What is the relationship between the properties of pvc film and plasticizers?
The performance of pvc film varies with the plasticizer used, and the relationship between the film performance and the chemical structure of the plasticizer. When the film is required to have certain special properties, it is very complicated to determine the film formulation, and some requirements for the film are sometimes contradictory. It is very difficult to manufacture a film with good cold resistance and flame retardancy. If oil resistance is also required, various plasticizers known at present can still not meet the requirements. Therefore, it is necessary to choose an appropriate ratio of plasticizers when making films, and make up for the defects of various plasticizers by complementing each other to meet the requirements of use.
Generally, the plasticizer content of PVC soft film is 18-45%. When the plasticizer is used as a processing aid, when the addition amount is less than 18%, a peculiar phenomenon can be seen, that is, the film with this content is not softer than the pure PVC rigid film but more brittle. Its impact strength and cold resistance are worse than that of pure PVC rigid film. This phenomenon may be due to the small amount of plasticizer, and it is impossible to "eliminate" the polarity of the PVC molecules.
Most of the films with a plasticizer content of less than 18-20% are not made of pure PVC, but are often impact-resistant PVC that is not brittle.
Films containing more than 45% plasticizer are difficult to manufacture, their strength is small, their elongation is high, and they are sticky, so they are rarely produced.
The higher the plasticizer content of the film, the more obvious the effect on the performance of the film. In order to achieve the same softness, if different plasticizers are used, the amount of plasticizer added is also different. When comparing different films, the film with the same hardness is often used as the benchmark, not the film with the same plasticizer content.
Generally, the plasticizer content of PVC soft film is 18-45%. When the plasticizer is used as a processing aid, when the addition amount is less than 18%, a peculiar phenomenon can be seen, that is, the film with this content is not softer than the pure PVC rigid film but more brittle. Its impact strength and cold resistance are worse than that of pure PVC rigid film. This phenomenon may be due to the small amount of plasticizer, and it is impossible to "eliminate" the polarity of the PVC molecules.
Most of the films with a plasticizer content of less than 18-20% are not made of pure PVC, but are often impact-resistant PVC that is not brittle.
Films containing more than 45% plasticizer are difficult to manufacture, their strength is small, their elongation is high, and they are sticky, so they are rarely produced.
The higher the plasticizer content of the film, the more obvious the effect on the performance of the film. In order to achieve the same softness, if different plasticizers are used, the amount of plasticizer added is also different. When comparing different films, the film with the same hardness is often used as the benchmark, not the film with the same plasticizer content.
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