Why is it difficult to recycle plastics?

(a) It is very hard

(b) It comes in different sizes

(c) It is adhesive

(d) It contains different types of polymer resins

The correct answer is (d) It contains different types of polymer resins.

The Challenge of Plastic Recycling

The primary reason plastics are difficult to recycle is that "plastic" isn't a single material.It's a category that includes many different types of plastics made from unique polymer resins.

Each type of resin has a different chemical composition, melting point, and color. For recycling to be successful, these different plastics must be meticulously sorted. If different types of plastic resins are melted together, they tend to separate (like oil and water), resulting in a structurally weak and low-quality final product that has very little value.

The most common types you see are identified by a number (the resin identification code):

• 1 PET (Polyethylene Terephthalate) - e.g., soda bottles
• 2 HDPE (High-Density Polyethylene) - e.g., milk jugs
• 5 PP (Polypropylene) - e.g., yogurt containers

This need for careful sorting makes the process complex, labor-intensive, and expensive, which is the main barrier to effective plastic recycling.