PVC sealing strip extrusion black lines when what is the reason?
That depends on the location of the black line:If the black line fixed appear continuously in the same place, it is often the mold or the extruder die dead, resulting in material in the long retention time and dead material after carbonization coke black from the same position with a continuous black line, produce.If it occurs at different times in different locations, it is more likely that the recipe system needs to be trimmedPVC is white powder amorphous structure, the degree of branching is small, the relative density of about 1.4, the glass transition temperature of 77~90 DEG, 170 DEG C to decompose, the stability of heat and light, at 100 DEG C or after long time exposure to sunlight, will decompose and produce hydrogen chloride, and further autocatalytic decomposition, causing discoloration also, the physical and mechanical properties decreased rapidly, in the practical application must be added in order to improve the stability of heat and light stabilizer of the.The molecular weight of PVC in industrial production in 50 thousand ~11 million range, with larger polydispersity of molecular weight increases with the decrease of the polymerization temperature; no fixed melting point, 80~85 C 130 C to begin to soften, the viscoelastic state, 160~180 C began to change into the viscous flow; have good mechanical properties, tensile the strength of about 60MPa, the impact strength of 5~10kJ/m2; have excellent dielectric properties.
If the black line fixed appear continuously in the same place, it is often the mold or the extruder die dead, resulting in black from the same location with continuity, produce the material in the dead long residence time and carbonization coke materials after blackening.If it occurs at different times in different locations, it is more likely that the recipe system needs to be trimmed
What colour is it? Transparent?
