Difference Between Polyester and Polypropylene

Main Difference

The main difference between Polyester and Polypropylene is that Polyester is a polymer formed by condensation polymerization between a dicarboxylic acid and a diol, whereas Polypropylene is a thermoplastic polymer that is formed by the addition polymerization of propylene.

Polyester vs. Polypropylene

Polyesters are the polymers formed by condensation polymerization of dicarboxylic acid and diols. Whereas the polypropylene has the characteristic of thermoplastic polymer and has applications of being used in plastics and fibers. Monomers of polyester are dicarboxylic acid and diol; however, in the case of polypropylene, as the name says propylene is in use as a monomer for its production. Polyesters are less hydrophobic than polypropylene. It means that polyester does not absorb much water whereas polypropylene being hydrophobic resists and does not absorb water at all. Polyester has a high melting point than polypropylene. It means polyester has the advantage to be used where operations conduct at higher temperatures rather than polypropylene that melts at much lower temperatures than polyester. Polyesters are more resistant to Ultraviolet radiations if compared with polypropylene.

Production of both of these synthetic materials, as polyesters are formed by the condensation polymerization whereas, polypropylene is formed by addition polymerization. Polyesters can be present in the form of semi-aromatic polymers, aliphatic polymers, and aromatic polymers. Whereas polypropylenes are present in the form of aliphatic polymers only. Polyesters are stronger and durable when compared with polypropylene, and with additional coatings, it can become more strong. Polyesters can be a bit costly due to the material used in its production. However, polypropylene is simple to produce, cost-effective, and widely available. Polyesters are not mildew resistant. However, additional coatings are used to achieve this objective. While on the other hand, polypropylenes have great mildew resistant naturally.

Comparison Chart

PolyesterPolypropylene
Polymers formed by condensation polymerization of dicarboxylic acid and diolsPolymers formed by the addition polymerization of propylene.
Procedure
Condensation polymerizationAddition polymerization
Monomers
Dicarboxylic acid and diolsPropylene
Melting Point
Higher Melting pointLower Melting point
Hydrophobic Ability
Absorbs waterRepels water
UV Absorption
Resistant to UV raysLess resistant to UV rays
Durability
Polyesters are stronger and durablePolypropylene is less durable than polyester
Cost
Expensive due to materials used in its production.Widely available and cost much less than polyesters.
Occurrence
Commonly found as aliphatic polymers, semi-aromatic polymers, and aromatic polymersCommonly found as aliphatic polymers only.

What is Polyester?

Polyesters are the polymers formed by the polymerization of dicarboxylic acid and diols. The procedure involved in its polymerization is known as condensation polymerization. . Polymers of diols and dicarboxylic acids are used in the manufacture of polyester. Polyesters are composed of at least 85% of ester, dihydric alcohol, and terephthalic acid by weight. Chemical reaction among alcohols and carboxylic acid also results in formation of polyester other than esters. Polyesters have their commercial uses because of their important properties such as high durability, nature towards the water, and quick-drying ability. These properties enable their use in the manufacturing of fibers, films, and packaging material, etc. Polyesters can resist higher temperature as it has a higher melting point. Polyesters are much durable and strong. Additional coatings like “vinyl” are added to obtain optimal strength. Polyesters are more resistant to Ultraviolet rays. In its production, polyesters can be found costly as compared to their other alternatives in the market.The occurrence of polyesters is present as semi-aromatic polymers, aliphatic polymers, and aromatic polymers. Polyesters combine with layers of vinyl that make it more abrasion resistant and thus used commercially for construction purposes. Polyesters are not mildew-resistant on their own. However, a vinyl coating can improve its resistance.

What is Polypropylene?

Polypropylenes are polymers formed by the polymerization of propylene. The procedure involved in its polymerization is known as addition polymerization. Polypropylenes are polymers of propylene alone. These are also known as thermoplastic polymers. These polymers have applications of being used in fibers and plastics.[CH(CH)3CH2]n is the common formula of polypropylene. Majorly they are used for their use as packaging material. Polypropylenes have a much lower melting point as compared to polyesters. Thus polypropylene gets soft when heated and then can be easily re-molded into any shape as required. Polypropylenes are considered highly hydrophobic as unlike polyesters, they do not absorb water at all, as of their ability to not react with water or any chemical. Polypropylene dries much faster than polyesters, but as they have a much lower melting point, they are limited for their wide use in conditions where temperatures are higher. However, they have a much lower heat transfer rate, which means it retains more heat than polyester but cannot face direct sunlight as it breaks down, and colors fade. As of their simple production process, polypropylene is widely available and much cost-effective as compared to its other alternatives. Unlike polyesters, polypropylene commonly occurs as aliphatic polymers only.

Key Differences

  1. Polyesters are polymers of dicarboxylic acids and diols, whereas polypropylenes are polymers of propylene.
  2. Condensation polymerization is the procedure that results in the formation of polyester. However, addition polymerization is the procedure that results in the formation of polypropylenes.
  3. Polyesters have higher melting points as compared to polypropylene who melt at a much lower melting point and can be re-molded in required shapes.
  4. Polyesters are less hydrophobic and absorb some water. On the other hand, polypropylene does not react with water and considered highly hydrophobic.
  5. Polyesters are more resistant to UV, but polypropylenes are less resistant and prone to direct sunlight.
  6. Polyesters have a higher heat transfer rate as compared to polypropylene.
  7. Polyesters are found expensive due to materials used in its production. However, polypropylenes are widely present and less costly.
  8. The occurrence of polyesters is present as semi-aromatic polymers, aliphatic polymers, and aromatic polymers. On the other hand, polypropylenes are found as aliphatic polymers only.

Conclusion

Polyesters are polymers formed by condensation polymerization of dicarboxylic acids and diols. Whereas, polypropylenes form by the addition polymerization of propylene.

Harlon Moss

Harlon currently works as a quality moderator and content writer for Difference Wiki. He graduated from the University of California in 2010 with a degree in Computer Science. Follow him on Twitter @HarlonMoss

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