What are Poly bags

  What is the difference between Poly bags and Plastic Bags? There really is no difference between poly bags and plastic bags. Poly is simply an abbreviation for polyethylene, which is plastic! Poly bags generally come in 3 types: Low density Polyethylene (LDPE), High density polyethylene (HDPE), and Poly propylene.

  Low Density Polyethylene LDPE is defined by a density range of 0.910 - 0.940 g/cc. LDPE has a high degree of short and long chain branching, which means that the chains do not pack into the crystal structure as well. It has therefore less strong intermolecular forces as the instantaneous-dipole induced-dipole attraction is less. This results in a lower tensile strength and increased ductility. LDPE is created by free radical polymerization. The high degree of branches with long chains gives molten LDPE unique and desirable flow properties. LDPE is used for both rigid containers and plastic film applications such as poly bags and film wrap.

  High Density Polyethylene HDPE is defined by a density of greater or equal to 0.941 g/cc. HDPE has a low degree of branching and thus stronger intermolecular forces and tensile strength. HDPE can be produced by chromium/silica catalysts, Ziegler-Natta catalysts or metallocene catalysts. The lack of branching is ensured by an appropriate choice of catalyst (e.g. Chromium catalysts or Ziegler-Natta catalysts) and reaction conditions. HDPE used in products and packaging such as milk jugs, detergent bottles, margarine tubs, and garbage containers.

  Polypropylene or polypropylene (PP) is a thermoplastic polymer, used in a wide variety of applications, including food packaging, textiles, plastic parts and reusable containers of various types, thermal pants and shirts made for the military, laboratory equipment, loudspeakers, automotive components, and polymer banknotes. An addition polymer made from the monomer propylene, it is rugged and unusually resistant to many chemical solvents, bases and acids.