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Differences between PP and PE Plastic that you need to know

jsalocal-uk18 min read

October 18, 2023

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Differences between PP and PE Plastic that you need to know

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This is a propylene monomer structure with two carbon atoms containing a double bond (C=C).

Polyethylene (PE):

• PE is a polymer made from ethylene monomer (ethylene) which has the following chemical structure:

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  H | CH2=CH2 | H 

  This is the structure of ethylene monomer, which has one double bond between two carbon atoms.

• Polymerization of ethylene produces long polymer chains with bonds single between carbon atoms. This chemical structure gives PE high flexibility and impact resistance.

So, the fundamental difference in chemical composition is in the type of monomer used and how the monomers are linked to each other in the polymer chain. That’s why PP and PE have different properties even though they are both thermoplastic polyolefin plastics.

Permanence and Flexibility

The most striking physical properties that distinguish between PP (Polypropylene) plastic and PE (Polyethylene) is eternity (rigidity) and flexibility. This difference is mainly related to the chemical structure and molecular structure of the plastic. The following is a comparison of the properties of eternity and flexibility of both:

Polypropylene (PP):

• Eternity: PP tends to be more stiff and has higher durability compared to PE. This means PP is less flexible and more likely to retain its shape when subjected to load or pressure. This stiffness makes it suitable for applications that require dimensional stability, such as food containers or automotive components.
• Flexibility: Although PP is less flexible than PE, it still has a fairly good degree of flexibility, especially at room temperature. However, PP tends to become stiffer at lower temperatures.

Polyethylene (PE):

• Eternity : PE is generally more flexible than PP. It has lower elasticity, which means PE is easier to bend and has the ability to return to its original shape after being stressed. Therefore, PE is often used in products that require flexibility, such as plastic bags, flexible pipes and packaging materials.
• Flexibility: PE has good flexibility even at temperatures low, making it suitable for various applications that require ductility at various temperature conditions.

This difference in impermeability and flexibility makes PP and PE more suitable for various applications based on design and functionality requirements. PP is more suitable for applications that require dimensional stability and resistance to pressure, while PE is more suitable for applications that require flexibility and ductility.

High Temperature Resistance

High temperature resistance is one one important factor influencing the use of plastics in various applications. The difference in resistance to high temperatures between PP (Polypropylene) and PE (Polyethylene) can be explained as follows:

Polypropylene (PP):

• High Temperature Resistance: PP has good resistance to high temperatures up to about 100-130 degrees Celsius (212-266 degrees Fahrenheit). This makes it a good choice for applications that require prolonged exposure to temperatures around that range. PP also has the advantage of maintaining its strength and structural integrity at high temperatures, so it is often used in automotive components, household appliances and food containers that are exposed to high temperatures.

• Disadvantages at Higher Temperatures:However, PP does not withstand very high temperatures, such as those found in industrial applications involving temperatures in excess of 130 degrees Celsius. At higher temperatures, PP tends to melt and change shape.

Polyethylene (PE):

• High Temperature Resistance: PE has a lower level of resistance to high temperatures compared to PP. PE is often used at lower operational temperatures, particularly in the temperature range of around 80-95 degrees Celsius (176-203 degrees Fahrenheit). This makes it suitable for applications such as water pipes and gas pipes, but is not as good as PP at handling higher temperatures.

• PE Type Variations: Please note that there are several types of PE, including High-Density Polyethylene (HDPE) and Low-Density Polyethylene (LDPE). HDPE has better high temperature resistance compared to LDPE, but both still have lower temperature limits compared to PP.

In selecting a plastic for a particular application, it is important to considering the required operational temperature range. If your application involves sustained high temperatures, PP may be a better choice. However, if the operational temperature is lower, PE or the HDPE variant of PE may be a suitable alternative.

Mechanical Strength

Difference in mechanical strength between PP (Polypropylene) and PE (Polyethylene) depending on the type of PE plastic used (HDPE or LDPE) and the conditions of use. In general, here is a comparison of the mechanical strength of the two:

1. Tensile Strength:

• PP has a higher tensile strength compared to LDPE (Low-Density Polyethylene), but may be lower than HDPE (High-Density Polyethylene). However, the tensile strength of PP is usually higher than that of PE at low temperatures.

2. Compressive Strength:

• PP has good compressive strength, and that makes it suitable for applications that require resistance to pressure or compression loads.

