Quick, what’s the difference between low-density polyethylene (LDPE) and high-density polyethylene (HDPE)? Yes, this will be on the quiz… To help you answer that question, I covered HDPE in a previous article, so you can bone up on that polymer if you need to. And I’ll cover LDPE here. Clearly these two polymers are similar because both are named polyethylene. In fact, LDPE was the first polyethylene to be produced, so it’s sorta like HDPE’s senior cousin, (which always causes problems at the Polymer family get-togethers). But as the names suggests, LDPE has a lower “density” than HDPE. That just means it has a bit less mass compared to its volume. For example, lead is dense. Whipped cream is not. LDPE also has more molecules that branch out, as opposed to staying in perfect rows. (That part will not be on the quiz…). LDPE’s lower density and branched molecules give it somewhat different properties than HDPE, although they do share some similar uses, such as packaging. LDPE/HDPE differences typically cause them to be collected separately for recycling … but not always (more on that later). LDPE is resistant to impact (doesn’t break easily), moisture (water proof), and chemicals (can stand up to many hazardous materials). Know it or not, you likely use LDPE every day, for many very good reasons. For example, let’s say you need to carry something home from your trip to the store (shopping bags). You may want to supply your child’s lunch with a non-refrigerated drink (juice boxes or “aseptic” packaging). Or your child may like playing make believe (toys). And, of course, nobody wants to grab naked copper electrical wire (insulation on electrical wires and cables).
Difference between low density polyethylene (ldpe) and high density polyethylene (hdpe)
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