The PVC board manufacturer Lixin introduced PP welding rod as a semi-crystalline material. It is harder than PE and has a higher melting point. Since homopolymer PP is very brittle when the temperature is higher than 0℃, many commercial PP materials are random copolymers with 1 to 4% ethylene or clamp copolymers with higher ethylene content.
The PP welding rod material in the PVC board factory has a lower thermal distortion temperature (100°C), low transparency, low gloss, and low rigidity, but it has stronger impact strength. The strength of PP welding rod increases with the increase of ethylene content. The Vicat softening temperature of PP welding rod is 150℃. Due to the high crystallinity, the surface stiffness and scratch resistance of this material are very good. There is no environmental stress cracking problem in PP welding rod. Usually, the PP electrode is modified by adding glass fiber, metal additives or thermoplastic rubber. The flow rate MFR range of PP electrode is 1-40. PP electrode material with low MFR has better impact resistance but lower elongation strength. For materials with the same MFR, the strength of the copolymer type is higher than that of the homopolymer type. Due to crystallization, the shrinkage rate of PP welding rod is quite high, generally 1.8~2.5%. And the direction uniformity of shrinkage is much better than that of PE-HD and other materials. Adding 30% of glass additives can reduce the shrinkage to 0.7%. Both homopolymer type and copolymer type PP welding rod materials have excellent moisture absorption, acid and alkali corrosion resistance, and solubility resistance. However, it has no resistance to aromatic hydrocarbon (such as benzene) solvents, chlorinated hydrocarbon (carbon tetrachloride) solvents, etc. PP does not have oxidation resistance at high temperatures like PE.
