EPDM4640 use silica as reinforcing agent, the appearance of extruded rubber hose will have sharkskin phenomenon (melt rupture), but will disappear when the speed is adjusted down, for example, the speed of 10 RPM will produce 1 RPM will not produce, the embryo material has the appearance of sharkskin will have the appearance of scales after stretching. I have read books and articles on the site, some say to processing aids but not resin is fatty acid type, some say to add high Menni main glue or oil-filled glue but can not understand the principle of it, there are rubber friends can explain the reason?
SNNY:
This phenomenon can be used pure plastic processing and molding process to better understand, molding - at high temperatures (in the temperature before the plastic cracking) plastic melting into a very low viscosity into the mold, followed by rapid cooling molding!
If there are glass fibers, rubber, fillers, etc. added to the plastic, the molding process is much more complicated.
Rubber - is an elastomer - changes in a variety of [slight changes in the formula, the extrusion process will have to make adjustments], such as in the case of other things remain unchanged, the faster the extrusion speed - the surface is not good - the mixing rubber Menni did not adjust the right, the mold temperature is not the right, the mixing rubber vulcanization before the strength is not enough, and so on! !
The reason for using oil-filled [the original rubber Menny high, high ethylene, their own training rubber is not prepared for defects can not be practiced well high doors and high ethylene, so have to use the ethylene-propylene has been filled with oil].
Auxiliaries - to reduce resistance, increase surface lubrication