Effect of CPE with different Mooney viscosity on PVC modification:
Although the CPE industry standard, Mooney viscosity has no requirements for plastic modification materials, but the Mooney viscosity of CPE can reflect the molecular mass of CPE, CPE molecular mass has a significant impact on its physical properties, such as material fluidity, aging resistance, strength and so on. High molecular quality is the product strength is high, but the molecular mass is too large, the viscosity is too large, will make the CPE modified PVC need a higher processing temperature to form, the processing temperature is too high, not only to bring difficulties to the processing process, but also to the quality of the product itself. Therefore, to ensure the physical properties of the product, the PE molecular quality is not required to be too high. The molecular weight of HDPE, a special raw material for CPE, is usually controlled at 100,000 to 150,000. The molecular mass of PE was characterized by the melt flow rate of PE, which was inversely proportional to the molecular mass. CPE Mooney viscosity can also reflect the molecular weight of CPE, high Mooney viscosity of CPE molecular weight is large, low Mooney viscosity of CPE molecular weight is small.
According to the experimental results of rheological curves, the rheological properties of CPE are different due to the difference in Mooney viscosity of CPE. The plasticizing time increases with the increase of Mooney viscosity of CPE. The difference in rheological properties is reflected as the extension of plasticizing time and the decrease of extruder torque in processing application experiments. And the reduction of extruder torque and the extension of plasticizing time have certain rules to follow.
The rheological properties of materials measured by torque rheometer can truly reflect the processing properties of CPE. The speed of plasticization time corresponds to the level of extruder torque, that is, the plasticization is fast, the torque is high, and the friction heat of materials increases at this time. Slow plasticizing, low torque, less friction heat generated. Although the experimental formula and processing conditions are different, it will not affect this trend [5].
It is found that the PVC/CPE composite profiles made from CPE with high molecular weight have higher properties and better impact modification effect. For low molecular weight CPE, the impact strength of its PVC/CPE composite has a downward trend [6].
Therefore, in practical applications, it is not the faster the plasticization of CPE, the better the use of CPE, should be combined with the actual production formula and processing technology of the processing manufacturer to select.