3. Impact Strength:

• HDPE tends to have better impact strength than PP, especially at low temperatures. LDPE has lower impact strength compared to HDPE and PP.

4. Stiffness (Rigidity):

• PP tends to be stiffer than PE. This means that PP is more resistant to plastic deformation or permanent shape changes when loaded.

5. Flexibility:

• PE, especially LDPE, is a much more flexible plastic than PP. This makes PE more suitable for applications that require flexibility and elasticity, such as plastic bags.

6. Strength at High Temperatures:

• PP is usually more resistant to high temperatures than PE, especially at temperatures above 100 degrees Celsius (212 degrees Fahrenheit). PP tends to maintain strength and stiffness at high temperatures better than PE.

7. Strength at Low Temperatures:

• HDPE has advantages in mechanical strength at low temperatures. It is often used in applications that require resistance to low temperatures such as water pipes in cold environments.

It is important to remember that in the case of PE, there are variations based on type (HDPE vs. LDPE) and condition specific use. In addition, the mechanical properties of plastics can also be influenced by the production method and composition of additives. Therefore, the choice of plastic must be based on the specific properties required for a particular application.

Chemical Resistant Ability

Both PP (Polypropylene) and PE (Polyethylene) have a number of resistant capabilities chemistry, but this capability may vary depending on the type of chemistry involved, type of plastic, and conditions of use. Here is a general view of their chemical resistance capabilities in hazardous environments:

Polypropylene (PP):

• PP has good chemical resistance capabilities against many harmful chemicals, including acids, bases, organic solvents, and various other chemical compounds.
• It is resistant to many types of acids, such as sulfuric acid, nitric acid, and hydrochloric acid.
• PP also has good resistance to strong bases such as sodium hydroxide (caustic soda).
• However, PP may not be resistant to some very strong or dangerous organic compounds, such as strong chlorinated hydrocarbons.

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Polyethylene (PE):

• The chemical resistance of PE can vary depending on the type of PE used (HDPE or LDPE) and conditions usage.
• HDPE (High-Density Polyethylene) has better resistance to chemicals than LDPE (Low-Density Polyethylene).
• HDPE is often used for chemical tanks, chemical pipes, and chemical storage systems.
• PE has good resistance to many weak acids and bases, but may be susceptible to strong acids and strong bases over long periods of time.
• PE is also resistant against commonly used organic solvents such as ethanol and methanol.

It is important to remember that the chemical resistance of plastics can be affected by the chemical concentration, temperature and duration of contact with the chemical. Before using PP or PE in a hazardous environment, it is important to check the plastic manufacturer’s guidelines or specifications as well as perform chemical compatibility tests to ensure the plastic will withstand certain environmental conditions. Also, it is best to consult a chemist or engineer to ensure the safety and suitability of plastic materials in applications involving hazardous chemicals.

Transparency

Main differences in transparency between PP (Polypropylene) and PE (Polyethylene) mainly depends on the type of PE plastic used (HDPE or LDPE) as well as its molecular configuration. In general, here is a comparison of the transparency of the two:

Polypropylene (PP):

• PP is a plastic that is usually not transparent or has very low level of transparency. This means that light cannot easily penetrate or pass through PP material, so PP is usually used for products that do not require transparent properties, such as food containers and automotive products.

• There are variants Certain PP designed with an increased level of transparency are called “transparent PP” or “glass PP.” However, transparent PP is still not as clear or bright as glass or some other transparent plastics.

Polyethylene (PE):

• Naturally, PE tends to be more transparent than PP. LDPE (Low-Density Polyethylene) has a better level of transparency than HDPE (High-Density Polyethylene).

• PE, especially LDPE, is often used for products that require properties transparent, such as plastic bags, cling film, or food containers where the contents can be seen.

It should be noted that although PE can be more transparent than PP, its transparency is not comparable to plastics such as PET (Polyethylene Terephthalate) or PVC (Polyvinyl Chloride), which is often used for beverage bottles or plastic windows. Therefore, the choice between PP and PE for a particular application must consider the level of transparency required to meet the design and functionality requirements of the product.

Manufacturing Process

Manufacturing process for manufacturing PP (Polypropylene) plastic ) and PE (Polyethylene) involve several stages involving the polymerization of monomer molecules into long polymer chains. The following are the general steps in making PP and PE:

1. Monomer Production:

• The first stage is the production of monomer which will be used as raw material for polymerization. For PP, the monomer is propylene, and for PE, the monomer is ethylene.

