Poor stability will affect the entire board, board can be yellow and the foam sheets'brittleness is large. Insufficient melt strength shall trigger the cell of foamed sheet becoming bigger and the longitudinal section bulbs longer. Probably the most direct way to judge whether the melt strength is insufficient would be to press the sheet wrapped in the channel speed roll with your fingers, if the melt strength is excellent, you can come to feel elasticity when pressing. If it is troublesome to bounce after pressing, then your melt durability is poor. Because there is larger difference between a screw structure and cooling method, it is troublesome to determine a reasonable temperature. If you need to get hold of uniform pvc foam board in the foam pipe, addititionally there is must ensure good financial power of PVC materials. Foaming help is developed to resolve this issue of the foamed content and effectively improve the quality of the foam pipe.
Lubricant is split into external lubricants and internal lubricants, outer slip is simply conducive to demolding and the surface gloss, if the outer slide is fewer, it is not easy to control and easy heating, which in turn causes the high temperature of confluence core, and there will be the nagging problems in the center of plate, such as a large bubble, string bubble, yellowish, and other problems. While if the surface of the plate the precipitation of the outer slide is not smooth; outer slide is extra, precipitation shall become serious. Inner slide is usually conducive to the fluidity of melt and plasticization, and then it really is difficult to control the thickness of structure foam board, if the inner slide is usually insufficient. If internal slide is too even more sufficient, it prone to the phenomenon of huge confluence core temperature.
Compared with the aforementioned fundamental problems, the procedure temperature control shall be much more intuitive, it is the surface problem, but if the temperatures control isn't good, it may bring about the emergence of the fundamental problems. Improving the processing temp, material stabilization time will be reduced, and the nagging concerns of stability will appear; the initial lubrication balance shall be broken, the general performance is the lack of the external lubrication, especially external lubrication in the later period of time, there is need to improve the amount of external lubrication; the raising of temperature shall lead to melt strength decreased, cell foam sheet increased, the amount of cell sheet reduced, the sheet is simple and brittle to break; raise the temp to lessen the melt strength and decrease the melt viscosity, decreasing of the viscosity reduces dispersing capacity, for the screw with poor dispersion, the phenomenon of uneven dispersion sometimes.