Polyethylene is one of the most widely used types of plastic material in the modern manufacturing industry. Polyethylene is a generic term that encompasses a broad range of thermoplastic classifications. Each unique classification is based on the molecular makeup of the polyethylene product in question.
Two prominent polyethylene classifications are used in modern manufacturing facilities. These are low density polyethylene (LDPE) and high density polyethylene (HDPE). Each has its own unique characteristics that contribute to the function of the finished products they are used to create.
Learn the differences between LDPE and HDPE so that you can select the appropriate plastic sheeting for your manufacturing needs.
1. Different Physical Characteristics
Although LDPE and HDPE are both types of polyethylene thermoplastics, their physical properties differ in many significant ways.
LDPE is a soft, flexible plastic. An LDPE sheet will have a lower melting point than its HDPE counterparts. LDPE sheets are also more transparent than HDPE sheets.
HDPE sheets are more rigid and durable than their LDPE counterparts. With a higher melting point and the ability to resist chemical corrosion, HDPE sheets have greater strength and opacity than other types of polyethylene plastics.
The unique physical characteristics of both LDPE and HDPE sheets help determine their end use. LDPE sheeting can be used to make plastic bags, molded components, and product packaging with ease. HDPE sheets are better suited for more rugged applications, like outdoor furniture and plumbing pipes.
2. Different Recyclability Levels
Another area in which LDPE and HDPE sheets differ is in their recyclability. Both types of polyethylene products can be recycled, but specialized equipment and processing techniques are required to recycle any plastic products made from LDPE.
The soft and flexible nature of LDPE products allows them to easily get caught up in traditional recycling machinery. LDPE products must be kept separate from other plastics and recycled individually.
All products made from HDPE sheets can be recycled in a traditional recycling facility. HDPE products tend to be easier to transport, and they require no specialized recycling accommodations.
3. Different Production Techniques
The process by which LDPE and HDPE sheets are produced differs greatly.
LDPE sheets are created when manufacturers compress a monomer ethylene gas. Compressing this gas in an autoclave chamber or reactor helps to facilitate the polymerization process.
It is polymerization that produces the molecular structure that gives plastics their unique properties. The polymer chains that are produced during compression have a branched molecular structure, which allows for the flexibility of LDPE sheets.
In order to produce HDPE sheets, manufacturers must heat petroleum to an incredibly high temperature. The heating process releases monomer ethylene gases, which then combine and form polymer chains.
The polymer chains that are created via the superheating process have a more crystalline structure. This molecular structure explains the rigidity of HDPE sheets when compared with their LDPE counterparts.
LDPE and HDPE sheets share the useful characteristics of low solubility and high chemical resistance, but it is the differences between the two materials that help set them apart within the manufacturing industry.
LDPE sheets provide you with a material that has high tensile strength, yet retains its ability to bend and flex without cracking. These properties can prove useful when you need a durable plastic that will allow for movement during processing.
HDPE sheets are better suited for applications where molding and shaping is required.
The more familiar you are with the similarities and differences between LDPE and HDPE plastics, the better equipped you will be to make good decisions when it comes to choosing the raw materials that will be used in your manufacturing facility. Contact a company like Seiler Plastics to learn more.