Polypropylene

Starting from 2000, bio-based polymers have attracted great interest, since in the last few years the development of new technological approaches has driven an interest in emerging new plastics obtained from renewable feedstocks.

Bio-based polypropylene (Bio-PP) is a polymer compound derived from plants and has balanced properties as standard polypropylene (a tough, rigid, and crystalline thermoplastic with low density and high heat resistance). This polymer is manufactured from materials such as corn, vegetable oils, and sugarcane. It is a sustainable alternative to traditional synthetic polypropylene. As with the industry growth of bio-based polymers, the demand for bio-based polypropylene increases.

Synthesis of Bio-based Polypropylene

Bio-polypropylene is usually obtained from biological resources by butylene dehydration of bio-isobutanol obtained from glucose and subsequent polymerization. The general scheme for bio-polypropylene is in figure 1.

Fig. 1 General scheme for bio-based polypropylene (Bio-PP)

There are two main steps for the synthesis of bio-polypropylene, namely the synthesis of green propylene and the polymerization.

• Synthesis of bio-based propylene

There are multiple pathways to obtain bio-based propylene. The two main routes are biochemical (typically fermentation) and thermochemical (involving gasification).

As for biochemical route, enzymes are used in the fermentation process to convert sugars into ethanol and butene. Propylene monomer is obtained by the metathesis of ethylene and butene.

Fig. 2 Biochemical route for propylene

As for thermochemical route, a wide variety of bio-based feedstocks including grass, agricultural wastes and corn, can be gasified to produce syngas. And bio-diesel and vegetable oils can also be used in the production of green propylene either. The thermochemical route is summarized in figure 3.

Fig. 3 Thermochemical route for propylene

• Polymerization

There are two main syntheses to produce polypropylene: Ziegler-Natta polymerization (polymerization usually taking place by the insertion of monomers where the transition metal ions are attached to the end of the growing chain) or Metallocene catalysis polymerization (resulting in very pure, and consistent resins with well-defined properties) (figure 4).

Fig. 4 Two main syntheses to produce polypropylene

Applications

The properties of bio-based polypropylene are similar to synthetic polypropylene. As an economical material, bio-based polypropylene can find its applications in every industrial and commercial application area today. Those include the packaging material, consumer goods, building & construction, automotive sector, textiles, medical sector, and industrial applications. The global bio-based polypropylene market share is as following ^[2]:

Fig. 5 Global bio-based polypropylene market share (2020)

Our Bio-based Polypropylenes

Alfa Chemistry provides a range of polypropylenes which are based on renewable raw materials.

Alfa Chemistry is a professional supplier of bio-based polypropylene. For high quality products, professional technical service, use suggestion and latest industry news, please feel free to contact us.

References

1. Siracusa, V., & Blanco, I. Bio-Polyethylene (Bio-PE), Bio-based polypropylene (Bio-PP) and Bio-Polyethylene terephthalate (Bio-PET): Recent Developments in Bio-Based Polymers Analogous to Petroleum-Derived Ones for Packaging and Engineering Applications. Polymers, 2020, 12(8), 1641.
2. Bio-based polypropylene market size, share & COVID-19 Impact Analysis, By Application and Regional Forecast.

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