Ultra high molecular weight polyethylene
DATE：2022/12/21 9:20:38 / READ： / SOURCE：This station
Ultra high molecular weight polyethylene (UHMWPE) is a thermoplastic engineering plastic with linear structure. Its production method and molecular structure are basically similar to those of high-density polyethylene (HDPE); It can be synthesized by low pressure polymerization, slurry method and gas phase method. The control of molecular weight depends on changing the proportion of catalyst components, adding modifiers and adjusting process parameters. UHMWPE is the abbreviation of UHMWPE. UHMWPE is powder with a density of 0.936~0.964g/cm3, non-toxic, difficult to absorb water, difficult to adhere, and no surface attraction; It has unique mechanical and chemical properties. It almost combines the advantages of various plastics, and has the incomparable wear resistance, self lubrication and noise attenuation properties of ordinary polyethylene and other engineering plastics; Impact resistance, low temperature resistance and low temperature impact resistance; High temperature creep resistance, good thermal stability, melting point temperature of 190~210 ℃, hot deformation temperature of 85 ℃ (at 0.46 MPa), and melt flow rate close to zero; Good cold resistance, brittleness temperature lower than 140 ℃; Tensile strength up to 39.2MPa; Good corrosion resistance and environmental cracking resistance.
Ultra high molecular weight polyethylene (UHMWPE), due to its high molecular weight, extremely low melt flow rate, extremely high melt viscosity, poor fluidity, and extremely sensitive to thermal shearing, is not suitable for molding products with general thermoplastic molding equipment and processes. Generally, hot mold pressing and cold press sintering are used for forming. In recent years, UHMWPE has been modified to improve the melt fluidity without reducing the molecular weight; The other point is to reform the equipment, using small compression ratio, large thread groove depth, and the property of the screw extruder and the two screws rotating in the same direction; The machine barrel at the feeding place shall be grooved, and the method of strong simultaneous feeding shall be adopted to achieve the smooth delivery of raw materials when the machine barrel is initially used; The extrusion process temperature shall be controlled within the range of 180~200 ℃, and the working speed of the screw shall be controlled within 10~15r/min to prevent the degradation of raw materials under the high shear rate of the production pipe. Now this extrusion process can be used to produce UHNABO WPE sheets, bars, hollow products and films.
Author：admin