2. Polymerization:

• The monomers produced in the first stage are then processed through a polymerization process. This involves combining thousands or even millions of monomer molecules into long polymer chains. Polymerization usually uses a catalyst and a certain temperature to trigger this chemical reaction.

3. Extrusion:

• After polymerization, plastic in the form of slurry or granulate can be extruded. This involves heating the plastic material until it becomes a liquid and pushing it through a mold or extrusion die to form the desired shape. The extrusion process is very important in making products in the form of tubes, pipes or other profiles.

4. Advanced Processing (Optional):

• As an optional step, PP or PE plastic can undergo various stages of advanced processing depending on the desired final product. This may include blending with additives, such as colorants or reinforcing enhancers, and additional processing such as injection molding, film molding, or casting.

5. Cutting and Finishing:

• Plastic products that have been formed are then cut or finished according to the final product specifications. This includes film cutting, container forming, or forming other plastic products.

6. Testing and Quality Control:

• During the entire manufacturing process, plastic products are tested and quality controlled to ensure that they meet established standards and specifications.

7. Packaging and Distribution:

• Plastic products that have been packaged and are ready to be distributed to various industries and end users.

This manufacturing process is common processes used in the manufacture of PP and PE plastics. It is important to note that various types of PP and PE plastics can be produced with different production methods and parameters, resulting in various types of plastic products with different properties according to application requirements.

General Applications

PP (Polypropylene) and PE (Polyethylene) plastics are used in various industrial applications due to their special properties. The following are some common applications for these two types of plastic in various industries:

General Applications of PP (Polypropylene) Plastic:

1. Food and Beverage Industry:

   • Food containers, including bottles, jars and sauce containers.
   • Frozen food bags and dry food bags.
   • Frozen food bags and dry food bags.
   • Frozen food bags and dry food bags.
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   • Bottle caps and covers.

2. Automotive Industry:

   • Interior panels , trim, and car interior parts.
   • Battery box.
   • Coolant tank.

3. Construction Industry:

   • Water and sewer pipes.
   • Road grilles and fences.
   • Highway siding and construction equipment .

4. Packaging Industry:

   • Bags for rice, sugar and other food products.
   • Chemical product and cleaning agent packaging.
   • Pharmaceutical packaging.

5. Medical Industry:

   • Disposable medical devices, such as blood sample storage containers.
   • Non-sterile medical device components.

General Applications of PE (Polyethylene) Plastic:

1. Packaging Industry:

   • Plastic shopping bags.
   • Frozen food bags.
   • Detergent bottles and cleaning products.
   • Cling film for food packaging.

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   • Agricultural Industry:

     • Irrigation pipes.
     • Storage tanks for water and agricultural chemicals.
     • Plastic film for plant covers and greenhouses.

   • Medical Industry:

     • Disposable medical gloves.
     • Intravenous (IV) fluid bags.
     • Health care products, such as wound sheets.

   • Chemical Industry:

     • Chemical storage tanks.
     • Hoses and pipes for sending chemical liquids.
     • Hazardous chemical containers.

   • Automotive Industry:

     • Bumpers and exterior components cars.
     • Fuel tanks.
     • Pickup bed box liners.

   • Construction Industry:

     • Sewer pipes and stormwater drains.
     • Films and membranes used in buildings and waterproof.
     • Insulation products.

Both types of plastic are very versatile, and their applications can vary depending on the specific variant of PP or PE used and the properties required for a particular application . In addition, these two plastics are often used in making environmentally friendly products because of their ability to be recycled.

Recycling and Environmental Impact

Recycling of PP (Polypropylene) and PE plastics (Polyethylene) has a significant environmental impact, and the comparison between the two can depend on several factors, including the type of plastic, recycling efficiency, and end product application. Here is a comparison in terms of recycling and environmental impact:

PP (Polypropylene) Recycling:

• PP is more difficult to recycle compared to some other plastics, such as PET (Polyethylene Terephthalate) or HDPE (High-Density Polyethylene).
• The recycling ability of PP is limited by the quality and purity of the recycled material produced. Over time, PP recycling has become more efficient, but still has challenges in achieving recycling yields similar to new plastic.
• In some cases, recycled PP is used in secondary products such as raffia, carpets, and related products, but are often not regenerated into PP products that are similar to new ones.

