By Josh Perry, Editor
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Researchers with the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB (Stuttgart, Germany) have created a new method for converting 3-carene, a component of turpentine that is a material in the conversion of cellulose from wood, into the building blocks for bio-based plastics.

Terpenes from turpentine are converted to bio-based, transparent and heat-stable polyamides under application of a new catalytic process. (Fraunhofer IGB)

According to a report from the institute, the new polyamides are transparent and have high thermal stability, which makes them viable for a variety of applications.

“In the joint project ‘TerPa – Terpenes as building blocks for biobased polyamides’, researchers at the Straubing BioCat branch of Fraunhofer IGB have now succeeded in optimizing the synthesis of lactams from the terpene 3-carene and converting them into a scalable, competitive process on a potentially industrial scale,” the report explained. “The Straubing experts could already show that terpenes such as α-pinene, limonene and 3-carene are suitable raw materials for the synthesis of biobased lactams.”

The new process requires four chemical steps but can be completed in one reactor because purification of the intermediate products is not required. Researchers were able to delive more than 100 grams of pure lactam monomer in the lab and the synthesis of the new material does not require any hazardous chemicals.

The structure of the 3-carene also inhibits the crystallization of the polymer, which makes them amorphous and largely transparent. The glass transition point of the polyamides is 110°C, which means that it can be used for high temperature applications such as components in engine compartments and will not discolor under the influence of UV light (as previous 3-carene-based polyamides made from fossil fuels will).

“They can also be produced with considerably less energy input than petroleum-based transparent polyamides,” the article continued. “In contrast to other bioplastics, which are mainly produced from corn, wheat or potato starch, biobased polyamides do not compete with food production. Rather, they add value to a waste stream that, so far, has been burned for energy production.”

Researchers have worked to create co-polymers with modified transparency and will now work to create industrial-scale amounts.