What is the Difference Between PP and LDPE

The key difference between PP and LDPE is that PP is a crystal-clear material, whereas LDPE is either translucent or opaque.

The term PP stands for polypropylene, while the term LDPE stands for low density polyethylene. These are polymers and plastics.

CONTENTS

1. Overview and Key Difference
2. What is PP 
3. What is LDPE
4. PP vs LDPE in Tabular Form
5. Summary – PP vs LDPE 

What is PP?

PP or Polypropylene is a plastic polymer. The monomer of polypropylene is propylene; it has three carbons and one double bond between two of those carbon atoms. We can manufacture this material from propylene gas in the presence of a catalyst such as titanium chloride. Furthermore, the production of this material is easy, and it gives a high purity.

The most important properties of PP are transparency, lightweight, high resistance to cracking, acids, organic solvents, electrolytes, etc., high melting point, nontoxic nature, good dielectric properties, and high economic value. Therefore, we can use this material for the production of pipes, containers, houseware, packaging, and automotive parts.

We can recycle PP, but it is difficult because due to its resilient nature and resistance to most of the solvents and glues. We can melt this material using a speed tip welding technique.

What is LDPE?

The term LDPE stands for low density polyethylene. It is a thermoplastic material. The monomer of this polymer material is ethylene. LDPE was first produced in 1933 by Imperial Chemical Industries using the process of high pressure free radical polymerization. This is the most common method of production for LDPE even today.

The density range of LDPE is between 917 to 930 Kg/m3. This material is inactive at room temperature in the absence of strong oxidizers and some solvents (that can cause the material to swell). LDPE is quite flexible and tough. The appearance of LDPE is usually either translucent or opaque.

Compared to other forms of polyethylene such as HDPE, LDPE has a high degree of branching, which makes it have weak intermolecular forces, low tensile strength, and high resilience. This branched structure can cause tight packing of molecules and less crystallinity. Moreover, it makes the material less dense.

There are many different uses of LDPE, such as the production of trays and general-purpose containers, corrosion-resistant work surfaces, snap-on lids, six-pack rings, juice and milk cartons, packaging material for computer hardware, playground slides, plastic wraps, etc.

What is the Difference Between PP and LDPE?

The term PP stands for polypropylene while the term LDPE stands for low density polyethylene. These are polymer materials that fall under the category of plastics. The key difference between PP and LDPE is that PP is a crystal-clear material, whereas LDPE is either translucent or opaque. Moreover, PP has a low degree of branching, whereas LDPE has comparatively a high degree of branching. In addition, PP is used for the production of pipes, containers, houseware, packaging, and automotive parts whereas LDPE is used for the production of trays and general purpose containers, corrosion-resistant work surfaces, snap-on lids, six pack rings, juice and milk cartons, packaging material for computer hardware, playground slides, plastic wraps, etc.

The below infographic lists the differences between PP and LDPE in tabular form for side by side comparison.

Summary – PP vs LDPE

The term PP stands for polypropylene and the term LDPE stands for low density polyethylene. The key difference between PP and LDPE is that PP is a crystal-clear material, whereas LDPE is either translucent or opaque. Moreover, PP is a three-carbon chemical compound, while LDPE is a two-carbon chemical compound (the carbon atoms per repeating unit).

Reference:

1. “What Is Polypropylene? COMPOSITION, Properties, and Applications (with FAQs).” BYJU’S, 22 May 2020.

Image Courtesy:

1. “Polypropylen” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia
2. “LDPE Foam” By Tpdwkouaa – Own work (CC BY-SA 4.0) via Commons Wikimedia