PE (Polyethylene) Recycling:

• PE, especially HDPE (High-Density Polyethylene), has a better recycling rate than PP. HDPE typically has a higher recycling potential in a variety of applications.
• Recycled HDPE is used in a variety of products, including plastic bottles, pipes, fences, and other related products. It is often used to make products with quality equivalent to new products.
• LDPE (Low-Density Polyethylene) can also be recycled, but has a lower recycling rate compared to HDPE.
• PE generally has better recyclability than PP in many applications due to its better recyclability properties.

The environmental impact of plastic recycling depends on a variety of factors, including recycling efficiency recycling, energy consumption, greenhouse gas emissions and waste reduction. In general, plastics that are more easily recycled have a lower environmental impact because they allow for reduced waste and resource savings. However, it is important to note that the importance of recycling as a plastic waste management strategy must always be accompanied by efforts to reduce single-use plastic consumption, stop plastic pollution in the environment, and promote more sustainable plastic use.

When to Use PP or PE in your Project?

The choice between PP (Polypropylene) and PE (Polyethylene) plastic in your project should be based on various factors, including the properties of the plastic, application needs and material availability. Here are some considerations that may help you decide when to use PP or PE in your project:

Considerations for Using PP:

1. Stiffness and Dimensional Stability: PP has higher stiffness than PE, making it suitable for applications that require dimensional stability and resistance to pressure or compression loads.

2. High Temperature Resistance: PP tends to be more resistant to high temperatures than PE, making it more suitable for applications involving high temperatures.

3. Resistant to Chemicals:PP has good chemical resistance to various acids, bases and organic solvents, so it is used in environments involving hazardous chemicals.

4. Medical Applications: PP is used in many medical applications due to its resistance to sterilization, such as blood sample storage containers or medical equipment components.

Considerations to Use PE:

1. Flexibility: PE, especially LDPE (Low-Density Polyethylene), is a much more flexible plastic than PP, making it suitable for applications that require elasticity and flexibility, such as plastic bags or cling film.

2. Low Temperature Resistance: HDPE (High-Density Polyethylene) has advantages in resistance to low temperatures, so it is used in water pipes, storage tanks, and other applications involving cold temperatures.

3. Food Packaging: PE used in a variety of food packaging applications, including frozen food bags, dry food bags, and visible food containers.

4. Agricultural Industry: PE is used in irrigation pipes, water storage tanks, and plant covers due to its resistance to the elements and suitable physical properties.

5. Recycling: PE, especially HDPE, is more easily recyclable than PP in many cases, thus influencing material selection in efforts for more sustainable waste management.

It is important to consider your application needs thoroughly and understand the properties -specific properties of PP and PE before making a decision. Sometimes, a combination of the two or the use of a special PP or PE variant can be the solution that best suits your project needs. In addition, consulting with a materials expert or engineer can help you make the right decision in selecting plastic for a particular project.

Conclusion Difference Between PP and PE Plastic

In conclusion, PP (Polypropylene) plastic ) and PE (Polyethylene) are two very versatile types of plastic with a variety of unique properties. Here are some important points that can be taken from the information above:

1. PP plastic (Polypropylene):

   • Stiffer and resistant to high temperatures.
   • Resistant to a wide range of chemicals, making it suitable for applications involving hazardous chemicals.
   • Used in the automotive, food and beverage industries, and many other applications requires stiffness and resistance to high temperatures.

2. PE (Polyethylene) plastic:

   • More flexible and resistant to low temperatures.
   • Can be recycled more efficiently than PP, especially HDPE.
   • Used in a variety of applications, including food packaging, agriculture, the medical industry, and construction.

The choice between PP and PE should be based on your specific application needs. Consider mechanical properties, chemical resistance, temperature resistance, flexibility, and recycling efficiency. It is always important to consider the environmental impact of plastic choices and strive to reduce the use of single-use plastics and promote more sustainable plastic use.

Regardless of the type of plastic you choose, strive to recycle and manage plastic waste wisely It must be a priority to reduce the negative environmental impact of plastic.

That’s the discussion regarding the differences between PP and PE plastic. If there are any errors, especially in writing, please forgive. If you have any questions regarding the differences between PP and PE plastic, you can write them in the comments column provided.