CPE,
Chlorinated Polyethylene, obtained by chlorination of a special High-Density Polyethylene (HDPE), that is, a product in which a chlorine atom partially replaces a hydrogen atom on a HDPE molecular chain. It is a white powder after drying and is non-toxic.
CPE formula: [CH2-CHCl-CH2-CH2]n
When the amount of CPE added is less than 5 PHR, the plasticization is delayed, and at 5 PHR, it has substantially no effect on the plasticization of the formulation system.
When the CPE exceeds 5 PHR, it plays a role in promoting plasticization. With the increase of CPE, the plasticizing time of the formulation is shorter and shorter, the maximum plasticizing torque and balance torque are increased, and the plasticizing temperature is gradually decreased.
CPE has a chlorine content of 35%.
There are two segments in its structure:
One is a chlorinated segment in which a hydrogen atom is replaced by a chlorine atom. This segment is structurally strong, similar to PVC, and has good compatibility.
The other is a PE segment in which the hydrogen atom is not replaced by a chlorine atom. This structure has a weak polarity and is poorly compatible with PVC. It acts as an external lubrication between PVC and can delay the plasticization of PVC.
The glass transition temperature of CPE is about 10 °C, and PVC is 80 °C. Under the test conditions, CPE shows a tendency to soften and soften earlier than PVC and a slightly higher viscosity.
When the amount of CPE added is small, the total amount of polar segments with good compatibility between CPE and PVC is small, the external lubrication of PE segments is dominant, and the plasticization of the retardation system is delayed.
With the increase of CPE, the softening and higher viscosity of a large number of CPE molecules promote the viscosity of the whole formulation system. At this time, the influence of CPE on the viscosity of the whole material overcomes the external lubrication of the PE segment in the structure. So that the entire formulation system begins to plasticize at a lower temperature, which promotes the plasticization of the material.