Low-density linear polyethylene
LLDPE is structurally identical to LDPE. LLDPE is created by copolymerizing 1-butene with 1-hexene and 1-octene using Ziegler Naatta or metallocene catalysts. Although the structure is linear, it also has uniform branches. These are similar to the long branches in LDPE. LLDPE is comparable to LDPE in terms of properties and can compete for the same markets. LLDPE has two main advantages: the polymerization conditions require less energy and the polymer's properties can be modified by changing the chemical ingredients. LLDPE's plastic recycling code is 4.
HDPE is high-density polyethylene. It's manufactured at low temperatures using Ziegler–Natta and metallocene catalysts or activated chrome oxide (also known as a Phillips catalyst). Because there are no branches in the structure, polymer chains can pack tightly together to form a dense, high-crystalline material with moderate strength and stiffness. It has a melting point of more than 20 degrees Celsius (36 degrees F) higher than LDPE and can withstand repeated exposures to 120 degrees Celsius (250°F) in order to sterilize. Blow-molded bottles for milk, household cleaners, construction film and agricultural mulch are some of the products. Injection-molded pails and caps, as well as appliance housings and toys, are also available.