toxic, anti-fungal and termite; good processing of products, easy to demould; reasonable price, etc.
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