25 janvier 2016 ~ 0 Commentaire

Problems in the Process of PVC Foam Board Extrusion

Poor stability shall affect the complete board, board can be yellow and the foam sheets’brittleness is large. Insufficient melt strength will cause the cell of foamed sheet becoming bigger and the longitudinal section bulbs longer. The most direct way to judge whether the melt strength is insufficient is to press the sheet wrapped in the moderate speed roll together with your fingertips, if the melt durability is excellent, you can feel elasticity when pressing. If it’s tough to bounce after pressing, the melt strength is poor then. Because there is bigger difference between a screw structure and cooling method, it really is complicated to determine a reasonable temperature. To be able to get uniform pvc foam board in the foam pipe, there’s need to ensure good financial strength of PVC materials also. Foaming aid is developed to solve this issue of the foamed content and effectively improve the quality of the foam pipe.

Lubricant is split into external lubricants and internal lubricants, external slip is simply conducive to demolding and the top gloss, if the outer slide is fewer, it is not an easy task to control and easy heating, which in turn causes the temperature of confluence core, and you will see the nagging problems in the middle of plate, such as a significant bubble, string bubble, yellow, and other problems. While if the surface of the plate the precipitation of the external slide isn’t smooth; external slide is even more, precipitation shall become serious. Inner slide is normally conducive to the fluidity of melt and plasticization, and then it is difficult to regulate the thickness of structure foam board, if the internal slide is insufficient. If internal slide is too extra sufficient, it susceptible to the phenomenon of big confluence core temperature.

plastic compounding machines

Compared with the above fundamental problems, the procedure temperature control shall be much more intuitive, it is the surface problem, if the temperature control isn’t good, it could give rise to the emergence of the fundamental problems. Improving the processing heat, material stabilization time will be reduced, and the problems of stability can look; the initial lubrication balance will be broken, the general performance may be the lack of the external lubrication, especially exterior lubrication in the late period of time, there is need to improve the amount of external lubrication; the increasing 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 temperature to lessen the melt strength and decrease the melt viscosity, reducing of the viscosity decreases dispersing ability, for the screw with poor dispersion, sometimes the phenomenon of uneven dispersion.

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