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Classification of PVC production problems

#1
In the PVC foam sheet extrusion process, the basic problems encountered can be grouped into four categories: first, the stability; second, the melt strength issues; third, lubrication problem; Fourth dispersion issues. In these four categories of issues, especially the first three categories of issues are mutual restraint, and influence crossly, while it is sometimes difficult to immediately distinguish from the surface phenomena of pvc foam boards. Lack of stability will affect the entire board, and the foam board will be yellow with large brittleness.

The deficiency of melt strength can lead to huge cell in the foam sheet and long longitudinal section bubble. The most direct way to determine whether the melt strength is insufficient is to press sheet wrapping the roller with your fingers and you can feel elasticity in the excellent melt strength. If it is difficult to bounce after the press, which means the poor melt strength.
 
#3
That is almost total information without wasted wordage addressing a problem I still don't know but with a couple more readings might.

I had an instructor in college who was an English major that was a manual writer for a hardware company. Words cost money and if they can work a paragraph down from 75 words to 50, they'll do it. It comes out fairly mechanical like the above. The information is there, it's just not a pleasant way to read it. My favorite live world example was from a 3174 71d diagnostic book where I was trying to test a specific baud rate to communicate with a modem. The sentence read for the 41, 51 and 61 a,b and c jumper should be set, not used on the 71d. It had us puzzled. If it isn't used how the heck do I test it and it certainly isn't working without the jumper being on. Then it finally clicked, it's a LOGICAL not. with the jumper set it was pinned to 5 volts. With the jumper NOT set it was pinned to ground. Pull the jumper off and it floats and doesn't work, which is why it wasn't working for us. Still, the sentence I had to work with was easier read then the paragraph up above. I think someone is telling us how to examine our foam sheet, maybe for flexibility in one direction more then others. For voids in material, and for whether the material is good for our use or not. I'm not sure.

It was a slow news day after all.