Two of the most widely used plastics in the world today are polyethylene, also known as PE, and polypropylene, otherwise known as PP.
These two plastics are commonly used for very similar applications. Despite this, and despite their similar names, there are some key differences between the two that affect their suitability in commercial and industrial applications.
Chemical Differences Between PE and PP
Polyethylene and polypropylene have very similar chemical structures, and they are both thermoplastic polymers known as polyolefins.
Polyethylene is a repeated chain of hydrogen and carbon monomers. This allows it to be produced in structures like LLDPE (linear low-density polyethylene) that offer excellent tensile strength and flexibility.
Polypropylene is a polyolefin produced through the juncture of multiple propylene (C3H4) monomers. It is more rigid and durable than polyethylene.
Both are very affordable and are thermoplastics, which means they can be heated and re-formed according to the needs of the application.
So how do these chemical differences affect the utility of each polymer?
How Does This Affect Packaging?
When it comes to producing packaging and other materials from these two thermoplastics, it’s important for users and producers to recognize that polypropylene can withstand higher temperatures than polyethylene.
Polypropylene is stable to temperatures as high as 338℉. Polyethylene is only stable up to 239℉, and often starts to melt at lower temperatures closer to 221℉.
However, the reverse is also true. Polyethylene retains its physical properties at much lower temperatures than polypropylene. PE remains flexible to temperatures as low as -112℉, over 130° lower than polypropylene will tolerate, which becomes brittle at 32℉.
When it comes to resistance to wear, tear, and puncturing, polyethylene takes the lead. It is more flexible, more puncture resistant, and stretches more readily than it tears.
However, with that said, polypropylene is harder and more rigid than polyethylene. Polypropylene also exhibits better resistance to harsh chemicals like acid than polyethylene.
Both are exceptionally resistant to moisture. Both are also susceptible to damage arising from exposure to high levels of UV radiation. They can also both be recycled, however, polyethylene is recycled with greater frequency than polypropylene.
Despite their differences, both PE and PP are widely used in food packaging, various consumer goods, cordage, buckets, bottles, jugs, and tanks.
Because of its excellent chemical and moisture resistance, easy recyclability, low cost, flexibility, and strength, polyethylene is one of the most widely used plastics in the world for food and other commercial packaging.
How Does This Affect Packaging Materials Like Flat Poly Bags on Rolls?
For the reasons mentioned throughout this article, many businesses in commercial and industrial verticals choose polyethylene packaging materials, such as flat poly bags on rolls, for their business needs.
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