High Density Polyethylene HDPE
Low pressure ethylene
Basic Characteristics : High density polyethylene is an opaque white wax like material with a specific gravity of 0.941-0.960, which is lighter than water. It is soft and tough, but slightly harder and more stretchable than LDPE. It is non-toxic and odorless.
Combustion Characteristics : Flammable, can continue to burn after leaving the fire, with a yellow flame at the top and a blue flame at the bottom. It melts during combustion, with liquid droplets and no black smoke emitted. At the same time, it emits the odor of paraffin burning.
Main advantages :Acid and alkali resistance, organic solvent resistance, excellent electrical insulation, and can maintain a certain degree of toughness even at low temperatures. Surface hardness, tensile strength, rigidity and other mechanical strengths are higher than LDPE, close to PP, and tougher than PP, but the surface smoothness is not as good as PP.
Main disadvantages :Poor mechanical performance, poor breathability, easy deformation, easy aging, easy brittleness, lower brittleness than PP, easy stress cracking, low surface hardness, and easy scratching. Difficult to print, surface discharge treatment is required during printing, electroplating is not allowed, and the surface is dull.
Application :Used for extruding packaging films, ropes, woven bags, fishing nets, water pipes; Injection molding of low-grade daily necessities and shells, non load bearing components, rubber boxes, turnover boxes; Extrusion blow molded containers, hollow products, bottles.
Injection molding process :HDPE has countless applications, ranging from reusable thin-walled beverage cups to 5-gsl cans, consuming 1/5 of domestically produced HDPE. The injection molding grade generally has a melt index of 5-10, with lower toughness and higher workability grades. Uses include thin-walled packaging for daily necessities and food; Resilient and durable food and paint cans; High resistance to environmental stress cracking applications, such as small engine fuel tanks and 90 gal garbage cans.
The melting point of general HDPE is 142 ºC, and the decomposition temperature is 300 ºC; The adjustable range of injection molding temperature is relatively large. During injection molding, the general operating temperature is between 180 ºC and 230 ºC
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