In the production of PVC foam board, to judge whether the melt strength is insufficient, the direct method is to press the sheet wrapped on the middle roll with three fingers behind the three rolls, and the elasticity can be felt when the melt strength is good. If it is difficult to pop up after pressing, the melt strength is poor.
Because the screw structure and cooling method are quite different, it is difficult to judge whether the temperature is reasonable. Generally speaking, within the load allowed by the extruder, the temperature is preferably low. In order to obtain uniform foaming products in PVC foamed boards, it is also necessary to ensure that the PVC materials have good melt strength.
Therefore, the quality of foaming regulators is very important in the production of PVC foamed boards. In addition to the basic functions of general-purpose processing aids, foaming regulators also have a high molecular weight and strong melt strength. Obviously improve the melt strength of PVC mixture, prevent bubbles from fused and cracking, which results in a more uniform cell structure and lower product density, and can also improve the surface gloss of PVC foam board products.
The above is the relevant introduction about the impact of melt strength on PVC foam board. We can see that insufficient melt strength has a certain impact on our products, so we should guarantee its melt strength in production. Yes, we should also use the correct addition of foaming regulators.
